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This is to certify that the
dissertation entitled

NUTRITIONAL QUALITY OF LOW-COST
SUPPLEMENTARY FOODS FOR SUPPORTING
GROWTH AND REHABILITATION OF
UNDERNOURISHED POPULATIONS IN TANZANIA

presented by
Theobald Conrard Edward Moshe

has been accepted towards fulfillment

of me requirements for the
Ph.D. degree in Food Science and Human
Nutrition

 

 

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Date

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NUTRITIONAL QUALITY OF LOW-COST SUPPLEMENTARY FOODS FOR
SUPPORTING GROWTH AND REHABILITATION 0F UNDERNOURISHED
POPULATIONS IN TANZANIA
By

Theobald Conrard Edward Mosha

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Food Science and Human Nutrition

2004

ABSTRACT

NUTRITIONAL QUALITY OF LOW-COST SUPPLEMENTARY FOODS FOR
SUPPORTING GROWTH AND REHABILITATION OF UNDERNOURISHED
POPULATIONS IN TANZANIA .
By

Theobald Conrard Edward Mosha

Severe undemutrition during childhood remains a common health problem in many parts
of the world and contributes immensely to childhood morbidity and mortality. According
to WHO/UNICEF, producing low-cost, ready-tO-feed, nutritious foods from locally
produced ingredients by using low-to—medium level technologies in local settings can
considerably help mitigate child undemutriton through increased access to food. The aim
of this study was to formulate, process, and evaluate the quality of processed, ready-to-
feed bean-based composite supplementary foods for pre-school age children in low-
income populations in Tanzania.

Supplementary foods based on cereal-bean-sardine mixtures were formulated
from ingredients produced locally in Tanzania. The products were formulated to
maximize the amino acid score as recommended by the F AO/WHO/UNU for pre-school
age children and to provide the desired amount of energy and fat as stated by the
FAQ/WHO Codex Alimentarius guidelines (CAC/GL 08-1991) for supplementary foods
for older infants and young children. Red beans (Phaseolus vulgaris), com/maize (Zea
mays), rice (Oryza sativa), sardines (Sardinops melanosticta) and red palm Oil (Elaeis
guineensis) were formulated into single/multi-mix diets and processed into ready-to-feed

powders by extrusion, drum-processing and conventional cooking. The processed

products were evaluated for true protein digestibility, net protein retention ratio, protein
digestibility-corrected amino acid scores (PDCAAS), amino acid profile, residual
phytohemagglutinins, trypsin, chymotrypsin, and a-amylase inhibitors. Foods were also
evaluated for potential to support normal growth and for rehabilitation of undernourished
children using a weanling rat model. Furthermore, the products were evaluated for
storage stability at 38°C.

The studies showed that corn-bean-sardine, sorghum-bean-sardine and rice-bean
sardine products had superior nutritional value compared to individual cereals or cereal +
bean blends. The composite products had high true protein digestibility, ranging fi'om 82
- 93%, high ratio of net protein retention ranging from 0.86 — 0.92 and PDCAAS ranging
from 77 — 89%. The composite products also showed a good potential to support growth
and rehabilitation of undernourished animals. Extrusion and drum-processing thoroughly
cooked the foods as characterized by high gelatinization rate (95 - 100%) and low
residual urease activity levels (5 0.05 units per 100 g food). They were also effective in
inactivating the phytohemagglutinins (91 — 97%) and the anti-nutritional factors - trypsin,
chymotrypsin and a-amylase inhibitors. Extrusion and drum-processing also resulted in
products that had high protein digestibility and PDCAAS. During storage at 38°C, the
food pH and total acids did not change significantly (p > 0.05). The products were shelf-

stable for at least 16 weeks.

Dedicated to my parents — Mzee Conrard Edward Mosha and Mama Lodwina Conrard
Mosha who instilled in me the value of education and truly believed I could attain

whatever education goal I set

iv

ACKNOWLEDGEMENTS

I gratefully acknowledge the financial support fi'om the United States Agency for
International Development through the Bean/Cowpea Collaborative Research Support Program

(CRSP), East, Central and Southern Africa region, which enabled me tO undertake this
program.

I would like to express my profound gratitude to my major Professor, Dr. Maurice
R. Bennink for his tireless guidance, encouragement and advice throughout the period of
this study.

I also would like to thank my graduate committee members - Drs. Mark
Uebersax, Lorraine Weatherspoon and Anne Ferguson for Offering professional advice,
brilliant insights and constructive criticism.

I want to thank also my lab mates and my dear fiiends in and outside the
department for providing social and moral support and interactions that made my stay at
MSU exciting and memorable.

I am also grateful tO the Sokoine University of Agriculture, Tanzania for granting
me the study leave to undertake this Ph.D. program.

Finally, I would like to express my profound appreciation and thanks to my wife
Esther and to my children Gloria and Collins for their patience, love and encouragement.
Without their constant support and prayers, I would have never been able to achieve my

educational goals at Michigan State University.

TABLE OF CONTENTS

Page
List of Tables ............................................................................ ix
List of Figures ........................................................................... xi
Acronyms .................................................................................... xii
Chapter One
1.0 Introduction .............................................................................. 1
1.1 Organization of the Dissertation ...................................................... 8
1.2 References ............................................................................... 11
Chapter Two
2.0 Review of Literature .................................................................... 14
2.1 Protein Energy Undemutrition .................................................. 14
2.2 Causes of Protein Energy Undernutrition ..................................... 14
2.3 Weaning and Supplementation of Infants ..................................... 16
2.4 Nutrition Rehabilitation ................................................................ 19
2.5 Supplementary Foods .................................................................. 22
2.5.1 Products Formulation and Ingredients ............................................. 23
2.5.2 Recommended Composition of Supplementary Foods .......................... 25
2.5.2.1 Energy Density ...................................................................... 25
2.5.2.2 Fat Content ......................................................................... 29
2.5.2.3 Protein Density ...................................................................... 33
2.5.5.4 Micronutrient Density ............................................................. 37
2.6 Processing of Supplementary Foods ................................................. 43

vi

2.6.1 Extrusion ............................................................................... 43

2.6.2 Drum-processing ...................................................................... 48
2.7 Evaluating the Quality of Processed Foods ........................................ 49
2.7.1 Protein Quality ...................................................................... 49
2.7.1.1 Effect of Protein Digestibility on Quality ....................................... 51
2.7.1.2 Methods of Evaluating Protein Quality .......................................... 55
2.7.1.2.] In Vivo Methods .................................................................. 56
2.7.1.2.2 In Vitro Methods ................................................................. 59
2.7.2 PDCAAS and Protein Requirement ............................................... 62
2.7.3 Starch Gelatinization and Dextrinization ......................................... 64
2.7.4 Anti-nutrients and Toxins in Processed Foods .................................... 66
2.7.5 Sensory Quality and Consumer Acceptability .................................... 70
2.7.5 Products Storage Stability ............................................................ 72
2.7.6 References ............................................................................. 76
Chapter Three

3.0 Evaluation of protein quality and growth/ rehabilitation potential of
drum-processed, ready-to-eat cereal-bean-sardine composite supplementary

foods for pre-school children ............................................................... 90
3.1 Abstract .................................................................................. 90
3.2 Introduction .............................................................................. 92
3.3 Materials and Methods ................................................................. 93
3.4 Results and Discussion ................................................................. 98
3.5 Conclusions ............................................................................... 107
3.6 References ................................................................................ 108

vii

Chapter Four

4.0 Nutritional quality of drum-processed and extruded ready-tO-eat composite

supplementary foods ................................................................................. 111
4.1 Abstract ......................................................... 111
4.2 Introduction ............................................................................... 113
4.3 Materials and Methods .................................................................. 114
4.4 Results and Discussion ................................................................. 123
4.5 Conclusions .............................................................................. 131
4.6 References ................................................................................ 133
Chapter Five

5.0 Protein digestibility-corrected amino acid scores and storage stability of
ready-to-eat supplementary foods for pre-school age children ........................ 137
5.1 Abstract ................................................................................... 137
5.2 Introduction ................................................................................ 139
5.3 Materials and Methods .................................................................. 141
5.4 Results and Discussion ................................................................. 149
5.5 Conclusions ............................................................................... 159
5.6 References ................................................................................. 160
Chapter Six

6.0 Summary and Conclusions ............................................................. 165
Chapter Seven

7.0 Recommendations for Future Research .............................................. 171

viii

LIST OF TABLES

Table
Chapter Two

Table 1. Minimum dietary energy density required to attain the level of energy needed
from supplementary foods in one, two, three or four meals/day by level of breast milk
energy (BME) intake and age group, for well- and under-nourished children .............

Table 2. Minimum daily number of meals required to attain the level of energy needed
from supplementary foods with mean dietary energy density of 80, 100 and

120 kcal/ 100 g for children with low level of breast milk energy intake, according

to age group ........................................................................................

Table 3. The involvement of amino acids in physiological and metabolic functions .. .

Table 4. Desired nutrient density of supplementary foods (per 100 kcal) by level
of breast milk intake ........................................................................

Table 5. Major classes of cooking extruders with typical operating data ..................
Table 6. Essential amino acid requirement patterns for people of various age groups
Chapter Three

Table 1. Composition (gkg'l) of the cereal-bean based supplementary foods
used for the in viva rat feeding study ....................................................

Table 2. Comparison of the amino acid composition (gkg'l of protein) of the
various food products with the F AO/WHO/UNU recommended requirement
patterns for pre-schOOl (2 — 5 years) children and infants and with the NRC
recommended pattern for rats .................................................................

Table 3. In viva true and apparent protein digestibility, net protein and food
efficiency ratios of the various cereal-bean based food products ..................

Table 4. Protein quality and energy content of selected test diets compared with the
recommendations of FAQ/WHO Codex Alimentarius for pre-school age children ......

Chapter Four

Table 1. Composition (g/ 100 g) of the cereal-bean based supplementary foods

used for the in viva rat feeding study .....................................................

Table 2. Percent starch gelatinization and residual urease activity of foods
processed by various methods ............................................................

ix

Page

27

28

34

41

47

61

96

101

102

105

118

124

Table 3. Residual activity/levels of various anti-nutritional factors in the foods
processed by the various methods ................................................................. 126

Table 4. Average food consumption (g/21 days) for experimental animals
receiving foods processed by the various methods .................................... 129

Table 5. Percent true protein digestibility of foods processed by various

methods ..................................................................................... 130
Table 6. Average weight gain (g/21 days) for experimental animals receiving

foods processed by the various methods ................................................ 131
Chapter Five

Table 1. Composition (g/100 g) of the cereal-bean based supplementary foods
used for in vivo rat feeding study .......................................................... 145

Table 2. Composition (g/ 100 g) of the extruded products used for evaluation of
consumer acceptability and storage stability ............................................. 146

Table 3. Amino acid profile of the supplementary foods processed by various
methods ....................................................................................... 150

Table 4. True protein digestibility and amino acid digestibility-corrected amino
acid scores for the food products processed by the various methods. ................ 152

Table 5. Changes in total titratable acidity (as g lactic caid/ 100g food) of the
cooked and uncooked foods during storage at 38°C. .................................... 155

Table 6. The pH in cooked and uncooked foods during storage at 38°C. ............ 156

Table 7. Changes in malondialdehyde concentrations (pg/kg) in cooked and
uncooked foods during storage at 38°C. ................................................. 157

LIST OF FIGURES

Figure Page
Chapter 2

Figure l: UNICEF conceptual framework for determination of nutritional status .. 15

Figure 2: Effect of deficiency of essential amino acids on gene translation ........ 35
Figure 3: Metabolic fate of excess amino acids ........................................ 64
Chapter 3

Figure 1: Growth patterns for rats fed varying sources of protein .................... 106
Figure 2: Growth patterns of rats during rehabilitation phase ......................... 107

xi

ACRONYMS

CRNPR — Corrected relative net protein ratio

FAO — Food and Agriculture Organization of the United Nations
MCH — Mother and Child Health

NCHS - National Center for Health Statistics

NPR — Net protein ratio

NPU - Net protein utilization

PAHO — Pan American Health Organization

PDCAAS — Protein Digestibility-Corrected Amino Acid Score
PER — Protein efficiency ratio

RNPR -— Relative net protein ratio

UNICEF — United Nations Fund for Children

UNU — United Nations University

WHO - World Health Organization

xii

CHAPTER ONE

1.0 INTRODUCTION

Childhood malnutrition remains a common problem in much of the
developing world today. A recent comprehensive report prepared by World Health
Organization using data collected from 1980 to 1992 indicates that, more than one
third of children less than five years of age in developed countries have a z-score
height-for-age less than 2 standard deviations (SD) with respect to international
reference data [1]. WHO report shows that the proportion of children who are
undernourished does not appear to have changed very much during the past 20 years
[2, 3, 4, 5]. Because of the considerable global population growth during this period,
the number of malnourished children continued to escalate.

Childhood growth retardation is associated with a broad range of adverse
functional consequences. For example, undernourished children have impaired
immune function [6] and increased rates [7, 8] and severity of enteric [9, 10] and
other infections [11] than children who are better nourished. Undemourished children
also have a higher risk of dying prematurely, and recent data indicate that as much as
one-third to one-half of childhood mortality can be attributed to undemutriton [12,
13]. In addition to this elevated mortality risk, delayed motor development [14] and
impaired cognitive function and intellectual performance are also associated with the
process of childhood undemutrition [15]. A

Inadequate consumption of protein, energy and micronutrients accounts for
most of the nutrition-related ailments among children under the age of five years in
the Sub-Saharan Africa [16]. In Tanzania, various forms of nutrient deficiencies such
as protein, iron, zinc and vitamin A have been associated with the high rates of

morbidity and mortality among children under the age of five years [17]. Young

1

children at the age of 6 — 60 months are the most affected with 31% of them having
low weight-for-age and weight-for—height less than -2 SD compared to their reference
peers [ 1 8].

The causes of under-nutrition are multifaceted by nature. The immediate
cause is inadequate intake and poor utilization of nutrients due to poor quality foods,
low feeding fiequency, high dietary bulk and a high incidence of diseases. Underlying
factors are insufficient household food security, an inadequate child-care system and
insufficient health services, while deeper-rooted basic factors relate to socio-economic
and political reasons. Factors directly related to the food component have been
highlighted in various reports [19 - 22] and have been reported to account for more
than 75% of the deaths of infants and young children in Tanzania [20]. Also,
childhood diseases such as malaria, diarrhea, acute respiratory infections, and measles
aggravate the nutritional problem by impairing intake and utilization of nutrients, and
destroying the body’s immune system thus predisposing the body to other infections
and increasing requirements for other nutrients [20].

Various reports have indicated that, most children in Tanzania start their life
in sound health as they are born with weights well above standard weight of 2.5 kg
[20, 22]. However, weight and height growths start to falter during weaning and/or
immediately after. Protein, energy and micronutrient deficiencies become a serious
problem during this period, as most weaning foods consumed do no supply adequate
amounts of these nutrients. Inadequate nutrient intake is caused not only by inherent
low protein, energy and other nutrient densities of the gruels fed to the children, but
also due to low frequency of feeding the child per day. Since most of the weaning
foods are made fi'om starchy staples with high dietary bulk, the children’s small

stomachs cannot handle enough food to last for 4 — 5 hours before they are Offered

another meal [22 - 24]. Under such conditions, the child would require feeding of
small portions 5 to 6 times per day [19]. Various studies in rural communities in
Tanzania have revealed that, average young child feeding frequency per day is three
to four times [22, 24]. Mothers who are traditionally responsible for child care do not
have much time to prepare gruels and feed the child several times in a day due to their
other competing roles such as agricultural production on farms, collecting fuel wood,
fetching water, washing and cleaning houses and caring for the other members of the
family [24 - 26]. Women’s heavy workloads therefore reduce the time the mothers
have to care for the children.

To cope up with the problem of low feeding fi'equency of young children,
mothers prepare a large amount of porridge that is stored and used to feed the child
several times during the day [22]. These gruels, when stored in hot tropical
conditions, and probably under low sanitary conditions, cause proliferation of
infective microorganisms that lead to increased incidences of childhood food-home
diseases. Children at the weaning stage (4 months — 3 years) are also more vulnerable
to infections due to a decline in the immunity acquired from their mother [23]. The
interaction between nutrient deficiencies and diseases during and/or immediately after
the weaning period has been reported as the major cause of high morbidity rates and
growth faltering among weaned infants and young children [20].

The traditional weaning foods of Tanzania, just like in other parts of sub-
Saharan Africa are based on the local starchy staples, usually cereals such as maize
(Zea mays), sorghum (Sorghum vulagare), finger millet (Pennisetum typhoideum) and
rice (Oryza sativa) or non-cereals such as cassava (Manihat esculenta), potatoes
(Ipomea tuberasum), and plantains (Musa paradisica). Food preparations based on

these staples supply between 70 - 80% of the energy, protein and micronutrient intake

of the weaned infants and young children [20]. The use of maize for preparation of
weaning foods has been extensive for the past two decades, but use of sorghum and
millets has increased steadily in the recent years, due to the fact that, millets and
sorghum are drought resistant, they have low average market prices and their supply
in markets is stable compared to maize [27]. Sorghum, millets and cassava based
weaning foods, however, have been pointed out to contribute immensely to the
prevalence of protein energy undemutrition among young children [27, 28].
Conversely, some common roots/tubers such as sweet potato (Ipamaea batatas) and
yams (Diascaria spp) that are rich in micronutrients such as B—carotene are not
utilized as weaning foods due to among others, lack of appropriate, low-cost
processing technology [27].

The traditional methods of preparing the weaning/ supplementary foods at
household level involve cooking the flours made from cereals or root/ tubers in
boiling water to a semi-liquid porridge (Uji) or by mashing boiled roots or tubers such
as cassava, yams or potatoes and diluting with some water to form paps. The major
problems associated with these porridges and paps include:

i) Bulkiness — foods have a stiff consistency that make them diffith for children to
consume enough amount to meet their protein, energy and micronutrient
requirements. With the exception of gruels prepared in some pastoral communities
where butter and/or lard is used, fat content in the gruels is generally very low. When
diluted to an edible consistency, the foods become too watery and hence are unable to
supply sufficient nutrients and calories.

ii) Monotonous - foods lack variety and hence are unappetizing. This limits children
from consuming enough food. Nutrient rich foods, which can add variety to the

weaning foods such as meat, fish, legumes, fruits and vegetables, are unfortunately

not readily available or are too cumbersome to incorporate into children’s foods. This
limits their use in children’s meals.

iii) Low protein and micronutrient density - these foods naturally are low in essential
nutrients such as protein, vitamin A/pro-vitamin A, iron and zinc. The dilution made
in the bid to attain the edible consistency reduces the nutrient density even further.
Food low in protein or with imbalanced essential amino acids (EAA) have also been
shown to suppress appetite [29, 30].

iv) Antinutritional factors — most cereals and legumes contain antinutritional such as
a-amylase, trypsin and chymotrypsin inhibitors, tannins and phytate that impair the
digestion of proteins and starch, and absorption of minerals such as iron, zinc and
calcium. Some foods also contain natural toxins such as phytohemagglutinins,
gossypols, cyanogens and allergens.

v) Contamination - foods are Often contaminated due to unhygienic handling, lack of
proper storage facilities and poor environmental sanitation.

vi) Low digestibility and bioavailability of essential nutrients such as protein, iron and
zinc.

Several strategies were suggested to improve the quality of the weaning
foods including multi-mix formulations [31, 32], reduction of anti-nutritional factors
and natural toxins through processing and cleaning [33 - 35] and reduction of dietary
bulk through malting/germination, fermentation, and enzyme treatment [23, 35].
Adoption of these strategies at household level caused an increase in mothers’
workload due to increased chores such as fetching more water for soaking, malting,
fermenting, collecting more fuel wood for roasting/toasting and spending more time
and energy on manual dehulling or peeling. Increasing the mothers’ chores

constrained further the time that the mother could avail herself for feeding and caring

for the children. Increased demand for water in the processing of these foods also
increased the risk for more contamination especially in some rural communities where
water is not potable and may require boiling before use. These strategies were
therefore not widely adopted in many households and the problem of low feeding
frequency of young children remained as mothers had even less time to feed their
children due to increased workloads [24, 25].

To address the problem of undemutrition among children, WHO [36],
WHO/UNICEF [37], and Dewey and Brown [38] recommends preparation of low-
cost, fortified supplementary foods from locally available ingredients using suitable
small-to-medium scale production technologies in community settings. According to
WHO/UNICEF [37] centrally processed, fortified ready-tO-eat “instant” products
would provide a reliable option for families and can thus contribute immensely in
mitigating the problem of protein and energy undemutrition among young children in
developing countries. Fully cooked, fortified ready-to-feed foods produced fi'om
locally produced ingredients have several advantages: i) the foods contain high a
nutrient density because they are enriched with high protein foods e. g. legumes and
fish and fortified with multivitamins and multi-minerals. ii) they relieve mothers of
some workload which avail them more time to care for the children and feed them
more frequently. They also reduce the need for the mothers to collect fuel wood and
cook frequently because the weaning/supplementary foods require only reconstitution
with boiling water prior to feeding. iii) the food products, which are produced
centrally reduce the use of firewood for fi'equent cooking, thus saving the
environment from further degradation. iv) the products minimize incidences of food-
bome infections, because they are produced under high sanitary conditions and

eliminate the need for mothers to keep cooked foods for later feeding during the day.

v) the products based on cereal-bean-sardine blends expand the utilization of beans
and provide more market outlets for the smallholder bean farmers and women bean
grower groups. vi) they serve as a source of income for private small scale
entrepreneurs, NGOs, women groups and other interested groups.

This study was designed as part of the national/intemational efforts to
address the problem of protein and energy undemutrition in Tanzania. It was planned
in accordance with the WHO/UNICEF [3 7] recommendation of producing low-cost,
fortified ready-to-feed supplementary foods from locally available materials using
appropriate small-scale technology. Specifically, this study aimed at formulating,
processing and evaluating the quality of low-cost, processed maize/sorghum/rice-
bean-sardine composite products suitable for feeding pre-school age children in low-
income communities in Tanzania. The products were formulated to maximize the
amino acid score and energy density as recommended by the F AO/WHO Codex
Alimentarius Standards [39] and the Tanzanian standard (725 [80:198) [40]
specifications for processed cereal-based weaning/supplementary foods for infants
and young children.

Hypothesis

It is hypothesized that, processed, ready-to-feed composite supplementary
foods formulated from locally produced food ingredients would be as good as the
standard dried skim milk and com-soy meals in supporting normal growth and
rehabilitating of undernourished children.

Smific Objectives
1. Formulate high nuuient-dense products from locally produced ingredients

such as corn, beans, sorghum, rice and sardines to meet the FAO/WHO/UNU

[41] amino acid recommendations for cereal-based weaning/ supplementary
foods.

2. 2. Determine optimal processing conditions for ready-tO-feed ”instant”
products from the formulated products using extrusion and/or drum-
processing methods.

3. Evaluate the nutritional quality of the processed products including:

i) amino acid profile,

ii) protein digestibility amino acid scores,

iii) residual levels of phytohemagglutinins and

iv) anti-nutritional factors (trypsin, chymotrypsin, and (It-amylase inhibitors),

v) evaluate cooking doneness (starch gelatinization rate and residual urease

activity).
4. Evaluate the potential of the supplementary foods to support normal growth and
rehabilitation of undernourished children using an animal model.

5. Evaluate the storage stability of the products under simulated tropical conditions.

1.1 Organization of the Dissertation

This dissertation is organized into six chapters. References are presented at the
end of each chapter for easy referencing by the reader. Chapter one provides the
general introduction of the problem and the rationale for the study. It points out the
specific objectives for the study. Chapter two provides a review of literature on the
broad concepts of food products formulation, processing methods and conditions,
evaluation of nutritional and sensory quality and storage stability. The chapter also
covers the most contemporary recommendations on supplementary foods

development based on the WHO/UNICEF [3 7] guidelines. Chapter three contains

article number one titled “protein quality of drum-processed cereal-bean-sardine
composite supplementary foods for preschool age children”. This study evaluated
the protein quality and growth/rehabilitation potential of supplementary foods
developed from locally produced materials in Tanzania. This article addressed
objectives number one, two and four of the study. Chapter four contains article
number two titled “nutritional quality of drum—processed and extruded composite
supplementary foods”. The study evaluated the suitability of two food processing
methods — extrusion and drum-processing for producing well-cooked, ready-to-feed
supplementary foods for pre-school age children. This article-addressed objectives
number three (ii and iv) of the study.

Chapter five contains article number three titled “protein digestibility
corrected-amino acid scores, acceptability and storage stability of ready-to-eat
supplementary foods for pre-school age children”. This study evaluated the amino
acid profile of the processed cereal-bean-sardine composite products and determined
the protein quality using the FAQ/WHO [42] approved — protein digestibility-
corrected amino acid scores and evaluated the storage stability of the processed
products under simulated tropical conditions. This article addressed objectives three
(ii and iii), and five of the study. Chapter six provides an overall summary of the three
studies and presents some conclusions. Chapter seven presents recommendations for
future research.

This report is intended primarily for nutrition and health professionals and
others concerned with nutrition, health, and well-being of children in developing
countries. The discussion and conclusions in this report focus on the particular needs
of children in low-income settings, as well as the economic and environmental

constraints, that are common in those areas. The level of presentation of this report

assumes that the reader has some familiarity with the basic concepts of food science,

nutrition, protein quality and food safety.

10

1.2 References

1. dc Onis M. (1993). The worldwide magnitude of protein-energy malnutrition: an
overview from the WHO Global Database on Child Growth. Bull. World Health Org.
71: 703 — 712.

2. Administrative Committee on Coordination - Sub-Committee on Nutrition (ACC-
SCN) (1987). The First Report on the World Nutrition Situation. Rome. United
Nations.

3. Administrative Committee on Coordination - Sub-Committee on Nutrition (ACC-
SCN) (1989). Update on the Nutrition Situation: Recent Trends in Nutrition in 33
caurtiers. Geneva. United Nations.

4. Administrative Committee on Coordination — Sub-Committee on Nutrition (ACC-
SCN) (1992). Second Report on the World Nutrition Situation. Vol.1. Global and
Regional Results. Geneva. United Nations.

5. Administrative Committee on Coordination — Sub-Committee on Nutrition (ACC-
SCN) (1994). Update on the Nutrition Situation, 1994. Rome. United Nations.

6. Chandra, R.K. (1991). Nutrition and immunity: lessons for the past and new
insights into the future. Am. J. Clin Nutr. 53: 1087 — 1101.

7. Tompkins, A. (1981). Nutritional status and severity of diarrhea among pre-school
children in rural Nigeria. Lancet. 1: 860 - 862.

8. Sepulveda, J ., Willett, W. and Munoz, A. (1988). Malnutrition and diarrhea: a
longitudinal study among urban Mexican children. Am. J. Epidemiol. 127: 365 — 376.

9. Black, R.E., Brown, K.H. and Becker, 8. (1984). Effect Of diarrhea associated with
specific enteropathogens on the growth of children in Rural Bangladesh. Pediatrics.
73(6): 799 - 805.

10. Bairagi, R. (1987). The association between malnutrition and diarrhea in rural
Bangladesh. Intl. J. Epidemiol. 16: 477 — 481.

11. Victora, C.G. (1990). Pneumonia, diarrhea, and grth in the first 4 y of life: a
longitudinal study of 5914 urban Brazilian children. Am. J. Clin. Nutr. 52: 391 — 396.

12. Pelletier, BL. (1994). The relationship between child anthropometry and
mortality in developing countries: implications for policy, programs and future
research. J. Nutr. 124 (10 Suppl): 2047S — 2081S.

l3. Schroeder, D. and Brown, K.H. (1994). Nutritional status as a predictor of child
survival: summarizing the association and quantifying its global impact. Bull. World
Health Org. 72: 569 — 579.

14. Pollitt, E. (1994). Stunting and delayed motor development in rural West Java.
Am. J. Hum. Biol. 6: 627 — 635.

ll

15. Martorell, R. (1992). Long-term consequence of growth retardation during early
childhood. In: Hernandez, M. and Argente, J (Eds). Human Growth: Basic and
Clinical Aspects. Amsterdam. Elsevier Science Publishers. Pp 143 — 149.

16. UN. (1992) United Nations. 2nd Report on the World Nutrition Situation: Global
and Regional Results. Vol. 1. Rome, CC/SCN.

l7. Kavishe, RP. (1992) Development Of Vitamin A Control Programs: An example
of Tanzania. NU - News and Health Care in Developing Countries; 3: 21 - 26.

18. TFNC - Tanzania Food and Nutrition Center (2002). Nutrition for Human and
Economic Development in Tanzania. Tanzania’s Nutrition Vision for the Year 2025.
TFNC Report. Dar es Salaam.

l9. Masha, AC. and Svanberg, U. (1983) Preparation of weaning foods with high
nutrient density using flour Of germinated cereals. UNU Food Nutr. Bull. 5(2): 10 -
14.

20. United Republic of Tanzania and UNICEF (1990). Women and Children in
Tanzania - A situational Analysis. Dar es Salaam, Goverment Printer.

21. Svanberg, U. (1987). Dietary bulk in waning foods. PhD Thesis. Department of
Food Science, Chalmers University of Technology, Goteborg, Sweden.

22. Mosha, T.C, Dakiyo, 8.0.8. and Laswai, H. (1998). Breastfeeding, weaning
practices and anthropometric patterns of children in Morogoro district, Tanzania.
Ecol. Food Nutr. 37(4): 309 - 339.

23. Walker, A.F. (1990) The contribution of weaning foods to protein energy
malnutrition. Nutr. Rev. Res. 3: 25 - 47.

24. Wandel, M. and Holmboe-Ottesen, G. (1992). Maternal work, child feeding and
nutrition in rural Tanzania. Food Nutr. Bull. 14(1): 68 - 71.

25. Bary, MP. (1980). Time allocation of the mother and child nutrition. Ecol. F oad.
Nutr. 9: l - 14.

26. Holmboe-Ottesen, G. and Wandel, M. (1991). Men’s contribution to the food and
nutrition situation in the Tanzanian household. Ecol. F aad Nutr. 26(1): 83 - 96.

27. Seenappa, M. (1987). Advantages of Sorghum and Millets in weaning Foods. In:
Alnwick, D., Moses, S. and Schmidt, O.G. (Eds). Proceedings of a Workshop on

Household Level Food Technologies for Improving Young Child Feeding in Eastern
and Southern Afiica, Nairobi, Kenya. October, 1987.

28. Hulse, J.H., Laing, EM. and Peterson, QB. (1980) Sorghum and Millets: Their
Composition and Nutritional Value. N.Y., Academic Press.

12

29. Sharp, J .W., Magrum, LJ. and Gietzen, D.W. (2002). Role of MAP kinase in
signaling indispensable amino acid deficiency in the brain. Molecular Brain Res. 105:
11 — 18.

30. Koehnle, T.J., Russell, MC. and Gietzen, D.W. (2003). Rats rapidly reject diets
deficient in essential amino acids. J. Nutr. 133: 2331 — 2335.

31. Pellett, PL. and Mamarbachi, D. (1979). Recommended proportions of foods in
home-made feeding mixtures. Ecol. F aad. Nutr. 7: 219 - 228.

32. Cameron, M. and Hofvander, Y. (1983). Manual on Feeding Infants and Young
Children. Oxford. Oxford University Press.

33. Reddy, N.S., Waghmare, S.Y. and Pande, V. (1990). Formulation and evaluation
of home-made weaning mixes based on local foods. Food Nutr. Bull. 12(2): 34 - 44.

34. Ngoddy, P.O., Nout, M.J.R. and Nche, PF. (1994). Optimization strategies for
weaning formula development for tropical areas. Paper Presented at the ECSAFOST
- 94 F aad Conference, Vistoria Falls, Zimbabwe, 12 — 16 September, 1994.

35. Nout, M.J.R. (1993). Processed weaning foods for tropical climates. Int ’1 J. Food
Sci. Nutr. 43: 213 — 221.

36. WHO (2002). Infant and Young Child Nutrition: Global Strategy on Infant and
Young Child Feeding. World Health Assembly Document WHA55/ 15. Rome. WHO
Press.

37. WHO/UNICEF (1998). Complementary Feeding of Young Children in
Developing Countries: a review of the Current Scientific Knowledge. WHO
Publications. Geneva.

38. Dewey, K.G and Brown, K.H. (2003). Update on technical issues concerning
complementary feeding of young children in developing countries and implications
for intervention programs. Food Nutr. Bull. 24 (1): 5 - 28.

39. FAO/WHO (1994). Codex Alimentarius Standards for Foods for Special Dietary
Uses (including foods for infants and children). Vol. 4. Joint FAO/WHO Food
Standards Program. Rome. WHO, Codex Alimentarius Commission.

40. TBS - Tanzania Bureau of Standards (1983). Tanzania Standards for processed
Cereal-based Weaning Foods —- Specifications. Dar es Salaam. Tanzania Bureau of
Standards.

41. 127. FAO/WHO/UNU (1985). Energy and Protein Requirements. Report of the
Joint FA O/WHO/UNU Expert Consultation. Technical Report Series NO. 724.
Geneva. FAQ.

42. FAO/WHO (1991). Protein Quality Evaluation. Report of the Joint FA O/WHO
Expert Consultation Rome. FAQ.

13

CHAPTER TWO

2.0 REVIEW OF LITERATURE
2.1 Protein Energy Undernutrition

Protein energy under-nutrition is a nutrition related disorder associated with
inadequate intake and/or poor utilization of protein, energy and micronutrients [1].
Protein energy undemutrition affects mostly children between the ages of 6 — 60 months
and accounts for the high rates of childhood morbidity and mortality [2]. Sub-Saharan
Africa contains the largest number of undernourished children in the world, experiencing
various types of nutrient deficiencies, such as protein, iron, zinc, vitamin A and iodine
deficiency [1]. In Tanzania, protein energy undemutrition affects many children under
the age of 5 years. According to the Tanzania Bureau Of Statistics [3] and Tanzania Food
and Nutrition Center (TFNC) [4], more than 44% of all the children in the country are
stunted (height-for-age less than 60% of the National Center for Health Statistics (NCHS)
reference values for children of the same age and sex), 30% are underweight (weight-for-
age less than 60% of the NCHS reference values for children of the age and sex), 66% are
anemic, 24% are vitamin A deficient and 7.2% are wasted. Infant mortality rate is 81 per

1000 live births while under-five mortality is 117 per 1000 live births [4].

2.2 Causes of Protein Energy Undernutrition

The major causes of protein energy undemutrition are summarized in the
UNICEF [5] conceptual framework (Fig. 1). The immediate causes of protein energy
undemutrition are inadequate intake of nutrients due to unavailability, low daily feeding

frequency, high dietary bulkiness, poor utilization of nutrients associated with low

14

digestibility and poor bio-availability, and high incidence of diseases. Underlying factors
include insufficient household food security, inadequate childcare system, insufficient
health services, poor sanitary, and environmental conditions; while the deep-rooted
causes include insufficient and poor allocation of human, economic and institutional
resources, political and ideological superstructure that lead to civil strife, poor ecological
conditions and misuse and/or misallocation of the available basic resources [5]. Factors
relating protein energy undemutrition with inadequate food intake have been highlighted

in various reports to account for more than 60% of deaths of children under the age of

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  
   
      
 
  

    
  

 

     
 

    
  

   

five years [6, 7].
(Nutritional Status > Manifestations
A
Diet < > Health Immediate
\ / Causes
Household Care of Environment, Underlying
Food Security Mother and Health and Causes
Child Sanitation

 

 

 

 

   

Human, Economic and
Institutional Resources

T Root

Political and Ideological Structure Causes
Ecological Conditions

(m 1WD

Fig l: UNICEF conceptual framework for determinants of nutritional status

  

 

 

 

 

 

 

 

 

 

15

Protein energy undemutrition has also been shown to delay motor development [8] and
impaired cognitive function and school performance [9]. Inadequate nutrient intake and
disease reinforce each other synergistically to cause protein energy undemutrition [10].
Protein energy undemutrition makes a child more susceptible to infection and decreases
the immune defenses against invading pathogens. In turn, certain pathogens influence the
nutritional status through reduced nutrient intake (anorexia), reduced nutrient absorption
(malabsorption and intestinal damage), nutrient losses (diarrhea, intestinal damage) and
increased nutrient requirement (increased metabolic rate, redistribution of nutrients in the
body and activation of inflammatory and/or immune response). Diseases such as malaria,
diarrhea, acute respiratory infections, measles and parasite infections by Entamaeba,
Ascaris, Schistosames, Trichuris and hookworrn are most common and most severe in
children [10]. Furthermore, about 200,000 children in Tanzania are infected with
HIV/AIDS mainly through mother-to-ehild transmission. It is estimated that by the end of
2005 the number of children orphaned in the country will exceed 3 million and most of
these will suffer from protein energy undemutrition due to lack of adequate food and

parental care[ll].

2.3 Weaning and Supplementation

The World Health Organization [12] recommends that infants should be
exclusively breastfed for the first six months of their life. From the age of six months
onwards, children enter a vulnerable period of weaning during which they make a gradual
transition to eating ordinary farrrily foods. To achieve a diet that is nutritionally adequate

and safe for children at the age of 6 - 24 months is difficult, particularly fiom plant-based

16

diets. Many supplementary foods are mainly based on starchy cereals and root tubers. A
diet prepared from these food sources usually result in a thick, gelatinous gruel with low
nutrient density. In addition, mineral bioavailability is poor in many plant-based foods
due in part to the high content of anti-nutritional factors such as tannins, lectins, trypsin,
chymotrypsin and a-amylase inhibitors which impair the bioavailability of nutrients [13].
Microbial contamination of the weaning foods is common and contributes to the high
rates of diarrhea] diseases, growth faltering, and death. Particular problems exist in
situations where the food is stored for some hours after preparation. Chemical toxins also
occur in some foods e. g. afflatoxins in peanuts and cereals, cyanogenic glycosides in
cassava and phytohemagglutinins in legumes [14]. The incidences of protein-energy
undemutrition rise sharply during the period from 6 — 18 months of age in most countries,
and the deficits acquired at this age are difficult to compensate for later in childhood [13].
Growth faltering is most evident in this age period and is often accompanied by
nricronutrient deficiencies and high rates of infection [15].

During the past decade, there have been considerable efforts to improve child-
feeding practices. These efforts have culminated in a series of WHO recommendations
and guidelines on complementary feeding of young children in developing countries [12,
l6, 17]. Nutritional benefits of food supplementation on children have been widely
documented in developing countries [18, 19]. A study to examine the impact of nutrition
supplementation on annual growth rates in length and weight in children from birth to 7 y
revealed that, during the first year of life, each 100 kcal/day supplemented resulted in ~ 9
mm in additional length/height gain and 350 g in additional weight gain. In the second

year of life, the benefits decreased slightly to 5 mm in height/length gain and 250 g in

17

weight gain. Between 24 and 36 mo of age, food supplement had significant impact only
on length but not on weight. Between 3 — 7 years of age, nutrition supplementation did
not have any impact on either height or weight gain [18]. In a study to investigate the
long-term effect of nutrition supplementation with high protein-energy food during early
childhood on body size and composition at adolescence, Rivera et al. [19] observed that,
the supplement improved significantly the dietary intake among 0 — 3 y children.
Consequently, the children grew better (weight and height) compared to their peers who
were receiving low protein-energy supplement. At adolescence, children who received
supplements at 0 - 3 y of age were heavier, taller, and had greater fat free mass compared
to their peers who received low protein-energy diet. A meta-analysis of 21 supplementary
feeding programs in 14 countries for children 6 — 12 mo revealed that nutrition
supplementation improved infants dietary intake by 65 - 302 kcal/day and infant growth
by 0.10 — 0.50 standard deviations (SD) (mean 0.46 SD) of the z-soores. This range of
improvement, in absolute terms, would reduce prevalence of protein energy
undemutrition (z-scores < -2 SD) at 12 mo of age by 1 — 19% and would reduce deaths
due to protein energy undemutrition by 2 — 13% [20]. Similar supplementation studies
conducted in Bolivia [21], Thailand [22], Guatemala [1 8], Colombia [23], Jamaica [24],
Congo (DR) [21], Senegal [21], and Indonesia [25] showed significant improvement in
both weight and length growth of young children.

Nutritional supplementation at childhood may also have long-term effects at adult
age. A 5 year longitudinal study of children who participated in a nutrition
supplementation program of high protein-energy diet at age 0 —- 3 y revealed that, at

adolescence, children who received nutrition supplementation had a greater physical

l8

work capacity (measured by oxygen consumption VOzm) compared to their peers who
did not receive the supplement [26]. The study also showed a positive relationship
between amount of supplement consumed and the physical work capacity. Also, early
nutrition supplementation has shown to increase biological/skeletal maturity at
adolescence [27] as well as increased bone mineral content, bone width and bone mineral
density [28]. Supplementation at early childhood therefore has long lasting effects in the
skeletal development, bone mineralization and physical performance of the individuals.
In a study to investigate the effect of early nutrition supplementation on cognitive
and intellectual development, Pollitt et a1. [29] observed that supplemented children
scored significantly higher at tests of knowledge, numeracy, reading and vocabulary
compared to those who did not receive the supplemental feeding. Supplemented children
also showed faster reaction time in information processing tasks. These studies give
considerable evidence that; addressing protein energy undemutrition early in life has
beneficial effects on human performance, health and survival. Continued reduction of
protein energy undemutrition and mortality will thus require improved nutrition through
interventions targeting marginal populations at the early stages of life [30]. The fact that
malnutrition impairs human function and its effects persist to the adult life, any effort to

address protein energy undemutrition at the early stages of growth is worthwhile.

2.4 Nutritional Rehabilitation
Children identified with mild and/or severe protein energy undemutrition are
usually referred to hospital-based (residential) or community-based (non-residential)

rehabilitation centers where they receive feeding supplements to restore their reference

19

body weights while continuing with medical treatment Of the complications associated
with protein energy undemutrition [31, 32]. The major criteria for admission into the
residential and non-residential rehabilitation centers are -- weight-for-age < 60% of
NCHS reference values for the age and sex or weight-for-height z-scores < -2 SD of the
NCHS reference values for children of the same age and sex. The child must also meet
the following criteria -- eating well, has improved mental state (e. g. can smile, respond to
stimuli, interested in surroundings), can sit, crawl, stand or walk alone (depending on
age), has normal body temperature (36.5 - 37 .5°C), has no vonriting or diarrhea, has no
edema and has started gaining weight at a rate of > Sg/kg body weight/day (for at least 3
consecutive days) after the edema phase [31].

The common food used for rehabilitation of malnourished children is “energy
food” made from dried skim milk and reconstituted with vegetable oil and sugar [31].
The average weight gain during rehabilitation for children on dried skim milk is 2 — 20
g/kg body weight/day [33]. A child in a residential facility is considered to be fully
rehabilitated and ready for discharge when his/her weight-for-height z-scores has reached
-1 SD of the median NCHS/WHO reference values for children of the age and sex.
Another criterion based on weight-for-age 2 80% of the NCHS reference values has also
been used for discharge [33]. Criteria for discharging children from non-residential care
are — child attained weight-for-height z-scores Of— 1 SD of the NCHS/WHO median
reference values, child able to eat adequate amount Of a nutritious diet that the mother can
prepare at home, child gaining weight at a normal or increasing rate, all vitamin and

mineral deficiencies have been corrected, all infections and other conditions have been

20

treated - including diarrhea, anemia, intestinal parasitic infestations, malaria, tuberculosis
and otitis media, and full immunization program has been started [32].

The major limitation with nutrition rehabilitation is the failure to sustain the
recovery attained at the centers once children return to their respective homes [34 - 36].
Reports by Roosrnalen-Wienbenga [35] and WHO [31] showed that the proportion of
relapses after discharge were 25 —- 35% and in some hospitals exceeded 50%. When
rehabilitated children return home from the hospital/ community-based rehabilitation
centers, they no longer have access to the “energy food”. Dried skim milk is imported,
and is not readily available in rural areas, and whenever available it is tOO expensive for
the low-income families to afford [31]. Return of the child to the unfavorable
socioeconomic conditions and lack of access to the “energy food” after discharge make
the children relapse to the same problem. Follow-up studies of some children discharged
fi'om such rehabilitation centers revealed that the rehabilitated children had higher
mortality rates compared to their non-referred peers; most remained underweight and
stunted until adulthood and only 30% attained satisfactory catch-up growth [3 7, 38]. The
major reason for the relapse into protein energy undemutrition is inadequate access to
well balanced nutritious foods.

In light of the foregoing, the report by the WHO [12] Global Consultation on
supplementary feeding emphasized that, in order to insure sustainable healthy growth of
normal and rehabilitated children, there must be adequate availability of low-cost
nutritious supplementary foods prepared from locally available ingredients using small-
scale production technologies in centralized or community settings. There is ample

evidence showing that if supplementary foods are formulated solely from unmodified

21

locally produced plant ingredients, they cannot meet the recommended energy and
nutrient needs for growing children [39 - 41]. Approaches to increase availability of
nutritious supplementary foods at household level should be emphasized including the
appropriate technologies to process them. Centrally processed and fortified foods
products can also play a significant role in insuring adequate availability of low-cost

supplementary foods for children.

2.5 Supplementary Foods

Supplementary foods may be processed at central strategic place where services
are available or at a community level. Centrally processed foods are marketed through the
existing commercial channels, with or without subsidization, or distributed through
public institutions, such as health clinics or ration shops. The foods may target specific
vulnerable subgroups of the population, such as low-income families or undernourished
children, or they may be distributed universally to children within a particular age range.
Community-based processing of foods involves special groups such as mother and child
health (MCH) group, mothers’ clubs, women groups or other similar community
organizations. In this approach, food is processed by the group members and distributed
for on-site consumption or as a take home ration [42]. In both central and community-
based processing approaches, a nominal charge may be assessed on the food to cover the
cost of the basic ingredients and labor (where applicable) and probably a little margin of
profit for the non-service groups. Reports from various groups of the world indicate that
high quality; low-cost fortified supplementary foods with good distribution system can be

effective in ameliorating protein energy undemutrition and micronutrient deficiency in

22

target populations [43]. For examples, Alli Alimentum — a fortified supplementary food in
Peru has shown to be effective in improving the energy intake and micronutrient status of
children and has reduced significantly the prevalence of iron deficiency anemia and
vitamin A deficiency among pre-school age children. Other foods that have Shown
considerable impact in ameliorating protein energy undemutrition among children under
the age of five in developing countries include Superamine (Algeria), T sabana
(Botswana), Ouando (Bennin), Musalac (Burundi), MICAF (Cape Verde), Vitafart
(Chad), Fafla (Ethiopia), Weanimix (Ghana), Likuni Phala (Malawi), Actamine
(Morocco), Bitamin (Niger), SOSMA (Rwanda), Lisha (Tanzania), and Nutrimr'x (Togo)

[42].

2.5.1 Products Formulation and Ingredients

The nutritional basis of supplementary food formulation is the principle of
nutrient complernentation described by Harper and Jansen [44]. Foods deficient in some
specific nutrients are blended with others that are rich on the deficient nutrients to correct
the deficiency. For example, cereal grains such as corn that are deficient in lysine but rich
in sulfur amino acids (Cysteine and Methionine) may be blended with legumes (rich in
Lysine, but low in sulfur amino acids) to correct the deficiency. A wide variety Of cereals
e.g. maize, millet, sorghum, rice and wheat; legumes e. g. kidney beans, cowpeas and
chickpeas; Oilseeds e.g. soybeans; and animal products e.g. dry milk, dry fish, beef and
chicken may be combined in carefully determined proportions to achieve optimum
nutrient content for promoting growth of the social group the product is formulated for.

Some of the optimum nutrient levels used as quality markers for supplementary foods

23

include protein (2 14 g/100 g dry food), protein-energy (2 14.5%), energy (> 360

kcal/ 100 g dry food), net dietary protein-energy (N DpE) (6 - 10%), essential amino acid
index (1.0), amino acids score (2 65%) and protein digestibility-corrected anrino acid
scores (2 60%) [45, 46, 47].

In the past, major emphasis was placed on food blends fi'om cereals and legumes
because the ingredients were readily available and inexpensive. Most blends from these
components however, could not meet the requirements for protein, essential amino acids,
energy, and micronutrients [42]. Recently, there have been deliberate efforts to make
food products providing not only adequate energy and high quality protein, but also
generous amounts of micronutrients such as iron, zinc and vitamin A. As a result,
supplementary food mixtures are increasingly containing animal source foods such as dry
milk and fish in combination with legumes and oil seeds [44]. Animal source foods
provide high quality and readily digested protein and an array of readily available
micronutrients that are Often limiting in plant-based diets [48]. A study by Ferdinandez et
a1. [49] has shown that, the protein efficiency ratio of 30:70 mixtures of animal: vegetable
protein was similar or higher than those of the animal foods alone. This implies that
blending plant-based foods with animal source foods even in modest amounts can greatly
improve the nutritional quality of the products and thus assist in mitigating multiple
nutrient deficiencies [48]. The WHO [50] global strategy on infant and young children
emphasizes that processed food products for infants and young children should, when
sold or otherwise distributed be of high quality by meeting the compositional, nutritional,
and safety standards recommended by the FAQ/WHO Codex Alimentarius Commission

[51] and the Codex Code of Hygienic Practice for Foods for Infants and Children [52].

24

2.5.2 Recommended Composition of Supplementary Foods
2.5.2.1 Energy Density

Dietary energy is important in maintaining the physiological functions of the body
and in sparing the body protein [53]. For infants and young children adequate energy
intake is important because they have higher rates of growth. Energy density also
influences the feeding frequency required per day to attain the recommended amount of
energy. For children in developing countries where the fiequency of feeding per day is
limited due to heavy maternal workload, energy density of their supplementary foods
should be high enough to be able to supply the recommended daily energy fiorn the few
meals taken. The recommended energy density in supplementary foods is based on the
WHO/UNICEF [42] recommendations for energy that were first presented by the
International Dietary Energy Consultative Group in 1994. Table 1 shows the minimmn
dietary energy density required to attain the level of energy needed from supplementary
foods in one, two, three or four meals per day by level of breast milk energy intake and
age group, for well-nourished and undernourished children aged 6 - 23 months. As
shown in Table 1, energy densities recommended for well-nourished, 6 - 8 mo children
who are no longer receiving breast milk energy are 342 kcal/100 g (receiving only one
meal per day), 171 kca1/100 g (receiving two meals per day), 114 kcal/100 g (receiving
three meals per day), and 86 kcal/ 100 g (receiving four meals per day). For children of
the same age group (6 — 8 mo) receiving low amount of breast milk energy, the
recommended energy densities in their supplementary foods are 255 kcal/100 g

(receiving only one meal per day), 128 kcal/ 100 g (receiving two meals per day), 85

25

kcal/ 100 g (receiving three meals per day), and 64 kcal/ 100 g (receiving four meals per
day). For undernourished, 6 — 8 months old children who are no longer receiving breast
milk energy, the recommended energy densities in their supplementary foods are 444-
kcal/ 100 g (receiving only one meal per day), 222-kcal/100 g (receiving two meals per
day), 148 kcal/ 100 g (receiving three meals per day), and 111 kcal/100 g (receiving four
meals per day). For their peers of the same age (6 — 8 mo) receiving low amount of breast
milk energy, the recommended energy densities in their supplementary foods are 331
kcal/ 100 g (receiving only one meal per day), 165 kcal/ 100 g (receiving two meals per
day), 110 kcal/ 100 g (receiving three meals per day), and 83 kcal/ 100 g (receiving four
meals per day). The variability in energy density requirement in supplementary foods for
children of same age receiving and not receiving low breast milk energy is 25%. This
underscores the importance of breast milk for older infants and young children. The
energy densities recommended for supplementary foods for undernourished children are
higher by 23% due to their low average body weights and gastric capacity. This would
imply that diets for undernourished children require high energy density to meet the
needs for compensatory or catch-up growth [54]. Estimation of the minimum appropriate
energy density for supplementary foods is made by dividing the amount of energy
required from supplementary foods by the number of meals providing these foods and by
an assumed gastric capacity of 249 g/meal at 6 — 8 mo, 285 g/meal at 9 — 11 mo, and 345
g/meal at 12 — 23 mo (30 g/kg reference body weight). The energy requirements from
supplementary foods are based on age-specific total energy requirements plus 2 SD (to

meet the needs of ahnost all children) minus the amount of energy provided by the breast

26

Table 1: Minimum dietary energy density required to attain the level of energy needed
from supplementary foods in one, two, three or four meals/day by level of breast milk
energy (BME) intake and age group, for well- and under-nourished children‘

 

 

 

 

 

 

 

 

 

Age Group Minimum enggy density (kcal/ 100g) Gastric Total
One Two Three Four Capacity energy/
Well-nourished meal/d meals/d meals/d meals/d (g) kcal
children required
+ 2 SD
6 - 8 mo
BME - None 342 171 114 86 249 852
- Law 255 128 85 64 249 852
- Average 176 88 59 44 249 852
- High 98 49 33 24 249 852
9 - 11 mo
BME - None 364 182 121 91 285 1038
- Low 309 155 103 77 285 1038
- Average 231 1 16 77 58 285 1038
- High 153 77 51 38 285 1038
12 - 23 mo
BME - None 396 198 132 99 345 1365
- Law 370 185 123 92 345 1365
- Average 295 148 98 74 345 1365
- High 221 111 74 55 345 1365
Undemourished
children
6 - 8 mo
BME - None 444 222 148 111 192 852
- Law 331 165 110 83 192 852
- Average 229 1 14 76 57 192 852
- High 127 63 42 32 192 852
9 - 11 mo
BME - None 455 228 152 1 14 228 1038
- Low 386 193 129 97 228 1038
- Average 289 145 96 72 228 1038
- High 192 96 64 48 228 1038
12 — 23 mo
BME - None 500 250 167 125 273 1365
- Law 467 234 156 117 273 1365
- Average 373 187 124 93 27 3 1365
- High 279 140 93 70 273 1365

 

 

 

 

 

 

 

 

 

lAssumesbodyweithBW) 0:33 kg (6—8mo), 9.5kg(9- 11 mo),and 11.5 kg(12—23 mo) forwell-
nourished children and BW of 6.4 kg (6 — 8 mo), 7.6 kg (9 — 11 mo), and 9.1 kg (12 - 23 mo) for under-
nourished children and gastric capacity of 30 g/kg BW. Energy needs from supplementary foods were set at
total energy requirement + 2 SD (i.e. 25%) minus estimated energy intake from breast milk. Adapted from
WHO/UNICEF [42].

27

milk [42, 54]. For general population feeding guidelines, data based on low-breast milk
energy or no-breast milk energy are used instead of average- and hi gh-breast milk energy
because these data provide the most conservative assumptions regarding the minimum
desirable energy density or number of meals [54].

Table 2 shows the minimmn daily number of meals required to attain the level of
energy needed from supplementary foods with mean dietary energy density of 80, 100
and 120 kcal/100 g for children with low level of breast milk energy intake, according to
age group. This implies that, when most households are able to prepare meals with
energy density of 120-kcal/100 g, children in all age groups would be able to consume
enough energy if they receive at least three meals per day. When most household are able
to prepare foods with minimum energy density of only 100 kcal/ 100 g, children flour 6 -
11 mo of age would be able to satisfy their energy needs from supplementary foods if
they receive at least three meals/day, whereas those from 12 — 23 mo of age would need

to consume at least four meals per day.

Table 2: Minimum daily number Of meals required to attain the level Of energy needed
fiom supplementary foods with mean dietary energy density of 80, 100 and 120 kcal/ 100
g for children with low level of breast milk energy intake, according to age group1

 

 

 

Energy density Number of meals
(kcal/100g) 6—8mo 9-llmo 12—23mo
80 3.7 4.1 5.0
100 2.8 3.1 3.7
120 2.2 2.5 3.0

 

 

 

 

 

 

Estimated energy requirement based on WHO/UNICEF [42] data averages plus 25% (2 SD). Assumed
functional gastric capacity (30 g/kg reference BW) is 249 g/meal at 6 — 8 mo, 285 g/meal at 9 — 11 mo and
345 g/meal at 12 - 23 months.

28

2.5.2.2 Fat Content

Lipids have traditionally been considered as part of the dietary energy supply.
Lipids are the main energy source in children foods, thus essential for normal and
physical activity. Fats enhance the taste and acceptability of foods, and lipid components
largely determine the texture, flavor and aroma of foods. In addition, they slow gastric
emptying and intestinal motility, affecting satiety [55, 56]. Dietary lipids provide
essential fatty acids and facilitate the absorption Of fat-soluble vitamins [57 - 59]. Lipids
are also structural components in all tissues and are indispensable for cell and plasma
membrane synthesis. The brain, retina and other neural tissues are particularly rich in
long-chain poly-unsaturated fatty acids [60]. Some long-chain poly-unsaturated fatty
acids derived fiom the n-6 and n-3 essential fatty acids are precursors for eicosanoid
production (prostaglandins, prostacyclins, thromboxanes and leukotrienes). These
autocrine and paracrine mediators are powerful regulators of numerous cell and tissue
functions e. g. thrombocyte aggregation, inflammatory reactions and leukocyte functions,
vasocontriction and vasodilation, blood pressure, bronchial constriction and uterine
contractility. Lipids, particularly essential fatty acids and long-chain poly-unsaturated
fatty acids have also been shown to affect neural development and function [56, 57, 61,
62]. Evidence indicates that specific fatty acids exert their effect by modifying the
physical properties or membranes, including membrane-related transport systems, ion
channels, enzymatic activity, receptor function and various signal transduction pathways.
More recently the role of specific fatty acids e. g. polyunsaturated fatty acids in

determining levels Of gene expression for key transcription factors, peroxisome

29

proliferator-activated receptors and retinoic acid receptors has renewed the interest in
better defining the role fatty acids in the regulation of lipid metabolism, energy
partitioning, insulin sensitivity, adipocyte development and neural functions across the
lifespan [56, 57, 61, 62].

The n-6 and n-3 essential fatty acids can be synthesized from their respective
precursors, linoleic and c—linolenic acid, but the synthesis capacity decreases
progressively in older infants and young children as intakes of breast milk decrease and
supplementary foods increase. F AO/WHO [57] recommends that linoleic acid provide at
least 3% of total energy in supplementary foods. Thus, if seed oils such as maize oil, or
soybean oil which contain more than 50% linoleic acid are used in the supplementary
foods, no more than 6% of total energy would have to be supplied by these sources to
meet the nutritional requirements for linoleic acid. Conversely, if fats such as palm oil or
coconut oil which contain less than 10% linoleic acid are used as major dietary sources,
as much as 30% of energy would be required fiom these fats to meet the nutritional
needs.

Although fat is essential in increasing the overall energy density of diets, the
dietary fat should not be too great as to dilute excessively the density of protein and
micronutrients per 100 kcal. Low dietary energy usually co-exists with low nutrient
density. Dietary modifications to increase energy density of supplementary foods such as
adding fats or sugar have a potential adverse affect on the protein and micronutrient
density since these nutrients are computed as proportions of total energy. Some concerns
have also been raised that dietary lipids affect cholesterol metabolism at an early age and

excessive intake of fat may predispose children to the risk of future hyperlipidernia and

30

cardiovascular morbidity and mortality, though little direst evidence is available to
support this [56, 62 - 65]. Expert consultative bodies have given varying
recommendations on fat intake for infants and young children [56]. While the American
Academy of Pediatrics Committee on Nutrition [66], American Academy of Pediatrics
[67] and the Canadian Society of Pediatrics [68] recommend that fats intake should not
be restricted for children under two years old, European Union [56] and European
Society for Pediatric Gastroenterology, Hepatology ad Nutrition Committee on Nutrition
[69] recommend fat intake of 2 40 - 58.5% of energy intake for 0 — 4/6 mo old children,
_>_32 — 58.5% Of energy intake for 6 - 12 mo old children, and 30 — 35% of energy intake
for children over two years old. NO restriction of fat intake was recommended for
children aged 12 — 24 months. Conversely, FAQ/WHO [57] recommends fat intake of 50
- 60% of energy intake for children aged 0 - 12 mo and 30 - 40% of energy intake for
children aged 12 - 36 mo.

In view of the current knowledge concerning low fat intakes fiom mixed diets in
developing countries and the potential difficulties in achieving adequate micronutrient
densities with high fat diets, it is recommended that fat content in supplementary foods
for older infants and young children be 30% of the total energy [57]. This would imply
that supplementary foods should contain at least 3.33 g of fat per 100 kcal. For under-
nourished 6 — 8 mo old children whose energy requirement is 852 kcal/day they would
need a total of 28.4 g of fat per day and if this energy is to be obtained from three
meals/day, each meal should contain at least 9.5 g of fat. For under-nourished older
infants (9 — 11 mo) whose average energy requirement is 1036 kcal/day, they need a total

of 34.6 g of fat per day and if this energy is to be obtained from three meals/day, each

31

meal should contain at least 11.5 g of fat. For under-nourished young children (12 - 23
mo) receiving an average of three meals/day, a greater proportion of fat — 15.2 g is
required per meal to meet the energy requirement of 1365 kcal/day. The recommended
fat contents of the supplementary foods are based on the assumptions that the under-
nourished children receive very low or no breast milk. If the children are still receiving
some amount of breast milk (Table 1), the recommended fat contents per meal of
supplementary food would be considerably lower.

The amount of fat recommended for supplementary foods may however pose a
significant quality problem during storage of dehydrated products. Auto—oxidation of
lipids occurs largely via a self-propagating free radical mechanism, in the presence of
light, metal catalysts, heat or other pro-oxidants to form hydroperoxides and a range of
low molecular breakdown products, some of which impart the rancid Off-flavor to the
food [70]. F at content, its molecular structure (i.e. the number and location of double
bonds), type of oxidant, oxygen tension, temperature, surface area, pH, storage time,
physical state and presence of pro- and anti-oxidants are the major factors that influence
the stability of dehydrated supplementary foods [70]. Numerous anti-oxidants, including
a-tocopherol, a—tocopherol acetate, ascorbyl palnritate, butylated hydroxytoluene,
butylated hydroxyanisole, di-t-butylhydroquinone, green tea catechins, and flavanoids
have been studies with mixed results [71]. It is therefore pertinent that in addition to
using antioxidants in supplementary foods, control of the type and amount of fat added is

critical in minimizing oxidative deterioration of the dehydrated products.

32

2.5.2.3 Protein Density

Protein is important for growth and well being of children because it is a major
source of essential amino acids that act as substrates for synthesis of new proteins and
maintenance of homeostatic balance of body fluids. Amino acids can also act as
gluconeogenic substrate, regulators of protein turnover, neurotransmitters or precursors
of signal transducers and as signaling molecules (Table 3) [72 - 76]. Since essential
amino acids are not stored in the body, amino acid metabolism can be drastically altered
in response to various forms of malnutrition or trauma (e. g. sepsis, fevers or thermal
burns). Alterations of amino acid profiles have been reported as a result of a deficiency of
any one of the essential amino acids, a dietary imbalance of amino acid or an insufficient
intake of protein. To adapt to the amino acid limitation, humans have to adjust several of
their physiological functions by regulating numerous genes. Example; an amino acid
limitation that occurs when animals take low protein diet causes an increase in the level
of insulin-like grth factor binding protein-1 mRN A, thereby participating in down
regulation of growth [77]. Likewise, deficiency of amino acids reduces the abundance of
C/EBP homologous protein (also called human gene for growth arrest and DNA damage
protein‘153), asparagines synthetase, and C/EBPB (ubiquitin) mRNAs [78]. The C/EBP
homologous protein encodes a transcription factor that regulates cellular response to
stress while asparagines synthetase is gene-encoding enzyme responsible for the
biosyntlresis of asparagine from aspartate and glutamate.

The mechanisms involved in the amino acid control of gene expression are poorly

understood, however, both transcription and translation are regulated by amino acid

33

availability. In this respect, essential amino acids serve as signaling molecules that

facilitate signal transduction process that leads to changes in transcription rates for

specific genes. As signaling molecules, essential amino acids cause changes in

phosphorylation thereby altering functions of a number of proteins that regulate the

Table 3: The involvement of amino acids in physiological and metabolic functions

 

 

System Function Product Precursor
Intestine Energy generation Adenosine Glutamine, Aspartate
tri-phosphate Glutamine
Proliferation Nucleic Acids Glutamine, Glycine, Aspartate
Protection Glutathione Cysteine, Glutamine, Glycine
Nitric oxide Arginine
Mucins Threonine, Cysteine,
Serine, Praline
Skeletal Muscle Energy generation Creatine Glycine, Arginine, Methionine
Peroxidative protection Taurine Cysteine
Nervous system Transmitter synthesis Adrenergic Phenylalanine
Serotinergic Tyrosine
Glutaminergic Glutamine
Glycine Glycine
Nitric oxide Arginine
Peroxidative protection Taurine Cysteine

Immune system

Cardiovascular

Lymphocyte proliferation Unknown
Peroxidative protection Glutathione

Blood pressure Nitric oxide
regulation

Peroxidative protection Red cell
Glutathione

Glutamine, Arginine, Aspartate
Cysteine, Glutamine, Glycine

Arginine

Cysteine, Glutamine, Glycine

 

34

initiation of mRNA translation. The major mechanism by which amino acid regulate
initiation of translation in mammalian cells include phosphorylation of eukaryotic
initiation factor-2a (eIF20t) which becomes a competitive inhibition Of eIF2B, thereby
making eIFZB inactive [7 5]. Since translation of essentially all mRNAs involve eIF2B,
phosphorylation of eIF2a (which renders eIFZB inactive) results in a decline in the
synthesis of almost all proteins. The effect of deprivation of essential amino acids on
translation inhibition is summarized on Fig. 2. As can be noted, deprivation of essential
amino acids inhibits the initiation phase of mRN A translation at one or more steps,
including those involving eukaryotic initiation factors - elF20t, elFZB, elF4E and S6 (rp

S6). A study of a DNA micro-array global analysis of gene expression in the liver of rats

 

Deficiency of Essential Amino Acids

 

 

 

 

 

 

elF4E rp S6
- Inhibition of eIF2B - Reduced eIF4F assembly -Decreased translation of
activity mRNSs with 5’terminal
- Decreased translation of oligopyrimidine (TOP)
- Decreased translation of most mRNAs e. g. ribosomal proteins,
essentially all mRNAs elongation factors etc

 

 

 

 

 

 

 

 

 

Fig. 2: Effect of deficiency of essential amino acids on gene translation.

35

fed inadequate and poor quality protein diet (wheat gluten) for one week revealed that,
the deprivation of essential amino acids caused changes in the expression of 111 genes.
When the animals were fed a protein-free diet for the same period of time, changes were
observed in the expression of 281 genes.

Among the genes affected were the Id proteins (inhibitor of DNA binding), which
are used in the regulation of multiple genes involved in various metabolic pathways [79].
Continuous supply of a complete complement of essential amino acids is thus a pre-
requisite for maintenance of optimal rates of protein synthesis. Deficiency of even single
essential arrrino acids causes a decrease in the synthesis of essentially all the cellular
proteins through an inhibition of the initiation phase of the mRNA translation and impairs
gene expressions for a number of key biochemical pathways. Deficiency of any essential
amino acids also affects feeding behaviors [80]. Studies based on animal models have
shown that animals rapidly reduce intake of diets deficient in any one of the essential
amino acids [81- 88]. Low plasma concentration of essential amino acids is associated
with decreases in the concentrations of limiting amino acids, norepinephrine and cyclic
medroxyprogesterone acetate and with altered protein synthesis. These changes are
sensed by the anterior pyriform cortex of the brain. In response, the brain induces release
of serotonin that mediates development of taste aversion at the level of the vagus. As a
result, animals modify their meal patterns by reducing both meal size and meal fiequency
[88]. This adaptive method has advantage to animals because it helps them to minimize
tissue breakdown to maintain nitrogen balance since essential amino acids are not stored
in the body [88]. The hypophagic behaviors shown in animals fed imbalanced protein or

low protein diets are similar to those observed in malnourished children fed low-protein

36

starchy diets. Many studies in developing countries [53] have cited anorexia and apathy
as sone of the major reasons for inadequate nutrient intake from traditional weaning
foods.

According to WHO/UNICEF [42], the recommended protein densities in
supplementary foods for children receiving low or no breast milk are 1.1-g/ 100 kcal (6 —
8 mo), 1.0 g/lOO kcal (9 — 11 mo), and 0.9-g/100 kcal (12 — 23 mo). For children
receiving an average amount of breast milk, the protein density recommended for their
supplementary foods is 0.7-g/ 100 kcal for all ages from 6 to 23 mo. Protein in

supplementary foods should be of high quality with high digestibility.

2.5.2.4 Micronutrient Density

Micronutrients are essential for the various physiological and metabolic processes
of the body. The most common “problematic nutrients” (those for which there is most
discrepancy between their content in supplementary foods and the amount required by
infants and young children) are iron, zinc, vitamin A and to some extent, calcium. Iron
has several vital functions in the body. It serves as a carrier of oxygen to the tissues fiom
the lungs by the red blood cell hemoglobin, as a transport medium for electrons within
cells and as an integrated part Of important enzyme systems in various tissues. Several
iron-containing enzymes (cytochromes) act as electron carriers within the cells by
transferring energy within the cells, especially in the mitochondria. Other key functions
of iron-containing enzymes (e. g. cytochrome P450) include the synthesis of steroid
hormones and bile acids, detoxification of foreign substances in the liver, and signal

controlling in some neurotransmitters e. g. dopamine and serotonin systems in the brain.

37

The role of iron in the growth of children has been shown in several studies [89,
90]. Iron supplementation of young children has shown a positive impact on both length
and weight gains, although a greater improvement was noted on the weight gain [89]. In a
study of Kenyan school children, iron supplementation improved appetite and doubled
the rate of weight gain [90]. The major limitation with the iron supplementation studies is
that the supplementation trials take only 2 — 3 months, which is long enough to treat
anemia, however this period is too short too detect improvement in the linear growth
[91].

Like iron, zinc is an essential component of a large number (> 300) of enzymes
participating in the synthesis and degradation of carbohydrates, lipids, proteins and
nucleic acids as well as in the metabolism Of other micronutrients [92]. Zinc stabilizes the
molecular structure of cellular components and membranes and contributes in this way to
the maintenance of cell and organ integrity. Furthermore, zinc has an essential role in
polynucleotide transcription and thus in the process of genetic expression. Its
involvement in such ftmdamental activities probably accounts for the essentiality of zinc
for all forms of life [92]. Zinc also plays a central role in the immune system, affecting a
number of aspects of cellular and hurnoral immunity [92].

Investigations of the impact of zinc supplementation on the growth of infants and
young children in developing countries have shown positive impact on improving
children’s linear growth. Example, providing a zinc supplement of 10 mg/day to 3 - 5
year old children resulted in significant increases in length within 6 months [93]. Several

studies have also demonstrated that zinc supplementation increases the rates of growth

38

r
:5

la

during recovery from severe malnutrition and reduces the rates of morbidity among
children [94, 95].

Vitamin A (retinol) is needed in small quantities by humans for the normal
functioning of the visual system, growth and development, and maintenance of epithelial
cellular integrity, immune function and reproduction. Vitamin A cellular functions are
mediated through specific nuclear receptors. These receptors are activated when they
bind with specific retinoic acid isomers (i.e. all-trans and 9-cis retinoic acid). The
activated nuclear receptors bind to DNA response elements to regulate the level of
expression of those genes [96]. The synthesis of a large number of proteins, vital to the
maintenance of normal physiological functions of the body, is regulated by these
retinoid-activated genes [96]. Supplementation of vitamin A to infants and young
children has shown a significant impact on reducing night blindness and xerophthalrnia,
improving weight gain and reducing the risk Of morbidity and mortality [89].

Meeting the micronutrient requirements of infants and young children fi'om
supplementary foods passes the greatest nutritional challenge. In many cases, plant-based
supplementary foods cannot provide adequate amount of iron, zinc, vitamin A and
sometimes calcium without addition of animal products or fortifying with micronutrients.
The recommended [42] densities for the “problematic” and other rrricronutrients in the
supplementary foods for children receiving low or no breast milk are summarized in
Table 4. Recommended iron concentrations for the moderately bioavailablc heme-iron
range from 2.3 mg/ 100 kcal for children aged 6 — 8 mo to 0.6 mg/ 100 kcal for those in
age 12 — 23 mo. For children receiving average amount of breast milk, the recommended

iron densities in their supplementary foods are 4.0-mg/ 100 kcal (6 — 8 mo), 2.4-mg/ 100

39

kcal (9 — 11 mo), and 0.8-mg/ 100 kcal (12 - 23 mo). For iron with low bioavailability
e.g. non-heme iron, higher densities of iron per 100 kcal would be needed to meet the
nutritional needs of the children (see Table 4). The recommended densities of zinc for
children receiving low or no breast milk range from 1.0 mg/ 100 kcal for children age 6 -
8 mo to 0.6-mg/ 100 kcal for children aged 12 - 23 mo. For children receiving average
amount of breast milk, the recommended zinc densities in the supplementary foods range
fiom 1.6-mg/ 100 kcal for children aged 6 — 8 mo to 0.8-mg/ 100 kcal for those in age 12 —
23 mo [42].

For vitamin A, the recommended densities for children receiving low or no breast
milk are — 35-ug RE (Retinol Equivalents)/ 100 kcal (6 — 8 mo), 32-ug RE / 100 kcal (9 -
11 mo), and 3l-ug RE / 100 kcal (12 — 23 mo) while those receiving average amount of
breast milk, the recommended vitamin A densities in the supplementary foods range from
5-ugRB / 100 kcal for 6 — 8 mo old children to 17-ugRE / 100 kcal for those aged 12 — 23
mo (Table 4). The recommended densities of calcium for children receiving low or no
breast milk range fiom 91-mg/ 100 kcal (for 6 —- 8 mo old children) to 30-mg/ 100 kcal (12
— 23 mo old children) while those receiving average amount of breast milk, the
recommended calcium densities in the supplementary foods range fiom 125-mg/ 100 kcal
(for 6 — 8 mo Old children) to 26-mg/ 100 kcal (for 12 -— 23 mo Old children) (see Table 4).
The recommended densities for the other micronutrients in the supplementary foods for
children of various age groups are summarized in Table 4.

Based on the recommended micronutrient densities, it is practically very difficult
to supply enough iron from unmodified supplementary foods based on cereal-legume

mixtures to meet the required needs of infants at 6 — 11 months of age. To meet

40

Table 4: Desired nutrient density of supplementary foods (per 100 kcal) by level of breast
milk intakel

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6 - 8 months 9 - 11 months 12 - 23 months
. Breast milk intake Breast milk intake Breast milk intake
Nutrrent
Low Avg High Low Avg High Low Avg High
Protein (g) 1.1 0.7 0 l 0.7 0 0.9 0.7 0.2
Vitamin A 35 5 0 32 9 0 31 17 0
W)

Folate (pg) 0 0 0 l 0 0 3 0 0
Niacin (mg) 0.6 1.1 4.1 0.7 0.9 1.7 0.8 0.9 1.4
Pantothenic acid 0.2 0.2 0 0.2 0.1 0 0.1 0.1 0
(mg)
Riboflavin (mg) 0.06 0.07 0.14 0.04 0.04 0.04 0.05 0.05 0.06
Thiamin (mg) 0.02 0.04 0 0.03 0.04 0.04 0.05 0.05 0.06
Vitamin B6 (mg) 0 0 0 0 0 0 0 0 0
Vitamin B]; (pg) 0 0 0 0.01 0 0 0.03 0 0
Vitamin C (mg) 2.2 0 0 2.1 0 0 2.3 1.1 0
Vitamin D (pg) 1.5 2.5 8.9 1 1.5 2.8 0.7 0.9 1.3
Vitamin K (pg) 2 3.3 11 1.4 2 3.5 1 1.2 1.6
Calcium (mg) 91 125 345 67 78 112 30 26 19
Chloride (mg) 74 81 123 57 53 42 73 76 84
Copper (pg) 0.04 0.04 0.14 0.03 0.02 0.04 0.04 0.04 0.04
Fluoride (pg) 0 0 0 0 0 0 0 0 0
Iodine (pg) 4 0 0 4 0 0 5 1 0
Iron (Med 2.3 4 14.7 1.6 2.4 4.7 0.6 0.8 1.2
bioav) (mg)
Magnesium (mg) 13 19 56 10 13 20 8 1 1
Manganese (pg) 3 4 l4 2 3 4 l 2 2
Phosphorus (mg) 75 114 360 54 70 116 25 26 29
Potassium (mg) 109 129 258 83 84 86 71 69 64
Selenium (pg) 0.6 0 0 0.7 0 0 1.1 0.5 0
Sodium (mg) 54 74 197 45 53 77 47 54 68
Zinc (mg) l 1.6 5.2 0.7 1 1.7 0.6 0.8 1.1

 

 

The categories Low, Average and High correspond to breast milk intake being mean -28D, mean and
mean +28D. Adapted fi'om WHO/UNICEF [42].

41

 

children’s needs for iron, they need to take large amounts of iron-rich animal foods such
as liver, fish and/or beef. Due to large quantities of these foods that would need to be
consumed to meet the iron requirements, supplementary foods designed for children < 23
months require to be fortified with iron [42]. Likewise, it is very difficult to meet zinc
requirements from unmodified supplementary foods at 6 - 8 mo of age unless there is a
high intake (totaling about 50 — 70 g/day) of liver, dried fish, milk powder, eggs, chicken
and/or beef [42]. At 9 — 12 mo of age, zinc needs can be met by relatively high intake (50
— 200 g/day) of zinc-rich foods. Sandstead [97] reported that zinc deficiency is more
prevalent in areas of the developing world where diets are low in animal products and
high in phytates e. g. where diets are based on maize, legume, whole wheat or unpolished
rice. In many parts of developing countries therefore animal food sources are scarce and
expensive and the practicality of such high intakes of animal foods for children is
questionable. The only practical alternative to supply adequate zinc in the supplementary
foods is thus to fortify with multi-nrinerals containing zinc [42].

Vitamin A requirements can be met from supplementary foods if good sources of
vitamin A such as liver, leafy greens, milk, eggs, cheese and some orange or red fruits are
incorporated. For infants aged 6 - 11 mo, the amounts of these foods required to supply
adequate amount of vitamin A or pro-vitamin A are not large (generally 1 — 50 g/day) in
part because breast milk is a rich source Of the vitamin. In situations where the red-palm
oil or other local food sources of easily absorbable precursor carotenoids are available
and can be incorporated into the supplementary foods, vitamin A requirements can be
met readily [42]. Likewise, calcium needs can be met if sufficient amounts of milk

products or fish (including the soft bones) are consumed. About 20 — 35 g/day of milk

42

powder or dried ground fish would provide adequate calcium for infants 6 — 11 mo of age
while 12 - 20 g/day of the same would meet the calcium needs for children at 12 — 23 mo

of age [42].

2.6 Processing of Supplementary Foods

The aims Of food thermo-processing are to make the food edible by developing
appealing texture, color, taste and flavor; pasteurizing/sterilizing the food and making it
rrrierobiologically safe, destroying natural toxins and anti-nutrients such as
phytohemagglutinins, enzyme inhibitors and cyanogenic glycosides; improving nutrient
digestibility and bioavailability, improving the shelf-life and making foods more
convenient for use [98]. There are a variety of thermo-processing methods that are
commonly used in food preparation such as baking, roasting, frying, conventional
cooking, drum processing and extrusion.

Selection of any one of these processing methods is influenced by a number of
factors including the nature and type of ingredients to be processed and the product
desired e. g. ready-to-eat products, availability of equipment and the cost of production.
WHO/UNICEF [42] recommends the use of low-cost extrusion and drum processing for
making supplementary foods in developing countries because these methods are low-cost

and they give products of high nutritional and sanitary quality.

2.6.1 Extrusion

Food extrusion is a process in which a food material is forced to flow, under one

or more varieties Of conditions of mixing, heating and shear, through a die that is

43

designed to form and/or puff-dry the ingredients. The use of extruders for food cooking
has been expanding rapidly in the food industry over the past few years due to their
versatility, high productivity, efliciency, hygiene conditions and low operation cost [99].
Extrusion involves hi gh-temperature-short-time processing which is able to denature
enzymes, inactivate antinutritional factors such as trypsin and chymotrypsin inhibitors,
and kill microorganisms present in food materials to render the food sterile. High-
temperature-short-time treatment also improves digestibility of the food ingredients by
gelatinizing starches or heat treating proteins while minimizing detrimental reactions
such as the loss of lysine through reactions with reducing sugars in browning reactions,
or reduction in the activity of enzymes [100, 101]. Other advantages of extruders include
ability to provide texture and shape to food constituents e. g. ready-to-eat cereals and
snacks, texturization of vegetable proteins to form fiber-like structures used as meat
analogs.

There are four types of extruders commonly used in food processing. These
include single screw, twin screw, dry extruders and interrupted flight screw extruders.
Single screw extruders are available in a number of sizes and shapes and their screw,
barrel and die configurations can usually be varied to suit a particular product’s
specifications [100]. Single screw extruders are classified into cold forming extruders
(low-shear machines with smooth barrels, deep flights and low screw speed), high
pressure forming extruders (low-shear machines with grooved barrels and compression
screws), low-shear cooking extruders (moderate—shear machines with high compression
screws and grooved barrels to enhance mixing but no puffing), collet extruders (high-

shear machines with grooved barrels and screws with multiple shallow flights to enhance

heating and puffing) and high-shear cooking extruders (high-shear machines, with screws
for changing flight depth and/or screw pitch to increase compression, pressure, heat and
puffing). These extruders may be adiabatic (autogenous) - generate all the heat by
friction in the barrel, isotherrnic — Operate at constant product temperature throughout the
entire length of the barrel or polytropic extruders - with provision to alternatively add or
remove heat depending on the specific process [99].

Collet extruders are the most commonly used machine for the production of
various low-cost puffed snacks and instant foods. They are designed to create extremely
high-shear environment within the flights Of the screws and grooves in the barrel. No
external heat is usually applied to the barrel and the entire heat input comes fiom the
viscous dissipation of mechanical shaft energy applied to the extruder. The short-barrel,
short flighted screws and high shear of the typical collet extruder limits its operations to
low-moisture ingredients that are used to produce highly expanded products e. g.
instant/convenience foods.

Collet extruders vary in Sizes and shapes and their screws, barrel and die
configuration can be varied to suit specific product’s cooking and shaping requirements.
Jacketed barrels, direct steam injection, and hollow screws fitted for cooling water or
steam help to regulate and control the extrusion operations. The wide range of moisture
contents (12 — 40%), wide variety of feed ingredients, cooking temperatures (80 — 200°C)
and controllable residence times, make the collet extruders greatly versatile. Table 5
shows the major classes of cooking extruders with typical operating data. As
requirements move from a low-temperature and-shear machine to a high-temperature-

and-shear extruder, several significant features change in the extruder design and

45

operation. The low-temperatIIre-and-shear extruder is characterized by the use of high
moisture foods, relatively deep flighted screws and low screw Speed. Under these
conditions, little mechanical energy input is dissipated as heat and the net energy per unit
mass of extrudate is low.

Conversely, high temperature-and-shear extruders operate on relatively low
moisture feeds with shallow flighted screws that result in high-shear rates and a
significant amount of heat energy entering the food product from viscous dissipation.
Example; a high-temperature-high-shear extrusion profile and screw configuration for
wheat flakes is as follows: - material — wheat flour, moisture content — 12.17%, feed rate
- 3.6 kg/h, moisture injection — 9%, screw speed — 300 rpm, barrel temperatures — 70°C
(zone 1), 100°C (zone 2), 122°C (zone 3), 143°C (zone 4), and 131°C (zone 5); product
temperature - 148°C, die pressure — 410 psi, die size - 3 mm, and torgue — 55.1%. Screw
configuration: - 8D (8 twin lead (TL) screws), 7x30° (7 forward kneading paddles (FKP)
at an angle of30°), 4D (4 TL screws), 4x60° (4 FKP at an angle of 60°), 4x30° (4 reverse
kneading peddles (RKP) at an angle of 30°), 2D (2 TL screws), 6x60° (6 FKP at an angle
of 60°), 4x300 (4 RKP at an angle of 30°), 1D (1 single lead (SL) screws), 7x900 (7 FKP
at an angle of 90°) and 2D (2 SL screws).

For a low-temperature-and-shear wheat product the screw configuration is as
follows:- 8D - (8 TL screws), 7x300 (7 FKP, at an angle of 30°), 8D (8 TL screws), 3x600
(3 FKP, at an angle of 60°), 3x30° (3 RKP, at an angle of30°), 2D (2 SL screws), 4x60°
(4 FKP, at an angle of 60°), 3x30° (3 RKP at an angle of 30°), and 2D (2 SL screws).

Screw diameter equals 19.0 mm (1 D) and one kneading paddle = ‘/4 D [102].

46

Table 5: Major classes of cooking extruders with typical Operating data‘

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Extruders — typical ograting data

Measurement Low-shear High- Low-shear Collet High-

Forming pressure cooking shear

forming cooking
Food moisture (%) 22 25 28 l l 15
Product moisture (%) 22 25 25 2 4
Max product temperature 52 79 149 199 149
(0C)
Screw diameter/flight 6 4.5 7 — 15 9 7
heig_ht ratio (D/H)
No.0fparallelscrew 1—2 1 1 2—4 1—3
fligts, p
Screw speed (rpm) 30 40 60 300 450
Shear rate in screw (sec") 9.5 9.5 22 - 47 140 165
Mechanical energy input 0.05 0.11 0.11 0.20 0.36
(kw-hr/kg)
Part of mechanical energy
dissipated as heat (kw- 0.02 0.03 0.02 0.10 0.11
hr/kg)
Heat transfer from barrel 0 0 0.05 0 -0.04
jackets, g, tkw-hr/kg)
Net energy input to 0.02 0.03 0.07 0.10 0.07
product (kw-hr/kg)
Soups Puffed Textured
RTE bases, sofi “instant” vegetable
Product type Pasta Cereals moist products protein
products

Adapted from Harper [100].

The screws are the central components of an extruder and their configuration

greatly influences the quality of the extruded product. Large extrusion screws

(length/diameter > 10) tend to have greater operating flexibility and allow greater

47

 

precision of control of the extrusion process. Usually, screws in the feed section of the
barrel contain deep flights, which easily accept food materials and begin to convey them
down the barrel. During conveying process, the food materials are worked into a
continuous mass and the air and voids are expelled such that the flights of the screws are
completely filled.

The compression or transition section of the barrel (middle) contains screws with
small flight heights, which restrict the cross-sectional area of the screw for flow. This
restriction or compression increases the shear rate and mechanical energy input to the
food, resulting in temperature rise. In some cases, screws are configured to reverse the
flow of the materials, which increases the shear, pressure, heat, and the residence time of
the food. Screws in the metering section of the barrel (end) have very shallow flights or
flights with decreasing pitch. In this section, the shear rate is very high, internal mixing
is increased dramatically and the dissipation of mechanical energy is at a maximum.
Correspondingly, the temperature rise in the metering section is very rapid and reaches
maximum just before the product emerges from the die. The puffed extrudates are usually

chopped or molded to desired shapes [99, 100].

2.6.2 Drum Processing

Drum processing involves use of twin-counter rotating, smooth surfaced drums
which are heated by steam or electric coils. A raw or pre-cooked slurry (~ 80 — 90%
water) of cereal, legume, food mixture or other suspended ingredients is spread in a thin
layer on the surface of the slowly rotating drums where the food gets cooked and dried

very quickly. The cooked, dry product is scraped from the drums surfaces before they are

48

recoated with slurry. The speed of the rotating drums is adjusted to increase/reduce the
product residence time on the drums. Likewise, the amount of heat in the drums can be
adjusted to regulate the cooking/drying process [44, 102]. Drum cooking is commonly
used for processing cereal and tuber flours and mixes (e.g. corn, sorghum, rice, wheat and
oats) and vegetable proteins (e. g. defatted soy flour). In some developing countries, drum
processing has been used to produce low-cost nutritious supplementary foods for children
[103]. The thin, dry, well-cooked flakes produced by drum processing are highly soluble
in water. This physical-chemical property makes drum processed products particularly

suitable for Older infants and young children [103].

2.7 Evaluating the Quality of Processed Foods

The quality of a supplementary food is influenced by both the quantity and the
relative proportions of the essential nutrients. A high quality product must contain
adequate amount of all the essential nutrients in the right proportions for supporting
optimal growth. It must also be - free of toxins and anti-nutrients, well cooked,
organoleptically acceptable and shelf-stable for a reasonable length of time. For ready-to-
eat supplementary foods, the key quality parameters include, protein digestibility-
corrected amino acid score, starch gelatinization and dextrinization rate, sensory quality

and acceptance, and the shelf-life.

2.7 .1 Protein Quality
The importance of protein to overall diet and health has been recognized for many

years; however, the quality of protein sources has been a subject of debate. Food proteins

49

vary greatly in their content of amino acids. Both plant and animal proteins are made up
of about 20 common amino acids, but only nine are essential. The concept Of essentiality
of amino acids underlies the whole concept of protein quality. According to Mercer et al.
[104], proteins are divided into three categories based on their absolute or relative
importance in protein synthesis in vivo: 1) indispensable amino acids — histidine,
isoleucinele, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and
valine; 2) conditionally indispensable amino acids — arginine, cysteine, and tyrosine; and
3) dispensable anrino acids — alanine, aspartate, aspartic acid, glutamine, glutarnic acid,
glycine, proline, and serine. Other amino acids have also been classed as indispensable
due to their specific physiological roles in promoting growth in children, preventing
diseases and maintaining a positive nitrogen balance in children and adults. These amino
acids are — taurine (for infants and feline), cysteine (for pro-term infants, older children
with metabolic disorders and malnourished patients suffering fi'om compromised liver
function such as cirrhosis), Tyrosine (for preterm infants, malnourished children and the
elderly) and basic amino acids — arginine, citrulline, omitlrine (for urea cycle) [72, 105,
106].

Protein quality is influenced by the concentration of both essential and non-
essential amino acids making up the protein. The greater the proportion of the essential
amino acids, the greater is the biological value or quality. Proteins that are deficient in
one or more of the essential amino acids are of poor quality and this is usually reflected
in their amino acid scores. Example, tryptophan and lysine are limiting in corn, lysine in

wheat and other cereals, and methionine in beans and other legumes.

50

2.7.1.1 Effect of Digestibility on Protein Quality

The effect of digestibility on protein quality has been widely reported [107 - 109].
Digestibility involves breakdown of large molecules e. g. protein to simple constituent
components 6. g. amino acids that can be absorbed into the body. Digestibility of protein
is facilitated by a number of hydrolytic enzymes such as trypsin, chymotrypsin, pepsin,
rennin (infants), carboxypepsidase and aminopepsidase. When a protein molecule cannot
be hydrolyzed into simple, absorbable amino acids, the protein is excreted undigested
through the feces. Likewise, if a protein is poorly digestible (cannot be hydrolyzed
completely), it limits the arrrino acid availability since only part of the protein is utilized
by the body. The indigested protein fiaction is lost through the feces. Digestibility
therefore influences the proportion of the ingested protein that would ultimately be
utilized by the body. When digestibility of a protein is low, so also the amount of its
constituent amino acids that would be absorbed into the body. Example, egg protein has a
digestibility rate of 99% and thus most of the protein (99%) is digestible and can be
utilized by the body. Its biological value is therefore very high. Conversely, bean protein
whose digestibility rate is 80% has only 80% of its protein digestible and utilizable while
20% of the bean protein is excreted in the feces.

The effect of digestibility on protein quality affects also availability of its
constituent amino acids. For example, isolated soy protein has 26 mg of histidine per
gram of protein. The digestibility rate for soy protein is 97%. This means that, out of 26
mg of histidine reaching the small intestine, only 25.2 mg would be absorbed while about
0.78 mg would be lost in feces. In the light of the foregoing, digestibility is an important

determinant of protein quality. Food proteins with high digestibility rate are of high

51

quality while those with low digestibility are Often of poor quality. Since digestibility
affects the amount of amino acids that are absorbed by the body, it thus affects growth
performance of the subjects fed on those proteins. Highly digestible proteins may thus
induce greater growth performance relative to poorly digestible proteins. A food with
high protein density may fail to elicit good growth if it is poorly digestible. Improving the
protein digestibility of a food may thus improve its protein quality.

Protein digestibility is determined by measuring nitrogen in food and in feces.
Apparent crude protein digestibility is given by the relationship:
Apparent crude protein digestibility (%) = {(total N consumed - total fecal N) x 100}/
total nitrogen consumed.
True crude protein digestibility (%) = [{total N consumed — (total fecal N - metabolic
fecal N)} x 100]/ total nitrogen consumed.
The focal nitrogen output on a nitrogen-free (non- or low-protein) diet provides the
estimate of metabolic fecal nitrogen i.e. nitrogen not derived from undigested residue of
foods such as microbial proteins, unabsorbed residue of gastrointestinal secretions and
mucosal cells of the intestinal lining [107]. Since true protein digestibility measurements
take into account the metabolic fecal nitrogen that is not of dietary origin, true protein
digestibility of a food is always higher that the apparent digestibility. Apparent protein
digestibility values increase with increase in food intakes whereas the true protein
digestibility values are not independent of protein intake [107]. Therefore, true rather
than apparent digestibility of protein and amino acids would provide more accurate value
for comparing different diets or protein sources and for diet formulations. Digestibility of

crude proteins varies widely among foods. While proteins in animal foods are often

52

highly digestible, proteins in plant foods e.g. cereals and grain legumes are often poorly
digestible [39].

There are several factors that influence protein digestibility. These include:
Structure of protein - the protein configtnation and amino acid bonding. Fibrous protein
such as collagen, keratins, and elastin tend to be insoluble, tough and resistant to
digestion. Conversely, globular protein such as alburnins, globulins and histines tend to
be fairly soluble with high solubility [108]. Example, inaccessibility of native phaseolin
protein by enzymes has been attributed to its structural constraints and its compact
structure [109]. Interaction of the phaseolin protein with carbohydrates to form stable
glycoproteins and the stearic hindrances of the proteases created by the saccharide chain
contributes to the difficulty of proteases to cleave the hydrogen and sulfirr-sulfirr bonds
near the glycosylation sites.

Presence of natm'al protease inhibitors also affects protein digestibility. During
processing and cooking, most of these inhibitors are inactivated; however, residual levels
of active inhibitors may remain, particularly in improperly cooked foods. Presence of
trypsin and chymotrypsin inhibitors in foods such as legumes has been reported to reduce
protein digestibility [110, 111]. Also, phytates have been implicated in protease inhibition
and therefore may affect protein digestibility. Production of adequate amounts of
digestive enzymes is a major determinant of protein digestibility. Trypsin acts t break-up
peptide linkages in the carboxyl sides of arginine and lysine. It also activates conversion
of chymotrypsinogen and procarboxydases to active forms chymotrypsin A, B, and C and
carboxydase A ad B. Chymotrypsin A, B and C all act to break peptide linkages on the

carboxyl side, but chymotrypsin A also acts on linkages next to phenylalanine,

53

tryptophan and tyrosine, chymotrypsin B acts on linkages next to leucine, while
chymotrypsin C acts on linkages next to methionine and glutamine [108].
Carboxypeptidase A breaks the peptide linkage on terminal amino acid that have a free
carboxyl group, but also aromatic and aliphatic side chains while carboxypeptidase B
slits off only the basic amino acids. Aminopeptidase on the other hand splits off the
terminal amino acids to form free amine groups. Any antinutritional factor e. g. lectins or
disease conditions e.g. Celiac’s sprue that causes absolute or apparent lack of these
digestive enzymes may cause significant decrease in the digestibility of food proteins and
hence lowering their biological quality [108, 109].

Formation of complexes between proteins and starch, hemicellulose, polyphenolic
compounds, fiber, and minerals greatly limits their digestibility. The decrease in protein
digestibility could be due to physical entrapment, premature release of food particles
fiom the stomach and/or direct inhibition of digestive enzymes [110]. Example,
conjugated proteins formed when protein interacts with lipids, metals, nucleic acids
and/or carbohydrates have different digestibilities depending on the nature of chemical
bonding formed [108]. Polyphenols on the other hand have been shown to form insoluble
complexes with protein, making the complexed proteins less susceptible to proteolysis
[112]. Polyphenolic compounds have been related to reduced digestibility of chickpeas
[113], drybeans [114] and the phaseolin protein Ofdry beans [109, 115]. Newman et al.
[116] reported also that the true digestibility of chickpeas was inversely associated with
their fiber content while Hughes [117] reported from a rat study that soluble dietary fiber
reduced significantly the digestibility of dry beans protein and increased the fecal

nitrogen.

54

Thermo-processing greatly improves digestibility of most protein fractions
however, heat treatment may reduce digestibility of other protein fractions. Example, an
in vivo study by Antunes and Sgarbieri [118] and an in vitro study by Sathe et al. [119]
indicated that heat treatment improved the digestibility of both albumin and globulin
fractions fi'om beans (Phasealus vulgaris). However, in vitro studies by Marguez and
Lajolo [120] and Deshpande and Nielesen [121] suggested that the digestibility of
albumin fraction might be reduced upon thermo-processing. Protein-protein interactions
in the albumin fraction apparently lead to the formation of hi gh-molecular weight
aggregates that are not readily degraded by the digestive enzymes. Other processing
conditions such as treatment with oxidizing agents (such as hydrogen peroxide which is
used widely in the food industry), organic solvents, alkalis and acids may result in the
formation of Maillard compounds (reaction of sugars with free NH2 group of lysine and
other amino acids), oxidized forms of sulfur amino acids (such as methionine sulfoxide,
methionine sulfone and cysteic acid), in racemization of optically active amino acids and
formation of cross-links in the protein (such as lysinoalanine, ornitlrionalanine and
lanthionnine), all of which tend to make amino acids less available, and in general the

protein less digestible [107].

2.7.1.2 Methods for Evaluating Protein Quality
Evaluating the adequacy of the protein component of a human diet is essential in
estimating the amount of the protein that is biologically available and utilizable. Such

estimates depend on the total amount of protein consumed, its quality and digestibility.

55

The common methods that are used to evaluate the quality of protein are in viva (using

e.g. rats, pigs, chicks or young children’s growth) and in vitro [47, 122].

2.7.1.2.1 In Vivo Methods

Rat growth assays are widely used for predicting protein quality in foods [123].
The most common rat growth models include:
(i) Protein efliciency ratio (PER) = weight gain of test group/protein consumed by the
test group. The most serious criticism of the PER assay is its inability to properly credit
protein used for maintenance purposes. A protein source may not support growth and
have a PER near zero, yet may be adequate for maintenance purposes. Due to the error
introduced by not making allowance for maintenance, the PER values of proteins of
differing quality are not proportional in protein quality to each other i.e. a PER of 2.0
cannot be assumed to be twice as good as a PER of 1.0. The lack of proportionality to
protein quality makes the PER method unsuitable for the calculation of utilizable protein
such as in protein rating (protein in a reasonable daily intake, g x PER), which is the
official method of evaluating protein claims in some countries e.g. Canada [123]. The
PER, which measures the ability of a protein to support growth in young rats, also
sevme overestimates the value of some animal proteins for human growth while
underestimating the value of some vegetable proteins for that purpose [124]. The more
rapid growth rate of rats, which increases their needs for certain essential amino acids
compared to humans and the differences between the amino acid requirements of rats
against humans are the reasons for this discrepancy.
(ii) Net protein ratio (NPR) = (weight gain of test group + weight loss Of non-protein
group)/protein consumed by test group. NPR method credits protein used for both growth

56

and maintenance. The method assumes, however, that the protein required to prevent
weight loss of the rats fed the non-protein diet is equivalent to the amount required for
maintenance purposes [123, 124]. As normally carried out, NPR values are uncorrected.
(iii) Biological Value = (retained nitrogen/absorbed nitrogen x 100).

(iv) Net protein utilization (NPID = (body nitrogen of test group — body nitrogen of group
fed non-protein diet) x 100/nitrogen consumed by test group. Both BV and NPU rate
proteins on a scale of 1 to 100.

(v) Relative NPR (RNPR) = NPR of test protein expressed relative to a value of 100 for
NPR of reference protein. RNPR is a corrected NPR and expressed in a scale of l to 100.
It is a modified NPU method (based on weight) that is shorter (2 wk) than the standard
PER method (4 wk). It is thus less expensive. Unlike PER values, RNPR values are
proportional to each other in protein quality within reasonable limits, are more accurate,
and more reproducible. RNPR is a better predictor of protein quality for human infants
than the other methods based on animal growth. RNPR method has a number of
weaknesses. RNPR method overestimates the quality of lysine-deficient proteins for the
rats [123]. Also, in the standard PER and NPR methods, foods are tested at 10% dietary
protein, and unsupplemented casein is used as the reference protein. However, diets
containing 8 - 10% protein from unsupplemented casein do not meet rat growth
requirements for sulfur amino acids [125]. Therefore, methionine supplemented casein
was used as the reference protein in the determination Of RNPR. Since it is now well
known that the requirements of rats for methionine + cysteine are much higher than those
of humans, then any rat growth assay (especially those which do not credit protein used

for maintenance such as PER) will underestimate the protein quality for humans

57

especially for products limiting in sulfirr amino acids such as soybean protein products,
peanuts, and legumes or pulses. Modifications for higher essential amino acids
requirements of rats compared with humans have been suggested for accurate prediction
of protein quality for humans by rat bioassays [123].

(vi) Corrected RNPR (CRNPR) = RNPR x Factor (1.5). Studies comparing the essential
amino acid requirements of rats and humans [126] Showed that, rat requirements for
sulfur amino acids was about 50% higher than that of humans, whereas the difference
between the requirements for other essential anrino acids were relatively small. Based on
these comparisons, a factor Of 1.5 was selected to correct the RNPR values (casein +
methionine = 100) of food products deficient in sulfur amino acids for rat growth. The
major limitation with CRNPR is that, it cannot be used to predict appropriately the
protein quality for infants because of higher essential amino acids requirements of infants
compared to adults and children [127]. Also, the CRNPR method cannot discriminate
against proteins deficient in sulfur amino acids because only the proteins deficient in
sulfur deficient amino acids are supposed to use the factor of 1.5. The use of the constant
factor 1.5 regardless of the degree of deficiency in sulfur amino acids can introduce a
significant variation in the total amount of sulfur amino acids in the diets. F A0 [128]
suggested the use of the correction factor basing on the total sulfur amino acids content of
the test proteins, however, this approach made the CRNPR method very inefficient
because its calculation would also require determination of total sulfirr amino acids.
Moreover, the accuracy of the sulfur anrino acid requirements of growing rats that would

be used in the CRNPR method would be a source of disagreement.

58

2. 7.1.2.2 In Vitro Methods

In theory, the most logical approach for evaluating protein quality is to compare
amino acid content of food with human amino acid requirements. Resulting amino acid
scores may be calculated from the content of the single most limiting amino acid or from
2, 3, 4 or 5 key essential amino acids (which are likely to be deficient in mixed human
diets) such as lysine, methionine, cysteine, threonine and tryptophan. The validity of
amino acid scoring procedures has been limited by lack of standardized and reproducible
procedures for determining tryptophan, methionine and cysteine. Insufficient data on
digestibility of protein and bioavailability of amino acids in foods and the uncertainty
about human amino acid requirements to be used for the scoring pattern have added to
the invalidity [128]. In the recent years however, significant advancements have been
made in standardizing amino acid methodology, in reaching a consensus about human
amino acids requirements and in Obtaining information about digestibility of protein and
bioavailability of amino acids in a number of protein sources [129]. These developments
have facilitated the use of amino acid scoring procedure that is a better predictor of
protein quality for humans than in viva methods [129].

The protein digestibility — corrected amino acid score method, recommended
initially by the FAQ/WHO Joint Expert Consultation on Protein Quality Evaluation [130]
is based on scoring the amino acids against reference values. The methodology takes into
account three critical parameters of protein quality: i) the food protein’s essential amino
acid profile ii) its digestibility and iii) its ability to supply the essential amino acids in the

amount required by humans. Amino acid requirements of humans vary depending on the

59

ratio of new protein synthesized versus protein that is maintained. Table 6 summarizes
the FAO/WHO/UNU [127] amino acid requirement patterns for various age groups,
including the mean and range recommended for infants and young children.

The protein digestibility — corrected amino acid score of a food protein is
established by comparing the essential amino acid profile of the food, corrected for
digestibility to the FAO/WHO/UNU [127] 2 - 5 year old essential amino acid
requirement pattern. The 2 — 5 year Old requirement pattern is used because it is the most
demanding pattern of any age group other than the infants. To determine the protein
digestibility — corrected amino acid score of a food protein, the following procedure is
used: (i) analyze the proximate nitrogen (N) composition of the food protein; (ii)
calculate the protein content (N x 6.25 or use a specific AOAC [13 1 ]-conversion factor).
For food products consisting of mixed protein sources, the factor 6.25 is used in
calculating protein content and a weighed average procedure based on the proportional
contribution of each protein component in the product is followed [130]; (iii) analyze for
essential amino acid profile; (iv) determine the amino acid score (uncorrected) using the
relationship: Amino acid score (uncorrected) = (mg of essential amino acid in l g of test
protein)/mg of essential amino acids in 1 g of reference protein. Reference protein
essential amino acids profile = FAO/WHO/UNU [127] requirement for 2 - 5 year Old
children; (v) analyze for the protein true digestibility using animal assay; (vi) calculate
the protein digestibility - corrected amino acid score from the relationship: Protein
digestibility - corrected amino acid score = Lowest uncorrected essential arrrino acid

score x protein digestibility.

60

When calculating protein digestibility - corrected amino acid score of a food
protein, any score above 100% is rounded to 100% for further calculations. There is no
nutritional advantage to consuming proteins with scores greater than 100% since the body
does not utilize the excess amino acids. All proteins with a protein digestibility —
corrected amino acid score of 100% complete proteins that meet the essential amino acid
requirements of humans. Food proteins with a protein digestibility — corrected amino acid
score of lower than 100% are of low quality and may fall short of meeting the 2 — 5 year
Old amino acid requirements for growth. Since the protein digestibility — corrected amino
acid score is based on human amino acids requirements and thus is inherently more
appropriate for evaluating protein quality of foods intended for human consurnptions,
FDA [132] adopted it as an official method of evaluating protein quality to replace the
PER. Protein digestibility — corrected arrrino acid score is now being used for nutritional
labeling purposes for all food products intended for young children above one year Old

and adults.

Table 6: Essential amino acid requirement patterns for people of various age groups1

 

Pattern of requirement in mg/ g crude protein

 

Essential amino acid Infants (mean) Infants (range)2 2 — 5 y 10 -— 12 y Adults

 

Histidine 26 18 - 36 19 19 16
Isoleucine 46 41 - 53 28 28 13
Leucine 93 83 — 107 66 44 19
Lysine 66 53 — 76 58 44 16
Methionine + Cystine 42 29 — 60 25 22 17
Phenylalanine + Tyrosine 72 63 — 118 63 22 19
Threonine 43 40 — 45 34 28 9

Tryptophan 17 16— 17 ll 9 5

Valine 55 44 — 77 35 25 13

 

' Adapted fiom FAO/WHO/UNU [127]
2 Amino acid composition of human milk

61

2.7.2. PDCAAS and Protein Requirement

For children and adults, protein is required for two major roles - first, for
maintenance of the normal physiological functions e. g. production of enzymes,
antibodies and hormones, and second, for normal growth e. g. production of new cells and
tissues. Protein requirement for maintenance for children aged 0 — 1 year is estimated at
0.75-g/kg-body weight/day. Maintenance requirement decreases gradually with age,
reaching 0.64 g/kgday at age 18 years. Likewise, the protein component that is required
to support growth is highest in infants and decreases gradually with age. According to
FAO/WHO/UNU [127], the safe protein intakes for people of various age groups are 1.47
g/kgday (0 - 5 mo), 1.15 g/kg/day (7 — 12 mo), 1.09 g/kg/day (3 — 4 years), 0.99
g/kg/day (9 — 10 years), 0.94 g/kg/day (girls 13 — 14 years), 0.97 g/kg/day (boys 13 — 14
years), 0.75 g/kg/day (young adults, 19+ years) ad 0.75 g/kg/day for elderly women.
These protein requirements however have been revised extensively by the International
Dietary Energy Consultative Group [133], Millward [134] and Young and Bergonha
[135] and lower levels of safe protein intakes have been suggested.

Meeting these protein requirements is strongly influenced by the quantity
consumed and the ability of the protein to provide sufficient amounts of the essential
amino acids after digestion. When the quantity of protein ingested is adequate for the age
group and the PDCAAS is 100%, the protein would provide adequate amount of essential
and non-essential amino acids needed for maintenance and growth. Nevertheless, as the
PDCAAS value decreases, the ability of the protein to meet the needs for maintenance
and growth decreases accordingly. For example, when the quantity of a dietary protein is

adequate but the PDCAAS value is low e. g. 80%, the protein would supply essential

62

amino acids that would be enough to support the maintenance component and probably a
limited growth. When the PDCAAS value decreases further, e. g. to 65%, the amount of
essential amino acids supplied from the protein would be adequate to support the
maintenance only and no growth will occur. If the food protein has a PDCAAS value
lower than 65%, the body would not be able to Obtain fiom the diet the necessary
essential amino acids to maintain it. As a result, the body will start breaking down body
cells and tissues to Obtain the essential amino acids needed for maintenance. To avoid
tissue breakdown therefore, the protein supplied in diet must have a PDCAAS value of at
least 65%. FAO/WHO/UNU [127] recommends the PDCAAS value of 65% as the
minimum cut-off score for growing children.

It may not be possible to provide adequate amount of essential amino acids by
increasing intake of low quality protein. This is because increased intake of low quality
protein would lower the plasma concentration of essential amino acids, which in turn
would suppress appetite [83 — 88]. Also, intake of large amount of incomplete protein
would provide excess non-essential amino acids. The excess non-essential amino acids
cannot be utilized to synthesize more proteins (because they do not alter the rate of
protein catabolism) and only a limited amount of it can be used to produce energy. Since
the non-essential amino acids cannot be stored in the body, any excess amount would be
catabolized into urea through the urea cycle (Fig. 3) [136]. In this pathway, both essential
and non- essential amino acids are indiscriminately dearninated to form urea, causing
more deficiency of the essential amino acids. In light of the foregoing, a child who is

receiving a low or poor quality protein may not compensate for the deficiency of essential

63

amino acids by eating larger amount of the food. Doing so would put the child into a

more negative nitrogen balance.

2.7 .3 Starch Gelatinization and Dextrinization
Starch is an important dietary source of energy in developing countries. Any
changes in starch during extrusion or drum processing may have important nutritional
effects. Gelatinization is the breaking of hydrogen bonds among and within starch
molecules that opens the granules to hydration and enzymic hydrolysis.
Pyruvate

A

Food —> Amino acids + Oxaloacetic —> a—ketoglutarate + Amino acids

protein E.g. Glutamine acid *— I E. g. Aspartate
Amino acids 1
E.g. Alanine
Urea cycle
Urea

Fig. 3: Metabolic fate of excess amino acids.

The crystalline structure of starch must be disrupted for complete enzymatic hydrolysis of
the starch to occur, especially when eaten. Starch gelatinization starts at 60 - 70°C and is
typically accomplished at 90 — 100°C [137]. Starch gelatinization is the major effect that
occurs on starch during drtnn and/or extrusion cooking and is often used as a measure of
the extent of cooking (cooking doneness) for the ready-tO-eat “instant” foods [138]. The
rate of gelatinization is greatly influenced by the extrusion/ processing conditions, and

the processing conditions must therefore be carefully controlled to achieve a complete

64

gelatinization. Gelatinization rate is also affected by the content of other food
components including lipids, proteins, sugars, salt and dietary fiber [137]. Several studies
have investigated the effects Of extrusion cooking on gelatinization rate of cereal
starches. According to Mercier and Feillet [139], extrusion cooking resulted in
gelatinization rates ranging from 80 to 100%. In modified versions of low-cost extruders
however, results on gelatinization rates have been inconsistent. In a model of low-cost
extruder developed for the developing countries, Harper and Jansen [44] reported starch
gelatinization rates above 90% while a similar model of a “very low-cost extruder”
showed a wide starch gelatinization rates ranging from 52 to 98% [140]. Starch
gelatinization rates above 80% have been associated with good sensory and eating
qualities and were thus accepted as ideal for processed ready-to-eat human foods [137].
Starch digestibility on the other hand is largely dependent upon gelatinization rate.
Incomplete gelatinization leads to low digestibility. In vitro starch gelatinization studies
have shown that starch in extruded foods was highly digestible compared to starch in
foods cooked by other methods [137, 140 - 142]. High starch digestibility is an essential
quality parameter for foods designed for older infants and young children.

Apart from gelatinization, extrusion cooking also induces dextrinization of starch
in foods. The high temperature, pressure and shear generated during extrusion process
cause degradation of the native starches in the food to form dextrins [137]. Starch
dextrinization in supplementary foods is desired because it improves the taste and
digestibility of the food and reduces bulkiness during meal preparation allowing more dry

matter to be consumed per meal [137].

65

2.7.3 Anti-nutrients and Toxins in Processed Foods

In many developing countries, plant foods such as cereals, root and stem tubers
and legumes are used as a basis for developing supplementary foods. These plant-based
foods contain a wide range of antinutritional factors and naturally occurring toxins.
Antinutritional factors are food components that interfere with the digestion, absorption
or with some other aspect Of metabolism of a nutrient or nutrients contained in that food
or other foods [42]. Of the antinutritional factors, enzyme inhibitors, phytates, lectins,
polyphenols and allergens are the most common. Some antinutritional and toxic factors
are specific to just a few plant species such as cyanogens in cassava and some cruciferous
vegetables, gossypol in cottonseed and favisrn in fava beans [143].

The nutritional significance of antinutritional factors has been widely reviewed
[42, 143, 144]. Protease inhibitors block the activity of pancreatic proteolytic enzymes
particularly trypsin and chymotrypsin, leading to enlargement of the pancreas
(hypertrophy) and hyperplasia. There is also an increase in the secretion of digestive
enzymes including trypsin, chymotrypsin and elastase, the action modulated by
cholecytokinin through a monitor peptide [143]. This effect suggests that, the growth
depression caused by the trypsin/chymotrypsin inhibitors is a result of poor digestibility
of proteins and endogenous loss of amino acids in the form of enzymes being secreted by
a hyperactive pancreas. Since pancreatic enzymes are rich in sulfur containing amino
acids, the effect of a hyperactive pancreas is to divert the amino acids from the synthesis
of body tissue proteins to the synthesis of these enzymes that are subsequently lost in the

feces [143, 144].

66

Alpha-amylase inhibitors, just like the other protease inhibitors, inhibit the
activity of (it-amylase enzyme. Alpha-amylase inhibitors have been reported in several
studies involving normal and diabetic rats to reduce starch digestion [145], reduce serum
glucose and insulin concentrations and increase metabolism of non-esterified fatty acids
from adipose tissues [146].

Phytohernagglutinins are natuial, high molecular weight glycoproteins that are
potent toxins to animals and humans. They are widely distributed in plants consumed as
part of human diet especially in legume seeds. Phytohernagglutinins have high affinity
for binding carbohydrate containing molecules, with high specificity towards the sugar
component. They have ability to agglutinate red blood cells and other cells from various
animals because phytohemagglutinins have multiple binding sites on their molecules that
interact with specific glyco-conjugate receptors on the surface of the cell membrane. The
lethal effects of phytohemagglutinins are therefore due to their adherence to
glycoproteins of the intestinal mucosal membrane surface, causing disruption on the
brush-border, atrophy of the microvilli, and reducing the viability of the epithelial cells.
In this case, they also adversely affect absorption of all nutrients. Due to interactions of
the phytohemagglutinins with epithelial surface of the small intestine, there is an increase
in weight of the small intestine because of the hyperplasia of the crypt cells.
Consumption of phytohemagglutinins also stimulates hyperplasia and hypertrophy of the
pancreas due in part to a mechanism similar to that in protease inhibitors reviewed [50,
143, 144]. Other nutritional and physiological effects of phytohemagglutinins are

lowering insulin levels in blood, inhibition of disaccharidases and proteases in the

67

intestines, degenerative changes in the liver and kidneys, and interference with absorption
of non-heme iron and lipid from diet [146].

Because of their protein nature, enzyme inhibitors and phytohemagglutinins are
inactivated under the conditions leading to irreversible protein denaturation. Thermo-
processing of foods denatures the inhibitors, however, because of the necessity Of
achieving a balance between the amount of heat necessary to destroy the trypsin
/chymotrypsin inhibitors and that which may result in damage to the nutritional or
functional properties of the protein, most commercially available edible grade products
e. g. soybean products, retain some amount of trypsin and chymotrypsin inhibitor activity
originally present in the raw food [143]. The most common food processing methods
such as conventional cooking, steaming, microwave cooking, drum processing and
extrusion are efficient in inactivating most or even all of the enzyme inhibitors [147].
Inactivation is dependent on cooking time, temperature, particle size, and moisture
conditions. Some reducing agents e. g. thiol-containing compounds such as cysteine, N-
acetyl-cysteine and glutathione help to effect inactivation of the inhibitors. Use of these
agents therefore allows processing of the foods at relatively lower temperatures, which
preserves other thermo-labile nutrients [148]. Ellenreider et al. [148] observed that in
natural food milieu, trypsin inhibitors are more resistant to thermo-denatmation than the
chymotrypsin inhibitors. In a dietary surveys in England and USA, Doell et al. [149] and
Billings et al. [150] Observed that many of the products consumed in these countries
contained some amounts of protease inhibitors.

Like protease inhibitors, phytohemagglutinins were inactivated by thermo-

processing when products were subjected to moist heat for 5 - 15 minutes. However,

68

phytohemagglutinins in ground flours appear to be more resistant to inactivation than in
whole grains and also to dry heat treatment than moist heat. Armour et al. [151] and
Coffey et al. [152] Observed that extrusion cooking was not effective in reducing
phytohemagglutinins in ground and split beans but was very effective in inactivating
protease inhibitors. Alpha-amylase inhibitors are effectively inactivated even by modest
thermo-processing conditions [153].

The physiological and nutritional significance of chronic ingestion of low-levels
of residual enzyme inhibitors and phytohemagglutinins is not clearly known. It has been
reported that, soy products retain 5 — 20% of the trypsin inhibitory activity due to
inadequate thermal treatment in the effort to minimize damage of functional and
nutritional properties of protein [143]. Burns [154] also Observed that, processed soy
products contained ~ 3% of trypsin inhibitory activity, which was equivalent to an
inhibition of 2 - 5 pg of trypsin/mg protein, the amounts that were insignificant
nutritionally or physiologically. In conventionally cooked beans, about 2 - 5% of trypsin
inhibitor activity was detected [155], while the same level of inhibitory activity was
detected in soy-based infant formulas. On the basis of these findings, Liener [143]
concluded that the residual trypsin inhibitor activities in most foods are safe and are
unlikely to cause any health risk to humans. However, the effect of long-term
consumption of low concentrations of trypsin and/or chymotrypsin inhibitors on hmnan
health is not known. Long-term feeding of rats with concentrated trypsin inhibitors or raw
soy flour resulted in development of adenomatous nodules in the pancreas and
significantly increased the probability of pancreatic adenoma formation [143, 144, 156].

Likewise, consumption of raw soy flour and/or concentrated trypsin inhibitors has been

69

shown to potentiate the carcinogenic effect of azaserine and di(2-hydroxyproxyl)
nitrosarnine on the pancreas of rats [144]. For phytohemagglutinins and d-amylase
inhibitors, there is usually no residual activity left if the foods are properly processed.
phytohemagglutinins however, are resistant to dry heat and hence flour-based dry

products such as cookies may contain some residual phytohemagglutinins activity [143].

2.7.4 Sensory Quality and Consumer Acceptability

The characteristics of a food product (i.e. appearance, flavor, and texture), the
conditions under which it is consumed, and the appeal that it has for a specific consumer,
determine its acceptance. Sensory evaluation is the science Of judging and evaluating the
quality Of food by the use of the five senses i.e. the taste, smell, sight, touch, and hearing.
Sensory measurement of liking is used during product development to predict consumer
response before investments are made in equipment, production and distribution [157].
Preference and liking are generally thought to be almost the same, and techniques used
for their measurement are Often similar [158]. However, preference implies a choice
between products, without considering how well liked each one is. Therefore,
measurement of the degree of liking or “hedonic value” is a means of determining not
only whether one food is preferred to another, but how acceptable or well liked it is. The
relevance and reliability of the hedonic scale method, based on known rating scale
methods used in psychology, were established through extensive field-testing of army
rations of many types [158]. Since the development of the technique, the nine-point and

five-point hedonic scales have been used extensively and validated by numerous studies

70

of food products. Hedonic rating is very popular because it may be used with trained and
untrained panelists with minimum literacy and communication skills [156, 159, 160].

In hedonic rating, testers are presented with a continuous or discrete scale with
five or nine points where 1 is “dislike extremely” and 3 or 5 is “neither like nor dislike”
and 5 or 9 is “like extremely” [158]. Other points are like, or dislike “very much”,
“moderately” or “slightly”. Samples are resented in succession and the testers are asked
to test the food product and express their honest opinion of liking accordingly on the
scales. They are reassured that there is no correct answer. The data are then interpreted
numerically and analyzed statistically. Interpretation of the hedonic testing results is
based on the food product; some novel products such as candy and ice cream usually
achieve higher hedonic ratings while staple foods usually receive slightly lower hedonic
ratings.

The weakest part of hedonic rating is its inability to predict consistently long-term
food acceptability [161]. A food with long-term acceptability is a food that can be
repeatedly (daily, weekly) eaten without the consumer becoming “tired” of eating it. Few
studies of repeated consumption or repeated taste tests suggest that initial hedonic ratings
of foods sometime, but not always, predict the long-term acceptability. In a repeated
consumption test of breakfast cereals, Goldman [162] found that the hedonic scores were
consistent over the five test days. Likewise, studies by Siegel and Pilgrim [163], Schutz
and Pilgrim [164], Kamen and Peyam [165] and Tuorila-Ollikainen et al. [166] showed
that initial hedonic ratings of some foods were maintained over repeated consumption
while the hedonic ratings of others decreased significantly. Foods with higher initial

hedonic ratings tended to maintain their ratings better than foods with initially lower

71

hedonic ratings. On the basis of these observations, Koster [167] concluded the rapid
preference test procedures are not valid for the prediction of long-term food acceptance
because the methods did not necessarily incorporate the effects of adaptation, habituation
or post ingestional effects. Both rapid and long-term acceptability is required for foods
that are to be consumed frequently e. g. supplementary foods [161].

Food product testing environment can strongly influerence consumer’s liking and
acceptance. Cardello et al. [168] reported that, determining consumer preference using
the standard, controlled or simulated testing situations e. g. in laboratories, might not be a
reliable method to predict consumer behavior towards a food product. They suggested
that, the best approach is to test the products in the real life situations using a test panel of
people who would eventually consume the foods. This approach however has been
shown to be intricate and costly. These limitations notwithstanding, hedonic scales
remain the most useful tools for determining consumer acceptance and an integral part of

food product development and marketing.

2.7 .5 Product Storage Stability

The length of time that a food product is acceptable and meets the consumer
expectations of its quality is considered to be its shelf life [169]. Procedures for
determining shelf life include microbiological, physical-chemical, and sensory
evaluation. These measurements give objective point for stating that the food product
meets or do not meet the expected quality. Other food parameter including moisture
content, water activity (aw), lipid oxidation and vitamin loses can be correlated with

sensory changes and serve as indices of shelf-stability. Water activity, which is defined as

72

the ratio of the equilibrium vapor pressure of food system (p) to the vapor pressure of
pure water (p0) (aW = p/po = ERH/ 100) at the same temperature, affects the shelf life, food
safety, texture, flavor and smell of foods. While temperature, pH and several other factors
can influence if and how fast organisms will grow in a food product, water activity may
be the most important factor in controlling spoilage. Most bacteria, for example, do not
grow at water activities below 0.91, while most molds and yeasts cease to grow at water
activities below 0.80 and 0.88, respectively [170]. By measuring water activity, it is
possible to predict which microorganisms will and will not be potential sources of
spoilage. Water activity-mot water content--determines the lower limit of available water
for microbial growth. In addition to influencing microbial spoilage, water activity can
play a significant role in determining the activity Of enzymes and vitamins in foods and
can have a major impact on their color, taste, and aroma.

Although reduction of moisture has beneficial effects of discouraging or
inhibiting growth of microorganisms in foods during storage, residual moisture when too
law may promote some chemical reactions such as non-enzymatic browning and enzymic
reactions that are detrimental to the food quality. In general, food systems have optimum
water activity-moisture range above and below which the food deteriorate at a more rapid
rate. Depending on the storage system, deteriorative chemical reactions are normally high
at elevated water activity (as. ~ 1.0) and decreases as the water activity decreases.
Example, at high water activity (0.91) (moisture > 14%) the rates of deterioration are
usually very high in most foods, but at low water activity (moisture 4 — 5%), the rates of
deterioration are very slow if the food products are properly formulated, processed, and

packaged and can thus remain in good condition for an extended period of time. There is

73

however an exception with respect to oxidative deterioration of lipids and fat-soluble
nutrients. It has been shown in various studies that lipid oxidation decreases as the water
activity decreases fiom the equilibrium (aw = 0.75) to the water activity 0.3. Further
reduction in water activity below this level (aw = 0.3) resulted in an increase in lipid
oxidation [171]. The water activity of 0.3 is therefore a critical value below which
oxidative deterioration increased at a rapid rate. This critical water activity level therefore
serves as a minimum demarcation for lowering water activities in dehydrated food
products that contain lipids. According to Nelson and Labuza [170], the water activity
range 0.15 — 0.3 enhances lipid oxidation whereas the range 0.3 -— 0.6 minimizes the lipid
oxidation and other deteriorative reactions. There are a number of proposed explanations
for this effect that implicate the state Of hydration of catalysts (e. g. metals), and
hydroperoxides, phase transition, mobilization of pro- and anti-oxidants, and diffusion-
related phenomena [172].

For dehydrated supplementary foods, oxidative changes in the lipid phase would
be of much concern especially when unsaturated vegetable and fish lipids and minerals
are present in significant amounts, for not only they will cause adverse changes in flavor
and acceptability, but also may produce non-desirable by-products and destruction of fat
soluble vitamins [17 3]. Conversely, lowering the water content of the product to a very
dry state (e.g. < 5% moisture) may promote lipid oxidation. A solution to this dilemma
would be to use antioxidants and packaging the product in air- and moisture-proof
polyethylene materials to minimize lipid oxidation. For products to be stored for a long
time (at least a year), such as cereal-based supplementary foods, oxidative rancidity,

sensory quality, and other physical-chemical changes (e. g. total acids and pH) must be

74

measured analytically and used to establish the storage stability. Data from such
parameters whether determined in real-time study or accelerated shelf-life testing
conditions [174], can be used to build prediction models for storage of similar products

[175].

75

REFERENCES

1. UN. (1992) United Nations. 2nd Report an the World Nutrition Situation: Global and
Regional Results. Vol. 1. Rome, CC/SCN.

2. Kavishe, RP. (1992) Development of Vitamin A Control Programs: An example Of
Tanzania. NU - News and Health Care in Developing Countries; 3: 21 - 26.

3. Bureau Of Statistics (1997). Tanzania Demographic and Health Survey - 1996. Bureau
of Statistics, Dar es Salaam.

4. TFNC — Tanzania Food and Nutrition Center (2002). Nutrition for Human and
Economic Development in Tanzania. Tanzania’s Nutrition Vision for the Year 2025.
TFNC Report. Dar es Salaam.

5. UNICEF (1996). Food Health and care: The UNICEF Vision and Strategy for a World
Free fi'am Hunger and Malnutrition. New York. UNICEF Division of Communication.
Pg 8.

6. United Republic of Tanzania and UNICEF (1990). Women and Children in Tanzania -
A situational Analysis. Dar es Salaam, Government Printer.

7. Kavishe, PP and Mushi, 8.8. (1993) Nutrition: Relevant Actions in Tanzania. Kavishe,
FP & Mushi, SS (Eds). T FNC Monograph Series No. 1, Dar es Salaam.

8. Pollitt, E., German, K.S., Engle, P.L., Rivera, LA. and Martorell, R. (1995). Nutrition
in early life and the fulfillment of intellectual potential. J. Nutr. 125: 11114S — 11188.

9. Martorell, R. (1995). Results and implications of the INCAP follow-up study. .1. Nutr.
125(4): 1127S - 1138S.

10. Calder, GP. and Jackson, A.A. (2000). Undernutrition, infection and immune
function. Nutr. Res. Rev. 13: 3 - 29.

11. UNAIDS/WHO (2003). High levels of new HIV infections are persisting and are now
matched by high levels of AIDS mortality. AIDS Epidemic Update: Sub-Saharan Afiica.
December. http//: www.unaids.org/wad/2003/Epiupdate2003_en/Epi03_04

-en.htm

12. WHO (2001). Complementary feeding. Report Of the Global Consultation. Summary
of Guiding Principles. Geneva. WHO.

13. Mensah, P. and Topkins, A. (2003). Household-level technologies to improve the
availability and preparation of adequate and safe complementary foods. F aad Nutr. Bull.
24(1): 104-125.

76

14. Gibbson, R.S., Ferguson, EL. and Lehrfeld, J. ( 1998). Complementary foods for
infant feeding in developing countries: their nutrient adequacy and improvement. Eur. J.
Clin. Nutr. 52: 764 - 770.

15. Dewey, KG. (2001). The challenges of promoting optimal infant growth. J. Nutr.
131: 1946 — 1951.

16. WHO (2002). Infant and Young Child Nutrition. 5“ WHO Assembly Resolution WHA
55.25. WHO. http//: WWW.Who.int/gb/EB_WHA/WHA55/ewha5525.pdf.

17. WHO/UNICEF (2003). Global Strategy for Infant and Young Child Feeding. Rome.
WHO/UNICEF. http//: www.who.int/nut/documents/gs_infant-feeding.pdf.

18. Schroeder, D.G., Martorell, R., Rivera, J.A., Ruel, MT. and Habicht, J. (1995). Age
difference in the impact of nutritional supplementation on growth. J. Nutr. 125: 10518 —
1059S.

19. Rivera, J.A., Martorell, R., Ruel, M.T., Habicht, J. and Haas, JD. (1995). Nutritional
supplementation during the pre-school years influences body size and composition of
Guatemalan adolescents. J. Nutr. 125: 10688 — 1077S.

20. Caulfield, L.E., Huffinan, S.L and Piwoz, E.G. (1999). Interventions to improve
intake of complementary foods by infants 6 to 12 months of age in developing countries:

Impact on growth and on the prevalence of malnutrition and potential contribution to
child survival. Food Nutr. Bull. 20 (2): 183 — 200.

21 . Simondon, KB. and Simondon, F. (1996). Effect of early, short-term
supplementation on weight and linear growth of 4 - 7 mo old infants in developing
countries: a four country randomized trial. Am. J. Clin. Nutr. 64: 537 - 545.

22. Gershoff, SN. (1988). Nutrition studies in Thailand: Effects of calories, nutrient
supplements, and health interventions on growth of pro-school Thai village children. Am.
J. Clin. Nutr. 48: 1214 -1218.

23. Lutter, GK. (1990). Age-specific responsiveness of weight and length to nutritional
supplementation. Am. J. Clin. Nutr. 51: 359 - 364.

24. Walker, SP. (1991). Nutritional supplementation, psychosocial stimulation, and
growth of stunted children: the Jamaican study. Am. J. Clin. Nutr. 54: 642 — 648.

25. Husaini, M.A. (1991). Developmental effects of short-term supplementary feeding in
nutritionally-at-risk Indonesian infants. Am. J. Clin. Nutr. 54: 799 — 804.

26. Haas, J .D., Martinez, E.J., Murdoch, S., Conlisk, E., Rivera, LA. and Martorell, R.

(1995). Nutrition supplementation during the preschool years and physical work
capacity in adolescent and young adult Guatemalans. J. Nutr. 125: 1078S — 10898.

77

27. Pickett, K.E., Haas, J.D., Murdoch, 8., Rivera, J.A. and Martorell, R. ( 1995). Early
nutritional supplementation and skeletal maturation in Guatemalan adolescents. J. Nutr.
125: 10978 — 11038.

28. Caulfield, L.E., Himes, J.H. and Rivera, J .A. (1995). Nutritional supplementation
during early childhood and ban e mineralization during adolescence. J. Nutr. 125:
111048— 11108.

29. Pollitt, E., German, K.S., Engle, P.L., Rivera, J. A. and Martorelli, RM. (1995).
Nutrition in early life and the fulfillment of intellectual potential. J. Nutr. 125: 11118 -
1 1 188.

30. Pelletier, D.L. and Frogillo, EA. (2003). Changes in child survival are strongly
associated with changes in malnutrition in developing countries. J. Nutr. 133: 107 — 119.

31. WHO (1976). Nutrition Rehabilitation. In: Nutrition in Preventive Medicine: The
Major Deficiency Syndromes, Epidemiology, and Approaches to Control. Geneva. WHO.

32. WHO - World Health Organization (1999). Management of Severe Malnutrition: A
Manual for Physicians and Other senior Health Workers. WHO Publications. Geneva.

33. Khanum, 8., Ashworth, A. and Huttly, 8.R.A. (1998). Growth, morbidity, and
mortality of children in Dhaka after treatment for severe malnutrition: a prospective
study. Am. J. Clin. Nutr. 67: 940 — 945.

34. Fjeld, C.R., 8coeller, DA. and Brown, K.H. (1989). Body composition of children
recovering from severe protein-energy malnutrition at two rates of catch-up growths. Am.
J. Clin Nutr. 50: 1266 — 1275.

35. van Roosmalen-Wienbenga, M. W., Kusin, J.A. and de With, C. (1986). Nutrition
rehabilitation in hospital — a waste of time and money? Evaluation of nutrition
rehabilitation in a rural district hospital in Southwest Tanzania. I — Short term results. J.
Trop. Pediatr. 32: 240 — 243.

36. van Roosmalen-Wienenga, M. W., Kusin, J.A. and de With, C. ( 1987). Nutrition
rehabilitation in hospital — a waste of time and money? Evaluation of nutrition
rehabilitation in a rln'al district hospital in South-west Tanzania. 11 — Long term results. J.
Trop. Pediatr. 33: 24 - 28.

37. Reneman, L. and Derwig, J. (1997). Long-tenn prospects of malnourished children
after rehabilitation at the nutrition rehabilitation center Of St. Mary’s Hospital, Murnias,
Kenya. J. T rap. Pediatr. 43: 293 - 296.

38. O’Dwyer, M., Gillam, 8.1. (1997). Children discharged following nutritional
rehabilitation: a follow-up study. Trap. Doctor 25 (4): 146 — 151.

78

39. Millward, DJ. (1999). The nutritional value of plant-based diets in relation to human
amino acid and protein requirements. Prac. Nutr. Soc. 58: 249 — 260.

40. Lutter, CK. (2000). Processed complementary foods: summary of nutritional
characteristics, methods of production and distribution, and costs. F aad Nutr. Bull. 21
(1): 95 — 100.

41. Lutter, OK. and Rivera, J.A. (2003). Nutritional status of infants and young children
and characteristics of their diets. J. Nutr. 133: 29418 — 29498.

42. WHO/UNICEF (1998). Complementary Feeding of Young Children in Developing
Countries: a review of the Current Scientific Knowledge. WHO Publications. Geneva.

43. Lutter, GK. (2003). Macro-level approaches to improve the availability of
complementary foods. Food Nutr. Bull. 24 (1): 83 - 103.

44. Harper, J.M. and Jansen, GR. (1985). Production of nutritious pre-cooked foods in
developing countries by low-cost extrusion technology. F oad Rev Intl. l (1): 27 - 97.

45. Pellett, PL. and Mamarbachi, D. (1979). Recommended proportions of foods in
home-made feeding mixtures. Ecol. Food. Nutr. 7: 219 — 228.

46. Cameron, M. and Hofvander, Y. (1983). Manual on Feeding Infants and Young
Children. Oxford. Oxford University Press.

47. FAQ/WHO (1991). Protein Quality Evaluation. Report of the Joint FAQ/WHO
Expert Consultation Rome. F A0.

48. Neumann, C., Harris, D.M., and Rogers, L.M. (2002). Contribution of animal source
foods in improving diet quality and fimction in children in the developing world. Nutr.
Res. 22: 193 — 220.

49. Fernandez, M., Montalvo, 1., Sousa, V. and Sotelo, A. (1996). The protein efficiency
ratios of 30:70 mixtures of animal: vegetable protein is similar or higher than those of the
animal foods alone. J. Nutr. 126: 574 — 581.

50. WHO (2002). Infant and Young Child Nutrition: Global Strategy on Infant and
Young Child Feeding. World Health Assembly Document WHA55/15. Rome. WHO
Press.

51. F AO/WHO (1994). Codex Alimentarius Standards for Foods for Special Dietary
Uses (including foods for infants and children). Vol. 4. Joint FAO/WHO Food Standards
Program. Rome. WHO, Codex Alimentarius Commission.

79

52. Shrimpton, R. and Clark, D. (2000). Complementary feeding, the code and the codex.
Food Nutr. Bull. 21 (1): 25 — 29.

53. Walker, A.F. (1990) The contribution Of weaning foods to protein energy
malnutrition. Nutr. Rev. Res. 3: 25 - 47.

54. Lutter, C.K. and Dewey, KG. (2003). Proposed nutrient composition for fortified
complementary foods. J. Nutr. 133: 30118 - 30208.

55. Sanchez-Grinan, M.I., Person, J.M., Brown, K.H. (1995). Effect Of varied dietary fat
and carbohydrate concentrations on total daily energy intake by recovering malnourished
children. FASEB J. 9: A1007 (Abstract).

56. Uauy, R. and Castillo, C. (2003). Lipid requirements of infants: implications for
nutrient composition of fortified complementary foods. J. Nutr. 133: 29628 — 29728.

57. FAO/WHO (1994). Fats and Oils in Human Nutrition. Report Of a Joint Expert
Consultation. Food and Nutrition Paper # 57. Rome. FAQ.

58. Koletzko, B., Tsang, R., Zlotkin, S.H., Nichols, B., Hansen, J.W. (1997). Importance
of dietary lipids. In: Koletzko, B. and Tsang, R. (Eds). Nutrition During Infancy:
Principles and Practice. lSt Ed. Cincinnati. Digital Educational Publishers. Pp 123 — 153.

59. Uauy, R., Mena, P and Rojas, C. (2000). Essential fatty acids in early life: structural
and functional role. Proc. Nutr. Soc. 59: 3 - 15.

60. Decsi, T. and Koletzko, B. (1994). Polyunsattn'ated fatty acids in infant nutrition.
Acta Paediatrica. Supplement, 83: 31 — 37 .

61. Uauy, R., Mize, C. and Castillo-Duran, C. (2000). Fat intake during childhood:
metabolic responses and effects on growth. Am. J. Clin. Nutr. 72 (Suppl): 13548 -
13608.

62. Innis, SM. (1991). Essential fatty acids in growth and development. Prag. Lipids
Res. 30: 39 - 109.

63. Friedman, G. and Goldberg, SJ. (1976). An evaluation of the safety of a low-
saturated-fat, low-cholesterol diet beginning in infancy. Pediatrics. 58: 665 — 657.

64. Gaull, G.E., Giombetti, T. and Woo, R.W. (1995). Pediatric, dietary lipid guidelines:
a policy analysis. J. Am. Coll. Nutr. 14: 411 - 418.

65. Olson, PE. (1995). The dietary recommendations of the American Academy of
Pediatrics. Am. J. Clin. Nutr. 61: 271 — 273.

80

66. American Academy of Pediatrics Committee on Nutrition (1986). Prudent life-style
for children: dietary fat and cholesterol. Pediatrics. 78: 521 — 525.

67. American Academy of Pediatrics (1992). Statement on cholesterol. Pediatrics. 90:
469 - 473.

68. Canadian Pediatric Society (1994). Nutrition Recommendations Update: Dietary Fat
and Children. Report of the Joint Working Group of the Canadian Pediatric Society
(CPS) and Health Canada — Ref. N94-01. http://www.cps.ca/english/statements/N/n94-
01.htrn.

69. ESPGAN Committee in Nutrition (1991). Comment on the content and composition
of lipids in infant formulas. Acta Pediatric Scand. 80: 887 — 896.

70. Nawar, W.W. (1996). Lipids. In: Fennerna, 0. (Ed). Food Chemistry. 3"d Ed. New
York. Marcel Dekker. Pp 255 — 264.

71. Lindsay, RC. (1996). Food additives. In: Fennerna, 0. (Ed). Food Chemistry. 3rd Ed.
New York. Marcel Dekker. Pp 780 - 782.

72. Young, V.R., El-Khoury, A.E., Melchior, 8., and Castillo, L. (1994). The
Biochemistry and Physiology of Protein Amino Acid Metabolism with Reference to
Protein Nutrition. In: Niels, C.R.R. (Ed). Protein Metabolism During Infancy. Vol. 33.
New York. Nestec Ltd. Pp 1 — 33.

73. Reeds, PJ. (2000). Dispensable and indispensable amino acids for humans. J. Nutr.
130: 18358 — 18408.

74. Jousse, C., Bruhat, A., Ferarra, M., and F afoumoux, P. (2000). Evidence for multiple
signaling pathways in the regulation of gene expression by amino acids in human cell
lines. J. Nutr. 130: 1555 — 1560.

75. Kimball, SR. (2002). Regulation of global and specific mRNA translation by amino
acids. J. Nutr. 132: 883 - 886.

76. Kilberg, KS. and Barbosa-Tessmann, LP. (2002). Genomic sequences necessary for
transcriptional activation by amino acid deprivation of mammalian cells. J Nutr. 132:
1801 — 1804.

77. Jousse, C., Bruhat, A., Ferarra, M., and Fafoumoux, P. (1998). Physiological
concentration of amino acids regulates insulin-like-growth—factor-binding protein-1
expression. Biochem. J. 334: 147 - 153.

78. Bruhat, A., Jousse, C., Wang, X.Z., Ron, D., Ferarra, M., and Fafournoux, P. (1997).
Amino acid limitation induces expression of CHOP, a CCAAT/enhancer binding protein-

81

related gene, at both transcriptional and post-transcriptional levels. J. Biol. Chem. 272:
17588 — 17593.

79. Endo, Y., Fu, 2., Abe, K. Arai, 8. and Kato, H. (2002). Dietary protein quantity and
quality affect rat hepatic gene expression. J. Nutr. 132: 3632 — 3637.

80. Koehnle, T.J., Stephens, A., and Gietzen, D.W. (2002). Alteration of the
microstructure of feeding behavior during the first meal of the threonine imbalanced diet.
Appetite. 39: 85. Abstract.

81. Sharp, J .W., Magrum, LJ. and Gietzen, D.W. (2002). Role of MAP kinase in
signaling indispensable amino acid deficiency in the brain. Molecular Brain Res. 105: 11
- 18.

82. Koehnle, T.J., Russell, MC. and Gietzen, D.W. (2003). Rats rapidly reject diets
deficient in essential amino acids. J. Nutr. 133: 2331 — 2335.

83. Peng, Y., Meliza, L.L., Vavich, MG. and Kemmerer, AR. (1975). Effects of amino
acid imbalance and protein content of diets on food intake and preference of young, adult,
and diabetic rats. J. Nutr. 105: 1395 — 1404.

84. Semon, B.A., Leung, M.B., Rogers, Q.R., and Gietzen, D.W. (1987). Effect of type of
protein on food intake of rats fed high protein diets. Physiology and Behavior. 41: 451 —
458.

85. Ashley, D.V.M. and Anderson, G.H. (1975). Food intake regulation in the weanling
rat: Effects of the most limiting essential amino acids of gluten, casein, and zein on the
self-selection of protein and energy. J. Nutr. 105: 1405 — 1411.

86. Hrupka, B.J., Lin, Y.M., Gietzen, D.W., and Rogers, Q. R. (1997). Small changes in
essential amino acid concentrations alter diet selection in amino acid-deficient rats. J.
Nutr. 127: 777 — 784.

87. Gietzen, D.W., Erecius, LR, and Rogers, Q. R. (1998). Neurochernical changes after
imbalanced diets suggest a brain circuit mediating anorectic response to amino acid
deficiency in rats. J. Nutr. 128: 771 — 781.

88. Gietzen, D.W. (1993). Neural mechanisms in the response to amino acid deficiency.
J. Nutr. 123: 610 — 625.

89. Allen, H.H. (1995). Malnutrition and human function: a comparison of conclusions
fiom the INCAP and nutrition CRSP studies. J. Nutr. 125 (4 Suppl.) 11198 — 11268.

90. Latham, MC. (1990). Improvement in growth following iron supplementation in
young Kenyan school children. Nutr. 6: 159 — 165.

82

91. FAG/WHO (2001). Human Vitamin and Mineral Requirements. Report of a Joint
FAO/WHO Expert Consultation. FAO. Rome.

92. Shanker, AH. and Prasad, A8. (1998). Zinc and immune function: The biological
basis of altered resistance to infection. Am. J. Clin. Nutr. 68 (Suppl): 817 — 819.

93. Dirren, H. (1994). Zinc supplementation and infant growth in Ecuador. In: Allen,
L.H., King, J ., Lonnerdal, B. (Eds). Nutrient Regulation During Pregnancy, Lactation
and Infant Growth. New York. Plenum Press. Pp 215 - 222.

94. Golden, BE and Golden, M.H.N. (1992). Effect of zinc on lean tissue synthesis
during recovery from malnutrition. Eur. J. Clin. Nutr. 46: 697 — 706.

95. Castillo-Durran, C. (1995). Zinc supplementation and growth of infants born small
for gestation age. J. Pediatrics. 127: 206 — 211.

96. Charnbon, P. (1996). A decade of molecular biology of retinoic acid receptors.
FASEB J. 10: 940 - 954.

97. Sandstead, H.H. (1991). Zinc deficiency. A public health problem? Am. J. Dis.
Childr. 145: 853 — 859.

98. Friedman, M. (1992). Dietary impact of food processing. Ann. Rev. Nutr. 12: 119 —
137.

99. Riaz, MN. (2000). Introduction to extruders and their principles. In: Riaz, M.N. (Ed)
Extruders in Food Applications. Lancaster. Technomic Publishing Co. Inc. pp 1 — 21 .

100. Harper, J .M. (1987). Extrusion processing of food. Food T echnol. 32 (7): 67 — 72.
101. Carnire, ME. (2000). Chemical and nutritional changes in food during extrusion. In:
Riaz, M.N. (Ed) Extruders in Food Applications. Lancaster. Technomic Publishing Co.
Inc. pp 127-147.

102. Ng, P. Personal communication. Food Science and Human Nutrition. MSU.

103. Jansen, GR. (1992). Centrally processed weaning foods for use in developing
countries. Food Rev. Intl. 8 (3): 307 - 345.

104. Mercer, L.P., Dodds, S.J., and Smith, S.L. (1989). Dispensable, indispensable, and
conditionally indispensable amino acid ratios in the diet. In: Friedman, M. (Ed).
Absorption and Utilization of Amino Acids. Vol. 1. Boca Raton. CRC Press. Pp 1 — 13.

105. Millward, J. (1994). Can we define indispensable amino acid requirements and
assess protein quality in adults? J. Nutr. 124: 15098 — 15168.

83

106. Laidlaw, SA. and Kopple, J .D. (1987). Newer concepts of the indispensable amino
acids. Am J. Clin. Nutr. 46: 593 — 605.

107. Sarwar, G. (1987). Digestibility of protein and bioavailability of amino acids in
foods: Effect on protein quality assessment. World Rev. Nutr. Diet. 54: 26 - 70.

108. Kies, C. (1981). Bioavailability: A factor in protein quality. J. Agric. Food Chem.
29: 435 - 440.

109. Nielsen, 8.8. (1991). Digestibility of legume proteins: Legumes — production,
processing, food value and health benefits. Food Technology. IFT Special Edition.
September.

110. Bennink, M. and Srisuma, N. (1989). Digestibility of dry legume starch and proteins. In:
Applewhite, T.H. (Ed). Proceedings of the World Congress on Vegetable Protein Utilization in
Human Foods and Animal Feedstujfs. Illinois. American Oil Chemists’ Society.

111. Reddy, N.R., Pearson, M.D., Sathe, S.K., and Salunkhe, D.K. (1989). Phytates in
Cereals and Legumes. Boca Raton, Fla. CRC Press, Inc.

112. Butler, L.G., Rogler, J.C., Mehansho, H. and Carlson, D.M. (1986). Dietary effect of
tannins. In: Cody, V., Harbome, J .B., and Middleton, E. (Eds). Plant Flavonoids in
Biology and Medicine: Biochemical, Pharmacological, and Structure-Activity
Relationships. New York. Alan R. Liss Inc. p 141.

113. Sigh, U. and J ambunathan, R. (1981). Studies on desi and kabul chickpea Cicer
arientinum L. cultivars: levels of protease inhibitors, phenolic compounds and in vitro
protein digestibility. J. Food Sci. 46: 1364 — 1371.

114. Phillips, D.8., Eyre, M.D., Thompson, A. and Boutler, D. (1981). Protein quality in
seed meals of Phaseolus vugaris L. and heat stable factors affecting the utilization of
proteins. J. Sci. Food Agric. 32: 423 — 428.

115. Romero, J. and Ryan, D8. (1978). Susceptibility of the major storage protein of the
bean, Phaseolus vulgaris L. to in vitro enzymatic hydrolysis. J. Agric. Food Chem. 26:
784 - 795.

116. Newman, C.W., Roth, N.J., Newman, R.K. and Loekerman, RH. (1987). Protein of
chickpea (Cicer arientinum L.). Nutr. Repr. Int ’1. 31: 1 — 3.

117. Hughes, 18. (1990). Effect of dietary fiber and tannins on protein nutritive value in
the common bean (Phaseolus vulgaris). Food Chem. 34: 56 - 68.

118. Antunes, P.L., and Sgarbieri, V.C. (1980). Effect of heat-treatment on the toxicity

and nutritive value of dry beans (Phaseolus vulagaris var. Rosinha G2) proteins. J. Agric.
Food Chem. 28: 935 — 940.

84

119. Sathe, S.K., Iyer, V., and Salunkhe, D.K. (1982). Functional properties of the Great
Northern bean (Phaseolus vulagaris L.) proteins. Amino acid composition, I vitro
digestibility, and application to cookies. J. Food Sci. 48: 8 - 17.

120. Marguez, U.M.L. and Lajolo, F .M. (1981). Composition and digestibility of
albumin, globulin, and glutelins from Phaseolus vulagaris L. J. Agric. Food Chem. 29:
1068 — 1074.

121. Deshpande, 8.8. and Nielsen, 8.8. (1987). In vitro digestibility of dry bean
(Phaseolus vulagaris L.) proteins. The role of heat-stable protease inhibitors J. Food Sci.
15: 1330 - 1335.

122. Friedman, M. (1996). Nutritional value of proteins from different food sources: a
review. J. Agric. Food Chem. 44: 6 29.

123. Sarwar, G. and McDonough, J. M. (1990). Evaluation of protein digestibility-
corrected amino acid score method for assessing protein quality of foods. J. Assoc. Ofl'
Anal. Chem. 73 (3): 347— 356.

*5

124. Henley, EC. and Kuster, J .M. (1994). Protein quality evaluation by protein
digestibility-corrected amino acid scoring. Food Technol. 48(4): 74 — 7 7.

125. Sarwar, G. and McLaughlan, J.M. (1981). Relative net protein ratio method for
evaluating protein quality. Nutr. Rep. Intl. 23: 1157 — 1166.

126. Sarwar, G., Peace, R.W., and Botting, H.G. (1985). Corrected relative net protein
ratio (CRNPR) method based on differences in rat and human requirements of sulfur
amino acids. J. Assoc. Ofif Anal. Chem. 68: 689 — 693.

127. FAO/WHO/UNU (1985). Energy and Protein Requirements. Report of the Joint
FAO/WHO/UNU Expert Consultation. Technical Report Series No. 724. Geneva. FAO.

128. FAO (1984). Codex Alimentarius Commission. Working Group’s Report No. 85/30
to the 3", Session of the CC VP on Methods for Evaluating Protein Quality. Rome. FAO.

129. FAQ (1989). Codex Alimentarius Commission Working Group ’s Report No. 89/3 0
of the 5‘” Session of the CC VP on Protein Quality Measurement. Rome. FAO.

130. FAO/WHO (1989). Protein Quality Evaluation. Report of the Joint FAD/WHO
Expert Consultation. Food and Nutrition paper No. 51. Rome. FAO/WHO.

131. AOAC (1995). Oflicial Methods of Analysis. 140: Edn. Association of Official
Analytical Chemists. Washington DC.

132. FDA (1993). Food Labeling, General Provisions, Nutrition Labeling, Label Format,
Nutrient Content Claims, Health Claims, Ingredient Labeling, State and Local

85

Requirements, and Exceptions, Final Rules. Food and Drug Administration. Fed Reg. 58
(3): 2101 - 2106.

133. Dewey, K.G., Beaton, G., Fjeld, C., Lonnerdal, B. and Reeds, P. (1996). Protein
requirements of infants and children. Eur. J. Clin. Nutr. 50: 8119 — 8150.

134. Millward, DJ. (1998). Metabolic demands for amino acids and human dietary
requirement: Millward and Rivers (1988) revisited. J. Nutr. 128: 25638 — 25768.

135. Young, V.R. and Borgonha, 8. (2000). Nitrogen and amino acid requirements: The
Massachusetts Institute of Technology amino acids requirement pattern. J. Nutr. 130:
18418 — 18498.

136. Groff, J .L., Gropper, 8.8. and Hunt, 8.M. (1995). Advanced Nutrition and Human
Metabolism. 2ml Edn. New York. West Publishing Company. Pp 154 — 196.

137. Carnire, M.B., Carnire, A. and Krumhar, K. (1990). Chemical and nutritional
changes in foods during extrusion. Crit. Rev. Food Sci. Nutr. 29 (1): 35 — 57.

138. Guy, R.C.E. and Osborne, B.G. (1996). The application of near-infiared reflectance
spectroscopy to measure the degree of processing in extrusion cooking process. J. Food
Engin. 27: 241 — 258.

139. Mercier, C. and Feillett, P. (1975). Modification of carbohydrate components by
extrusion cooking of cereal products. Cereal Chem. 52: 283 — 287.

140. Mouquet, C., Salvignol, B., Van Hoan, N., Monvois, J. and Treche, S. (2003).
Ability of a “very-low-cost extruder” to produce instant infant flours at a small scale in
Vietnam. Food Chem. 82: 249 — 255.

141. Dahlin, KM. and Lorenz, K. (1993). Carbohydrate digestibility of laboratory-
extruded cereal grains. Cereal Chem. 70 (3): 329 — 333.

142. Wang, W.M., Klopfeinstein, CF. and Ponte, J .G. (1993). Effect of twin-screw
extrusion on the nutritional quality of wheat, barley and oats. Cereal Chem. 70: 712 —
7 l 5.

143. Liener, LE. (1994). Implications of antinutritional components in soybean foods.
Crit. Rev. Food Sci. Nutr. 34: 31 — 67.

144. Lajolo, RM. and Genovese, MI. (2002). Nutritional significance of lectins and
enzyme inhibitors from legumes. J. Agric. Food. Chem. 50: 6592 - 6598.

145. Menezes, E.W. and Lajolo, RM. (1987). Inhibition of starch digestion by a black
bean a-mylase inhibitor, in normal and diabetic rats. Nutr. Rep. Intl. 36: 1185 — 1189.

86

146. Pusztai, A., Grant, G., Dunguid, T., Brown, D.8., Peumans, W.J. and van Darnme,
E.J.M. (1995). Inhibition of starch digestion by a-amylase inhibitor reduces the efficiency
of utilization of dietary proteins and lipids and retards the growth of rats. J. Nutr. 125:
1554 — 1562.

147. Rackis, J .J ., Wolf, W.J. and Baker, EC. (1986). Protease inhibitors in plant foods:
content and inactivation. In: Friedman, M. (Ed). Nutritional and Toxicological
Significance of Enzyme Inhibitors in Foods. New York. Plenum Press. Pp 299 - 335.

148. Ellenreider, G., Blanco, S. and Bondoni, A. (1981). Thermal inactivation of trypsin
inhibitors in aqueous extracts of soybeans. Studies on substances that accelerate
inactivation. Cereal Chem. 58: 291 — 303.

149. Doell, B.H., Ebden, CI. and Smith, CA. (1981). Trypsin inhibitor activity of
conventional foods which are part of the British diet and some soya products. Plant
Foods Hum. Nutr. 31: 139 — 144.

150. Billings, P.C., Longnecker, M.P., Keary, M. and Taylor, PR. (1990). Protease
inhibitor content of human dietary samples. Nutr. Cancer. 14: 81 — 93.

151. Armour, J.C., Perera, R.L.C., Buchan, W.C., and Grant, G. (1998). Protease
inhibitors and lectins in Soya beans and effects of aqueous heat-treatment. J. Sci. Food
Agric. 78: 225 — 231.

152. Coffey, D.G., Uebersax, M.A., Hosfield, G.L., and Bennink, MR. (1993). Thermal
extrusion and alkali processing of dry beans (Phaseolus vulgaris L.). J. Food Proc. Pres.
16: 421 - 431.

153. Grant, G., Edwards, J .E. and Pusztai, A. (1995). Alpha-amylase inhibitor levels in
seeds generally available in Europe. J. Sci. Food Agric. 67: 235 — 238.

154. Burns, RA. (1987). Protease inhibitors in processed plant foods. J. Food Prat. 50:
161 - 166. .

155. Kakade, M.L., Simons, N., and Liener, LE. (1969). An evaluation of natural vs
synthetic substances for measuring the anti-tryptic activity of soybean samples. Cereal
Chem. 46: 518 — 526.

156. Belitz, H.D. and Weder, J .K.P. (1990). Protein inhibitors of hydrolases in plants
foodstuffs. Food Rev. Intl. 6: 151 — 211.

157. Stone, H. and Side], IL. (1993). Sensory Evaluation Practices. 2"‘1 Ed. San Diego.
Academic Press. Pp 243 — 270.

158. Peryarn, PR. and Pilgrim, F.J. (1957). Hedonic scale method of measuring food
preferences. Food T echnol. 11: 9 — 14.

87

159. Lawless, HT & Heymann, H (1998). Sensory Evaluation of Foods: Principles and
Practices. N.Y. Chapman and Hall.

160. Meilgaard, M. Civille, G.V., Carr, B.T. (1999). Sensory Evaluation Techniques. 3rd
Edn. New York. CRC Press. Pp 231 — 263.

161. Vuickers, Z. (2000). Long-term acceptability of limited diets. J. Sensory Studies. 14:
249 - 262.

162. Goldman, A. (1994). Predicting product performance in the marketplace by
immediate- and extended use sensory testing. Food Technol. 48(10): 103 - 106.

163. Siegel, PS, and Pilgrim, F.J. (1958). The effect f monotony on the acceptance of
food. Am. J. Psychol. 17: 765.

164. Schutz, H.G, and Pilgrim, F.J (1958). A field study of food monotony. Psychol.
Repts. 4: 559 — 565.

165. Kamen, J .M. and Peryarn, DR. (1961). Acceptability of repetitive diets. Food
Techn. 26: 173 — 177.

166. Tuorila-Ollikainen, H. Lahteenrnaki, L. and Lasovara, H. (1986). Attitudes, norms,
intentions and hedonic responses in the selection of low salt bread in a longitudinal
choice experiment. Appetite. 7: 127 — 139.

167. Koster, RP (1981). Time and frequency analysis: a new approach to the
measurement of some less-well-known aspects of food preferences. In: Solrns, J. and
Hall, R.L. (Eds). Criteria of Food Acceptance. Zurich. Foster Verlag.

168. Cardello, A.V., Schulz, H., Snow, C., Lesher, L. (2000). Predictors of food
acceptance, consumption and satisfaction in specific eating situations. Food Qua]. Prefer.
11: 201 — 216.

169. Lubuza, T.P. (1982). Shelf life Dating of Foods. Westport, CT. Food and Nutrition
Press.

170. Nelson, K.A. and Labuza, T.P. (1992). Understanding the relationship between
water and lipid oxidation rates using aw and glass transition theory. In: St. Angelo, M.
(Ed). Lipids and Food Stability. AC8 Symposium Series 500. Washington DC.
American Chemical Society. Pp 93 — 103.

171. Nelson, K.A. and Lubuza, T.P. (1992). Relationship between water and lipid
oxidation rates — water activity ad glass transition theory. In: St. Angelo A.J. (Ed). Lipid
Oxidation in Food. AC8 Symposium Series 500. Washington DC: American Chemical
Society.

88

172. Fritsch, CW. (1994). Lipid oxidation - the other dimensions. Inform. 5: 423 — 436.

173. Gregory, J .F 111(1996). Vitamins. In: Fennema, 0. (Ed). Food Chemistry. 3"1 Ed.
New York. Marcel Dekker. Pp 545 — 559.

174. Ragnarsson, J .O. and Labuza, T.P. (1977). Accelerated shelf-life testing for
oxidative rancidity in foods — a review. Food Chem. 2: 291 — 308.

175. Labuza, T.P. and Schmidl, MK. (1988). Use of sensory data in the shelf-life testing
of foods: Principles and graphical methods for evaluation. Cereal Food World. 33: 193 —

206.

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CHAPTER THREE

3.0 EVALUATION OF PROTEIN QUALITY AND GROWTH/ REHABILITATION
POTENTIAL OF DRUM-PROCESSED, READY-TO-EAT CEREAL-BEAN-
SARDINE COMPOSITE SUPPLEMENTARY FOODS FOR PRE-SCHOOL

CHILDREN.

3.1 Abstract

Acute, severe undemutrition during childhood remains a common health problem in
many parts of the world and makes significant contribution to childhood mortality. This
study was conducted to evaluate protein quality and growth/rehabilitation potential of
supplementary foods developed from locally produced materials in Tanzania.

Six diets namely rice-meal (RM), bean-meal (BM), rice-bean composite meal
(RBM), rice-bean-sardines composite meal (RBSM), com-bean-sardines composite meal
(CBSM) and com-bean meal (CBM) were formulated to maximize amino acid score as
recommended by FAO/W HO/UN U (1985) for preschool children. Biological qualities of
the diets including apparent and true protein digestibility, net protein retention ratio, food
efficiency ratio, protein digestibility corrected amino acid scores (PDCAAS%) and
rehabilitation potential were evaluated using Sprague Dawley weanling rats.

Our results showed that, net protein retention ratios varied significantly (p < 0.05)
among the products. The net protein retention ratios were; control diet (0.93 ), RBSM
(0.92), CBSM (0.86), RM (0.66), RBM (0.44), CBM (0.28), BM (0.12) and CM diet (-
0.40). True protein digestibility ranged between 82 and 99% with BM showing the lowest

digestibility. The protein digestibility corrected amino acid scores (PDCAAS%) were

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100% (control diet), 77% (CBSM), 89% (RBSM), 58% (RM), 90% (RBM), 47% (CBM),
85% (BM) and 48% (CM). Two test diets, CBSM and RBSM showed greatest potential
to support growth and rehabilitation of undernourished rats, while CBM, RBM, BM and
CM did not display acceptable growths. These results suggest that, cereal-bean-sardine
composite were of high quality and have a potential for use as supplementary/

rehabilitation foods for pre-school and school-age children and adults.

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3.2 Introduction

Acute, severe malnutrition during childhood remains a common health problem
in many parts of the world and makes significant contribution to childhood mortality [1].
In Tanzania, more than 200,000 children die before reaching their fifth birthday due to
inadequate intake of protein, energy and/or micronutrients [2]. The situation is worsened
by the current scourge of HIV /AIDS, which renders many children orphans and leaves
them with no adults to take care of them [3 — 4]. The causes of malnutrition are multi-
factorial, however, the immediate cause of this condition is inadequate intake of nutrients
due to inadequate food or poor quality foods [5 — 7]. Lack of nutrient-dense foods
especially during and afier weaning and during illness has been associated with more
than 75% of the infant and young children mortalities [5]. Usually, children identified
with mild or severe protein energy malnutrition (PEM) are referred to hospital-based or
community-based rehabilitation centers where they receive feeding supplements while
continuing with medical treatment of the complications associated with PEM [8 — 10].

The common food used for nutritional rehabilitation is dried skim milk (DSM),
which is reconstituted with vegetable oil and sugar to increase the energy density “energy
food” [11]. The DSM is imported by the government as part of its public social support
service. The rapid increase in the number of children needing nutritional rehabilitation
has left the government unable to import adequate amount of DSM for all children. When
the rehabilitated children return home from the treatment centers, they no longer have
access to the DSM. Dried skim milk is not readily available in rural areas, and where
available, it is too expensive for the majority of the low-income families to afford. As a

result, children who were discharged from the nutritional rehabilitation centers often

92

become malnourished again as they return to the same dietary regime that caused PEM
originally. Such children often become malnourished again and are readmitted to the
same centers [8 — 10].

F ollow-up studies of children discharged from nutritional rehabilitation centers
indicated higher mortality rates compared to their non-referred peers. Most remained
underweight until adulthood and only 30% attained satisfactory catch-up grth [12 —
13]. An inexpensive follow-up diet is therefore critical for the rehabilitated children to
survive and attain normal growth. Shortage of DSM-based diet to feed the large number
of malnourished children in the households, rehabilitation centers, orphanages, street
children homes, and refugee camps has been a major problem limiting nutritional
improvement of children in Tanzania. As part of the efforts to address this problem, this
study was designed to evaluate the nutritional quality and growth/ rehabilitation potential
of formulated supplementary foods from locally produced food ingredients. It is
hypothesized that, developing high quality supplementary foods based on locally
produced ingredients would enhance availability, affordability and will strongly augment
the nutritional care and nutritional rehabilitation efforts, thus, improving the survival and

well-being of vulnerable populations in the country.

3.3 Materials and Methods
3.3.1 Product Formulation

Six products namely rice meal (RM), rice-bean meal (RBM), rice-bean-sardine
meal (RBSM); com-bean meal (CBM), com-bean-sardine meal (CBSM) and bean meal

(BM) were formulated in the laboratories of the Department of Food Science and Human

93

Nutrition, Michigan State University. Products were optimized to deliver greatest amino
acid score and the desired amount of energy and fat according to the FAO/WHO Codex
Alimentarious guidelines (CAC/GL 08-1991) for supplementary foods for older infants
and young children [14]. The products were designed for enhancing growth and for
nutrition rehabilitation interventions. All the ingredients used i.e. rice (Oryza sativa),
com/maize (Zea mays), beans (Phaseoulus vulgaris), sardines (Sardinops melanosticta)
and red palm-oil (derived from the mesocarp of the oil palm (Elaeis guineensis) are

commodities that are inexpensive and readily available in Tanzanian markets.

3.3.2 Product Processing

The raw materials were processed into pre-cooked flour that could be
reconstituted into porridge for child feeding as recommended by FAO/WHO Codex
standard [14] for processed cereal-based foods for infants and children (CODEX STAN
74-1991). The beans, corn, and rice were sorted to remove extraneous materials, washed
in double distilled water, dried and milled into fine flours (mesh size 0.8 mm). The sun-
dried small fish (sardines - Sardinops melanosticta) were sorted to remove pebbles and
other extraneous materials and washed in double distilled water. The fish were thereafter
cooked in boiling water for 30 min, then dried and ground into a fine powder. The basic
ingredients — rice, rice-bean, rice-bean-sardine, corn, com-bean, corn-bean-sardine and
beans - were separately mixed with distilled water in a 25:75 solid: water ratio to form
thin slurry. The slurry was thereafter cooked in a steam heated drum drier set at 100.60C.

Residual moisture in the products was removed by additional drying in an oven.

94

3.3.3 Diet Preparation

Six test diets were formulated to meet the FAO/WHO [14] Codex Alimentarius
(CAC/GL 08-1991) guidelines (Table 1). A cornmeal was prepared according to the
traditional processing practices in Tanzania [15]. A modified AIN 93G diet [16] was used
as a control. A low protein diet was also prepared in which the casein in the control diet
was replaced by cornstarch and 2 g of lactalbumin per 100 g of diet. The low protein diet
was used to estimate the endogenous nitrogen excretion of the rats. Lipid content of the
control, the test and the low protein diets was adjusted to 13% using a mixture of red-

palm oil (10%) and corn oil (3%).

3.3.4 In vivo study

Growth Study: This study was conducted according to the AOAC [17] procedure 45.3.06.
Male Sprague Dawley rats (Harlan Sprague Dawley, Indianapolis, IN), 21days old and
weighing 35 — 50 g were housed individually in suspended stainless steel cages with wire
bottoms. The temperature of the animal room was set at 22°C and 40 — 60% relative
humidity with alternating 12-hour periods of light and darkness throughout the study. The
weanling rats were fed a stock diet for an acclimatization period of three days.
Subsequently, the rats were weighed and those rats at the extremes of the distribution
curve were excluded from the study. The remaining animals were randomly assigned into
seven groups of six animals each. The differences in mean weight between any two
groups did not exceed 2 g. Each group was randomly assigned to a diet and food and
water were provided ad libitum. The animals were allowed to acclimatize to the test diets

for three days before data collection started. Feed intake and weight changes of the

95

animals were monitored and recorded daily for the study period of 21 days. Feces were

collected from individual rats during the last three days of experiment.

Table 1: Composition (g kg") of the cereal-bean based supplementary foods used for the
in vivo rat feeding studyl

 

 

Ingredients/Diet: CTRL RM RBM CBSM RBSM CBM BM CM
Bean 00.0 00.0 453.4 102.0 153.0 434.4 566.8 00.0
Corn 00.0 00.0 00.0 570.9 00.0 312.6 00.0 770.0
Rice 00.0 740.0 314.6 00.0 519.1 00.0 00.0 00.0
Sardines 00.0 00.0 00.0 73.8 73.8 00.0 00.0 00.0
Sucrose 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0
Cornstarch 535.8 03.3 41.4 50.0 29.5 72.2 244.3 13.7
Cystine 02.3 00.0 00.0 00.0 00.0 00.0 00.0 00.0
Casein 152.2 00.0 00.0 00.0 00.0 00.0 00.0 00.0
Red Palm on 100.0 100.0 100.0 100.0 95.4 100.0 100.0 99.2
Corn oil 30.0 05.9 12.9 12.9 00.0 10.9 21.4 00.0
Fiber 112.2 83.3 10.2 10.2 61.7 00.4 00.0 49.6
Multi-mix’ 47.514 47.514 47.514 47.514 47.514 47.514 47.514 47.514
TOTAL 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0 1000.0

 

l FAO/WHO Codex standard for processed cereal-based foods for older infants and young children
(CODEX STAN 74-1991)[l4].

2 Diets — CTRL = control, RM = rice meal, RBM = rice-bean meal, CBSM = com-bean-sardine meal,
RBSM = rice-bean-sardine meal, CBM = com-bean meal, BM = bean meal and CM = corn meal

3 Multi-mix = (mineral mix —- 3.5 g + vitamin mix — 1.0 g, + choline bitartate — 0.25 g + butylated
hydroxytoluene - 0.0014 g).

3.3.5 Rehabilitation Study

Animals on low protein diet, CM, BM and CBM, which did not Show satisfactory
growth, were rehabilitated by feeding them the diets that showed the greatest potential to
support growth, i.e. Icontrol diet, RBSM and CBSM. The animals were rehabilitated for

14 days and their feed intake and weight changes monitored daily.

96

3. 3. 6 Computations
The following protein quality indices were calculated from the data collected:

Net Protein Retention Ratio = (g of weight gain + g of weight loss in protein free diet)
g of protein consumed

Food Efficiency Ratio = g of weight gain/ g of food consumed
Apparent Protein Digestibility = I—_F

True Protein Di gestibility = I — (F — F9)

Where I = Nitrogen intake of theItest diet

F = Fecal nitrogen of the test diet

F0 = Fecal nitrogen of the 2% lactalbumin diet

3.4 Chemical Assays

Feces collected in the balance period (last three days of the experiment) were
separated from the spilled food, dried to a constant weight at 100°C and ground. Total
nitrogen in the feces and diets was determined by Kjeldahl method [17] and the crude
protein content was calculated using the factor of 6.25. The moisture content of food and

fecal matter was determined by AOAC [l7] procedure 925.09.

3. 4. 1 Protein Digestibility Corrected Amino Acid Score (PDCAAS)

The PDCAAS was determined using the F AO/W H0 [18] and Gertjan [l9]
procedure. The essential amino acid profile of the test diets was compared with the
FAO/W HO/UN U [20] essential amino acid requirement pattern for a pre-school (2 — 5

year old) child to compute the amino acid scores. The PDCAAS index was computed for

97

all experimental diets using their essential amino acid profile compiled from the USDA
database [http://www.nal.usda. gov] and mean true digestibility value for each diet.

PDCAAS = True Digestibility x Lowest Amino Acid ratio

3.5 Statistical Analysis

Results are presented as mean values and standard deviations. Data were
subjected to one-way analysis of variance (ANOVA) where applicable, using the SAS
system for Windows® Version 8B, 2000 and a difference was considered to be
Significant at p < 0.05. Post hoc analysis of means was done by the Duncan’s Multiple

Range Comparison Test.

3.6 Results and Discussion
3.6.1 Amino Acid Profile

Proportionality pattern of amino acids in foods is the most important determinant
of protein quality [18]. Table 2 data Show the proportions of the various essential amino
acids in the control and test food products relative to the FAO/WHO/UNU [20] reference
patterns for children 0 — 1 year and 2 — 5 years and for NRC [21] amino acid reference
pattern for growing rats. All the products except RM, CBM and CM had amino acid
patterns that are considered acceptable for preschool children aged 2 — 5 years i.e. His -
19, Ile - 28, Leu - 66, LyS - 58, 8AA (Met + Cys) - 25, AAA (Tyr + Phe) - 63, Thr - 34,
Trp - 11 and Val - 35 gkg'l. The PDCAAS index reflects the estimated ability of the test
protein to meet the protein needs of an individual. The FAO/WHO/UNU [20]

recommended the use of the amino acid requirement pattern for the 2 — 5 year old child

98

as the reference for foods meant for preschool children and the amino acid composition
of human milk for foods intended for infants. PDCAAS values ranged from 47 - 91%
when the amino acid profile of 2 — 5 yr old children was used as reference. Rice-bean
meal, RBSM and CBSM had the highest PDCAAS values (p < 0.05) while RM, CBM
and CM had the lowest scores. The most limiting amino acids were Lys in RM and CM
and Trp in CBM. Lys and Trp are inherently limiting in rice and maize/corn-based
products, respectively [22]. The CBSM was limiting in Trp, however, the PDCAAS value
for the food product was higher than the minimum score (70%) recommended by the

F AO/W H0 [14] Codex Alimentarius. This could be attributed to the presence of fish
protein (5.30 gkg'1 of dried product), which improved its amino acid profile.

When the FAO/WHO/UNU [20] amino acid profile for breast milk was used as a
reference pattern, all products except the control diet had serious deficiencies in essential
amino acids. Trp was the most deficient amino acid (in control diet, CBSM, RBSM,
CBM and CM meals), followed by Sulfur containing Amino Acid (in RBM and BM).
Lys was limiting in RM. The PDCAAS values (range 30 - 94%) for all food products
except the control were lower than the minimum level (85%) recommended by
FAO/WHO [14] Codex Alimentarius for follow-up infant foods (CODEX STAN 156-
1989). This would imply that, although these food products can adequately meet the
nutritional needs of preschool children (2 — 5 years), school children (10 - 12 years) and
adults [18, 20], they would be suitable only as supplements for infants and should not be

used to substitute the mother’s breast milk.

99

The NRC [21] requirements of Sulfur containing Amino Acid for rats are much
greater than for pre-school children. This explains the low PDCAAS values (range 33 —
70%) for rats. Most test diets (RBSM, CBSM, RBM, CBM and BM) were limiting in
sulfur containing amino acids for rats while CM and RM were limiting in Lys. The
control diet contained the minimum PDCAAS (70%) required for growing rats. Since the
amino acid requirements for growing rats are much higher than that of pre-school age
children, the growth patterns observed in the growing rats are lower than what would
have been if the test diets were fed to children. For this reason, diets with protein that
supports only modest growth in rats would be adequate to support optimal grth in pre-

school age children.

3. 6.2 Protein Quality

Table 3 shows the apparent and true protein digestibility, net protein retention and
food efficiency ratios for the various cereal-bean formulations. The casein in the control
diet was Significantly (p<0.05) more digestible than the protein in the other products,
while BM, RBM and CBM were the least (p < 0.05) digestible. The apparent and true
protein digestibility levels observed in the BM, RBM and CBM diets were Similar to
those reported in other studies [22, 24 — 25]. A study by Sarwar [24] on protein and
amino acids digestibility in various foods revealed that, products containing beans usually
have low digestibility ranging from 70 to 85% resulting in lower overall utilization of the

protein in the foods.

100

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101

In a feeding study of young children, Graham et al. [23] observed low protein
digestibility in diets containing beans and inferred that, poor protein digestibility was the
major limiting factor for efficient utilization of bean-based proteins by small children.
Protein digestibility levels in these trial products influenced the ratio of net protein
retained. Net protein retention was significantly higher (p < 0.05) in the control (93%),
RBSM (92%), and CBSM (86%) meals compared to the CM (- 40%), BM (12%), CBM
(28%) and RBM (44%). Inclusion of sardines in the RBSM and CBSM significantly

improved net protein retention. The ratio of net protein retained reflects the

Table 3: In vivo true and apparent protein digestibility, net protein and food efficiency
ratios of the various cereal-bean based food products1

 

 

Diet2 True Protein Apparent Protein Net Protein Ratio3 Food Efficiency
Digestibility (%) Digestibility (%) Ratio4
CTRL 99 : 1.2‘I 95 i 1.23‘ 0.93 3: 026' 0.15 i 004‘
RM 96 i 2.1" 85 3: 197° 0.66 : 0.22hc 0.05 1 002°
RBM 83 : 1.5f 75 : 2.24f 0.44 : 019°d 0.06 1 003°
CBSM 94 1 20° 86 : 1.62° 0.86 i 025'” 0.10 t 003"
RBSM 90 : 1.7‘l 83 : 0.97d 0.92 : 017‘I 0.12 i 002"
CBM 86 1 13° 78 3: 096° 0.28 : 0.01"° 0.03 : 001°"
BM 82 : 1.5f 72 i 1.56‘ 0.12 4; 002° 0.01 : 000°l
CM 95 : 1.7b 88 i 1.68" -040 : 0.67f -003 : 003°

 

1 Means (n = 6) within a column with different superscripts are significantly different at p< 0.05.

2 Diets — CTRL = control, RM = rice meal, RBM = rice-bean meal, CBSM = com-bean-sardine meal,
RBSM = rice-bean-sardine meal, CBM = com-bean meal, BM = bean meal and CM = corn meal

3 (g of weight gain + g weight loss in low-protein diet)/g of protein consumed

4 g of weight gain/g of food consumed.

102

ability of the animal to grow. F AO/W H0 [14] recommends addition of edible fishmeal
and fish protein concentrate to cereal-based supplementary foods to increase their protein
quality. Fish protein has high content of Lys and is highly digestible [24].

Amount and type of protein in these food products greatly influenced their intake.
As reported in previous studies [26 —— 28], foods containing low and/or imbalanced
protein suppress food intake. Likewise, foods containing too high protein content (>
40g/100g) suppress food intake [29]. In this study, the highest levels of food intake (p <
0.05) were observed in RM (15.54 g/day) followed by RBSM, control and CBSM (12.22,
11.55, and 11.43 g/day, respectively; p > 0.05). Commeal was the least consumed (5.21
g/day). Food intake is a critical factor for growth as it influences both energy and protein
intake. Low food intake in animals receiving CM, BM, RBM and CBM diets could have
adversely affected their growth. Both sensory and metabolic effects have been described
to influence the food intake. Sensory attributes influence the food taste, physical
characteristics, and overall acceptability (immediate effect) while metabolic factors
influence plasma amino acid homeostasis and satiety (long-term effect) [28 — 29].

Food efficiency ratio was significantly higher (p < 0.05) in the control diet than in
the other food products. The food efficiency ratio ranged from 15% in the control diet to -
3% in CM. Food efficiency ratio was significantly lower (p > 0.05) in the products that
contained beans, which could be attributed to poor digestibility of bean protein [23].

The low- protein digestibility of food products containing beans could be
associated with presence of strong, covalent disulfide linkages between Cys residues in
some of the bean protein fractions e. g. globulins GII, glutellins and protease inhibitor

proteins that form compact, dense polymers which prevent proteolytic enzymes — pepsin,

103

trypsin and chymotrypsin from reaching the internal catalytic sites. Other factors such as
high dietary fiber, residual activity of lectins after cooking, steric hindrance of proteolysis
by the carbohydrate moieties of the glycoproteins (especially in globullin G11 and
protease inhibitor protein fractions), and presence of carbohydrate-protein and protein-
protein bands that are not susceptible to mammalian protease hydrolysis have been
reported to reduce the overall protein digestibility [30]. High food efficiency ratio is an
important quality attribute for supplementary foods, especially the cereal-based foods that

have a high dietary bulk which limits the amount of food children can take in a day [31].

3. 6.3 Assessment of the cereal-bean products as supplementary foods

Table 4 shows protein quality attributes and energy content of the test products
compared to the recommendations of FAQ/WHO [14] Codex Alimentarius for pre-school
age children diets. FAQ/WHO [l4] recommends that, supplementary foods for children
have PDCAAS value 3 70%, 2 400 kcal per 100 g of dry product, 27.0% of the energy
obtained from protein, net dietary protein energy value _>_ 7.0% and protein quality index
of 100% [32]. All products except CBM and CM met the recommended requirements of
protein and energy for young children. These products therefore are suitable for

maintenance and growth of pre-school, school age children and adults [20].

3.6.4 Evaluation of rehabilitation potential
Fig. 1 shows the effect of protein quality on growth. Weight gain was significantly
greater (p < 0.05) (2.69 g/day) for rats eating the control diet while rats receiving the CM

diet lost weight (-0.17 g/day). Rates of weight gain for animals receiving the other food

104

products were 1.65 g/day (RBSM), 1.4 g/day (CBSM), 0.57 g/day (RM), 0.37 g/day

(CBM), 0.45 g/day (RBM), and 0.21 g/day (BM).

Table 4: Protein quality and energy content of selected test diets compared with the
recommendations of FAQ/WHO [l4] Codex Alimentarius for pre-school age childrenl

 

Quality Criteria

 

Diet2 Total Energy (kcal) Protein-energy (%) PDCAAS (%) NDpE%3 PQI (%)J

 

CTRL 400 15.2 100 9.6 159
RM 405 4.94 58 3.1 52
RBM 405 14.1 83 8.8 97
CBSM 400 11.9 77 7.2 121
RBSM 400 11.8 90 7.9 121
CBM 401 16.4 47 6.2 97
BM 400 17.6 82 9.6 90
CM 412 6.8 46 3.4 42
FAO/WHO' 3 400 _>_7.0 2 70 27.0 2100

 

1 FAQ/WHO [14] Codex Alimentarius quality criteria for supplementary foods for older infants and young
children.

2 Products — CTRL = control, RM = rice meal, RBM = rice-bean meal, CBSM = corn-bean-sardine meal,
RBSM = rice-bean-sardine meal, CBM = corn-bean meal, BM = bean meal and CM = corn meal

3 Net dietary protein energy % = (1.25 x Protein energy % x Amino acid score)/(100 + 0.064 x Protein
energy % x Amino acid score) [32].

4 Protein quality index = requirement of protein for 2 — 5 y child (1.09 g/kg/day)/Amount of test protein to
satisfy requirement of the most limiting amino acid for a 2-5 y old child

Both food intake and protein adequacy strongly affect growth. As discussed
above, low protein quality results in reduced food intake and therefore reduced growth.
Two trial products (RBSM and CBSM) and the control diet were used to rehabilitate the
undernourished rats. As shown in Fig. 2, the rate of weight gain during rehabilitation was
significantly higher (p < 0.05) than during the normal growth phase. During nutritional
rehabilitation, the rate of weight gains for the animals receiving the test diets RBSM and
CBSM did not differ significantly (p > 0.05) from the weight gained by the rats receiving

the control diet. During nutritional rehabilitation the rates of weight gain were 5.61, 5.47

105

and 5.29 g/day for the animals receiving the control, RBSM and CBSM diets,

 

 

 

 

 

respectively.
120 -
CNTL
110 —
A 100 — . ' RBSM
£9
:38 90 —
D
3 - . f » ‘ '
80 — . 3 - - RBM RM CBSM
70 _ . ‘ , I’f’.=.gf£- >_.‘./ fl...“
24:", ——-""" ’ -fl' .
60‘vav::2:fi:5:::==:::::::
\
CM BM CBM
50 — L l 1 1
0 5 10 15 20

Days

Fig. 1: Growth patterns for rats fed varying sources of protein

The catch-up growth phenomenon observed in these animals was similar to that
observed in malnourished children during nutritional rehabilitation. Fjeld et al. [33] and
Rowland et al. [34] reported a rapid increase in weight gain ranging between 3 -— 8 times
the average daily grth rates when undernourished children were rehabilitated using
high energy, protein diets. In this study, the rates of catch-up growth were 2 — 3 times the
average daily rate of growth. Hastening catch-up grth would be advantageous because
it reduces the residence time in a hospital or community-based rehabilitation centers, thus

reducing the cost and enabling more children to be served.

106

150
130 ”

110 h

Weight (g)

90’

 

70

 

..
50 1 1 1 1 1 1 1

 

Days

Fig. 2: Growth pattern during rehabilitation phase

3.7 Conclusion

This study showed that, the drum-processed RBSM and CBSM products
developed fi'om locally produced ingredients were of high quality and displayed a great
potential to support normal and catch-up growth during nutritional rehabilitation of
undernourished animals. Values of true protein digestibility and growth response based
on rat feeding trials correspond closely with human measurements [18]. These results

therefore, may be extrapolated to pre-school and school—age children.

107

3.8 References

1. Pelletier, D.L. (1995). Potentiating effects in child mortality: epidemiological evidence
and policy implications. Food Nutr. Bull. 16: 206 - 213.

2. URT - United Republic of Tanzania and UNICEF (1993). Women and Children in
Tanzania — A Situational Analysis. Dar es Salaam; Tanzania. Government Printer.

3. URT - United Republic of Tanzania (1 999). Ministry of Health, National AIDS Control
Program Report. Epidemiological Unit, Dar es Salaam.

4. Mears, C. and Young, H. (1998). Acceptability and use of cereal-based food in refugee
camps: case studies from Nepal, Ethiopia and Tanzania. Oxford, Great Britain.
Humanities Press International.

5. Tomkins, A., Alnwick, D. and Haggerty, P. (1987). Fermented Foods for Improving
Child Feeding in Eastern and Southern Africa. In: Alnwick, D., Moses, S. and Schmidt,
O.G. (Eds). Proceedings of a Workshop on Improving Young Child Feeding in Eastern
and Southern Africa — Household Level Technology. Nairobi, Kenya. Kenya Publishing
House.

6. Mosha, AC. and Svanberg, U. (1990). The acceptance and food intake of bulk-reduced
weaning foods: The Liganga village study. Food Nutr. Bull. 12: 69 — 74.

7. Williams, CD. (1933). A nutritional disease of childhood associated with a maize diet.
Arch. Dis. Child 8: 423 - 33.

8. Reneman, L. and Derwig, J. (1997). Long-term prospects of malnourished children
after rehabilitation at the nutritional Rehabilitation Center of St. Mary’s Hospital,
Mumias, Kenya. .1. Trap. Pediatr. 43 (5): 293 — 6.

9. van Roosmalen-Wienbenga, M.W., Kusin, J .A. and de-With, C. (1986). Nutrition
rehabilitation in hospital - a waste of time and money? Evaluation of nutrition
rehabilitation in a rural district hospital in southwest Tanzania. Short-term results. .1.
Trap. Pediatr. 32(5): 240 - 243.

10. van Roosmalen-Wiebenga, M.W., Kusin, J .A. and de With. C. (1987). Nutrition
rehabilitation in hospital — a waste of time and money? Evaluation of nutrition
rehabilitation in a rural district hospital in Southwest Tanzania. Long-term results. .1.
T rap. Pediatr. 33 (l ): 24 — 28.

11. King, RS. and Burgess, A. (1993). Nutrition for Developing Countries. 2nd Edn.
London, Great Britain. ELBS with Oxford University Press.

108

 

12. Perra, A. and Costello, L. (1995). Efficacy of outreach nutrition rehabilitation centers
in reducing mortality and improving nutritional outcome of severely malnourished
children in Guinea Bissau. Eur. J. Clin. Nutr. 49(5): 353 - 359.

13. O’Dwyer, M. and Gillam, SJ. (1995). Children discharged following nutritional
rehabilitation: a follow-up study. Trap. Doctor 25(4): 146 — 51.

14. F AO/W HO (1994). Codex Alimentarius: F aods for Special dietary Uses (Including
Foods for Infants and Children). Joint FAO/WHO Food Standards Program, Codex
Alimentarius Commission, Vol 4. 2"d Edn. FAO Publications, Rome.

15. Mosha, T.C.E., Laswai, HS. and Tetens, I. (2000). Nutritional composition and
micronutrient status of homemade and commercial weaning foods consumed in Tanzania.
Plant F aads Hum. Nutr. 55: 185 — 205.

16. Reeves, P.G., Nielsen, RH. and Fahey, GO (1993). AIN-93G purified diets for
laboratory rodents: Final report on American Institute of Nutrition ad hoc writing
committee on the reformulation of the AIN-76A rodent diet. J. Nutr. 123: 1939 — 1951.

17. Association of Official Analytical Chemists International (1995). Oflicial Methods of
Analysis. 6th Edn. AOAC. Washington DC.

18. FAO/W HO (1991 ). Protein Quality Evaluation. The Report of the Joint FA O/WHO
Expert Consultation. Bethesda, MD, USA. 4 — 8 December. FAO Publications. Rome.

19. Gertjan, S. (2000). The protein digestibility-corrected amino acid scores. J. Nutr 130:
1865S — 1867S.

20. FAO/WHO/UNU (1985). Energy and Protein Requirements. Expert of the
FAO/WHO/UNU Expert Consultation. Technical Series No. 724. FAO/W HO/UN U
Publications, Geneva.

21 . National Research Council (1995). Nutrient Requirements of Laboratory Animals. 4th
Edn. Pp 11 — 79. National Academy of Sciences. Washington DC.

22. Milward, DJ. (1999). The nutritional value of plant-based diets in relation to human
amino acid and protein requirements. Prac. Nutr. Soc. 58: 249 — 260.

23. Graham, G.G., Morales, E., Placko, PR. and McLean Jr, WC. (1979). Nutritive
value of brown and black beans for infants and small children. Am. J. Clin. Nutr. 32:
2362 - 2366.

24. Sarwar, G., Peace, R.W., Batting, H.G. and Brule, D. (1989). Digestibility of protein

and amino acids in selected foods as determined by a rat balance method. Plant F aad
Hum. Nutr. 39: 23 — 32.

109

25. Occena, L.G., Bennink, M.R., Uebersax, M.A. and Chung, Y.S. (1997). Evaluation of
drum-dried meals prepared from split beans (Phaseolus vulgaris L.): Protein quality and
selected anti-nutritional factors. J. F aad Prac. Pres. 21: 335 344.

26. Ashley, D.V.M. and Anderson, G.H. (1975). Food intake regulation in the weanling
rat: Effects of the most limiting essential amino acids of gluten, casein and zein on the
self-selection of protein and energy. J. Nutr. 105: 1405 — 1411.

27. Peng, Y., Meliza, L.L., Vavich, MG. and Kemmerer, AR. (1975). Effect of amino
acid imbalance and protein content of diets on food intake and preference of young, adult
and diabetic rats. J. Nutr. 105: 1395 — 1404.

28. Radcliffe, J .D. and Webster, A.J.F. (1979). The effect of varying the quality of
dietary protein and energy on food intake and growth in the Zucker rat. Brit. J. Nutr. 41:
111 — 124.

29. Semon, B.A., Leung, P.M.B., Rogers, OR. and Gietzen, D.W. (1987). Effect of type
of protein on food intake of rats fed high protein diets. Physiol Behav. 41(5): 451 — 458.

30. Bennink, MR. and Srisuma, N. (1988). Digestibility of Dry Legume Starch and
Protein In: Applewhite TH (Ed) Proceedings of the World Congress on Vegetable
Protein Utilization in Human F aads and Animal F eedstuffs; Champaign, Illinois. Kraft
Inc. Illinois, USA,.

31. Ljungqvist, B.G., Mellander, O. and, Svanberg, U.O. (1981). Dietary bulk as a
limiting factor for nutrient intake in pre-school children: Problem description. J. Trap.
Pediatrics 27: 68 — 73.

32. Pellett, PL. and Mamabranchi, D. (1978). Recommended proportions of foods in
homemade feeding mixtures. Ecol. Food Nutr. 7: 219 — 228.

33. Fjeld, C.R., Schoeller, DA. and Brown, K.H. (1989). Body composition of children
recovering from severe protein-energy malnutrition at two rates of catch-up growth. Am
J. Clin. Nutr. 50: 12266 — 1275.

34. Rowland, M.G.M., Cole, T]. and Whitehead, R.G. (1977). A quantitative study into

the role of infection in determining the nutritional status in Gambian village children.
Brit. J. Nutr. 37: 441 - 450.

110

CHAPTER FOUR

4.0 NUTRITIONAL QUALITY OF DRUM-PROCESSED AND EXTRUDED READY-TO-

EAT COMPOSITE SUPPLEMENTARY FOODS

4.1 Abstract

This study was conducted to evaluate the nutritional quality of ready-to-eat composite
foods cooked by extrusion, conventional and drum-processing methods. Four
supplementary foods, namely com-bean-sardine meal (CBSM), bean meal (BM),
sorghum-bean-sardine meal (SBSM), and rice-bean-sardine meal (RBSM) were
formulated according to the FAO/WHO/UNU guidelines. The food mixtures were
extruded, drum-processed, and cooked conventionally in the traditional way. Cooking
doneness was evaluated by percent starch gelatinization and residual urease activity while
biological qualities -- true protein digestibility and growth performance -- were evaluated
using Sprague Dawley weanling rats. Efficiency in destroying phytohemagglutinins and
the anti-nutritional factors — trypsin, chymotrypsin and a-arnylase inhibitors were also
evaluated. Results of the study showed that starch gelatinization and residual urease
activity were not significantly different (p > 0.05) between the extruded and drum-
processed diets. Relative to conventional cooking, starch gelatinization was 95 - 100% in
extruded and 90 - 100% in drum-processed products. Inactivation of urease activity
ranged from 93 to 100% in extruded and 83 to 100% in drum-processed diets. The true
protein digestibilities were significantly (p5 0.05) higher when extruded foods compared
to drum-processed foods were fed to experimental animals. Animals fed extruded

products showed slightly greater but insignificant grth rates relative to those fed drum-

111

 

processed foods. Destruction of phytohemagglutinins was ranged between 91— 97% in
extruded and between 90 - 95% in the conventionally cooked and drum processed foods.
Extrusion, drum-processing and extrusion cooking also resulted in a significant
destruction of the anti-nutritional factors - trypsin, chymotrypsin and a-amylase
inhibitors. These results suggest that extrusion and drum-processing of cereal-bean-

sardine composite foods resulted in products meeting the required nutritional quality.

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4.2 Introduction

Protein energy under-nutrition during childhood remains a common health
problem in many parts of sub-Saharan Africa and contributes significantly to childhood
morbidity and mortality [1]. In Tanzania for instance, more than 30% of young children
suffer from protein, energy and micronutrient under-nutrition whereas more than 0.2
million children are estimated to die before reaching their fifih birthday [2, 3]. The first
year of life is usually the vulnerable period for developing under-nutrition, which usually
coincides with the introduction of weaning foods. Various studies have shown that
children in Tanzania, as is elsewhere in developing countries, start their life in a sound
health and their growth rate during the first 4 — 6 months is comparable to that of children
in developed countries [4 — 6]. Growth however, starts to falter during weaning and/or
thereafter [6].

Inadequate intake of nutrients due to low nutrient density and infrequent feeding
of children due to heavy maternal workload have been identified as some of the
underlying causes of acute and severe undemutrition. Due to mothers’ competing roles
such as working in farms, collecting firewood, fetching water, washing clothes, cleaning
house and caring for the other members of the family, they do not have time to prepare
meals and feed the child in a frequency (4 — 6 times/day) that would provide enough
nutrients [7, 8]. This period also is accompanied with high incidences of childhood
diseases due to increased infections caused by contaminated weaning foods and decline
in the immune-related factors acquired from the mother [9]. According to WHO [10],
WHO/UNICEF [11], and Dewey and Brown [12], preparing low-cost, fortified

supplementary foods from locally available ingedients using suitable small-to-medium

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scale production technologies in community settings, can help to meet the nutritional
needs of young children hence reducing the prevalence of under-nutrition drastically.
Likewise, centrally processed, fortified and ready-to-eat products would provide a
reliable option for families who have the means to buy them and can thus contribute
immensely in mitigating the problem of protein energy under-nutrition among older
infants and young children in developing countries. It is thus hypothesized that
developing nutrient-dense, fully cooked, ready-to-eat, inexpensive and culturally
acceptable supplementary foods from locally grown ingredients would help mitigate child
under-nutrition by increasing nutrient intake through increased feeding fiequency and
reducing food-borne diseases caused by the intake of contaminated and/or improperly
cooked foods. Identifying an appropriate processing method is therefore critical because
it determines the food quality, digestibility, palatability, overall acceptability, market
price and sustainability of production. This study was designed to evaluate the nutritional
quality of processed, ready-to-eat composite products cooked by extrusion, drum-
processing and conventional cooking methods. Specifically, this study was aimed at
identifying an appropriate method(s) of choice for processing ready-to-eat composite

foods for undernourished children in developing countries.

4.3 Materials and Methods
4.3.1 Products formulation and composition

Four supplementary products, namely corn—bean-sardine meal (CBSM), bean
meal (BM), sorghum-bean-sardine meal (SBSM) and rice-bean-sardine meal (RBSM),
were formulated in the laboratories of the Department of Food Science and Human

Nutrition, Michigan State University. Products were Optimized to deliver greatest amino

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acid score and the desired amount of energy and fat according to the F AO/W HO Codex
Alimentarius guidelines (CAC/GL 08-1991) for supplementary foods for older infants
and young children [13]. The products were designed for enhancing grth and for
nutrition rehabilitation interventions. All the ingredients used, i.e., rice (Oryza sativa),
com/maize (Zea mays), dry beans (Phaseoulus vulgaris), sardines (Sardinops
melanosticta), and red palm-oil [derived from the mesocarp of the oil palm (Elaeis
guineensis)] are commodities that are inexpensive and readily available in Tanzanian

markets.

4.3.2 Product Processing

The raw materials were processed into pre-cooked flour that could be
reconstituted into porridge for child feeding as recommended by FAO/W HO Codex
standard [13] for processed cereal-based foods for infants and children (CODEX STAN
74-1991). The dry beans, corn, sorghum, and rice were sorted to remove extraneous
materials, washed in distilled water, dried and milled into fine flours (mesh size 0.8 mm).
The sun-dried small fish (sardines - Sardinops melanosticta) were sorted to remove
pebbles and other extraneous materials and washed in distilled water. The fish was
thereafter cooked in boiling water for 30 min, then dried and ground into a fine powder.
The basic ingredients were formulated into diets: com-bean—sardine, bean flour, sorghum-
bean-sardine, and rice-bean-sardine. Each diet was divided into four portions. The first,
second and third portions of each diet were processed by drum-processing, extrusion and
conventional cooking, respectively into pre-cooked, ready-to-feed flour that could be

reconstituted into porridge for child feeding as recommended by FAO/WHO [13] Codex

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standard for processed cereal-based foods for infants and children (CODEX STAN 74-
1991). The fourth portion was analyzed unprocessed.

Extrusion of the formulated foods was carried out in a small laboratory twin-
screw extruder type APV-MP19T2-28 (APV Baker Ltd, Staffs, UK) with a barrel
length/diameter ratio of 25. The following extrusion conditions were adopted: feed
moisture content - 12 — 14.4%, moisture injection — 9 — 15%, feed rate — 3.61 kg/h,
screw-speed — 300 rpm, barrel temperatures — 70°C (zone 1), 100°C (zone 2), 127°C
(zone 3), 141°C (zone 4), 131°C (zone 5 - die), product temperature — 147°C, die pressure
— 350 psi, die diameter - 3 mm, motor load — 52.4% and mechanical energy input — 0.174
kw-hr/kg. Drum-processing was done by mixing the food ingredients with distilled water
in a 25:75 solid: water ratio to form a thin slurry. The slurry was slowly poured between
the two counter-rotating drums, which were heated by steam. The slurry was spread on
the surface of the slowly rotating drums to form a thin layer. High temperatures on the
surface of the drums cooked and dehydrated the food swiftly. The cooked, dehydrated
food product was scraped out of the drum surface before it was recoated with fresh food
slurry. The speed of the rotating drums was adjusted to increase/reduce product residence
time on the drums. Likewise, the amount of steam in the drums was adjusted to regulate
the cooking and drying process.

Conventional cooking of the food products followed the traditional Tanzanian
cooking practices adapted to the laboratory conditions as described by Mosha and
Svanberg [14] and Kikafunda et al. [15]. It involved preparing a smooth slurry of the
foods containing 10% solid matter and pouring the slurry into boiling water. The mixture

was stirred constantly until boiling. The heat was thereafter reduced from high to medium

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and the porridge was allowed to simmer while maintaining gentle constant stirring until
the desired cooking time was completed. The CBSM, SBSM and RBSM were cooked for
25 min each while the BM was cooked for 35 min. After cooking, the conventionally
cooked foods were freeze-dried while the extruded and drum-processed foods were dried

further in an air oven (set at 60 0C) for 3 h.

4.3.3 Diet Preparation

Four test diets were formulated to meet the F AO/WHO [13] Codex Alimentarius
(CAC/GL 08-1991) guidelines (Table 1). A modified AIN 93G diet [16] was used as a
control. A low protein diet (METDIET) was also prepared in which the casein in the
control diet was replaced by cornstarch and 2 g of lactalbumin per 100 g of diet. The low
protein diet was used to estimate the endogenous nitrogen excretion of the rats. Lipid
contents of the control, the test and the low protein diets were adjusted to 13% using a

mixture of red-palm oil (10%) and corn oil (3%).

4.3.4 In vivo Study

Growth Study: This study was conducted according to the AOAC [17] procedure 45.3.06.
Male Sprague Dawley rats (Harlan Sprague Dawley, Indianapolis, IN), 21days old and
weighing 35 — 50 g were housed individually in suspended stainless steel cages with wire
bottoms. The temperature of the animal room was set at 22°C and 40 — 60% relative
humidity with alternating 12-hour periods of light and darkness throughout the study. The
weanling rats were fed a stock diet for an acclimatization period of three days.

Subsequently, the rats were weighed and those rats at the extremes of the distribution

117

Table 1: Composition (g/100 g) of the cereal-bean-based supplementary foods used for
the in viva rat feeding studyI

 

 

 

Ingredients CBSM BM SBSM RBSM
Bean 10.20 56.68 11.28 15.30
Corn 57.09 0.00 0.00 0.00
Rice 0.00 0.00 0.00 51.91
Sorghum 0.00 0.00 49.68 0.00
Sardines 7.38 0.00 7.38 7.38
Sucrose 2.00 2.00 2.00 2.00
Cornstarch 5.00 24.43 10.56 2.95
Red Palm Oil 9.02 10.00 9.65 9.54
Corn Oil 0.00 2.14 0.00 0.00
Fiber 4.56 0.00 4.70 6.17
Mineral Mix 3.50 3.50 3.50 3.50
Vitamins Mix 1.00 1.00 1.00 1.00
Choline Cl 0.25 0.25 0.25 0.25
BHT 0.0014 0.0014 0.0014 0.0014

 

T FAO/WHO [13] Codex standard for processed cereal-based foods for older infants and young children

(CODEX STAN 74-1991).

2 BM - bean meal; CBSM - com-bean-sardine meal; SBSM - sorghum-bean-sardine meal; RBSM - rice-

bean-sardine meal

curve were excluded from the study. The remaining animals were randomly assigned into

13 groups of six animals each. The differences in mean weight between any two groups

did not exceed 2 g. The animals were divided into 12 groups in a 4 X 3 factorial design of

four different diets (CBSM, BM, SBSM, and RBSM) each processed by three different

methods (drum-processing, extrusion and conventional cooking). The 13‘h group of rats

was fed the modified AIN-93 control. Food and water were provided ad libitum. The

animals were allowed to acclimatize to the test diets for three days before data collection

started. Feed intake and animal weight were recorded daily for 21 days. Feces were

collected from each rat during the last three days of experiment. On day 22 one rat was

118

randomly selected from each group to form a 14th group. These rats were fed a stock diet
for three days after which they received a low-protein - metabolic diet. As for the other
groups, feed intake and animal weights were recorded daily for 3 days and feces were
also collected from each rat during the last three days. Fecal protein and metabolic fecal

protein were determined using the protein intake and fecal output data.

4.3.4.1 Computations
The following protein quality index was calculated from the data collected:
True protein digestibility = P1 - (F P — MFP)/ PI x 100%; where P1 = protein intake, FP =

fecal protein, MFP = metabolic fecal protein

4.4 Chemical Assays
4. 4. 1 True Protein Digestibility

Feces collected in the balance period (last three days of the experiment and the
during metabolic study) were separated from the spilled food, dried to a constant weight
at 100°C and ground. Total nitrogen in the feces and diets was determined by Kjeldahl
method [17] and the crude protein content was calculated using the factor of 6.25. The
moisture content of food and fecal matter was determined by AOAC [17] procedure

925.09.

4.4.2 Starch gelatinization
The degree of starch gelatinization in the cooked and raw products was

determined by using an enzyme hydrolysis method [18]. A dry sample ca 0.8 g was

119

hydrolyzed with 0.2 mL invertase (3000 IU/mL) at 37°C for 30 min. The free glucose
(FG) formed was condensed with a-Dianisidine (colorless) in presence of glucose
oxidase and peroxidase to form oxidized a-Dianisidine (brown color). Absorbance was
determined at 510 nm with a spectrophotometer. Percent free glucose was computed from
the relationship:

FG% = (A, x V, x C x D X 100%)/As,,, x Wt (mg) where A, = absorbance of the test food,
V, = total volume of test food solution (25.2 mL), C = concentration of glucose standard
(0.394 mg/mL), A5“, = absorbance of glucose standard solution, D = dilution factor (18)
and W, = weight of dry food sample used in mg.

The sample residue was subsequently digested with 0.1 mL arnyloglucosidase to
determine total glucose (TG). The glucose liberated was analyzed as above and
calculated from the relationship:

TG% = (A, x V, x C x D X 100%)/As,d x Wt (mg) where A, = absorbance of the test food,
V, = total volume of taste food solution (35.7 mL), C = concentration of glucose standard
(17.55 mg/mL), As“, = absorbance of glucose standard solution, D = dilution factor (1)
and W, = weight in mg of dry food sample used.

Total starch (TS) was thereafter calculated from the FG% and TG% values using the
relationship: TS = (TG% - FG%) x 0.9 [18]. The total starch served as an index of the
rate of starch gelatinization because it measured the amount of glucose released by
enzymic hydrolysis of the food samples after gelatinization. Total starch was corrected

for the free glucose.

120

4.4.3 Urease Activity Test
Residual urease activity in the cooked and raw foods was determined by the

AOCS [19] method Ba 9-58.

4.4.4 Tryspin Inhibitor Assay

Trypsin inhibitor activity (TIA) was determined by the method of Smith et al. [20]
as modified by Liu and Markakis [21]. One g of ground sample was extracted in 50 mL
of 10 mM NaOH and the pH adjusted to 9.4. The extract was then incubated with trypsin
enzyme at 37°C. Tyrpsin inhibitor activity (TIA) was determined by the reduction in
hydrolysis of a substrate — benzoyl-DL-arginine-p-nitroanilidine hydrochloride (BAPNA)
by the enzyme trypsin. TIA was defined as mg of pure trypsin inhibited per g of food

sample at 410 nm.

4.4.5 Chymotrypsin Inhibitor Assay
Chymotrypsin inhibitor activity (CIA) was assayed by the procedure of Kakade et
al. [22]. CIA was defined as the number of chymotrypsin units inhibited per mg of the

food sample at 275 nm under the conditions of the experiment.

4.4.6 Alpha-amylase Inhibitor Assay

Alpha-amylase inhibitor activity was determined by the method of Bernfend [23]
as modified by Deshpande et al. [24]. Alpha-amylase inhibitor activity was defined as mg
maltose equivalent inhibited from (it-amylase hydrolysis under the conditions of the

experiment.

121

4.4.7 Phytohemagglutinins Assay

Active phytohemagglutinins in the food samples were determined by enzyme-
linked immunosorbent assay (ELISA) described by Boniglia et al. [25]. One g of finely
ground food sample was extracted in 20 mL of PBS (phosphate buffer solution, 10 mM,
pH 7.2 containing 150 mM NaCl) by stirring overnight at room temperature. A 96-well
microtier plate (NUNC, USA) was coated with 0.1 mL/well of porcine thyroglobulin and
incubated overnight at 4 0C. The treated microtiter wells were treated with 0.1 mL/well of
PBS supplemented with 0.5% bovine serum albumin (BSA) and the plate incubated for
60 min at 37°C. Aliquots of 0.1 mL of sample extracts were loaded into each well of the
microtiter plate and the plate incubated at 37°C for 60 min. The plate was thereafter
washed twice with PBT (phosphate buffer 10 mM, pH 7.2 containing 0.05% Tween 20)
and once with PBS. The microtiter plate was subsequently treated with: l) 0.1 mL
aliquots of BSA (0.05% BSA in PBS); 2) rabbit anti-phytohemagglutinin IgG (diluted
1:5,000 in PBS containing 0.25% BSA); 3) alkaline phosphate-conjugate monoclonal
anti-rabbit IgG (diluted 1:10,000 in PBS containing 0.25% BSA); and 4) color
development solution — p-nitrophenyl phosphate (Sigma Cat. N7653). Between each
treatment, the microtiter plate was incubated for 60 min at 37°C and rinsed twice with
PBT and once with PBS. Finally, 50 uL of 3M NaOH was added to each well to stop the
reaction. Absorbance of the resulting solution was measured at 405 nm using a Synergy
HT Multi-detection Microplate reader (Bio-Tek® Instruments Inc., Winooski, VT 05404-
0998, USA). Samples and phytohemagglutinin standard solutions were loaded in the

microtiter plate in triplicate.

122

4.5 Statistical Analysis

Results are presented as mean and stande values. Data were subjected to one-
and two-way analysis of variance (ANOVA) where applicable, using the ProStat
[Version 3.01 (Poly Software International, Pearl River, NY. 10965)] and a difference
was considered to be significant at p g 0.05. Since the TPD values were in percent, the
data were subjected to arcsine transformation [26] prior to analysis by ANOVA. Past hac

analysis of means was done by the Fisher’s LSD test.

4.6 Results ad Discussion

The percent starch gelatinization and residual urease activity for foods processed
by extrusion, drum-processing and conventional cooking are summarized in Table 2.
Starch gelatinization rates were highest in the extruded and conventionally cooked foods
(94.8 - 100.0%) but were slightly lower (p > 0.05) in the drum-processed products.
Starch gelatinization rates in the drum-processed foods were 90.4% in BM, 93.1% in
RBSM, and 100.0% in CBSM and SBSM. Starch gelatinization rate is an important food
quality index for processed, ready-to-eat foods because it measures the cooking doneness
and also influences food palatability, digestibility, and consumer acceptance [27].
According to Camire et al. [27] and Camire [28], levels of starch gelatinization that are
palatable and acceptable to consumers range from 80 to 100%. All our experimental
foods had starch gelatinization rates within the acceptable range.

Urease activity was reduced significantly (p 5 0.05) by all the processing
methods. The thermo-processing methods reduced the urease activity by 97 — 99%.

Urease activity is a measure of cooking doneness for foods that contain legumes. This

123

Table 2: Percent starch gelatinization and residual urease activity of foods processed by
various methods].

 

 

 

 

Food Food Processing Method
Product2
Extrusion Drum-processing Conventional cooking Uncooked food
% SG3 UA‘ % 8G3 UA" % SG3 UA‘ UA“

CBSM 100.0' 0.020be 100.0‘ 0.030” 100.0' 0.015c 1.460‘
BM 94.8‘ 0.030bc 90.4b 0.020c 100.0a 0.040b 2.166'
SBSM 100.0' 0.030b 100.0' 0.015c 100.0‘ 0.025"c 1.330'
RBSM 99.6' 0.050" 93.1” 0.010c 100.0' 0.016c 1.460'

 

1 Residual urease activity (UA) and starch gelatinization (SG) values in a row with similar superscripts are
not significantly different at p 5 0.05.

2 CBSM - com-bean-sardine meal, BM - bean meal, SBSM - sorghum-bean—sardine meal, RBSM
- rice-bean-sardine meal

3 Starch gelatinization

4 Residual urease activity

quality indicator is particularly important for processed ready-to-eat foods that do not
involve further cooking prior to feeding. A residual urease activity level of 0.8 units has
been recommended for all infants’/young children’s supplementary foods that contain
legumes [29]. High levels of residual urease enzyme in foods containing legumes have
been associated with gastrointestinal illness and diarrhea in children [29]. In the drum-
processed foods, residual levels of urease activity ranged between 0.01 and 0.03 units
while in the extruded and conventionally cooked products the residual activities ranged
between 0.02 and 0.05 and between 0.015 and 0.04 units, respectively. Although the
reduction in the urease activity was significant (p 5 0.05) for all the cooking methods, the
residual enzyme activities were in fact about 10-fold lower than the recommended

maximum allowable residual activity (0.8) units [29]. Based on the residual urease

124

activity levels therefore, all the processing methods were effective in inactivating the
enzyme and the foods were thus suitable for children consumption.

Table 3 data show the residual activity/units of different anti-nutritional factors in
the foods processed by extrusion, drum-processing and conventional cooking. Trypsin
inhibitors (TIU/ g) were significantly reduced (p 5 0.05) by all the heat-processing
methods. Residual trypsin inhibitors in the drum-processed foods ranged from 1.04 —
7.94 TIU/ g while in the extruded and conventionally cooked foods residual levels of
trypsin inhibitors were 0.29 — 0.78 and 0.43 — 0.72 TlU/ g of food, respectively. These
results suggest that, extrusion and conventional cooking were more effective in
inactivating the trypsin inhibitors compared to the drum-processing. The thermo-
processing methods also resulted in a significant reduction (p _<_ 0.05) in the amount of
chymotrypsin inhibitors in the foods. The residual levels of chymotrypsin inhibitors in
the drum-processed, extruded and conventionally cooked foods were 0.00 — 9.01 , 0.00 —
8.08 and 0.00 — 1.05 CIU/g of food, respectively. In this case, conventional cooking was
superior in inactivating the chymotrypsin inhibitors while extrusion and drum-processing
were equally effective in inactivating the inhibitors.

The extent of the trypsin and chymotrypsin inhibitor inactivation by the various
cooking methods was comparable to those reported in other studies [30, 31]. Ellenreider
et al. [32] and Armour et al. [33] observed that in natural food milieux, like the ones used
in this study, trypsin inhibitors were more resistant to heat-inactivation than
chymotrypsin inhibitors. Because of the necessity of achieving a balance between the
amount of heat necessary to destroy the trypsin/chymotrypsin inhibitors and that which

may result in damage to the nutritional or functional properties of the protein, most foods,

125

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even the commercially available edible grade products, e. g., soybean products, retain
some amount of trypsin and chymotrypsin inhibitor activities originally present in the raw
food [34]. In dietary surveys in England and U.S.A., Doell et al. [35] and Billings et al.
[3 6] observed that many of the products consumed in these countries contained residual
amounts of protease inhibitors. In a study of ready-to-feed forms of commercial soybean
infant formulas, Churella et a1. [37] reported residual TIU ranging from 0.24 — 1.21 TIU
per gram of the foods while Rackis and Gumbmann [3 8] reported higher trypsin inhibitor
residues in commercial soy protein products ranging from 3.2 — 13.7 TIU per g of the
products. Trypsin inhibitor residues in our test products ranged fi‘om 0.3 to 7.9 TIU per g
of cooked food. These residual typsin inhibitor units were comparable to those reported
in commercial soybean products and infant formulas [37 — 39]. The residual trypsin
inhibitor levels found in these products were considerably low and may not present a
health risk to consumers. Liener [34] concluded in this regard that the residual trypsin
and chymotrypsin inhibitor activities in most foods are safe and are unlikely to cause any
health risk to humans. For the a-amylase inhibitors, extrusion, drum-processing and
conventional cooking resulted in 100% inactivation of the enzyme inhibitors. Grant et al.
[40] have stated that a-amylase inhibitors are readily inactivated even by modest thermo-
processing conditions.

Phytohemagglutinins were reduced significantly (p _<_ 0.05) by all the thermo-
processing methods (Table 3). Reduction in the concentration of phytohemagglutinins for
the drum-processed products ranged between 90% (in SBSM) and 95% (in BM) while for
the extruded products the reduction ranged between 91% (in SBSM) and 97% (in BM).

For the conventionally cooked products, reduction in phytohemagglutinins ranged

127

between 91% (in SBSM) and 97% (in BM). The residual levels of phytohemagglutinins
in our food products were lower than those reported in other studies [25, 41]. In a study
of two commercial dietary supplements containing kidney bean protein, Boniglia et al.
[25] reported residual phytohemagglutinins concentrations of 1.7 and 7.74 mg/ g. Rizzi et
al. [41] on the other hand reported residual phytohemagglutinins concentrations of 2.5
and 4.7 ug/g g in soy hamburger and soymilk, respectively. Since the residual
phytohemagglutinins in our food products were considerably low (range 0.1690 — 0.3131
ug/ g), it suggested that the foods were safe for human consumption. Ingestion of active
phytohemagglutinins interferes with the intestinal mucosal membrane brush-border
function by causing atrophy of the microvilli, thus, disrupting the absorption of all
nutrients [34, 42].

Data in Table 4 show the average food consumption for the experimental animals
receiving foods processed by the various methods. Diet influenced food intake
significantly (p 5 0.05). Variations in amino acid balance affect the acceptance of foods.
According to Koehnle et al. [43], a deficiency of any essential amino acid alters feeding
behavior. Studies based on animal models indicate that animals rapidly reduce intake of
food if there is deficiency in any one of the essential amino acids [44 — 47].

The average food consumption for animal groups receiving extruded, drum-
processed and conventionally cooked foods were not significantly (p > 0.05) different.
The average 21-day food intakes were 287.63, 258.34 and 277.12 g for animal groups
receiving extruded, drum-processed, and conventionally cooked foods, respectively.
Although the consumption of the foods processed by the various methods were not

statistically different (p > 0.05), there was however a significant interaction between the

128

Table 4: Average food consumption (g/21 days) for experimental rats receiving
composite foods processed by the various methods1

 

 

 

Food Product2 Food Processing Method

Extrusion Drum-processing Conventional cooking
CBSM 317.50 i 31.07‘l 274.53 : 52.43b 324.30 : 34.72‘I
BM 178.92 _+_ 28.92‘ 132.13 : 24.02b 183.14 1 24.02'
SBSM 325.32 : 20.14‘I 325.10 1 21 .52' 305.43 : 17.75'
RBSM 323.80 1 12.52‘ 319.93 1 36.00' 303.42 : 24.27‘l
Mean group intake 287.63 : 66.56‘l 258.34 : 87.14" 277.12 1 63.74‘

 

I Mean i SD based on duplicate analyses. Food consumption values in a row with different superscripts are
significantly different at p 5 0.05.

2 CBSM - corn-bean-sardine meal, BM - bean meal, SBSM - sorghum-bean—sardine meal, RBSM - rice-
bean-sardine meal

food products and the processing methods that influenced the amount of food consumed.
For each of the composite foods, the extruded and the conventionally cooked products
were the most consumed while the drum—processed foods were the least consumed.
Extrusion and conventional cooking therefore produced products that were slightly more
acceptable by the animals than the drum-processing. Thermo-processing plays a
significant role in improving the physical-chemical and sensory characteristics of foods
that lead to development of appealing taste, flavor, and aroma. Well-cooked foods are
more palatable, appealing and more acceptable [27].

Data in Table 5 show the true protein digestibility for the composite foods
processed by the various methods. Extrusion cooking resulted in products with a
significantly higher (p _<_ 0.05) protein digestibility compared to the drum-processing and
conventional cooking. The true protein digestibilities of the foods processed by drum-

processing and conventional coking were not significantly different (p _<_ 0.05). Extruded

129

Table 5: Percent true protein digestibility of foods processed by various methods1

 

 

 

 

Food Product2 Food Processing Method
Extrusion Drum-processing Conventional cooking
TPD3 TPD3 TPD’

CBSM 93.7 i 0.6“ 88.4 i 1.4” 90.5 :t 0.9”
BM 91.1 i 3.0‘ 86.4 : 4.3b 82.4 : 4.8c
SBSM 91.4 i 1.1' 88.2 i 1.0" 86.4 i 1.9b
RBSM 91.3 i 0.4' 89.2 i 1.2' 88.9 i 1.2‘
Mean group TPD 91.8 i 1.8‘ 88.0 : 2.6b 87.0 : 4.1b

 

1 Mean : SD based on duplicate analyses. Values in a row with different superscripts are significantly
different at p 5 0.05.

2 CBSM - corn-bean-sardine meal, BM - bean meal, SBSM - sorghum-bean-sardine meal, RBSM - rice-
bean-sardine meal

3 TPD — True protein digestibility

CBSM had the highest true protein digestibility (93.7%) while the conventionally cooked
BM showed the lowest digestibility (82.4%). There were also significant (p 5 0.05)
interactions between the types of foods and the processing methods that influenced
protein digestibility. In this case, extrusion cooking resulted in products whose proteins
were significantly (p 5 0.05) more digestible compared to the other processing methods.
True protein digestibility is a key food quality index because it indicates whether the
amino acids present in a food protein would be digested and become available for
utilization by the body [48]. Low protein digestibility limits the amount of amino acids in
a food that can be absorbed into the body, and can therefore adversely affect growth [48].
The high levels of food consumption and high protein digestibility of the extruded

products were echoed in the average weight gain of the experimental animals. Data in

130

Table 6 show the average weight gain (g/21 days) for the animals receiving the food
products processed by the various methods. As for the food consumption and true protein
digestibility, there were significant (p 5 0.05) interactions between the types of food
products and the processing methods that influenced the average weight gain. Animals
receiving the extruded products tended to gain more weight, even though their average
weight gain did not differ significantly (p > 0.05) from those receiving the drum-
processed and conventionally cooked products. This suggests that foods processed by
extrusion, drum-processing and/or conventional cooking were equally good in supporting

grth of the experimental animals.

Table 6: Average weight gain (g/21 days) for experimental rats receiving composite
foods processed by the various methods

 

 

 

Food Product2 Food Processing Method

Extrusion Drum-processing Conventional cooking
CBSM 105.44 i 14.07b 87.01 : 13.46c 117.01 : 7.41'
BM 26.00 :1; 3.76'” 16.56 i 3.63b 27.27 i 6.36‘
SBSM 113.27 : 7.16‘ 111.72 i 8.56’” 100.57 : 5.77"
RBSM 122.00 _+_ 5.13' 117.08 118.07' 103.70 :11.71b
Group weight gain 92.23 1 39.55' 80.68 : 42.88‘I 85.98 : 37.66‘

 

1 Mean 1 SD based on duplicate analyses. Weight values in a row with different superscripts are
significantly different at p 5 0.05.

2 CBSM - corn-bean-sardine meal, BM - bean meal, SBSM - sorghum-bean-sardine meal, RBSM - rice-
bean-sardine meal

4.7 Conclusion
High rate of starch gelatinization in the foods and inactivation of urease enzyme

affirmed that the foods were fully cooked. Residual levels of anti-nutritional factors -

131

trypsin, chymotrypsin and a-amylase inhibitors and the phytohemagglutinins were
negligibly small. The composite food products had high true protein digestibility and
supported normal weight gain in the experimental animals. Both extrusion cooking and
drum-processing produced foods that met the required nutritional and consumption
quality characteristics. Availability of equipment and energy costs will thus dictate the

ultimate method of choice for processing these foods in developing countries.

132

4.8 References

1. UN. (1992). United Nations. 2nd Report on the World Nutrition Situation: Global and
Regional Results. Vol. 1. Rome, CC/SCN.

2. Kavishe, PP. (1993). Nutrition: Relevant Actions in Tanzania Tanzania Food and
Nutrition Center Monograph Series No. 1, Dar es Salaam.

3. Bureau of Statistics (1997). Tanzania Demographic and Health Survey - 1996. Bureau
of Statistics, Dar es Salaam.

4. Mosha, T.C., Dakiyo, S.O.S. and Laswai, H. (1998). Breastfeeding, weaning practices
and anthropometric patterns of children in Morogoro district, Tanzania. Ecol. Food Nutr.
37(4): 309 — 339.

5. Dewey, K.G., Peerson, J ,M., Heinig, M.J., Nommsen, L.A., Lonnerdal, B., Lopez-de-
Romana, G., Creed—de—Kanashiro, H., Black, RE. and Brown, K.H. (1992). Growth
patterns of breast-fed infants in affluent (United States) and poor (Peru) communities:
Implications for timing of complementary feeding. Am. J. Clin. Nutr. 56 (6): 1012 —
1018.

6. URT - United Republic of Tanzania, UNICEF. (1993). Women and Children in
Tanzania — A Situational Analysis. Dar es Salaam; Tanzania. Government Printer.

7. Bary, MP. (1980). Time allocation of the mother and child nutrition. Ecol. Food. Nutr.
9: 1 — 14.

8. Holmboe-Ottesen, G. and Wandel, M. (1991). Men’s contribution to the food and
nutrition situation in the Tanzanian household. Ecol. Food Nutr. 26(1): 83 — 96.

9. Walker, A.F. (1990). The contribution of weaning foods to protein energy
malnutrition. Nutr. Rev. Res. 3: 25 - 47.

10. WHO (2002). Infant and Young Child Nutrition: Global Strategy on Infant and
Young Child Feeding. World Health Assembly Document WHA55/15. Rome. WHO
Press.

1 l. WHO/UNICEF (1998). Complementary Feeding of Young Children in Developing
Countries: a review of the Current Scientific Knowledge. WHO Publications. Geneva.

12. Dewey, K.G. and Brown, K.H. (2003). Update on technical issues concerning

complementary feeding of young children in developing countries and implications for
intervention programs. Food Nutr. Bull. 24 (1): 5 — 28.

133

13. FAO/WHO (1994). Codex Alimentarius: Foods for Special dietary Uses (Including
Foods for Infants and Children). Joint FAO/WHO Food Standards Program, Codex
Alimentarius Commission, Vol 4. 2nd Edn. FAO Publications, Rome.

14. Mosha, AC. and Svanberg, U. (1983). Preparation of weaning foods with high
nutrient density using flour of germinated cereals. Food Nutr. Bull. 5(2): 10 - 14.

15. Kikafunda, J .K., Walker, A.F. and Abeyasekera, S. (1997). Optimising viscosity and
energy density of maize porridges for child weaning in developing countries. Intl J. Food
Sci. Nutr. 48: 401 - 409.

16. Reeves, P.G., Nielsen, F .H. and Fahey, G.C., (1993). AIN-93G purified diets for
laboratory rodents: Final report on American Institute of Nutrition ad hoc writing
committee on the reformulation of the AIN-76A rodent diet. J. Nutr. 123: 1939 - 1951.

17. AOAC (1995). Official Methods of Analysis; Association of Official Analytical
Chemists, Washington DC.

18. Englyst, H.N., Kingman, S.M. and Cummings, J.H. (1992). Classification and
measurement of nutritionally important starch fractions. Eur. J. Clin. Nutr. 46 (Suppl. 2).
S33 - S50.

19. AOCS (1980). Oflicial Methods of the America] Oil Chemists ’ Society. 3rd Edn. IL.
American Oil Chemists’ Society.

20. Smith, C., Van Megen, W., Twaalfhoven, I. and Hitchcock, C. (1980). The
determination of trypsin inhibitor levels in foodstuffs. J. Sci. Food Agric. 31: 341 — 350.

21. Liu, K., Markakis, P. (1989). Trypsin inhibition Assay a related to limited hydrolysis
of inhibitors. Analitical Biochem. 178:159 — 165.

22. Kakade, M.L., Swenson, DH. and Liener, LE. (1970). Note on the determination of
chymotrypsin and chymotrypsin inhibitor activity using casein. Analitical Biochem. 33:
255 — 258.

23. Bernfend, P. (1970). Amylases - Alpha and Beta In: Colowick, SP and Kaplan, NO
(Eds). Methods in Enzymology. Vol. 1. New York. Academic Press.

24. Deshpande, S.S., Sathe, S.K., Salunkhe, D.K. and Comforth, DP. (1982). Effects of
dehulling on phytic acid, polyphenols, and enzyme inhibitors of dry beans (Phaseolus
vulgaris L.) J. Food Sci. 47: 1846 — 1850.

25. Boniglia, C., Fedele, E. and Sanzini, E. (2003). Measurement by ELISA of active

lectin in dietary supplements containing kidney bean protein. J. Food Sci. 68 (4): 1283 —
1286.

134

26. Snedecor, G.W. and Cochran, W.G. (1969). Statistical Methods. 6‘h Ed. Ames, Iowa.
The Iowa State University Press. Pp 327 - 569

27. Camire, M.B., Carnire, A. and Krumhar, K. (1990). Chemical and nutritional changes
in foods during extrusion. Crit. Rev. Food Sci. Nutr. 29(1): 35 — 57.

28. Camire, ME. (2000). Chemical and nutritional changes in food during extrusion. In:
Riaz, M.N. (Ed) Extruders in Food Applications. Lancaster. Technomic Publishing Co.
Inc. pp 127 — 147.

29. TBS - Tanzania Bureau of Standards (1983). Tanzania Standards for processed
Cereal-based Weaning Foods — Specifications. Dar es Salaam. Tanzania Bureau of
Standards.

30. Harper, J .M. and Jansen, GR. (1985). Production of nutritious pre-cooked foods in
developing countries by low-cost extrusion technology. Food Rev. [ml 1 (1 ): 27 — 97.

31. Carvalho, M.R.B. and Sgarbieri, V.C. (1997). Heat treatment and inactivation of
trypsin-chymotrypsin inhibitors and lectins from beans (Phaseolus vullgaris L.). J. Food
Biochem. 21 (3): 219 -— 233.

32. Ellenreider, G., Blanco, S. and Bondoni, A. (1981). Thermal inactivation of trypsin
inhibitors in aqueous extracts of soybeans. Studies on substances that accelerate
inactivation. Cereal Chem. 58: 291 — 303.

33. Armour, J .A., Perera, R.L.C., Buchan, WC. and Grant, G. (1998). Protease inhibitors
and lectins in soya beans and effects of aqueous heat-treatment. J. Sci. Food Agric. 78:
225 - 231.

34. Liener, LE. (1994). Implications of anti-nutritional components in soybean foods.
Crit. Rev. Food Sci. Nutr. 34: 31 — 67.

35. Doell, B.H., Ebden, CJ. and Smith, CA. (1981). Trypsin inhibitor activity of
conventional foods which are part of the British diet and some soya products. Plant
Foods Hum. Nutr. 31: 139 — 144.

36. Billings, P.C., Longnecker, M.P., Keary, M. and Taylor, PR. (1990). Protease
inhibitor content of human dietary samples. Nutr. Cancer 14: 81 - 93.

37. Churella, H.R., Yao, B.C.and Thomson, W.A.B. (1976). Soybean yrypsin inhibitor
activity of soy infant formulas and its nutritional significance for the rat. J. Agric. Food
Chem. 24(2): 393 — 397.

38. Rackis, J .J . and Gumbmann, MR. (1986). Protease inhibitors: Physiological
properties and nutritional significance. In: Ory, R.L. (Ed). Antinutrients and Natural
Toxicants in Foods. Westport, CT. Food and Nutrition Press. Pp 203.

135

39. Dipietro, CM. and Liener, LE. (1989). Soybean protease inhibitors in foods. J. Food
Sci. 54(3): 606 - 609.

40. Grant, G., Edwards, J .E. and Pusztai, A. (1995). Alpha-amylase inhibitor levels in
seeds generally available in Europe. J. Sci. Food Agric. 67: 235 - 238.

41. Rizzi, C., Galeoto, L., Zoccatelli, G., Vincenzi, S., Chignola, R. and Peruffo, A.D.B.
(2003). Active soybean lectin in foods: quantitative determination by ELISA using
immobilized asialofetuin. Food Res. Ind 36: 815 — 821.

42. Lajolo, F.M. and Genovesse, M.I. (2002). Nutritional significance of lectins and
enzyme inhibitors from legumes. J. Agric. Food Chem. 50: 6592 — 6598.

43. Koehnle, T.J., Stephens, A. and Gietzen, D.W. (2002). Alteration of the
microstructure of feeding behavior during the first meal of the threonine imbalanced diet.
Appetite 39: 85. Abstract.

44. Sharp, J .W., Magrum, L.J. and Gietzen, D.W. (2002). Role of MAP kinase in
signaling indispensable amino acid deficiency in the brain. Molecular Brain Res. 105: 11
— 18. .

45. Koehnle, T.J., Russell, MC. and Gietzen, D.W. (2003). Rats rapidly reject diets
deficient in essential amino acids. J. Nutr. 133: 2331 —— 2335.

46. Hrupka, B.J., Lin, Y.M., Gietzen, D.W. and Rogers, OR. (1997). Small changes in
essential amino acid concentrations alter diet selection in amino acid-deficient rats. J.
Nutr. 127: 777 -- 784.

47. Gietzen, D.W., Erecius, LP. and Rogers, OR. (1998). Neurochemical changes after
imbalanced diets suggest a brain circuit mediating anorectic response to amino acid
deficiency in rats. J. Nutr. 128: 771 — 781.

48. Sarwar, G. (1987). Digestibility of protein and bioavailability of amino acids in
foods: Effect on protein quality assessment. World Rev. Nutr. Diet. 54: 26 — 70.

136

CHAPTER FIVE

5.0 PROTEIN DIGESTIBILITY-CORRECTED AMINO ACID SCORES AND
STORAGE STABILITY OF READY-TO-EAT SUPPLEMENTARY FOODS FOR PRE-

SCHOOL AGE CHILDREN

5.1 Abstract

Severe under-nutrition during childhood remains a common health problem in many parts
of the world and contributes immensely to childhood morbidity and mortality. Foods
formulated to ameliorate this condition must provide adequate protein of high quality and
also must have reasonable shelf-life. This study was conducted to evaluate the protein
quality (as measured by the FAO approved true protein digestibility and protein
digestibility-corrected amino acid scores), acceptability and storage stability of processed
cereal-bean-sardine composite supplementary foods for pre-school age children in
Tanzania. Four composite products namely com-bean-sardine meal (CBSM), bean-meal
(BM), sorghum-bean-sardine meal (SBSM) and rice-bean-sardine meal (RBSM)
(processed by extrusion, drum-processing and conventional cooking) were formulated to
maximize the amino acid score as recommended by F AO/WHO/UNU for pre-school age
children. The products were evaluated for true protein digestibility (TPD) and true
protein digestibility-corrected amino acid score (PDCAAS). Extruded and drum-
processed CBSM and SBSM were evaluated for storage stability. Results showed that
TPD and PDCAAS were highest in the extruded products. The TPD values for the
products ranged from 82 — 93% and the PDCAAS values were 51 — 86%. There were no

significant (p > 0.05) variations in the amino acid contents for foods processed by either

137

extrusion, drum-processing or conventional cooking. Threonine was most limiting in the
CBSM, SBSM and RBSM while cysteine + methionine (SAA) was most limiting in the
EM. Storage of the products up to 16 weeks at 380C resulted in a significant increase (p _<_
0.05) in the malondialdehyde concentrations; nevertheless, the levels remained within the

acceptable range found in processed commercial supplements. Total acids and pH did not

change significantly (p > 0.05) during storage.

138

5.2 Introduction

Childhood undemutrition remains a common problem in much of the developing
world. A recent comprehensive report prepared by World Health Organization using data
collected from 1980 to] 992 indicates that, more than one third of children less than five
years of age in developed countries have a weight/height-for—age less than 2 standard
deviations (SD) with respect to international reference data [1]. The WHO report shows
that the proportion of children who are undernourished has changed very little during the
past 20 years [2 — 5] and because of the considerable global population grth during
this period, the number of undernourished children continues to escalate, especially in
sub-Saharan Afiica [6]. In Tanzania, about 40% of young children suffer from protein-
energy undemutrition (PEU) [7, 8]. Apart fi'om PEU, other deficiencies, particularly of
micronutrients, are widespread among infants and young children and account for the
high rates of child morbidity and mortality[8, 9]. The most prevalent nutrient deficiencies
in Tanzania are protein, iron, vitamin A and iodine. Other macro- and micronutrient
deficiencies (e. g. zinc, selenium, copper, manganese, calcium, folate, and B-vitamins) are
prevalent and have adverse effect on the nutritional status of children; however, their
deficiency disorders are not clinically pronounced, thus, masking their public health
significance[8, 1 1].

The causes of undemutrition are multifaceted by nature. The immediate cause of
undemutrition is inadequate intake and poor utilization of nutrients due to the high
incidence of disease. Underlying factors are insufficient household food security, an
inadequate childcare system and insufficient health services while the deeper-rooted basic

factors relate to socioeconomic conditions [7]. Factors directly linked to food components

139

have been highlighted in many reports and have been reported to account for more than
75% of the deaths of infants and young children in Tanzania [12]. Also, childhood
diseases such as malaria, diarrhea, acute respiratory infections, and measles aggravate the
nutritional problems by impairing intake and utilization of nutrients, lowering the body’s
defense system thus predisposing the body to other infections and increasing
requirements for other nutrients [12].

PEU and micronutrient deficiencies begin during weaning and/or immediately
thereafter as most food used for weaning do not provide adequate amounts of energy,
protein and micronutrients. The traditional weaning foods of Tanzania are based on
starchy staples such as maize (Zea mays), sorghum (Sorghum bicolor L.), finger millet
(Eleucine coracona), and rice (Oryza sativa) or non-cereals such as cassava (Manihot
esculenta), round potato (Solanum tuberosum), sweet potato (Ipomea batatas), yams
(Dioscorea spp) and plantains (Musa paradisiaca sapientum) and these foods have been
widely associated with nutrient deficiencies among pre-school age children [13, 14].
Developing nutrient-dense, fully cooked, ready-to-eat, inexpensive weaning/
supplementary foods from the locally grown food ingredients using suitable household-
level or small-to-medium scale production technologies in community settings has been
strongly recommended as a viable and sustainable approach to address the problem of
undemutrition in developing countries [15 — 22]. According to WHO [17],
WHO/UNICEF [15], and Dewey and Brown [18] centrally processed, fortified and
ready-to-eat low-cost foods would provide a reliable option for many families and can
thus contribute immensely in ameliorating the problem of protein-energy and

micronutrient undemutrition among older infants and young children in developing

140

countries. The food however, must be nutritionally sound to provide the essential amino
acids needed for growth and the processing methods used should insure maximum
retention of the essential nutrients in the food. Furthermore, the processing methods must
result in products that are organoleptically acceptable to consumers. The products must
also be stable during storage so as to allow ample time for transportation, storage, and
marketing while still maintaining their nutritional and sensory wholesomeness [23. This
study was conducted to determine the protein digestibility corrected amino acid scores of
supplementary foods formulated for older infants and pre-school age children and the
effect of various processing methods - extrusion, drum-processing and conventional
cooking on the retention of essential amino acids. The study also evaluates the storage

stability of the products processed by extrusion.

5.3 Materials and Methods
5.3.1 Product Formulation

Four supplementary products namely com-bean-sardine meal (CBSM), bean meal
(BM), sorghum-bean-sardine meal (SBSM) and rice-bean-sardine meal (RBSM) were
formulated in the laboratories of the Department of Food Science and Human Nutrition,
Michigan State University. Products were optimized to deliver greatest amino acid score
and the desired amount of energy and fat according to the FAO/WHO Codex
Alimentarius guidelines (CAC/GL 08-1991) for supplementary foods for older infants
and young children [24]. The products were designed for enhancing grth and for
nutrition rehabilitation interventions of pre-school age children. All the ingredients used

i.e. rice (Oryza sativa), com/maize (Zea mays), dry beans (Phaseoulus vulgaris), sardines

141

(Sardinops melanosticta) and red palm-oil (derived from the mesocarp of the oil palm
(Elaeis guineensis) are commodities that are inexpensive and readily available in

Tanzanian markets.

5.3.2 Product Processing

The raw materials were processed into pre-cooked flour that could be
reconstituted into porridge for child feeding as recommended by FAO/W HO Codex
standard [24] for processed cereal-based foods for infants and children (CODEX STAN
74-1991). The dry beans, corn, sorghum and rice were sorted to remove extraneous
materials, washed in distilled water, dried and milled into fine flours (mesh size 0.8 mm).
The sun-dried small fish (sardines) were sorted to remove pebbles and other extraneous
materials and washed in distilled water. The fish were thereafter cooked in boiling water
for 30 min, then dried and ground into a fine powder. The basic ingredients were
formulated into diets — com-bean-sardine, bean flour, sorghum-bean-sardine and rice-
bean-sardine. Each formulation was divided into four portions. The first, second and third
portions of each product were processed by drum-processing, extrusion and conventional
cooking, dried and ground into pre-cooked, ready-to-feed flour that could be
reconstituted into porridge for child feeding as recommended by FAO/WHO [24] Codex
standard for processed cereal-based foods for infants and children (CODEX STAN 74-
1991). The fourth portion was analyzed unprocessed.

Extrusion of the composite foods was canied out in a small laboratory twin-screw
extruder type APV-MPF-19 (APV Backer Ltd, Staffs, UK) with a barrel length/diameter

ratio of 25. The following extrusion conditions were adopted: feed moisture content 12 —

142

14.4%, moisture injection — 9 — 15%, feed rate — 3.61 kg h", screw-speed — 300 rpm,
barrel temperatures — 70°C (zone 1), 100°C (zone 2), 127°C (zone 3), 141°C (zone 4),
131°C (zone 5 - die), product temperature - 147°C, die pressure - 350 psi, die diameter —
3 mm, motor load — 52.4% and mechanical energy input — 0.174 kw-hr kg'l. Drum-
processing was done by mixing the food ingredients with distilled water in a 25:75 solid:
water ratio to form a thin slurry. The slurry was slowly poured between the two counter-
rotating drums, which were heated by steam. The slurry spread on the surface of the
slowly rotating drums to form a thin layer. High temperatures on the surface of the drums
cooked and dehydrated the food swiftly. The cooked, dry food product was scraped off
from the drum surface before they were recoated with fresh food slurry. The speed of the
rotating drums was adjusted to increase/reduce product residence time on the drums.
Likewise, the amount of steam in the drums was adjusted to regulate the cooking and
drying process.

Conventional cooking of the food products followed the traditional Tanzanian
cooking practices adapted to the laboratory conditions as described by Mosha and
Svanberg [9] and Kikafimda et al. [25]. It involved preparing smooth slurry of the foods
containing 10% solid matter and pouring the slurry into boiling water. The mixture was
stirred constantly until boiling. The heat was thereafter reduced from high to medium and
the porridge was allowed to simmer while maintaining gentle constant stirring until the
desired cooking time was completed. The CBSM, SBSM and RBSM were cooked for 25
min each while the BM was cooked for 35 min. After cooking, the conventionally cooked
foods were freeze-dried while the extruded and drum-processed foods were dried further

in an air oven (set at 60°C) for 3 h.

143

5.3.3 Diet Preparation for Protein Quality Evaluation

Four test diets were formulated to meet the FAO/WHO [24] Codex Alimentarius
(CAC/GL 08-1991) guidelines (Table 1). A modified AIN 93G diet [26] was used as a
control. A low protein diet (METDIET) was also prepared in which the casein in the
control diet was replaced by cornstarch and 2 g of lactalbumin per 100 g of diet. The low
protein diet was used to estimate the endogenous nitrogen excretion of the rats. Lipid
content of the control, the test and the low protein diets was adjusted to 13% using a

mixture of red-palm oil (10%) and corn oil (3%).

5.3.4 In vivo study

Growth Study: This study was conducted according to the AOAC [27] procedure 45.3.06.
Male Sprague Dawley rats (Harlan Sprague Dawley, Indianapolis, IN), 21days old and
weighing 35 — 50 g were housed individually in suspended stainless steel cages with wire
bottoms. The temperature of the animal room was set at 22°C and 40 — 60% relative
humidity with alternating 12-hour periods of light and darkness throughout the study. The
weanling rats were fed a stock diet for an acclimatization period of three days.
Subsequently, the rats were weighed and those rats at the extremes of the distribution
curve were excluded from the study. The remaining animals were randomly assigned into
13 groups of six animals each. The differences in mean weight between any two groups
did not exceed 2 g. Twelve groups were assigned to experimental diets (four diets with
each diet processed by either extrusion, drum-processing or conventional cooking). The

13‘h group of rats was fed the modified AIN-93 control. Food and water were provided ad

144

Table 1: Composition (g kg") of the cereal-bean based supplementary foods used for the
in vivo rat feeding study‘I

 

 

 

Dietb
Ingredients CTRL METDIET BM CBSM SBSM RBSM
Beans 00.0 00.0 566.8 102.0 112.8 153.0
Corn 00.0 00.0 00.0 570.9 00.0 00.0
Rice 00.0 00.0 00.0 00.0 00.0 519.1
Sorghum 00.0 00.0 00.0 00.0 496.8 00.0
Sardines 00.0 00.0 00.0 73.8 73.8 73.8
Sucrose 20.0 20.0 20.0 20.0 20.0 20.0
Cornstarch 535.8 535.8 244.3 50.0 105.6 29.5
Cystine 02.3 02.3 00.0 00.0 00.0 00.0
Casein 152.2 00.0 00.0 00.0 00.0 00.0
Lactalbumin 00.0 20.0 00.0 00.0 00.0 00.0
Red Palm Oil 100.0 100.0 100.0 90.2 96.5 95.4
Corn oil 30.0 30.0 21.4 00.0 00.0 00.0
Fiber 112.2 112.2 00.0 45.6 47.0 61.7
Mineral mix 35.0 35.0 35.0 35.0 35.0 35.0
Vitamins mix 10.0 10.0 10.0 10.0 10.0 10.0
Choline CI 02.5 02.5 02.5 02.5 02.5 02.5
BHT 00.014 00.014 00.014 00.014 00.014 00.014

 

‘ FAO/WHO [24] Codex standard for processed cereal-based foods for older infants and
young children (CODEX STAN 74-1991).

CTRL = modified AIN-93 diet; METDIET = Metabolic diet; BM = Bean meal; CBSM
= Com-bean-sardine meal; SBSM = Sorghum-bean-sardine meal; RBSM = Rice-bean-
sardine meal
libitum. The animals were allowed to acclimatize to the test diets for three days before
data collection started. Feed intake and animal weight were recorded daily for 21 days.
Feces were collected from each rat on day 19 — 21. On day 22 one rat was randomly
selected from each goup to form a 14th group. These rats were fed a standard AIN 93G
diet for three days after which they received the low-protein — metabolic diet (Table 1)

for seven days. Feces were collected on days 5 — 7 to estimate the metabolic fecal

nitrogen. Fecal protein and metabolic fecal protein were determined using the protein

145

intake and fecal output data. The following protein quality index was calculated from the
data collected: True protein digestibility = P1 - (FP - MFP)/ PI x 100%;

where P1 = protein intake, FP = fecal protein, MFP = metabolic fecal protein.

5.3.5 Preparation of Products for Storage Stability Study

Extruded CBSM and SBSM were formulated as shown in Table 2. The extruded
and drum-processed CBSM and SBSM were used in the storage stability study.
Uncooked CBSM and SBSM were used as controls.

Table 2: Composition (g kg") of the extruded products used for evaluation of storage
stability

 

 

 

Diet'I
Ingredients CBSM SBSM
Bean 250.0 250.0
Corn 510.0 00.0
Rice 50.0 50.0
Sorghum 00.0 510.0
Sardines 65.0 65.0
Sucrose 55.0 55.0
Red Palm Oil 50.0 50.0
Vegetable oil 00.0 00.0
Mineral/Vitamin mix 10.0 10.0
Baking soda 05.0 05.0
Table salt 05.0 05.0
BHT+ BHA" 00.15 00.15

 

' CBSM = Com-bean-sardine meal; SBSM = Sorghum-bean-sardine meal
° BHT = Butylated hydroxytoluene, BHA = butylated hydroxyarrisole

5.3.6 Evaluation of Storage Stability
The extruded, drum-processed and uncooked CBSM and SBSM were packed and sealed

in airtight polyethylene bags, with 500 g per bag. The food packages were stored in a

146

thermo-regulated room (simulating tropical temperature) with temperature set at 38°C.
The foods were stored at this temperature for up to 16 weeks. Sensory evaluation, total
titratable acidity (TTA), pH and malondialdehyde (MDA) concentrations were
determined in the food samples at baseline. Thereafter, a packet of each food sample and
a control were removed from the stored lot at intervals of every two weeks and analyzed

for TTA, pH and MDA concentration as in baseline.

5.4 Chemical Assays
5.4.1 Crude Protein and Amino Acid Profile

Feces collected in the balance period (last three days of the experiment) were
separated from spilled food, dried to a constant weight at 100°C and ground. Total
nitrogen in the feces and diets was determined by Kjeldahl method [27] and the crude
protein content was calculated using the factor of 6.25. The moisture content of food and
fecal matter was determined by AOAC [27] procedure 925.09.

Amino acid concentrations (except tryptophan) were determined by reverse phase
HPLC using the Pico Tag method [28]. For all amino acids except methionine,
cystine/cysteine and tryptophan, food samples were hydrolyzed in 6 N HCl. The
methionine and cystine/cysteine in foods were oxidized by perforrnic acid to methionine
sulfone and cysteic acid prior to hydrolysis by 6 N HCl. All amino acids (except
tryptophan) were derivatized by phenylisothiocayanate (PITC) and detected at 254 nm.
Tryptophan was analyzed by the ion exchange chromatographic method as described in
the AOAC [27] method 988.15. Protein in the food was hydrolyzed under vacuum with

4.2 N NaOH. After pH adjustment and clarification, tryptophan was separated by ion

147

exchange chromatography (DC5A cation exchange resin) with measurement of the
ninhydrin chromophore.

The essential amino acid profile of the test products was compared with the
FAO/W HO/UN U [29] essential amino acid requirement pattern for pre-school age (2 — 5
year) children to compute the amino acid scores. The amino acid scores were used to
compute the protein digestibility-corrected amino acid score (PDCAAS) values as

follows: PDCAAS = True Digestibility x Lowest Amino Acid ratio [30, 31].

5.4.2 Thiobarbituric acid — malondialdehyde test
Lipid oxidation products in the foods were determined by the thiobarbituric acid —

C13 solid-phase acid extraction method [32].

5.4.3 Total titratable acidity and pH

Ten g of the dry foods were reconstituted with 90 mL of ultrapure water into
porridge. The TTA of the resulting porridge was determined by potentiometric titration
using 0.1 M NaOH to pH 8.5 while stirring [33, 34]. Acidity was calculated as lactic acid
equivalent as follows:
1 mL 0.1 M NaOH = 0.0090 g lactic acid
% Lactic acid = Titer x 0.0090 x 100/weight of sample.

The pH of the reconstituted foods was determined by the standard AOAC [27] procedure.

5.5 Statistical Analysis
Results are presented as mean and standard values. Data were subjected to one-

and two-way analysis of variance (ANOVA) where applicable, using the ProStat

148

(Version 3.01; Poly Software International, Pearl River, NY. 10965) and a difference
was considered to be significant at p 5 0.05. Since the TPD values were in percent, the
data were subjected to are sine transformation [35] prior to analysis by ANOVA. Post

hoc analysis of means was done by the Fisher’s LSD test.

5.6 Results and Discussion

Table 3 presents the amino acid profile (g kg'1 crude protein) of the
supplementary foods processed by extrusion, drum-processing and conventional cooking.
Lysine concentrations in CBSM, BM, SBSM and RBSM were 90 - 98, 93 — 95, 83 - 96
and 91 — 95 percent, respectively, of the FAO/WHO/UNU [29] recommended amount for
pre-school age children (58 g kg'1 crude protein). The concentrations of sulfur-amino
acids (SAA = cysteine + methionine) in the CBSM, BM, SBSM and RBSM were 112 -
132, 60 — 76, 160 - 176 and 104 — 124 percent, respectively, of the FAO/WHO/UNU [29]
recommendation (25 g kg‘1 crude protein) while for tryptophan the concentrations in the
various foods as a proportion of the FAO/WHO/UNU [29] recommendation (11 g kg'1
crude protein) were CBSM (91 — 100%), BM (118 — 136%), SBSM (109%) and RBSM
(90 — 136%). The concentrations of threonine, (the most limiting amino acid) in the
various foods as a proportion of the F AO/WHO/UNU [29] recommendation for pre-
school age children (34 g kg'1 crude protein) were CBSM (76 — 91%), BM (76%), SBSM
(71 - 82%) and RBSM (74 -— 82%). These data suggest that all our composite
supplementary foods were good sources of the essential amino acids as they contained
close to or more than the recommended amino acid concentrations. Lysine, SAA,

tryptophan and threonine are the most common limiting amino acids in plant-based

149

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weaning/ supplementary foods in developing countries [36, 37]. Lysine, tryptophan and
threonine are usually limiting in cereal grains while SAA are limiting in legumes. The
combination of com/sorghum (with relatively good concentration of SAA) with beans
and sardines (rich in lysine) helped to increase the protein quality of the products through
nutrient complementation. The concentrations of the essential and non-essential amino
acids also were not significantly (p > 0.05) different among the foods processed by either
extrusion, drum-processing or conventional cooking. This would suggest that none of the
processing methods caused a significant loss of the total amino acids.

Table 4 presents the TPD and PDCAAS (expressed as percent) for the food
products processed by the various methods. All the food products had relatively high
TPD values ranging from 88 to 94%, 82 to90%, 86 — 91% and 89 to 91% in CBSM, BM,
SBSM and RBSM, respectively. There were significant differences (p 5 0.05) in the
digestibility of the foods, with the casein diet being the most digestible (TPD = 95%). For
all the foods, the highest TPD were observed in the extruded products. High TPD values
in extruded products could be due to the high mechanical shear occurring during
extrusion which in turn lead to molecular fragmentation and high protein digestibility. As
a result of high TPD, extruded products also have better PDCAAS [3 8]. A two-way
analysis of variance for the TPD values (Table 4) showed significant (p 5 0.05)
interactions between the food products and the processing methods that influenced the
protein digestibility. In this case, extruded foods had the highest TPD values while the
drum-processed foods, with an exception of CBSM, had the next highest TPD values.
Food cooked by conventional method had the lowest TPD values, except in CBSM where

TPD value was lowest in the drum-processed product. True protein digestibility is a key

151

Table 4. True protein digestibility (TPD) and protein digestibility-corrected amino-acid
scores (PDCAAS) for the food products processed by the various methods1

 

 

 

 

Food Product2 Cooking Method TPD% PDCAAS% LAA3
CBSM Conventional 90.5" 74.6 Threonine
Extrusion 93.7' 86.4 Threonine
Drum-processed 88.4b 67.6 Threonine
BM Conventional 82.4” 51.3 SAA‘
Extrusion 90.1” 60.4 SAA“
Drum-processed 86.4b 65. l SAA4
SBSM Conventional 86.4” 63.7 Threonine
Extrusion 91 .4“b 64.0 Threonine
Drum-processed 88.2” 72.9 Threonine
RBSM Conventional 88.9” 67.1 Threonine
Extrusion 91 .4'” 75.8 Threonine
Drum-processed 89.2b 64.3 Threonine
CONTROL - 95.1a 84.3 Threonine
Source of Variation5 Mean TPD% P-Value
Food Products 0.01
CBSM 90.9
BM 86.3
SBSM 88.7
RBSM 89.8
Cooking Methods 0.01
Extrusion 91.8
Drum-processing 88.0
Conventional 87.0
Products x Cooking Interaction 0.05

 

1 Values in a column with different superscripts are significantly different at p 5 0.05.

2 CBSM - corn-bean-sardine meal, BM — bean meal, SBSM - sorghum-bean—sardine meal, RBSM — rice-
bean-sardine meal.

3 LAA - limiting amino acid
4 SAA— sulfur containing amino acids - methionine + cysteine
5 A two-way analysis of variance for the TPD of the food products cooked by the various methods

152

food quality index because it indicates whether the amino acids present in a food protein
would be digested and become available for utilization by the body [39]. Low protein
digestibility limits the amount of amino acids in a food that can be absorbed into the body
and can therefore adversely affect growth [3 9].

The TPD values observed in this study were higher than those reported for bean-
based products by Sarwar et al. [40] and by Kannan et al. [41] In a study to evaluate
protein and amino acid digestibility in food mixtures, Sarwar et al. [40] reported that,
products containing beans usually have low TPD ranging from 70 - 85% which adversely
affected the PDCAAS and overall utilization of nitrogen in the foods. The high TPD
values observed in our food products containing beans could be due to the effect of
grinding the raw beans into flour prior to cooking. In the studies by Sarwar et al. [40] and
by Kannan et al. [41], the dry beans were cooked whole and ground to flour after
cooking. Grinding of the beans prior to cooking might have disrupted the protein
structure, thus increasing the degree of protein denaturation during cooking. This in turn
could have rendered the protein fractions in the cooked foods more susceptible to
hydrolytic enzymes. Low TPD of food products containing beans has been associated
with the presence of strong covalent disulfide linkages between cysteine residues in some
of the bean protein fractions e. g. globulins GII, glutelins and protease inhibitors, that
form compact, dense, polymers that hinder proteolytic enzymes from reaching the
internal catalytic sites [42]. Low TPD can also be associated with high dietary fiber,
presence of phytohemagglutinins in foods, stearic hindrance of proteolysis by the
carbohydrate moieties of the glycoproteins (especially in globulin G11, and protease

inhibitor protein fractions) and presence of carbohydrate-protein and protein-protein

153

bonds that are not susceptible to mammalian protease hydrolysis [42]. The data reported
here indicate that grinding raw beans and then cooking the flour overcomes many of the
factors reported to limit protein digestion when whole beans are cooked.

The amino acid scores and PDCAAS for the food products were computed
according to FAO/WHO [30] using the F AO/W HO/UNU [29] amino acid reference
pattern for pre-school age (2 — 5 y) children (Table 3), and are presented in Table 4. The
PDCAAS values were generally high, ranging from 68 — 86% (CBSM), 51 — 65% (BM),
60 — 73% (SBSM) and 64 — 75% (RBSM). Extruded CBSM (86%) and RBSM (75%)
showed the highest PDCAAS while the conventionally cooked BM (51%) and extruded
BM (60%) and SBSM (60%) displayed the lowest PDCAAS. The product that showed
the highest average PDCAAS was CBSM (76%) followed by RBSM (69%), SBSM
(66%) and lastly by the BM (59%). The PDCAAS index reflects the ability of the test
protein to meet the protein needs of an individual. The FAO/WHO/UNU [29]
recommends that the PDCAAS be > 60% to meet the amino acid needs of preschool age
children (2 — 5 years). Threonine was the most limiting amino acid in all the foods except
in the extruded, drum-processed and conventionally cooked BM in which the sulfur
amino acids — cysteine and methionine - were most limiting.

Table 5 data show the changes in TTA (g lactic acid per kg food) of the cooked
and uncooked foods during the 16-week storage at elevated temperatures (3 8°C). For
both cooked and uncooked CBSM and SBSM, storage at elevated temperature did not
result in a significant increase (p > 0.05) in TTA. For extruded products, TTA increased

by 0.95-g kg'1 (5.4%) in CBSM and 4.47- g kg" (19.2%) in SBSM. For the drum-

154

processed products, TTA increased by 1.60- g kg" (5.9%) in CBSM and 1.38 g kg"

(3.9%) in SBSM. The TTA in the uncooked foods during storage increased by 4.59 g kg"

Table 5. Changes in total titratable acids (as g lactic acid kg" food) of the cooked and
uncooked foods during storage at 38°Cl

 

 

 

 

Period of Extruded products Drum-processed products Uncooked
storage

(Weeks) CBSM SBSM CBSM SBSM CBSM SBSM
0 17.50 23.33 25.44 35.07 44.66 34.95
2 17.54 23.39 25.64 35.52 44.91 35.76
4 17.54 23.39 25.65 35.52 44.91 35.77
6 17.67 23.93 26.99 35.53 45.91 36.36
8 17.79 24.18 26.78 35.57 47.02 36.33
10 17.90 24.49 26.99 35.59 47.23 37.39
12 18.28 25.98 26.84 35.84 47.60 38.03
14 18.23 26.06 26.94 36.09 48.79 39.80
16 18.45 27.80 27.04 36.45 49.25 39.88

 

I No significant differences (p > 0.05) in total titratable acids were observed during
storage at 38°C. CBSM = com-bean-sardine meal; SBSM = sorghum-bean-sardine meal.
(10.3%) in CBSM and 4.93- g kg" (14.1%) in SBSM. The insignificant changes in the
TTA during storage were also reflected in stable pHs of the products (Table 6). For both
cooked and uncooked products, there was no significant decrease (p > 0.05) in the pH
during storage. The pH of the foods decreased by only 1.5 — 2.0% in extruded, 0.5 — 1.6%
in drum-processed and by 0.6 — 1.0% in uncooked products. Since the TTA and pH
values in the cooked and uncooked foods were similar (p > 0.05), it suggested that
thermo-processing did not have an influence on the rate of food deterioration by
acidification. The method and materials used to package the foods played a significant
role in protecting the foods from deterioration. The moisture proof, airtight polyethylene

bags used to package the foods excluded air and moisture from the foods, thus

155

minimizing lipid oxidation and fermentation. Oxygen and moisture are the major factors
that catalyze lipid oxidation in food systems [43, 44]. An increase in TTA and a decrease

in pH of foods could be a result of low-grade fermentation of the starch in the stored

Table 6. The pH in cooked and uncooked foods during storage at 38°C1

 

Period of Extruded products Drum-processed products Uncooked
storage

 

 

(Weeks) CBSM SBSM CBSM SBSM CBSM SBSM
0 6.63 6.61 6.46 6.37 6.25 6.35
2 6.60 6.53 6.44 6.30 6.24 6.30
4 6.55 6.55 6.45 6.32 6.23 6.32
6 6.53 6.53 6.42 6.32 6.22 6.32
8 6.51 6.52 6.41 6.30 6.22 6.30
10 6.50 6.54 6.42 6.29 6.20 6.31
12 6.51 6.52 6.42 6.28 6.21 6.31
14 6.51 6.51 6.41 6.26 6.20 6.30
16 6.50 6.51 6.43 6.27 6.21 6.29

 

1 No significant decrease (p > 0.05) in pH was observed during storage at 38°C. CBSM =
com-bean-sardine meal; SBSM = sorghum-bean-sardine meal
foods (due to moisture) to produce organic acids, which in turn lower the pH [33, 34].
Alternatively, a decrease in pH could be a result of lipid oxidation, which might have led
to formation of complex secondary lipid oxidation products such as organic acids,
alcohols, and hydrocarbons that increase food acidity and lower pH [43]. Increase in food
TTA and/or decrease in food pH are food quality indices for deterioration. They
adversely affect the food taste and overall acceptability [44].

Table 7 data show the changes in MDA concentrations (ug kg") in the cooked
and uncooked foods during the 16 wk elevated temperature storage. There was a

significant (p 5 0.05) increase in the concentrations of MDA for both the cooked and

156

uncooked foods during storage. The SBSM had highest MDA concentrations at both the
baseline (Week 0) and during storage. For the extruded CBSM, MDA concentration
increased by 178-ug kg" over the 16 wk period, while for the SBSM the MDA

concentration increased by 306-ug kg" over the same period. For drum-processed

Table 7. Changes 1n malondialdehyde concentrations (ug kg") in cooked and uncooked
foods during storage at 38°Cl

 

Period of Extruded products Drum-processed products Uncooked

 

 

 

storage

(Weeks) CBSM SBSM CBSM SBSM CBSM SBSM
0 208° 595f 615° 1232° 201° 515°
2 212°° 609f 630° 1239° 238°° 533°
4 245° 657° 632° 1246° 267‘l 650°
6 260° 692° 626° 1249° 332° 721°
8 260° 782° 625° 1281° 388° 796°
10 268° 792° 627° 1325d 391° 853'
12 380‘ 818° 650° 1609° 393° 863‘
14 383‘ 843‘ 665° 1715° 413° 869'
16 385' 901' 718‘ 1822' 520' 872'

 

1 Malondialdehyde values in a column with similar superscripts are not significantly
different at p > 0.05. CBSM = corn-bean-sardine meal; SBSM = sorghum-bean-sardine
meal

CBSM, the MDA concentrations were stable for the first 6 weeks but increased
significantly (p 5 0.05) thereafter. In CBSM, the MDA concentration increased by 103-
ug kg" and by 590-ug kg" in SBSM. For the uncooked CBSM, the MDA concentration
increased by 319-ug kg" while the increase for SBSM was 357-ug kg". These results

suggest that both cooking and length of storage had a significant (p 5 0.05) influence on

the MDA concentrations.

157

MDA is a secondary product of lipid autoxidation and is often used as an
indicator for deterioration of food quality. The concentrations of MDA observed in these
test products are similar with those reported in others studies [45 — 47]. In a study of
commercial infant milk formulas and infant formula powders, Cesa [45] reported MDA
levels ranging between 163 — 362 ug kg" (milk formula) and 278 — 1094 pg kg'1 in infant
formula powders. In a similar study involving milk powder samples, Botsoglou et al. [47]
reported MDA concentrations ranging between 845 and 1572 pg kg" while unsweetened
condensed milk and infant milk formula contained 782 and 2633 pg of MDA per kg,
respectively. Draper et al. [48] reported that MDA in commercial foods ranged from <
100 11g kg" to about 10,000 ug kg" depending upon their fatty acid composition and
conditions of storage. Although the concentrations of the MDA in our test products
increased significantly during storage, the concentrations were lower than or within the
normal ranges reported in commercial infants and young children foods. Therefore the
small amounts of MDA even after 16-week storage at 38 0C would not be expected to
pose health risks. The effect of long-term consumption of low concentrations of MDA by
humans and/or animals is still unknown. However, long — term consumption by
experimental animals of large amounts of MDA (~ 10,000 ug kg"1 per day) was found to
cause hepatic nucleotoxicity, liver lesions, liver cancer and increased mortality [48, 49].

Significant correlation exists between TBA-MDA concentrations and off-flavor
formation in cooked foods [50 — 52]. In a study by Poste et al. [50], a significant
relationship was found between MDA concentrations and sensory aroma scores whereby
sensory scores corresponding to MDA concentrations of 7,830 - 10,000 ug kg" were

associated with weak off-flavor while the sensory scores corresponding to MDA

158

concentrations > 10,600 ug kg" were associated with strong rancid flavor. In our study,
the concentration of MDA in test products ranged between 208 - 718 ug kg" (CBSM)
and between 595 - 1,822 11g kg'l (SBSM). These MDA concentrations were lower than

the levels (> 10,600 ug kg") that can cause detectable rancidity.

Conclusions

These data show that both extrusion and drum-processing can be used to produce
highly nutritious products suitable for supplementation of pre-school age children. The
protein in the cereal-bean—sardine mixtures was highly digestible and the PDCAAS
exceeded the minimum value set by the FAO/WHO. Extruded CBSM and SBSM were
shelf-stable for at least 16 weeks when stored at 38°C in airtight polyethylene bags.
Development and consumption of such nutritious composite foods would be expected to
help ameliorate the problem of undemutrition among pre-school age children in

developing countries.

159

6.8 References

1. de Onis, M. (1993). The worldwide magnitude of protein-energy malnutrition: an
overview from the WHO Global Database on Child Growth. Bull. World Health Org. 71:
703 — 712.

2. Administrative Committee on Coordination - Sub-Committee on Nutrition (ACC-
SCN), (1987). The First Report on the World Nutrition Situation. Rome. United Nations.

3. Administrative Committee on Coordination — Sub-Committee on Nutrition (ACC-
SCN). (1989). Update on the Nutrition Situation: Recent Trends in Nutrition in 33
courtiers. Geneva. United Nations.

4. Administrative Committee on Coordination — Sub-Committee on Nutrition (ACC-
SCN). (1992). Second Report on the World Nutrition Situation. Vol.1 . Global and
Regional Results. Geneva. United Nations.

5. Administrative Committee on Coordination — Sub-Committee on Nutrition (ACC-
SCN). (1994). Update on the Nutrition Situation, 1994. Rome. United Nations.

6. UN. - United Nations (1992). 2nd Report on the World Nutrition Situation: Global
and Regional Results. Vol. 1. Rome, CC/SCN.

7. Kavishe, RP. (1992). Development of Vitamin A Control Programs: An example of
Tanzania. NU - News and Health Care in Developing Countries; 3: 21 - 26.

8. TFNC — Tanzania Food and Nutrition Center (2002). Nutrition for Human and
Economic Development in Tanzania. Tanzania’s Nutrition Vision for the Year 2025.
TFNC Report. Dar es Salaam.

9. Mosha, AC. and Svanberg, U. (1983). Preparation of weaning foods with high nutrient
density using flour of germinated cereals. UN U Food Nutr. Bull. 5(2): 10 — 14.

10. United Republic of Tanzania and UNICEF (1990). Women and Children in Tanzania
- A situational Analysis. Dar es Salaam, Government Printer.

11. Svanberg, U. (1987). Dietary bulk in waning foods. PhD Thesis. Department of Food
Science, Chalmers University of Technology, Goteborg, Sweden.

12. Mosha, T.C., Dakiyo, S.O.S. and Laswai, H. (1998). Breastfeeding, weaning practices
and anthropometric patterns of children in Morogoro district, Tanzania. Ecol. Food Nutr.
37(4): 309 — 339.

13. Walker, A.F. (1990). The contribution of weaning foods to protein energy
malnutrition. Nutr. Rev. Res. 3: 25 — 47.

160

14. Seenappa, M. (1987). Advantages of Sorghum and Millets in weaning Foods. In:
Alnwick, D, Moses, S & Schmidt, OG (Eds). Proceedings of a Workshop on Household
Level Food Technologies for Improving Young Child Feeding in Eastern and Southern
Africa, Nairobi, Kenya. October.

15. WHO/UNICEF (1998). Complementary Feeding of Young Children in Developing
Countries: a review of the Current Scientific Knowledge. WHO Publications. Geneva.

16. Dijkhuizen, P. (2000). Processed complementary foods in the World Food program.
Food Nutr. Bull. 21 (l): 62 - 64.

17. WHO (2002). Infant and Young Child Nutrition: Global Strategy on Infant and
Young Child Feeding. World Health Assembly Document WHA55/15. Rome. WHO
Press.

18. Dewey, K.G. and Brown, K.H. (2003). Update on technical issues concerning
complementary feeding of young children in developing countries and implications for
intervention programs. Food Nutr. Bull. 24 (1 ): 5 - 28.

19. Lutter, CK. (2000). Processed complementary foods: Summary of nutritional
characteristics, methods of production and distribution, and costs. Food Nutr. Bull. 21
(1): 95 — 100.

20. Lutter, CK. (2003). Macro-level approaches to improve the availability of
complementary foods. Food Nutr. Bull. 24 (l): 83 — 103.

21. Mensah, P. and Tomkins, A. (2003). Household-level technologies to improve the
availability and preparation of adequate and safe complementary foods. Food Nutr. Bull.
24 (1): 104 —125.

22. Lutter, OK. and Dewey, K.G. (2003). Proposed nutrient composition of fortified
complementary foods. J. Nutr. 133: 30118 — 3020S.

23. King, RS. and Burgess, A. (1993). Nutrition for Developing Countries. 2dn Edn.
London. ELBS with Oxford University Press.

24. FAO/WHO (1994). Codex Alimentarius: Foods for Special dietary Uses (Including
Foods for Infants and Children). Joint FAO/WHO Food Standards Program, Codex
Alementarius Commission, Vol 4. 2"d Edn. FAO Publications, Rome.

25. Kikafunda, J .K., Walker, A.F. and Abeyasekera, S. (1997). Optimising viscosity and
energy density of maize porridges for child weaning in developing countries. Int] J Food
Sci Nutr 48: 401 — 409.

26. Reeves, P.G., Nielsen, RH. and F ahey, GO (1993). AIN-93G purified diets for
laboratory rodents: Final report on American Institute of Nutrition ad hoc writing

161

committee on the reformulation of the AIN-76A rodent diet. J. Nutr. 123: 1939 —
1951.

27. Association of Official Analytical Chemists International. (1995). Official Methods of
Analysis. 6th Edn. AOAC. Washington DC.

28. Cohen, S.A., Meys, M. and Tarwin, TL. (1989). The Pico Tag® Method: A manual
of Advanced Techniques for Amino Acid Analysis. Milford, MA. Waters Division of
Millipore.

29. FAO/WHO/UNU (1985). Energy and Protein Requirements. Expert of the
FAO/WHO/UNU Expert Consultation. Technical Series No. 724. FAO/WHO/UNU
Publications. Geneva.

30. FAO/WHO (1991). Protein Quality Evaluation. The Report of the Joint FAO/WHO
Expert Consultation. Bethesda, MD, USA. 4 — 8 December. FAO Publications. Rome.

31. Gertjan, S. (2000). The protein digestibility-corrected amino acid scores. J Nutr. 130:
1865S — 1867S.

32. Raharjo, S., Sofos, J .N. and Schmidt, GR. (1993). Solid phase acid extraction
improves thiobarbituric acid method to determine lipid oxidation. J Food Sci 58 (4): 921
— 924.

33. Nout, M.R.J., Rombouts, F.M. and Hautvaust, G.J. (1989). Accelerated natural lactic
acid fermentation of infant food formulations. Food Nutr. Bull. 11: 65 — 73.

34. Onyango, C., Okoth, M.W. and Mbugua, S.M. (2000). Effect of drying lactic acid
fermented uji (an East Afiican sour porridge) on some carboxylic acids. J Sci Food Agric
80: 1854 — 1858.

35. Snedecor, G.W. and Cochran, W.G. (1969). Statistical Methods. 6th Ed. Ames, Iowa.
The Iowa State University Press. Pp 327 — 569.

36. Young, V.R. and Pellett, PL. (1994). Plant proteins in relation to human protein and
amino acid nutrition. Am J Clin Nutr 59 (Suppl): 1203S — 1212S.

37. Millward, DJ. (1999). The nutritional value of plant-based diets in relation to human
amino acid and protein requirements. Proc Nutr Soc 58: 249 - 260.

38. Campos, M.A. and Areas, J .A.G. (1993). Protein nutritional value of extrusion-
cooking defatted lung-flour. Food Chem. 47(1): 61 — 66.

39. Sarwar, G. (1987). Digestibility of protein and bioavailability of amino acids in
foods: Effect on protein quality assessment. World Rev Nutr Diet 54: 26 — 70.

162

40. Sarwar, G., Peace, R.W., Botting, H.G. and Brule, D. (1989). Digestibility of protein
and amino acids in selected foods as determined by a rat balance method. Plant Food
Hum. Nutr. 39: 23 — 32.

41. Kannan, S., Nielsen, S. and Mason, A. (2001). Protein digestibility-corrected amino
acids scores for bean and bean—rice infant weaning food products. J. Agric. Food Chem.
49: 5070 — 5074.

42. Bennink, M. and Srisuma, N. (1989). Digestibility of dry legume starch and proteins.
In: Applewhite TH (Ed). Proceedings of the World Congress on Vegetable Protein
Utilization in Human Foods and Animal F eedstuflfs. Illinois. American Oil Chemists’
Society.

43. St. Angelo, A.J. (1996). Lipid oxidation in foods. Crit. Rev. Food Sci. Nutr. 36(3):
175 - 224.

44. Fennema, OR. (1996). Food Chemistry. 3rd Edn. New York. Marcel Decker. Pp 121
— 238.

45. Cesa, S. (2004). Malondialdehyde contents in infant milk formulas. J Agric Food
Chem 52: 2119 — 2122.

46. Fenaille, F., Mottier, P., Turesky, R.J., Ali, S. and Guy, P.A. (2001). Comparison of
analytical techniques to quantify malondialdehyde in milk powders. J. Chromatogr. 921:
237 — 245.

47. Botsoglou, N.A., Fletouris, D.J., Papageorgiou, G.E., Vassilopoulos, V.N., Mantis,
A.J. and Trakatellis, AG. (1994). Rapid, sensitive, and specific thiobarbituric acid
method for measuring lipid peroxidation in animal tissue, food, and feedstuff samples. J
Agric Food Chem 42: 1931 - 1937.

48. Draper, H.H., McGirr, LG. and Hadley, M. (1986). The metabolism of
malonaldehyde. Lipids. 21(4): 305 — 307.

49. Aubourg, SP. (1993). Interaction of malondialdehyde with biological molecules -
new trend about reactivity and significance: review. Int] J. Food Sci. T echn. 28: 323 —
335.

50. Poste, L.M., Willemot, G. and Patterson, C. (1986). Sensory aroma scored and TBA
values as indices of warmed-over flavor in pork. J. Food Sci. 51(4): 886 — 888.

51. Brewer, M.S., Ikins, W.G. and Harbergs, C.A.Z. (1992). TBA values, sensory

characteristics, and volatiles in ground pork during long-term frozen storage — effect of
packaging. J. Food Sci. 57 (3): 558 — 567.

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52. Lai, S.M., Gray, J .I., Booren, A.M., Crackel, R.L. and Gill, J .L. (1995). Assessment
of off-favor development in restructured chicken nuggets using hexanal and TBARS
measurements and sensory evaluation. J. Sci. Food Agric. 67 (4): 447 — 452.

164

CHAPTER SIX

6.0 SUMMARY AND CONCLUSIONS
This study focused on the problem of undemutrition among pre-school age
children in Tanzania and the role that supplementary foods could play in ameliorating
these conditions and thus increase quality of life and child survival. The study was
conducted based on the WHO/UNICEF [1] recommendation that production of ready-to-
feed fortified supplementary foods using locally produced ingredients at community
settings is the most practical and sustainable approach to mitigate the problem of
undemutrition in developing countries. The objectives of the study were to:
l. Formulate nutrient-dense products from locally produced ingredients such as com,
beans, sorghum, rice and sardines to meet the FAO/W HO/UN U [2] amino acid
recommendations for cereal-based weaning/supplementary foods.
2. Determine suitable processing conditions for preparation of ready-to-feed ”instant”
products using extrusion and drum-processing methods.
3. Evaluate the nutritional quality of the processed products including:
i) amino acid profile.
ii) true protein digestibility.
iii) protein digestibility-corrected amino acid scores (PDCAAS).
iv) residual levels of phytohemagglutinins; anti-nutritional factors (trypsin,
chymotrypsin, and or-amylase inhibitors); and evaluate cooking doneness
(starch gelatinization rate and residual urease activity).
4. Evaluate the potential of the supplementary foods to support optimal grth and

rehabilitation of undernourished children using an animal model.

165

5. Evaluate the storage stability of the products under simulated tropical conditions.

The first study was conducted to evaluate the protein quality and
growth/rehabilitation potential of supplementary foods developed from locally produced
materials in Tanzania. Six trial diets namely rice meal (RM), rice-bean meal (RBM), rice-
bean-sardine meal (RBSM), bean meal (BM), corn-bean meal (CBM) and com-bean-
sardine meal CBSM) were processed by a drum-drier. The diets were formulated to
maximize the amino acid scores as recommended by the F AO/W HO/UN U [2] for pre-
school age children and evaluated for protein quality — true protein digestibility,
PDCAAS and net protein retention ratio. They were also evaluated for their potential to
support grth and for rehabilitating undernourished animals. The study showed that
composite diets containing cereal-bean-sardine had high net-protein retention ratio, true
protein digestibility, and PDCAAS. The composite products also showed potential to
support growth during normal and rehabilitation of undernourished animals. Overall, the
cereal-bean-sardine composite products were of highest quality and displayed good
potential for use as supplementary and rehabilitation foods for pre-school age children (2
— 5 y) as well as adults.

Study two evaluated the safety and nutritional quality of the composite foods
processed by extrusion and drum-processing. The study was based on the concept that the
cereal-bean-sardine composite foods contain 20 — 30% beans, which contain high
amounts of phytohemagglutinins toxins and anti-nutritional factors — trypsin,
chymotrypsin and a-amylase inhibitors. Consrnnption of active phytohemagglutinins in
foods interferes with the function of the gastrointestinal tract by binding to the brush-

border cells of the intestinal mucosa and thus disrupting absorption of all nutrients.

166

Active phytohemagglutinins also cause hyperplasia and hypertrophy of the pancreas [3,
4, 5] thus disrupting secretion of other digestive enzymes. Likewise, consumption of
active inhibitors of trypsin and chymotrypsin interferes with the activity of the pancreatic
proteolytic enzymes particularly trypsin, and chymotrypsin leading to poor digestion of
protein and enlargement of the pancreas. They also cause an increase in the secretion of
digestive enzymes including trypsin, chymotrypsin and elastase, which in turn increase
the loss of endogenous amino acids in the form of the secreted enzymes. These effects on
the other hand depress growth and interfere with other metabolic processes of the body
[6]. Alpha-amylase inhibitors reduce digestibility of starch, limiting its utilization by the
body. Raw starch is also poorly digested and its presence in processed ready-to-feed
foods may cause gastrointestinal illness. For these reasons, the food processing methods
used must produce products that are fully cooked, free of active phytohemagglutinins and
anti-nutritional factors.

Four composite food products, namely CBSM, BM, RBSM and sorghum-bean-
sorghum meal (SBSM) were formulated according to the FAO/WHO/UN U [2]
guidelines. The food mixtures were processed by extrusion, drum-processing and also
cooked by conventional method. Cooking doneness of the processed foods was evaluated
by the rates of starch gelatinization, and urease enzyme inactivation. Destruction of
phytohemagglutinins and anti-nutritional factors — trypsin, chymotrypsin and a-amylase
inhibitors were also determined. The final assessment of safety was done by using animal
model to evaluate true protein digestibility and potential to support growth. The study
showed that, foods were well-cooked for both extruded and drum-processed foods. Starch

gelatinization was 3 90% while the residual urease activity was 5 0.05 units per 100 g of

167

processed food. Extruded products had higher (p 5 0.05) true protein digestibility and
produced greater growth when fed to experimental animals compared to the drum-
processed foods. Both extrusion and drum-processing were equally effective in
destroying the phytohemagglutinins and the anti-nutritional factors. The study suggested
that, extrusion of cereal-bean-sardine composite foods result in products of nutritional
quality similar to that of conventionally cooked foods but slightly higher than that of
drum-processed foods. Both processing methods however, produced foods meeting the
required nutritional quality. Availability of processing equipment and energy costs would
therefore be the major factors dictating the ultimate method of choice for processing of
these foods in developing countries.

Study three was based on the concept that foods produced to ameliorate
undemutrition must provide protein of high quality, and must have reasonable shelf-life.
This study 1) evaluated the amino acid profile of the processed cereal-bean-sardine
composite products, 2) determined protein quality by using the FAO/W HO [7] approved
— PDCAAS, and 3) evaluated the storage stability of the processed products at simulated
tropical conditions. Results showed that extruded products had higher (p 5 0.05)
PDCAAS than the drum-processed foods. No significant variations in the amino acids
concentrations were found among foods processed by either extrusion or drum-
processing. Threonine was the most limiting amino acid in the CBSM, RBSM and SBSB
while sulfur amino acids — cysteine and methionine - were limiting in the BM. The
processed cereal-bean-sardine composite products were shelf-stable for at least 16 weeks
at 38°C.

Overall, the following conclusions could be drawn.

168

. Cereal-bean-sardine composite products formulated fiom locally produced
ingredients are of high nutritional quality, with potential for use as supplementary
and rehabilitation foods for undernourished pre-school age children.

. High quality, fully cooked, ready-to-eat foods may be produced by either
extrusion or drum-processing. Both processing methods produced food products
meeting the required nutritional quality.

. Composite cereal-bean-sardine products have protein that is highly digestible,
with PDCAAS values equal or higher than the FAO/WHO/UNU [2]
recommended score of _>_ 60% for pre-school age children.

. The processed cereal-bean-sardine composite products are shelf-stable for at least

16 weeks when stored at elevated temperature — 38°C.

169

 

6.1 References

l. WHO/UNICEF (1998). Complementary Feeding of Young Children in Developing
Countries: a review of the Current Scientific Knowledge. WHO Publications. Geneva.

2. FAO/WHO/UNU (1985). Energy and Protein Requirements. Expert of the
FAO/WHO/UNU Expert Consultation. Technical Series No. 724. FAO/W HO/UN U
Publications. Geneva.

3. WHO (2002). Infant and Young Child Nutrition: Global Strategy on Infant and Young
Child Feeding. World Health Assembly Document WHA55/15. Rome. WHO Press.

4. Liener, LE. (1994). Implications of antinutritional components in soybean foods. Crit.
Rev. Food Sci. Nutr. 34: 31 — 67.

5. Lajolo, F .M. and Genovese, MI. (2002). Nutritional significance of lectins and
enzyme inhibitors from legumes. J. Agric. Food. Chem. 50: 6592 - 6598.

6. Menezes, E.W. and Lajolo, F.M. (1987). Inhibition of starch digestion by a black bean
a-mylase inhibitor, in normal and diabetic rats. Nutr. Rep. Intl. 36: 1185 — 1189.

7. F AO/W H0 (1991). Protein Quality Evaluation. The Report of the Joint FA O/WHO
Expert Consultation. Bethesda, MD, USA. 4 — 8 December. FAO Publications. Rome.

170

CHAPTER SEVEN

7.0 RECOMMENDATIONS FOR FUTURE RESEARCH

1. Evaluation of the efficacy of the processed composite foods to support normal grth
and rehabilitation of undernourished children was done by using an animal model. It is
recommended that a clinical study using human subjects be conducted to re-evaluate the
food products. This will help to corroborate the results from the current study before

recommending the products for large-scale use.

2. This study successfully developed the processing conditions for the cereal-bean-
sardine composite products. It is recommended that similar studies be conducted for other
staple foods such as pearl-, finger- and bulrush-millet, cassava, yarns, sweet potatoes,
peanuts, lentils and other legumes which are widely available but underutilized for child
feeding in Tanzania. The study should also investigate on the feasibility of incorporating
sun-dried vegetables and hits in the composite products to increase the mineral and

vitamin density.

3. There is currently a new generation of very low-cost extruders [1] and simple food
texturizers that are very appropriate for rural settings. Such simple food processors have
the advantage that they are manual or semi-automated and can use conventional and/or
non-conventional sources of energy such as charcoal, firewood, electricity and/or
kerosene. Most of the low-cost extruders and texturizers, however, are still on the trial
stages and the quality of the foods processed by these equipments is not clearly known. It

is recommended that, studies be conducted to determine if the quality of foods produced

171

in these small scale equipments meet the required nutritional and safety quality for ready-

to-feed products for young children.

4. For sustainable production of these products there should be a good market structure
that allows efficient distribution of the foods. It is recommended that, a marketing study
be conducted to establish the consumer preferences, market prices and the appropriate
marketing channel to reach our target populations in the rural communities. The study
should also try to do some cost-benefit analysis of the products, recommend appropriate
market prices for the products and identify the potential players for the production and

distribution of the foods.

172

7.1 Reference

1. Mouquet, C., Salvignol, B., Van Hoan, N., Monvois, J. and Treche, S. (2003). Ability
of a very low-cost extruder to produce instant infant flours at a small scale in Vietnam.

Food Chem. 82: 249 — 255.

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