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unmv ' 21211200655o
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This is to certify that the
thesis entitled
FRACTIONATION AND RECONSTITUTION 0F SOFT WHEAT
FLOURS, AND GLUTEN QUANTITY AND QUALITY EFFECTS
ON THE TEXTURAL CHARACTERISTICS OF PASTRY

preser‘ed by

ROSEMARY J . COOKE

has been accepted towards fulfillment
of the requirements for

 

 

M. S . degree in Food Science

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FRACTIONATION AND RECONSTITUTION 0F SOFT WHEAT
FLOURS,_AND GLUTEN QUANTITY AND QUALITY
EFFECTS ON THE TEXTURAL CHARACTERISTICS OF PASTRY

By

Rosemary J. Cooke

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Food Science and Human Nutrition

1986

219740619?

ABSTRACT
FRACTIONATION AND RECONSTITUTION OF SOFT HHEAT

FLOURS. AND GLUTEN QUANTITY AND QUALITY
EFFECTS ON THE TEXTURAL CHARACTERISTICS OF PASTRY

By

Rosemary J. Cooke

Soft wheat pastry flours were fractionated into gluten
and starch + water-solubles. The gluten was subsequently
fractionated by pH according to the method of Shogren et al.
(l969). Flours were reconstituted to their original protein
contents from whole crude gluten, single gluten fractions
and all gluten fractions in their original proportions.

Fractionation patterns among flour cultivars differed
significantly. The low pH fractions had a glutenin-like
character, whereas the high pH fractions were gliadin-like.

Full restoration of original flour properties upon flour
reconstitution was not achieved, as evidenced by differences
in textural characteristics of pastry. Among the single pH
fraction flours, flakiness. crust shrinkage and surface
blistering increased as pH increased, whereas crust surface
browning decreased.

Significant correlations were found between flour protein
content and flakiness, crust shrinkage, surface blistering
and crust surface browning. Breaking strength was found to

be clearly flour cultivar-dependent.

‘TO‘my parents and Mike

for their love and support.

ii

ACKNOWLEDGMENTS

Many individuals have contributed to the success of this
project. I wish to extend thanks to my major professor,
Dr. M.E. Zabik, and to the members of my guidance
committee, Dr. P. Markakis, Dr. S.K. Ries, and Dr. M.A.
Uebersax.

Sincere thanks and appreciation are extended to Samir M.
Rabie for the invaluable discussions and constant encourage-
ment. Many thanks are also given to: Margaret Connor,
Janice Harte, Ursula Koch, Andrew Kohnhorst, Nancy
Lorimer, Sue Morehouse, Mary Schneider, Rick Tomkinson,
Marce Weaver and Dr. T. Hishnetsky, for the encouragement
and help in the various stages of this project.

Last, but not least, I wish to thank my family and Mike
for their patience, love and support throughout the course

of my study.

TABLE OF CONTENTS

LIST OF TABLES.

LIST OF FIGURES .
INTRODUCTION.

REVIEW OF LITERATURE.

Wheat Classification . . . . . . .

Wheat Composition. . . . . . . . .
Carbohydrate . . . .
Effect of Milling on Composition .
Flour Streams Effect on Composition.
Total Protein Content. . .

Protein Classification .

Soluble Proteins .
Gluten Proteins. .
Gluten Functionality .

Gluten Viscoelasticity and Thermal Stability :
Gluten Rheology and Secondary Bond Structure .

Electrophoresis of Wheat Proteins. . . .
Fractionation and Reconstitution Studies .
Hard Wheat Functionality . . . . .
Soft Wheat Functionality .

Cake . . . .

Cookies. . . . .

Pastry . .
Browning Reaction in Wheat Products.
Textural Studies .

MATERIALS AND METHODS .

Wheat Samples. . . .
Classification .
Composition.
Flour Fractionation.
Gluten Washing
Grinding of Fractions. .
Fractionation of Gluten by pH.
Protein Content. . .

iv

Page
vi

ix

OmQOlmU'l-b-bw w

18

Moisture Content. . . .

Flour Reconstitutions .
Calculations.

Dry Blending. .
Humidification of Flours.
Final Sample Materials.

Baking Test for Pastry.
Experimental Design .
Ingredients .

Formula . .

Mixing Procedure.

Baking Procedure. . . .

Physical Testing Procedures .
Statistical Analysis of the Data.

RESULTS AND DISCUSSION.

Flour Composition . . . . . . . . . . . .
Flour Fractionations. . . . . . . . . . . . .

Gluten Washing. .

Fractionation. by pH (Isoelectric Precipita-

t on . . . . . . . . . . . .

Flour Reconstitutions .
Baking Test for Pastry.

Flakiness . . .

Crust Shrinkage . . .

Surface Blistering Scores

Breaking Strength . . . . . . . . . . . .

Crust Surface Browning. . . . .
Correlations Among Dependent Variables.

Correlations Between Dependent Variables and Flour

Protein Content .

Correlations Between Pastry Textural Characteris- .

tics and Flour Fractionation Patterns .
Effect of Fractionation/Reconstitution Procedures
on Pastry Textural Characteristics. . . .
Implications of the Data. . .

SUMMARY AND CONCLUSIONS .
APPENDIX.
REFERENCES.

Table

10

ll

12

LIST OF TABLES

Extraction rates of flour samples.
Pie dough formulation.

Moisture and protein contents of parent soft
wheat varietal flours. . . . . . . . .

Percentage by weight and protein content of
crude gluten and starch + water-solubles
obtained by gluten washing soft wheat flours

Percentage by weight of each gluten fraction
recovered by precipitating at various pH levels.

Protein contents of gluten fractions obtained
from varietal flours by precipitating at various
pH levels. . . . . . . . . . ... . . . .
Percentage of total gluten protein contributed

by each gluten fraction obtained by precipi-
tating at various pH levels. .

Percentage of total flour protein contributed by
each flour fraction obtained by gluten washing
and pH fractionation . . . . . . . . . .

Flakiness of pastry wafers baked from varietal
parent and reconstituted flours. .

Flakiness. crust shrinkage, surface blistering
score and breaking strength means for reconsti-
tution types . . . . .

Flakiness, crust shrinkage, surface blistering
score and breaking strength means for varietal
flours . . . . . . . . . . . . . . . . . .

Crust shrinkage of pastry wafers baked from
varietal parent and reconstituted flours .

vi

Page
51
64

72

72

76

79

79

83

9O

92

95

97

Table Page

13 Surface blistering scores of pastry wafers baked
from varietal parent and reconstituted flours. . 101

14 Breaking strength of pastry wafers baked from
varietal parent and reconstituted flours . . . . 106

l5 Lightness values of pastry wafers baked from
varietal parent and reconstituted flours . . . . III

16 Lightness. redness and yellowness value means
for reconstitution types . . . . . . . . . . . . 114

l7 Lightness, redness and yellowness value means .
for varietal flours. . . . . . . . . . . . . . . 116

18 Redness values of pastry wafers baked from
varietal parent and reconstituted flours . . . . 118

19 Yellowness values of pastry wafers baked from
varietal parent and reconstituted flours . . . . 122

20 Correlation coefficients among textural charac-
teristics of pastry wafers . . . . . . . . . . . 128

21 Correlation coefficients of flour protein
content and percentage of gluten fractions with
textural characteristics of pastry wafers. . . . I30

22 Agronomic and compositional data of varietal

soft wheats. I42
23 Experimental milling data for varietal soft a

wheats . . . . . . . . . . . . . . 1 2
24 Experimental milling and baking data for

varietal soft wheats and their flours. ‘43
25 Standard pie dough formulations used in the

baking test for pastry . . . . . . . . 143

26 Final moisture contents of humidified
reconstituted flours . . . . . . . . . . . 144

27 Protein contents of reconstituted flours ‘44
28 Analysis of variance for flakiness . 145
145

29 Analysis of variance for crust shrinkage .

vii

Table Page

30 Analysis of variance for surface blistering
scores. . . . . . . . . . . . . . . . . . . . . . ‘45

31 Analysis of variance fOr breaking strength. . . . 145
32 Analysis of variance for lightness ("L"). . . . . 147
33 Analysis of variance for redness ("a"). . . . . . I47

34 Analysis of variance for yellowness ("b”) . . . . ‘43

viii

Figure

10

LIST OF FIGURES

Overall fractionation scheme for parent soft
wheat flours. . . . . . . . . . .

Scheme for fractionation of gluten by pH,
following solubilization in 0.005 N lactic acid .

Scores used for evaluating surface blistering .

Percentage by weight of each gluten fraction
recovered by precipitating at various pH levels

Protein contents of flour fractions obtained by
gluten washing and precipitation by pH. I =
insoluble, S = soluble; S+WS = starch + water-
solubles. . . . . .

Percentage of total gluten protein contributed by
each gluten fraction obtained by precipitating at
various pH levels

Percentage of total flour protein contributed by
each flour fraction obtained by gluten washing
and pH fractionation. . . . . . . . . .

Flakiness of pastry wafers baked from varietal
parent and reconstituted flours. Above: PF =
parent flour, WG = whole crude gluten, AFR = all
fract. reconst. Below: I = insol., S = sol..

Flakiness of pastry wafers. Above: Means for
reconstitution types. PF = parent flour, WG =
whole crude gluten, AFR = all fract. reconst.,

I = insol., S = sol. Below: Means for varietal
flours. . . . . . . . . . . . . . . .
Crust shrinkage of pastry wafers baked from
varietal parent and reconstituted flours. Above:

PF = parent flour, NC = whole crude gluten, AFR
all fract. reconst. Below: I = insol., S = sol..

ix

Page
52

.55
68

77

80

BI

84

91

93

Figure Page

ll Crust shrinkage of pastry wafers. Above: Means
for reconstitution types. PF.= parent flour,
WG = whole crude gluten, AFR = all fract.
reconst., I = insol., S = sol. Below: Means for
varietal flours. . . . . . . . . . . . . . . . . 99

12 Surface blistering scores of pastry wafers baked
from varietal parent and reconstituted flours.
Above: PF = parent flour, WG = whole crude
gluten, AFR = all fract. reconst. Below: I =
insol., S = sol. . . . . . . . . . ‘03

13 Surface blistering scores of pastry wafers.
Above: Means for reconstitution types. PF
parent flour, WG = whole crude gluten, AFR
fract. reconst., I = insol., S = sol. Below:
Means for varietal flours. . . . . .

all
l04

14 Breaking strength of pastry wafers baked from
varietal parent and reconstituted flours.
Above: PF = parent flour, WG = whole crude
gluten, AFR = all fract. reconst. Below: I =
insol., S = sol. . . ‘07

l5 Breaking strength of pastry wafers. Above:
Means for reconstitution types. PF = parent
flour, WG = whole crude gluten, AFR = all fract.
reconst., I = insol., S = sol. Below: Means for
varietal flours. . . . . . . . . . . . 109

16 Lightness ("L") of pastry wafers baked from
varietal parent and reconstituted flours.
Above: PF = parent flour, WG = whole crude
gluten, AFR = all fract. reconst. Below: I =
insol., S = sol. ‘12

l7 Lightness ("L") of pastry wafers. Above: Means
for reconstitution types. PF = parent flour,

WG = whole crude gluten, AFR = all fract.
reconst., I = insol., S = sol. Below: Means for
varietal flours. . . . . . . . . 1‘5
l8 Redness ("a") of pastry wafers baked from
varietal parent and reconstituted flours.
Above: PF = parent flour, WG = whole crude
gluten, AFR = all fract. reconst. Below: I =

insol., S = sol. ll9

Figure Page

19 Redness ("a") of pastry wafers. Above: Means
for reconstitution types. PF = parent flour,
WG = whole crude gluten, AFR = all fract.
reconst., I = insol., S = sol. Below: Means
for varietal flours. . . . . . . . . . . . . . . 120

20 Yellowness ("b") of pastry wafers baked from
varietal parent and reconstituted flours.
Above: PF = parent flour, WG = whole crude
gluten, AFR = all fract. reconst. Below: I =
insol., S = sol. . . . . . . . . . . . . . . . . 123

21 Yellowness ("b") of pastry wafers. Above:
Means for reconstitution types. PF = parent
flour, WG = whole crude gluten, AFR = all
fract. reconst., I = insol., S = sol. Below:
Means for varietal flours. . . . . . . . . . . . ‘25

xi

INTRODUCTION

Although soft white and soft red winter wheats constitute
less than one-fourth of the total United States wheat
production, soft wheats are utilized in a wide range of
commercial products. Cakes, cookies, crackers, doughnuts,
pie pastry, and pretzels are some of these. In contrast,
hard wheats are used in one major industry - bread-making,
which is still the largest flour consumer. Thus, early
chemical and functional studies were focused on the hard
wheats suitable for bread production. Due to changing
economy and 1ifestyle,a significant increase in the use of
soft wheat flour has resulted. A higher average standard of
living, plus an increased demand for convenience foods, has
led to a larger consumption of soft wheat products such as
cake mixes, pastry mixes, and ready-to-eat cookies and
crackers.

Soft wheats are suited for chemically-, air-, and steam-
leavened products where no fermentation is required for
ripening and mellowing of the gluten. The gluten of soft
wheat is characteristically soft and produces a light and
tender product. Although the functionality of soft wheat
has been studied using fractionation techniques, in cookies

and cakes, no such studies have been reported for pie pastry.

Protein content and gluten quality required for soft wheat
flours vary widely with product application. Thus, the
functionality of flour components in pastry would be expected
to differ from that of other soft wheat products.

The purpose of this study was to fractionate and reconsti-
tute four soft wheat flours of different protein contents to
determine effect of both gluten quantity and quality on
textural characteristics of pastry. Each flour was separated
into a starch and water-solubles fraction, and gluten. The
gluten was further fractionated by pH, such that subfractions
varying in glutenin/gliadin ratio were produced. Flours were
reconstituted from the gluten subfractions, starch and water-
solubles fraction; pie pastry baked from these flours was
evaluated for textural properties. Tenderness measurements
were made using an F.T.C. Kramer shear press. The height of
a stack of four pastry wafers was used as an index of flaki-
ness. Shrinkage was determined by measuring areas of pastry
wafers before and after baking. A HunterLab Color Difference
Meter was used to obtain lightness, redness and yellowness
values as a description of surface browning. Subjective
observations were made regarding surface blistering of pastry

wafers.

REVIEW OF LITERATURE

A11 cereals, including wheat, are grasses (Gramineae).
The genus Triticum has 14 species, of which only three are
commercially important. These are Triticum vulgare, common
wheat; Triticum compactum, club wheat; and Triticum durum,
durum wheat (Shellenberger, 1982). Triticum aestivum also
refers to common wheat and the name is now used in preference

to Triticum vulgare (Everson, 1985).
Wheat Classification

Wheats are classified as spring or winter. Winter wheats
are planted during fall, become dormant during winter, and
are harvested in early summer. Spring wheats are planted
during spring in locations where severe winter weather would
damage winter wheat. Spring and winter wheats are further
classed as red, white or amber based on bran color; color is
a varietal characteristic (Zeleny, 1978). Another culti-
varietal characteristic is kernel hardness. Wheats are
classed as hard or soft according to the way the endosperm
breaks down during the milling process. These cultivarietal
differences are due to the spatial arrangement of endosperm
components during dessication; more continuous, densely

packed components result in harder wheat (Stenvert and

Kingswood, 1977). Environment also influences hardness.
Miller et a1. (1984) found that both soft and hard wheats
were “softest" when grown in a soft wheat area and "hardest"
when grown in a hard wheat area. Average rainfall and time

to grind were positively correlated at the 10% level.
Wheat Composition

The intact wheat kernel consists of three parts: the
endosperm, germ and bran; their respective percentages are
83%, 2.5%, and 14% (Shellenberger, 1982). The chemical
compositions of the three kernel parts differ greatly.

The germ of wheat contains 28.5% protein, 11.7% moisture,
10.4% fat and 44.5% total carbohydrate. Bran has 14.4%
protein, 13.2% moisture, 4.7% fat and 60.8% total carbo-
hydrate. There is an average of 9.6% protein, 14.0% moisture,
1.4% fat, and 74.1% total carbohydrate in the endosperm of
wheat (Kent-Jones and Amos, 1967).

Carbohydrate

The individual carbohydrate constituents also vary widely
among the three kernel components. The bran contains high
percentages of cellulose (21.4%) and hemicellulose (26.7%);
germ consists of 7.5% cellulose, 6.8% hemicellulose, 14.0%
starch and 16.2% sugars. Starch, the major carbohydrate of
endosperm, accoUnts for 71.0% of total kernel weight
(KEITt-Jones and Amos, 1967). Wheat starch consists of 25%

linear amylose and 75% branched amylopectin.

Effect of Milling on Composition

The process of milling plays a significant role in
determining the chemical composition of a flour. The
extraction rate, or parts of flour per hundred parts of
.wheat, describes efficiency of separation of the outer
coverings from the endosperm. The outer coverings include
the bran, aleurone layer of the endosperm and germ. An
increased extraction rate results in more aleurone layer
remaining with the endOSperm being reduced; since the aleurone
layer has higher protein content, more protein is contained
in the flour product (Kent-Jones and Amos, 1967). Mineral
content also increases with flour extraction rate (Miller
and Johnson (1954).

Davis and Eustace (1984) studied milling stages of soft,
hard and durum wheats using electron microsc0py. Fractures
in hard wheat delineated endosperm cells, but in soft wheat
the endosperm was more randomly disrupted with additional
smaller cracks. By the third break roll stage, the soft
wheat had negligible amounts of cell wall structure adhering
to the aleurone layer, in contrast to the hard wheat. This
suggested that soft wheat was more readily removed from its
bran, and disintegration was more rapidly accomplished.

Both protein and starch are subject to heat damage from
the friction of break and reduction roll systems. Soft wheat
flours, offering less resistance to the break rolls are less

susceptible to such damage. Miller et a1. (1964) showed that

starch damage is largely responsible for differences in
water absorption, handling properties of dough, and sugar

production due to increased susceptibility to enzymatic

action.

Flour Streams Effect on Composition
Streams from the different reduction stages can be
combined to produce different grades of flour. In the U.S.
a “straight grade" flour contains all streams and consists of
72% of the whole wheat. By selecting streams "patent" flours
result. ”Shorter" patents contain a lower proportion of
streams and represent a lower extraction (Campbell, 1972).
The application of a flour is based upon the extraction
and proximate composition. An average straight grade, hard
wheat flour suited for bread production contains 11.8%
protein, 1.2% fat, 74.5% total carbohydrate and 0.46% ash.
In contrast, a cake flour from soft wheat contains 7.5%
. protein, 0.8% fat, 79.4% total carbohydrate and 0.37% ash
(Adams, 1975).

Total Protein Content

The quantity of protein in a specific flour is largely
determined by environmental factors. Swanson (1924) stated
that climatic conditions, including amount and distribution
of rainfall, temperature, wind velocity, and evaporation, had
the greatest influence on quantity and quality of protein in

wheat. That varieties adapted to the climatic conditions of

the wheat growing region would have the highest protein
content and best quality, was also emphasized.

The amount of available nitrogen is a major determinant
of protein production in maturing wheat; environmental
conditions influence nitrogen availability. Strbac et al.
(1974) studied the effects of applying nitrogen-containing
chemicals to samples of Arthur winter and Inia spring wheat.
Application of 225 kg nitrogen per hectare to Inia signifi-
cantly increased the nitrogen content of wheat meal, and
also the absolute amounts of the major protein fractions. A
foliar application of 70 g per hectare of terbacil increased
the total nitrogen content of Arthur winter wheat 14%, and
increased the gliadins 24% as compared with the control. Wu
and McDonald (1976) found that high nitrogen fertilization
at seeding time significantly increased content of protein,
~gluten, soluble protein, nonprotein nitrogen, and nitrate,
but proportions of nonprotein and protein nitrogens were not
affected.

Just as environment affects protein content and yield,
protein quantity and nutritional quality vary with yield.
Protein content is inversely proportional to crap yield
(Hansel and Seibert, 1978; Mesdag, 1979); yet since hexaploid
wheats do not have three times as much protein, on a percent-
age basis, as diploid species, Kasarda et a1. (1976) quoted
that Wong suggested that there may also be genetic controls

limiting the total amount of protein synthesized.

Mitra et a1. (1979) stated that enhancing grain yield or
grain protein requires extra energy expenditure, with an
improvement in one leaving less energy for the other. They
also found a negative correlation between achieving a more
balanced amino acid composition and energy expenditure
required for synthesis of the more nutritious proteins.
McDermott and Pace (1960) found an inverse relationship
between protein and amount of lysine in the protein. The
soft wheats, with lower protein, have a higher content of
lysine, arginine, and other essential amino acids (Hepburn
and Bradley, 1965; Lawrence et al., 1958; Waggle et al.,
1967).

Protein Classification

Wheat proteins are commonly classified as to their solu-
bility. Osborne (1907) designated four solubility classes:
the water-soluble albumins, salt-soluble globulins, aqueous
alcohol-soluble gliadins, and the glutenins, soluble in

dilute acid or alkali.

Soluble Proteins

The albumins constitute 6-12% of the total flour protein,
have a high tryptophan content, and are associated with
pentosans. Globulins account for 5-12% of the total flour
protein, are high in arginine, but are low in tryptophan.

These two are often referred to as "soluble proteins". The

majority of the soluble proteins are located in the cytoplasm
(Graham, 1963; Graham et al., 1963). The enzymes of wheat
are generally albumins or globulins and are, thus, in this
soluble fraction.

Pratt (1978) quoted unpublished data of Greenberg that
showed the ratio of soluble protein to total protein in soft
wheat flours to be substantially higher than that of hard
wheat flours. Cluskey et a1. (1961) found that the amount
of water-soluble protein recovered from soft wheat was
approximately the same as that of hard wheat. Baking quality
of flours was negatively correlated with percentage of water-
soluble protein, in a study by Maes (1966). More salt-soluble
proteins were found in better-quality flours by Koenig et a1.

(1964).

Gluten Proteins

The gluten proteins are also referred to as the storage
proteins of wheat since they serve a storage function; they
are rapidly hydrolyzed to amino acids and peptides during
germination and supply the developing embryo with nitrogen
for protein synthesis. The storage proteins account for
about 70% of the total wheat flour protein (Kasarda et al.,
1976).

Gliadins. Kasarda et al. (1976) described the gliadins
as the least charged proteins known; they may also represent
the most heterogeneous groups of closely related proteins

known. Low electrophoretic mobilities at any pH, due to

10

their low charge, impede the resolution of gliadin compo-
nents. Nevertheless, Wrigley (1970) separated the gliadins
into over 40 distinguishable components using two-dimensional
electrophoresis. Wrigley and Shepherd (1973) similarly
found 46 different components. Reversed-phase high-
performance liquid chromatography (RP-HPLC) differentiated
'30-40 gliadin components (Bietz et al., 1984).

When determined by sodium dodecyl sulfate-polyacryla-
mide gel electrophoresis (SDS-PAGE), after reduction of
disulfide bonds, molecular weights (M.W.'s) of most gliadin
components approached 36,000 (Bietz and Wall, 1972; Ewart,
1973; Hamauzu et al., 1972). Graveland et a1. (1982) reported
an average M.W. of 35,000 for the gliadins. Moderate amounts
of components with M.W.‘s of 11,400, 44,200, 69,300, and
78,100 were found by Bietz and Wall (1972); trace amounts of
components with M.W.‘s of 25,600, 48,800 and 57,300 were
also identified by these authors.

From gel filtration of gliadins, M.W.‘s ranging from
25,000-50,000 were found (Beckwith et al., 1966; Bernardin
et al., 1967; Meredith and Wren, 1966). Two higher M.W.
fractions were isolated by Beckwith et a1. (1966) from a 70%
ethanol gluten extraction. A M.W. of 100,000 was determined
for the major of the two fractions; it constituted 6% of
the total gliadin, and resembled a low M.W. glutenin.

Békés et a1. (1983) found that reversible aggregation of

some subunits to form aggregates of higher M.W. was mediated

11

by the lipids extracted with the gliadin proteins by 70%
aqueous ethanol solution. Tighter folding of the polypep-
tides, and a greater level of hydrophobic bonding were
observed by nuclear magnetic resonance spectroscopy in the
gliadin-enriched fraction, as compared with the glutenin-
enriched fraction (Schofield and Baianu, 1982).

A-gliadin, or aggregable a-gliadin has been extensively
characterized (Bernardin et al., 1967). At increasing salt
concentrations, and pH's close to neutrality, A-gliadin
aggregated to microfibrillar forms having diameters of 70-80 A.
Particle weights in the millions were found for A-gliadin in
the aggregated form. In 0.001 M HCl, a reversible dissocia-
tion into monomeric subunits occurred. Kasarda et a1.

'(1968) determined from optical activity measurements that the
polypeptide chain of monomeric subunits was comprised of
about one-third a-helical conformation, 10% 8-structure, and
the remainder, flexible random structure. Greene and Kasarda
(1971) studied the binding of 2-p-toluidinylnaphthalene-6-
sulfonate (TNS). Binding at pH 3 was more than double of
that at pH 5, suggesting that aggregation at pH 5 possibly
Caused steric hindrance of binding sites. The partial
unfolding of A-gliadin at pH 3 (Kasarda et al., 1968) may
have exposed hydrophobic regions to TNS. Ion-exchange
chromatography was used by Platt and Kasarda (1971) to
separate Az-gliadin from A1-gliadin, and the latter into

three fractions. Cole et a1. (1983) observed enhanced

12

aggregation of A-gliadin with increased ionic strength, and
dissociation of A-gliadin with increasing temperature. These
results implicated hydrogen bonding as the major stabilizing
force among aggregates, with possible lesser contributions
from salt linkages and hydrophobic interactions.

Glutenin. Glutenin represents about 50% of the total
protein of wheat flour and is the least soluble half. The
terminology used to describe glutenin was clarified by
Kasarda et a1. (1976). Glutenin fraction refers to any
preparation including less than a third of the total protein.
A preparation including a third to a half of the total
protein is referred to as the glutenin complex. A clearly
defined, single polypeptide chain derived from the glutenin
complex or glutenin fractions, is termed a glutenin subunit.

Use of different glutenin preparation methods result in
large quantitative differences. In the classical glutenin
separation of Osborne (1907, 1924), dilute salt solutions are
used to extract albumins and globulins, 70% aqueous ethanol
removes gliadins, and the residue is extracted with acid or
alkali to solubilize glutenin. Only a small amount of
glutenin is isolated with this method. Jones et a1. (1959)
directly extracted a gluten ball with 70% aqueous ethanol,
leaving glutenin as a residue. A second method by these
workers involved the dispersing of gluten ball in 0.01 M
acetic acid, making the dispersion 70% in ethanol, then

adding NaOH to pH 6.5; this precipitated half the gluten as

13

glutenin. Glutenin obtained by the method of Orth and Bushuk
(1973) constituted only 10% of the total protein. This
procedure entailed a gluten extraction using A.U.C. solvent
(0.1 M acetic acid, 3 M urea, and a cationic detergent,

0.01 M cetyltrimethylammonium bromide), ethanol addition to

a 70% concentration, and lastly, addition of 1 M NaOH to pH
6.4, with subsequent glutenin precipitation. An ammonium
sulfate precipitation of an A.U.C. extract of flour yielded
27% of the total protein as glutenin (Wasik and Bushuk,
1974).

Glutenin has also been fractionated by gel filtration
and SOS-PAGE. Huebner and Wall (1976) used agarose columns
to separate A.U.C. extracts of flour into two peaks -
glutenin I and glutenin II. Increased dough strength was
correlated with larger amounts of glutenin I and insoluble
residue by these authors. Gel filtration was also performed
on reduced glutenin by Huebner and Wall (1974), yielding
three fractions, A, a, and c. When subjected to SOS-PAGE,
fraction A displayed streaking characteristic of aggregation
from strong secondary bonding. The M.W. of this fraction
ranged between 200,000 - 800,000. Fractions 8 and C had
M.W.‘s near 100,000 and 40,000, respectively.

Jones et a1. (1961) determined M.W.‘s for the glutenin
complex. They found a broad range of M.W.‘s from 40,000 to
many millions, indicating heterogeneity. A weight-average-

M.W. of 2 million was reported by these workers. A

l4

number-average-M.W. of 121,000 was reported by Wu et a1.
(1967). Bietz and Wall (1972) identified 15 subunits of
glutenin having M.W.‘s of: 133,000, 124,000, 102,000, 87,000,
79,100, 71,000, 64,300, 49,400, 44,600, 42,200, 36,000,
32,600, 27,500, 18,000, and 11,600. Different estimates of
M.W.‘s haVe been given by other investigators. SOS-PAGE

and densitometric tracing revealed that the glutenin subunits
with M.W.‘s near 44,000 and 36,000 constituted a major portion
of the glutenin complex (Huebner and Wall, 1974).

Less a-helical, but more flexible random structure is
found in glutenin proteins than gliadin proteins (Wu et al.,
1967). Kasarda et a1. (1978) suggested that significant
differences in the primary structure of glutenin and gliadin
may account for differences in secondary structure; gliadin
molecules tend to form intramolecular disulfide bonds and.
tightly folded structures, as opposed to glutenin molecules,
which form intermolecular disulfide bonds and loosely folded
structures.

Cleavage of disulfide bonds leads to rapid viscosity
decreases in glutenin preparations (Nielsen et al., 1962;
Pence and Olcott, 1952) corresponding to dissociation of
high M.W. glutenin to low M.W. components (Nielsen et al.,
1962). This sensitivity to disulfide-bond cleaving agents
has led to structural models emphasizing intermolecular
disulfide bonds. Ewart (1979) proposed a linear model for

glutenin, in which adjacent chains are joined by only one

15

interchain disulfide bond, and an average of one strained
intrachain disulfide bond per chain. Glutenin molecules are
prevented from aligning themselves with one another along
their entire lengths by gliadin, which acts as a plasticizer.
Khan and Bushuk (1979) postulated that the glutenin complex
or aggregate (micelle) consists of many noncovalently bound
subunits of glutenin. Smaller subunits are non-covalently
bound in a network of high M.W. glutenin. This network is
held together by either covalent disulfide bonds or extremely
strong noncovalent forces.

An alternate model was proposed by Kasarda et al. (1976).
They suggested glutenin proteins strongly aggregate through
such secondary interactions as hydrogen, ionic, or hydro-
phobic bonds to form microfibrils. These microfibrils also
aggregate into sheet-like structures called macrofibrils,
which in turn interact to form a lattice.

Role of Sulfhydryls and Disulfides in Gluten and Dough.
Cysteine side chains of gluten and nongluten proteins, and
low-M.W. thiols present in doughs contribute free sulfhydryl
(SH) groups that provide sites for sulfhydryl-disulfide
(SH-SS) interchange (McDermott et al., 1969). Pomeranz (1978)
quoted Goldstein (1957) as postulating that thiol4fisulfhka
interchange allows the breakage and reformation of SS bonds
that occur during mixing. If during the mechanical breakdown
of SS bonds, SH groups are lacking, free radicals form (Axford

and Elton, 1960; Redman et al., 1966). New SH groups are

16

formed as free radicals remove protons from the surrounding
dough (Ewart, 1968). The number of intermolecular SS bonds

and their rate of interchange influence the rheological proper-
ties of dough (Frater et al., 1960). These authors speculated
that oxidizing improvers inhibit SS interchange, thus strength-
ening the dough; reducing agents lower the number of inter-
molecular SS bonds, causing breakdown of dough structure.

Hard wheat flours were found by Tsen and Anderson (1963)
to contain the most SS bonds. Soft wheat flours contained
the fewest SS bonds and SH groups, but these same flours had
the most SS bonds per unit protein, and hard wheat flours
the fewest. Mecham (1968) stated that there is an inverse
relationship between flour protein content and SS content
per unit protein.

Role of Other Bonds in Gluten and Dough, The prevalence
of amide side chains in the gluten proteins provides ample
opportunity for hydrogen bonding (Beckwith et al., 1963;

Holme and Briggs, 1959; Ronalds and Winzor, 1969). That the
hydrogen-bond breaking agents have a pronounced effect on
dough rheology emphasizes the significance of these bonds
(Bushuk et al., 1968; Holme and Briggs, 1959).

The many nonpolar side chains present in the gluten
proteins similarly allow hydrophobic bonding as both protein-
protein and protein-lipid interactions. Wehrli and Pomeranz
(1970) identified such bonds using nuclear magnetic resonance

spectroscopy.

17

Addition of salts to doughs results in increased rigidity
and resistance to extension (Bennet and Ewart, 1965). This
provides evidence of ionic bonds in gluten and dough.

Gluten Washing. Gluten, the cohesive mass obtained by
washing starch from dough, essentially consists of storage
protein; Kasarda et a1. (1978) stated that 85% of endosperm
(storage) proteins are gluten proteins. Woychik et al.
(1961b) also found albumins in gluten. Membrane proteins
have also been observed (Simmonds, 1972). On a dry basis
gluten contains 75-85% protein, 5-10% lipids and 10-15%
carbohydrates (Kasarda et al., 1971; Shellenberger, 1982).
TheSe percentages are dependent upon the thoroughness of
washing. .

Kasarda et a1. (1976) cited that Beccari was first to
report the separation of gluten from flour by washing dough
with water. Early this century, weights of wet crude and dry
gluten were commonly used to estimate protein content; in
addition the "feel" of the gluten was used as an index of
quality. Dill and Alsberg (1924) attempted to standardize
the gluten washing test, and Optimize precision. They
recommended use of a neutral 0.1% sodium phosphate buffer to
prevent gluten dispersion, as is common with the less cohe-
sive soft wheat flours. Fisher and Walton (1936) noted
personal error in hand-washing of gluten and recommended a
mechanical apparatus. Complete starch removal is not

possible, and when the gluten content exceeds the protein

18

content, this is evident. Greenaway and Watson (1975)
suggested a standard automatic gluten method to increase
precision, yet still had 3% starch remaining in their gluten
samples. In the formation of a gluten ball, about 14% of the
total flour protein, corresponding to albumins, globulins

and small amounts of gliadins, was lost (Jones et al.,

1959).
Gluten Functionality

The strength of gluten is key to determining the potential
quality of a particular flour for a given end-use. The
strength and viscoelastic properties of gluten, which can be
physically and chemically modified, are primarily a function

of secondary structure.

Gluten Viscoelasticity and Thermal Stability

Wet crude gluten is heat-sensitive. Alsberg and Griffing
1(1927) noted decreased swelling of gluten in acid as tempera-
ture increased from 50-800C and suggested denaturation was
occurring (no definite coagulation temperature was given).
From 30-50°C they observed increased swelling power.

At low moisture contents, rates of denaturation of
gluten at 800 and 90°C were negligible, but rose rapidly to
maxima at 35-40% moisture (Pence et al., 1953). Rates
declined slightly toward intermediate values at higher

moistures. Complex relationships were found among pH,

l9

temperature, and rate of denaturation. Damage occurred to

baking properties at low pH values which was not caused by

heat. No consistent trend was evident between denaturation
rate and flour quality.

Moderate heat treatment of gluten, such as 70°C for
1-4 hr., or 80°C for 1 hr, did not significantly affect
farinograph curves (Doguchi and Hlynka, 1967). Upon exposure
to higher temperatures, or longer mixing times than 80°C for
2.5 hr, gluten lost its cohesiveness and stickiness.

Jeanjean et a1. (1980) observed modifications in protein
solubility and viscoelastic properties of gluten exposed to
the heat of boiling water for 2 min. Decreased compressi-
bility and increased gluten relative elastic recovery
resulted. Heating also insolubilized ethanol-soluble
proteins possibly through formation of new disulfide bonds.
Better quality common wheats had higher tendency of aggre-
gation of ethanol-soluble proteins. Salt-soluble protein
decreased similarly among all cultivars.

In a study by Eliasson and Hegg (1980), differential
scanning calorimetry was used to locate thermal transitions
of gluten between 30-115°C. They observed peaks at 64.6 and
118°C, corresponding to transitions in starch; there was a
7% starch contamination in the gluten. Peaks at 88.4 and
101.4°C corresponded to transitions in gluten. The small
enthalpies of the thermal transitions in gluten did not

support the concept of protein denaturation as being important

20

in the baking process.

In early rheological tests on gluten,torsion viscosi-
meters were used. Gortner (1924) stated that viscosity was
a useful measure of gluten quality, and was determined by
the quantity and quality of glutenin present in gluten.
Smith (1925) found all flours of high viscosity to have
excellent baking quality; low viscosity flours ranged from
poor to excellent baking quality. Thus, it was concluded
that viscosity was not a measure of baking quality.

Force required to entend gluten to the breaking point
was used in a study by James and Huber (1927). Hard red
spring wheats had the highest breaking point. Fine grinding
in a cool grinder had no effect on quality, but chlorine
treatments considerably increased breaking force. Baker
et a1. (1943) used puncture-force to test gluten balls, and
found a direct relationship with baking results.

Gluten Rheology and Secondary Bond Structure

Doguchi and Hlynka (1967) studied rheological properties
of gluten exposed to various solvents, in the farinograph.
Salt, urea, acetamide, and guanidine hydrochloride increased
mobility (lowered consistency); weak glutens have a lower
consistency at a given water content. Urea also made gluten
more sticky, and increased the time needed to reach maximum
consistency. The organic solvents acetone, butanone-Z,

dimethylformamide, dioxane and 4-methylpentanone-2 had an

21

effect similar to urea. These workers explained that the
similarity between urea, a hydrogen bond breaking agent,

and acetone, a hydrophobic-bond breaking agent, could be due
to their dissociating effects on secondary bond structure of
gluten. The possibility of protein-lipid interaction was not
dismissed.

Glutens from strong wheat, stretched under constant load,
were more resistant to stretch and mixing than glutens from
weaker wheats (Butaki and Dronzek, 1979). Tatham et a1.
(1985) proposed a model for gluten elasticity, in which the
high molecular weight (HMW) subunits are major elastic
components. They suggested the importance of B-turn confor-
mation in secondary structure, from observations made with
circular dichroism spectroscopy. Bietz and Wall (1980)
described a model of gluten formation involving six major
types of polypeptides, that can interact by disulfide inter-
change, hydrophobic and hydrogen bonding. These workers
also noted changes in the relative proportions of each type

of protein would change dough properties.
Electrophoresis of Wheat Proteins

Kasarda et a1. (1978) stated that "in general, no report
of experimental work on wheat protein fractions or components
is adequate without gel-electrophoresis patterns of the
proteins or reference to such patterns for material prepared

in an identical way." Jones et a1. (1959) established

22

several suitable buffer systems for performing free boundary
electrophoresis on wheat gluten proteins. An aluminum
lactate-lactic acid buffer at pH 3.1 with an ionic strength
of 0.03-0.12 was recommended by these workers. Zonal electro-
phoresis was performed on starch gels with pH 3.1 aluminum
lactate-lactic acid buffer with and without 3 M urea

(Woychik et al., 1961a). The presence of urea permitted
greater resolution of gluten bonds. A substantial amount of
protein remained at the origin, which was further character-
ized as glutenin. Lawrence et al. (1970) postulated that the
accumulation of too much protein at the origin could hinder
the entrance of other protein into the gel. These workers
also recommended the inclusion of urea in the buffer to
prevent formation of protein aggregates.

Variable protein content within a variety had no effect
on electrophoretic patterns (Tanaka and Bushuk, 1972). The
alcohol-soluble gliadin proteins exhibited obvious varietal
differences in patterns. These workers could not relate the
genotypic electrophoretic patterns to breadmaking quality.
However, Wrigley (1980) stated that the high mobility
gliadins were richer in sulfur than those of low mobility.
Severe changes in dough properties resulted when high-sulfur
gliadin proportions were reduced by sulfur deficiency during
grain growth. Differences in dough properties between
cultivars were suggested as being partially attributable to

genotypic differences in proportions of high- and low-sulfur

23

proteins. Germination up to 44 hr., equivalent to severe
sprout damage, did not affect cultivar identification by
gliadin electrophoresis (Lookhart et al., 1984). Gliadin
electrophoregrams were also not affected by adverse weather
that produced differences in kernel shapes. Thus, gliadin
electrophoregrams do not depict wheat quality, rather only
genotype.

Wrigley et a1. (1982) credited development of procedures
for wheat varietal identification using starch gel electro-
phoresis to Autran (1973), Autran and Bourdet (1973, 1975)
and Wrigley and Shepherd (1974). Bushuk and Zillman (1978)
developed a procedure using polyacrylamide gels as a support
medium rather than starch. These authors stated that poly-
acrylamide gels, having equal resolving power, were more
uniformly reproducible and easier to prepare than starch
gels. Wrigley et a1. (1982) gave detailed procedures for
several electrophoretic techniques used in wheat varietal
identification. Further attempts to standardize polyacryla-
mide gel electrophoresis (PAGE) procedures have been made in
various laboratories. Lookhart et a1. (1982) developed a
procedure for use with a commercially-available vertical
slab apparatus; these authors recommended purifying aluminum
lactate prior to use. A sodium lactate buffer was recommended
by Khan et a1. (1983) in preference to aluminum lactate,
since some gliadin components were better resolved. Other

modifications made by these workers were: use of a shallower

24

slot former, application of a smaller sample volume,
recrystallization of acrylamide and bis-acrylamide, vacuum
removal of dissolved oxygen from the gel solution, and a
doubling of the methyl green marker dye. Lookhart et a1.
(1985) also compared sodium lactate and aluminum lactate
buffer systems, and found that each resolved certain
proteins better. Thus, the sodium and aluminum laCtate
complexes differed in their interaction with the proteins.
A temperature of 7 or 10°C during electrophoresis, rather
than 21°C, resulted in less curved, better resolved; and
more sharply defined gliadin bonds.

By varying relative amounts of gel catalysts, Khan et a1.
(1985) produced gels with different firmness, stickiness,
pore size, and polymerization times. Gel firmness was most
affected by ferrous sulfate, followed by ascorbic acid and
hydrogen peroxide. 'Scanning electron microscopy revealed
that pores were more uniform, with thicker walls, in firm
gels than soft gels; the latter contained large pores. The
firm gels were less sticky, less likely to break, and gave
better resolution than soft gels. Increasing the amount of
ferrous sulfate or hydrogen peroxide, dramatically reduced
polymerization time, ferrous sulfate having a greater
effect. Polymerization time was not affected by ascorbic
acid.

Computer programs are currently being used in the

identification of wheat cultivars by their electrophoregrams.

25

In all programs, the protein band arrays of all known
cultivars stored are compared with the unknown cultivar.
Bushuk and Zillman (1978) assigned the center of a heavy
single band in the electrophoregram of the cultivar Marquis
a relative distance of 50 units; band mobilities were
measured against this arbitrary value. Band densities were
also considered by Zillman and Bushuk (1979), who subject-
ively assigned numerical values from 1 (very light) to 5
(very dark). A program by Lookhart et a1. (1983) compared
bands progressively from low to high mobility, as to
correlation of protein band density and mobility; relative
percent similarities between the unknown and standard
cultivars are assigned and listed. These authors suggested
that the unknown and most similar cultivars be electrophoresed
on the same gel for absolute confirmation. Sapirstein and
Bushuk (1985) designed a program comparing three reference
bands of the cultivars Marquis and Neepawa, designated at
R24 and R79 in relation to the established R50 reference.
band. The two additional reference bands should increase
precision and interlaboratory agreement, and should also

allow better estimates of gliadin heterogeneity.
Fractionation and Reconstitution Studies

Recombined wheat starch and gluten formed doughs
that were similar in baking characteristics to the original

flour doughs (Sandstedt et al., 1939). Finney (1943)

26

further fractionated flour into starch, gluten and water-
solubles, and extracted fat from some of the glutens. From
flour fractions recombined in their original proportions, it
was possible to obtain bread equal to that made with the
original, unfractionated flour. The water-soluble fraction
was found to be essential for two of the three flours tested.
With water-solubles present, differences in the gluten
fractions were entirely responsible for differences in bread
quality. Interchange of fats extracted from glutens did not
affect baking tests. Pence et a1. (1951) confirmed the
importance of the water-solubles to bread-baking, and
further separated the solubles into a dialyzable and a
non-dialyzable fraction. The dialyzables (sugars, low-
molecular weight nitrogenous compounds and ash salts)
increased mixing time and produced a smaller volume response
than the nondialyzables (albumins and a small amount of
globulins). Hoseney et al. (1969a) also dialyzed the water-
solubles and stated that their dialyzable fraction contributed
to gas production, and that the fraction containing soluble
pentosans and glycoproteins contributed to gas retention
and/or gluten extensibility. Substitution of yeast food
for the dialyzable fraction resulted in equal gas production,
demonstrating that albumin and globulin proteins were not
involved in breadbaking performance.

‘Flour separated into gluten, starch, and a combined

tailings starch and water-solubles fraction by Walden and

27

McConnell (1955) gave optimum loaf volumes 15% lower for the
reconstituted flours as compared with the original flours.
Incorporation of sodium chloride in the mixing water of
separation reduced the damage to loaf volume to within
experimental error.

Sollars (1956) compared an acid extraction procedure for
fractionation with a conventional dough kneading procedure.
He found the acid extraction process more time-consuming and
recommended it for use only with low protein flours or those
with damaged or altered gluten.

In fractionating soft wheat flours into starch, gluten,
and water-solubles for cookie baking tests, Yamazaki (1950)
found it necessary to mix a dough from the fractions to
optimum gluten development, and to then freeze dry and grind
it to form a reconstituted flour. Dry blends of fractions
baked into poor cookies. Yamazaki and Donelson (1976)
found that removal of free lipids by extraction, prior to
fractionation into gluten, tailings, starch, and water-
solubles, permitted dry blending of fractions without a
doughing stage, and obtained resultant good cookies from
these blends. Flours were rehydrated to 12-13% moisture
prior to baking.

Zaehringer et a1. (1956) separated soft wheat into four
fractions: starch, gluten, "amylodextrin", and water-solubles.
No doughing stage was necessary in reconstituting flours for

production of satisfactory baking powder biscuits. Fractions

28

were rehydrated by leaving them near an open beaker of
water.

Cake flours were fractionated into water-solubles, gluten,
tailings starch, and prime starch by Sollars (1958a).
Extremely poor cakes resulted from simple blends of dry
fractions. However, satisfactory white layer cakes could be
obtained by mixing a well-developed dough and then incorpo-
rating it directly into the baking test; this eliminated time
necessary for lyophilization, grinding, rehydration, and
redetermination of moisture content. For angel-food cakes
it was necessary to fully reconstitute by lyophilizing and
grinding the developed dough. Donelson and Wilson (1960a)
confirmed the necessity of the preliminary doughing step
for cake testing, and suggested that intimate recombination
of components occurred during the doughing. Lyophilizing
reconstituted doughs before baking gave cakes of very low
volume.

Hexane extraction of free lipids from chlorinated and
untreated cake flours, prior to acetic acid fractionation
into gluten, water-solubles, prime starch and tailings
starch, permitted dry blending of the fractions without a
doughing step (Johnson and Hoseney, 1979). Cakes produced
from the chlorinated dry blends were of good overall quality.
By the interchanging of prime starches from chlorinated and
untreated flours, the reconstituted flour containing the

chlorinated prime starch gave a cake equal in volume to the

29

chlorinated control. Donelson et a1. (1984) also hexane-
extracted free lipids, prior to an aqueous fractionation into
the above fractions and were able to dry blend fractions
without a doughing step. Flour fraction interchange illus-
trated the primary importance of chlorinated lipids,
regardless of source, to cake-quality potential.

Standard fractionation and reconstitution procedure
resulted in 10-20% higher water-retention capacities (WRC) of
reconstituted flours as compared with those of the original
flours (Sollars, 1973a). Longer mixing times, or use of a
sodium chloride solution during kneading separation, lowered
WRC. Flours reconstituted from fractions of an acetic acid
procedure and simple blends of fractions both had higher
vac. Sollars (1973b) also determined vac for gluten,
tailings.and starch individually. Gluten, starch and
tailings from hard wheat flours all had higher WRC than
those from soft wheat flours. Gluten and tailings had lower
retentions when dilute sodium chloride was used in kneading
separation, and higher retentions when an acetic acid method
was used. By using one-fraction-at-a-time interchanges,
tailings were shown to be responsible for half of WRC
differences. Water-solubles, gluten, and starch contributed
equally to the remaining half of the WRC difference.

Further study by Sollars and Rubenthaler (1975) showed that
very satisfactory farinograph curves could be obtained from
blended wheat flours. Reconstituted flours using doughing

steps resulted in poorer performance on the farinograph.

30

These workers concluded that reconstitution procedure,
rather than fractionation, may have caused unsatisfactory
characteristics in baked products. Differences in farino-
graph absorption between soft wheat and hard wheat flours
were not accounted for by any one fraction, although the
tailings produced half the differences.

Fractionation and interchange of starch, gluten, tailings
and water-solubles has been used to illustrate importance of
each in the differential bromate response of hard wheat
flours (Marais and D'Appolonia, 1981). Malecki et al. (1980)
used flour fractionation to study components responsible for
differences in staling rate of bread. Their findings
‘implicated the gluten fraction.

Shogren et a1. (1969) were first to further fractionate
the gluten obtained by dough kneading procedures and recon-
stitute flours from individual gluten fractions with a
combined starch and water-solubles fraction. The glutens
were ground, solubilized in 0.005 N lactic acid and then the
proteins precipitated at various pH levels. Between each pH
adjustment with 0.1 N sodium carbonate, lactic acid-insoluble
material was removed by centrifugation. As pH was increased
the glutenins decreased and gliadins increased and, thus,
fractions differing greatly in gliadin/glutenin ratio were
obtained. By baking breads from the reconstituted flours, it
was found that the pH 6.1 insoluble-fraction reconstituted

flour, containing little or no glutenins and a high

31

concentration of gliadins, baked into bread with a loaf
volume higher than the original flour.

Two hard wheat flours of different baking quality were
fractionated and component fractions were interchanged
(Hoseney et al., 1969b). Gluten governed mixing time and
loaf volume; bromate requirement was influenced by both
gluten and water-solubles. Gluten soluble at pH 4.7 was
also ultracentrifuged at 100,000 x g for 5 hr. The centrifu-
gate (100-5C) and supernatant (100-55) contained approximately
15% and 85% of the protein, respectively. In baking tests,
the 100-5S fraction controlled the loaf volume. Starch gel
electrophoresis of the two fractions showed large amounts of
protein too large to enter the starch gel contained in the
lOO-SC fraction, and a high concentratiOn of the seven
slowest moving bands in the 100-55 fraction. Thus, the
proteins migrating into the starch gel (gliadins) were
interpreted as being responsible for loaf volume by these
authors.

Finney et a1. (1982) also used ultracentrifugation as a
fractionation method. A force of 435,000 x g separated
gluten, previously hand-washed from flour, into four
fractions: a pellet (high molecular weight insoluble gluten-
ins), a gel (low molecular weight soluble glutenins), a
viscous layer (high molecular weight, soluble gliadins) and
a supernatant (low molecular weight, soluble gliadins).

Mixing requirement and baking absorption were controlled by

32

the gel glutenin proteins. Supernatant gliadin proteins

determined loaf volume and crumb grain. Since very short
(poor) mixing requirement is almost always associated with
low (poor) loaf volume potential, these workers suggested
good and poor glutenins are associated with good and poor

gliadins, respectively.
Hard Wheat Functionality

The functionality of wheat fractions in bread has been
extensively reviewed (Pomeranz, 1978). Bushuk (1985)
reviewed research on structure and functionality of flour
proteins in dough and bread. Conflicting results have been
obtained by different researchers. Doekes and Wennekes
(1982) observed gliadin-to-glutenin ratio increases with
corresponding loaf volume increases; Orth and Bushuk (1972)
and Axford et al. (1978) correlated levels of acid-insoluble
(glutenin) proteins with loaf volumes. Preston and Tipples
(1980) observed that loaf volume increased similarly when
acid-soluble gluten proteins were added. These workers
suggested that mechanically disaggregated, acid-insoluble
flour proteins that are present in the acid-soluble gluten

fraction are of major importance in determining bread-making

quality, rather than the more insoluble gluten proteins.

 

33

Soft Wheat Functionality

Unlike the hard wheats, where strength and high protein
are desirable, soft wheat quality is associated with tender-
ness and delicacy. Soft wheat flours generally require only
mild, gentle mixing action to produce desired results.

Flour specification will vary as to end use. Alexander
(1939) noted that very short patent, highly bleached, and
finely granulated flours are suited for angel food cake,
‘high sugar/liquid formulas, and for cakes where a very white
crumb is desired. A longer patent also well bleached is
used for loaf cakes, sponge cakes, and general purposes.
Third and fourth grades of flour are suited for pastry and
cookies, respectively.

Chlorination is essential to baking performance of cakes.
Cakes baked from flours with too high a pH will fall or
shrink during cooling. Soft wheat biscuit flours should not
be subjected to the gluten-dispersing chlorine action,
since gluten strength is needed (Alexander, 1939). For
cookies and pastries a low pH flour is also undesirable,
since crispness and tenderness are the desired qualities.
Cookies baked from chlorinated flours will lack spread, t0p
grain, and crispness.

Alexander (1939) also stated that the most important
single factor determining soft wheat character is the flour

gluten. A small quantity of somewhat short gluten is needed

34

for cookies. For angel-food cakes, a small amount of firm,
elastic gluten is optimal; other cakes need soft, spongy
gluten in slightly larger amounts.

Despite the diversity of soft wheat products and, thus,
end-uses for soft wheat flours, milling and baking quality
evaluation of breeding lines by the USDA concentrates on
cookies and cakes (Yamazaki, 1969). The majority of litera-

ture on soft wheat also concentrates on these two products.

Cake

 

In order to evaluate soft wheat varietal performance in
cake, Kissell (1959) developed a lean-formula cake method
that eliminated usual structure-producing components, such
as egg whites and milk solids. This placed maximum stress
on the structure-forming ability of the flour (gluten) and
increased the sensitivity of the baking test.

Donelson and Wilson (1960b), using fraction interchange
techniques, found that gluten had the greatest effect on
cake volume and structure. They noted that gluten acts as a
binder rather than as a structural element in the cake
batter, and that quality gluten is readily solubilized.
Gluten development is minimal due to formulation and mixing
procedure; that is, neutral to slightly alkaline pH, very
high sugar concentration, and short mixing time.

Gluten addition and air classification were used by

Gaines and Donelson (1985a) to vary cake flour protein

35

content from 7-16%. Flour protein content did not signifi—
cantly affect volume and tenderness of white layer cakes.

In angel food cakes, 2% increases in flour protein content
were necessary to effect decreases in height and tenderness.
Gaines (1985) observed greater cake volume among the

soft wheat cultivars of low protein content that were

capable of producing high break flour yield and smaller flour
particle size. These flours required more chlorine to reach
the.desired pH 4.8, possibly because of the increased surface
area from the smaller particle size.

Contributions of the flour fractions to the drop in pH
during chlorination were studied by Sollars (1958b). Nearly
50% of the total change in pH was caused by gluten. He
concluded that protein of bleached flour caused change in pH.
Destruction of normal gluten characteristics are believed

indicated by reduction in pH.

Cookies

Cookie spread values of air-classified soft wheat flour
fractions (expressed as width divided by thickness, W/T)
were reported by Pratt (1963). The high-protein fines
fractions had a W/T of 5.1; a W/T of 8.5 was found for the
low-protein fines. Cookies baked from the parent flour had
a W/T of 7.2. Since larger W/T values are desirable, it
would appear that high protein flours,.by decreasing cookie

spread, are unsatisfactory. Brenneis (1965) stated that

36

puffed, peaked crown cookies resulted from high-protein_
flours. More sugar and shortening were required for these
flours for production of cookies of eating quality similar
to those made with flours of 8.5% protein or less.

Abboud et a1. (1985) found, among soft wheat varieties,
cookie diameter was not related to protein content. Within
a protein series of the soft white winter wheat variety
Nugaines, protein content was highly negatively correlated
with cookie diameter, however. Whole wheat protein was not
significantly correlated with whole wheat cookie spread
(Gaines and Donelson, 1985b).

Kissell and Yamazaki (1975) increased cookie-crumb
protein levels 150% with commercial gluten addition, before
significant reduction in baking performance was incurred.
Use of natural surfactants permitted maximum crumb protein
increases of 375%, with maintenance of acceptable top grain,
cookie spread, and internal appearance in the sugar-snap
cookies. Hard wheat flours treated with surfactants produced
cookies with higher spread ratios than soft wheat flours
(Tsen et al., 1975); top-grain scores were also improved.
Children's taste preference for these two types of cookies
did not differ at the 5% level.

As with pastry doughs, insufficient water is available
in cookie doughs for development of a continuous gluten
network (Steel, 1977). Olewnik and Kulp (1984) studied

cookie dough behavior in the farinograph. Rotary molded

37

doughs, containing a relatively low shortening level, had a
limited amount of gluten development. With an additional

10% water, gluten formation occurred initially, but as mixing
time increased, shortening was dispersed which by coating
flour particles prevented further hydration and gluten
development. Wire-cut doughs, having an intermediate level
of shortening, also had increased gluten formation as a
result of additional water. Deposit doughs, with a charac-
teristically high fat content, were unaffected by additional

water content.

Pastry
Soft wheat flours to be used for pie pastry ideally

should contain 8.0-9.8% protein, 0.38-0.44% ash,-and have a
pH value of 6 (Tsourides, 1968). Since flour pigments
contribute to a desirable crust color, flours should be
unbleached; gluten would also be adversely affected by
bleaching. Dunn (1930) stated that the shortening require-
ment for pie crusts could be calculated from the protein
content; the protein content multiplied by a factor of ten
gave the number of pounds of shortening required per barrel
of flour for average crust production. Granulation is
inversely proportional to the shortening requirement since
finer particles have more surface area to be coated.

A pie crust should exhibit a small amount of blistering

which is indicative of some strength in the gluten (Kress,

38

1932). The pie crust from a good quality flour will remain
dry, tender and flaky; conversely, gummy and soft pie crusts
result from poor quality flours. It was recommended by
Kress (1936) that tests for moisture, ash, protein, color,
viscosity and absorption, plus pie crust and filled pie
baking, are necessary for determining quality of a pie
flour. The pie baking test would also indicate shortening
requirements of the flour.

Flakiness. Matz (1972) defined flakiness as “the tendency

 

of the crust to separate into strata or layers when it is
broken." Flakiness has also been described as open spaces
separating thin layers of dough (Bennion, 1980). Greater
and lesser concentrations of fat sandwiched between layers
of flour result in flakiness in pastry (Lowe, 1943). Dough
coats the fat particles during mixing, and these coated
particles are flattened into thin layers during rolling.
The fat melts and is absorbed into the dough during baking,
leaving open spaces between baked dough layers.

Pyler (1973) noted that hardened shortening resists
uniform distribution during mixing, and therefore contributes
to flakiness in the finished crust. Use of chilled water in
the formula has a hardening effect on shortening. Flour not
surrounded by fat absorbs water more readily (Lowe, 1943).
The absorbed water allows some gluten development. The
unabsorbed water is converted to steam during baking.

Greater gluten development possibly helps retain steam needed

39

to force dough layers apart.

Re-rolling of pastry, by attenuating gluten formation,
increases pastry flakiness significantly, but toughness may
also result (Lowe, 1943). Due to their weaker gluten, soft
wheat flours generally produce less flaky, more mealy pastry
than do hard wheat flours. Berger (1970) remarked that in
order to achieve sufficient cohesion of pastry for handling
and shaping, a minimum gluten network is necessary. A pie
dough composed only of flour and shortening, by precluding
gluten development, results in a dough lacking in tensile
strength and a crust too weak to be handled (Miller and
Trimbo, 1970). These workers also found increased flakiness
in crusts from high protein flour. Varying shortening level
between 40 and 80% did not affect flakiness. Flakiness is
decreased by too much or too little water in proportion to
the amount of fat (Bennion, 1980).

Flakiness defines the class of a pie crust. Knuepfer
(1960) described the mixing process used for each type of
crust. Mealy crusts are produced when flour particles are
completely surrounded by fat as a result of thorough blending.
Matz (1972) stated that mealy crusts fracture in a straight
line. Semi-flaky crusts are formed by blending only half the
flour with the fat to a uniform consistency, adding the
remaining flour, and mixing until lumpy. After adding the
water, mixing is continued until absorption is complete.

Blending flour and shortening into small lumps produces a

4O

flaky crust. A long-flake crust is produced similarly except
that fat lumps must remain the size of walnuts. For both the
flaky and long-flake crusts, firm shortening must be used,
all ingredients chilled, and doughs refrigerated before
rolling for maintenance of discrete shortening particles.

Lack of flakiness in crusts can be caused by addition of
too much fat, use of a low-protein flour, too complete a
dispersion of fat, too little water, or undermixing the final
dough (Gates, 1976). Amendola (1972) cited that insufficient
shortening, too much liquid, and baking at too low a tempera-
ture can result in a solid crust.

Several methods have been used in flakiness measurement.
Lowe (1943) measured the height of the pastry before and
after flattening the layers. Height in centimeters of ten
wafers (Briant and Snow, 1957), and height of stacks of four
wafers (Griswold, 1962; Howard and Morse, 1973; Ostrander
et al., 1971) have also been used. Matthews and Dawson
(1963) scored flakiness subjectively, with pastry having
many thin layers receiving optimum scores; lower scores were
given to pastry having thick layers, as they were considered
not flaky enough. Scores above 5.0 indicated samples with
indistinct layers that were judged too flaky. Miller and
Trimbo (1970) photographed cross-sections of pastry and
judged these subjectively.

Tenderness. Denton et al. (1933) observed increased

 

breaking strength (using a Bailey shortometer) of pastry as

41

flour protein content increased; a low-fat formula better
distinguished differences among flours. Miller and Trimbo
(1970) confirmed that protein content was related inversely
to tenderness, and observed that increased water in the dough
formula attenuated this relationship. These workers also
found increased tensile strength, shear values, and stretch-
ability of pie dough with increased flour protein content;
dough stickiness decreased.

Increasing water from 25 to 40% resulted in increased
breaking strength (Swartz, 1943). Breaking strength also
increased with increased mixing time after water addition,
when both fat and water were cold. More complete hydration
and development of gluten occurred with both increased
water, and increased mixing. At room temperature, the fat,
being more plastic, effectively coated the flour particles,
impeding hydration of gluten.

Fat has a tenderizing effect on pastry. However, use of
different fats resulted in highly significant differences in
breaking strengths of pastry (Hornstein et al., 1943). The
most tender pastries were produced from the softest, most
plastic fats. The amount of liquid glycerides, or the ratio
of liquid to solid glycerides were suggested as determinants
of the shortening power of a fat, by these workers.

Matthews and Dawson (1963) found a 41% level of fat to be
critical for assessing shortening values. The tenderizing

effect of the fat at lower levels is of lesser importance.

42

Taste panel scores for Optimum tenderness of pastries made
with oils and solid fats occurred at shortening levels of
45 and 51%, respectively. Thus, oils were the more efficient
form of shortening. Pastries scored high for tenderness
were also scored high for flakiness. Increasing the level of
substitution of elaidinized lipid decreased pastry tenderness
as measured by both taste panel and shortometer (Ostrander
et al., 1971).

Method of fat and water incorporation had a significant
effect on breaking strength of pastry (Rose et al., 1952).
A water-in-fat emulsion method produced more tender pastry
than did the conventional method. Fewer gluten strands were
observed in the water-in-fat emulsion method pastry.

Gluten formation in pastry dough was observed by micro-
scopic appearance (Hirahara and Simpson, 1961). In all
dough types, oval formations of gluten were found surrounding
starch granules. Gluten strands, in standard doughs, had
cloudy edges with small finger-like structures attached.
Excess dough manipulation formed definitive gluten strands,
with a loss of the cloudiness present in standard dough.
Dough containing excess water formed a large amount of gluten.
Mean breaking strengths were significantly higher for doughs
with either excess water or excess manipulation.

Freezer storage of baked pastry and unbaked pastry dough
did not significantly affect tenderness as detected by a taste

panel (Briant and Snow, 1957). Significant differences were

43

detected in breaking strength using the shortometer, espe-
cially in those frozen unbaked. Flakiness was not affected
by freezing. Hirahara and Simpson (1961) found increased
breaking strength in pastry baked from dough frozen in
aluminum foil, but not from that frozen in waxed paper.
Dough frozen in waxed paper had “specks" of gluten appearing
throughout. More distinct clumps of gluten were evident in
the dough frozen in aluminum foil.

Dough Mixing and Handling. Loving and Brenneis (1981)
recommended use of slow-speed mixers in commercial operations,
to avoid gluten development.. Lowe (1943) stated that
increased mixing of fat and flour until an optimum level
decreased breaking strength, yet toughness increased with
increaSed mixing after water addition. Noble et a1. (1934)
found that breaking strength decreased when the fat was
creamed to maximum volume. They also found that thoroughly
mixing after flour and liquid addition, resulted in more
tender wafers. Miller and Trimbo (1970) found that more
tender, but mealy crusts resulted from increased mixing at
50, 60 and 70% shortening levels. Crusts baked with 40%
shortening increased slightly in toughness with increased
mixing.

Doughs are usually subjected to a resting period of
several hours to overnight. Bennion (1980) asserted that
increased elasticity and extensibility of the dough; after a

few minutes standing, facilitates dough handling and rolling.

44

Preonas et a1. (1967) recommended a 3 hr resting period,
since increased shrinkage was found in crusts from doughs
stored overnight. Other authors (Dietrich, 1967; Gates,
1976; Pyler, 1973) suggested that overnight storage of dough
decreased crust shrinkage during baking. Additional advan-
tages in favor of overnight storage were: improved handling
properties of dough as a result of being fully hydrated and
relaxed, and of the hardened fat being less likely to liquify;
an even water distribution throughout the dough. Dietrich
(1967) noted that more liquid could be used in such doughs,
resulting in crusts both more crisp and puffy. Overnight
storage allows enzymatic modification of the gluten and
reduces soaking tendency of the crust (Pyler, 1973).

The method of rolling pastry also influences tenderness.
Use of additional flour to prevent sticking during rolling
increased breaking strength in proportion to the amount used
(Noble et al., 1934). They suggested rolling between sheets
of waxed paper without such dusting flour.

Crust Shrinkage. Shrinkage of pie crusts during baking

 

is undesirable. Preonas et al. (1967) encountered shrinkage
in pie crusts with their continuous production method, which
they attributed to over-development of gluten occurring
during the final mixing. These workers suggested overnight
storage of dough contributed to shrinkage. Amendola (1972)
also attributed shrinkage to overmixing and overworking of

dough. Insufficient shortening, too much liquid, and

4S

improper flour were cited as additional causes. Pyler (1973)
advised against stretching of doughs before baking to avoid
shrinkage. Shrinkage was found by Miller and Trimbo (1970)
to increase substantially with increasing flour protein
content; noticeable thickening of the pie crust accompanied
shrinkage. Little effect on degree of shrinkage could be
imputed to varying the shortening level between 40-80%, or
varying the water level between 12-36%. Less shrinkage
occurred when pie doughs were over-mixed by electric mixer.
Miller and Trimbo (1970) measured top surface area of
doughs before and after baking and reported per cent decrease
in surface area. Ostrander et a1. (1971) cut aluminum foil
squares to the size of wafers before and after baking.
Ratios of weights of solvent-cleaned foil replicas of baked

wafers to original wafers were reported as shrinkage index.
Browning Reaction in Wheat Products

Hlynka and Anderson (1951) found that the reaction of
reducing carbohydrates with wheat proteins was significantly
influenced by the protein level of flour. After 6m05 storage,
these high protein flours had the greatest increases in
reducing value. All doughs mixed with glucose, air-dried,
and then re-ground (dough + glucose) gave the highest initial
reducing values, and the largest increases in reducing value
after 30 wks storage, as compared with mechanical mixtures

of flour and glucose, or flour and dough alone. Greater

46

reactivity towards added glucose was found for glutens from
low protein flour. A positive correlation between protein
content and browning was found by Smak (1972) to be variety
dependent. Free amino acid content was not correlated with
crust color of bread.

Rubenthaler et a1. (1963) added the amino acids glycine,
lysine and glutamic acid to a bread formula alone and in
combination with each of 17 sugars and observed effects on
crust color. Glycine and lysine produced marked crust
browning. Browning increased slightly with glutamic acid
addition. Raffinose and pentose sugars produced deepest
crust browning. Effect of each sugar on crust color was
augmented by adding certain amino acids.

Increased browning occurred in sugar cookies after
addition of 5% glucose (Griffith and Johnson, 1957). The
reductones formed during browning conferred antioxidant
properties, giving the cookies greater stability to oxidative
rancidity. High concentrations of honey or reducing sugars
in cakes may produce excessive browning of cake crumb
(Miller et al., 1957). By maintaining a pH of ~6.3, the
excessive browning could be inhibited. Increasing the pH

enhanced browning reactions.
Textural Studies

In the objective evaluation of tenderness in pastry,

the Bailey shortometer has been almost exclusively used

47

(Briant and Snow, 1957; Denton et al., 1933; Hirahara and
Simpson, 1961; Hornstein et al., 1943; Matthews and Dawson,
1963; Noble et al., 1934; and Ostrander et al., 1971).
Stinson and Huck (1969) compared the shortometer, Kramer
shear press, tenderpen and sensory taste panel as methods
of pastry tenderness evaluation. The Kramer shear press
had the highest correlation with the sensory panel, the
tenderpen, the least. Comparison of relative precision of
each method showed the organoleptic panel to be the most
precise; the Kramer shear press was the most precise
objective method. Therefore, these authors recommended the
Kramer shear press for tenderness measurement of pastry.
Comparable results between the Kramer shear press and taste
panel methods of evaluating pastry tenderness were also found
by Miller and Trimbo (1970).

The Kramer shear press was used by Funk et a1. (1965) to
measure compressibility, tensile strength and tenderness of
angel cakes; highly significant correlations were found
between the shear press and sensory results. Gruber and
Zabik (1966) similarly tested butter cakes and also found
agreement between sensory and shear press data.

Szczesniak et a1. (1970) tested 24 foods varying widely
in texture, in the standard shear compression cell, and
demonstrated that these products could be grouped into three
general categories: those exhibiting a constant force,

independent of sample weight, those exhibiting a continuously

48

decreasing force to weight ratio, and those exhibiting a
constant force to weight ratio. Extrusion was found to occur
at a significant level in many foods. It was also concluded
that foods tested in the shear compression cell are generally
subjected to two or more of the following forces: shear,
compression and extrusion. Pure shear is uncommon.

Friction was considered as another force acting after the
blades meshed with the cell bottom.

Voisey (1977a) suggested that adhesion and cohesion
also influenced force-deformation curves obtained in the
standard shear compression cell. At the cell surface, food
may adhere; in the plane of rupture, cohesion may occur
between food surfaces. As a result of the compaction
necessary for initiation of rupture, changes in sample volume
occurred during testing; the properties of the compacted
food may be different from those of the original state of
the food. Thus, the mode of rupture for each food must be
determined experimentally, since it is too complex for
prediction.

In order to standardize readings by eliminating friction,
Voisey (1977b) reduced blade thickness. He also recommended
use of steel blades, rather than the usual aluminum, since
they were less variable in thickness. Neither force varia-
tion within foods nor the characteristic shape of force-

deformation curves was affected by these modifications.

49

Kramer (1972) stated that in any objective test of
texture food sample preparation and loading must be clearly
Specified. He recommended testing larger sample units in
order to improve precision. Peleg (1983) cautioned against
reporting instrumental mechanical parameters in terms of
sensory properties, without evidence of a correlation. Each

individual food must be tested to establish such a correlation.

MATERIALS AND METHODS

This research project was divided into two sections.
The first section involved the preparation of soft wheat
flours varying in gliadin-to-glutenin ratios through
fractionation/reconstitution procedures. The second section
was the evaluation of physical characteristics of pie pastry

baked from these reconstituted, plus their parent, flours.
Wheat Samples

Wheats grown at Michigan State University from certified
seed (1983 crop) were used. Each variety used received

90 lbs/acre of nitrogen topdressing.

Classification

The four soft wheat varieties tested were Augusta,
Frankenmuth and Tecumseh, all white wheats, and Hillsdale,
a red wheat. The yield (bu/acre) for each variety is

provided in the Appendix.

Composition
Wheats were milled at the USDA Soft Wheat Quality
Laboratory (Wooster, OH) on a Miag Multomat mill. Extraction

rates are given in Table 1. Additional milling, composition

50

51

Table 1. Extraction rates of flour samples1

 

 

Variety Break Flour (%) Straight Grade (%)
Augusta 36.4 72.7
Hillsdale 32.3 72.5
Frankenmuth 35.1 72.8
Tecumseh 32.2 75.5

1Soft Wheat Quality Laboratory, Wooster, OH.

and baking data are provided in the Appendix.
Flour Fractionation

The overall fractionation scheme is illustrated in
Figure 1. Gluten was first separated from the flour, and

subsequently fractionated by pH.

Gluten Washing

 

Gluten was separated from the starch-water solubles
(starch + w.s.) by hand-washing using a slight modification
of the method of Dill and Alsberg (1924). Approximately
50 g batches of flour were thoroughly mixed with 30 ml
aliquots of 0.1% sodium phosphate buffer (pH 6.0) to form
dough balls. The dough balls were flattened, covered with
additional buffer, and allowed to stand 1 hr. Flour being

separated was at room temperature. The buffer was prepared

52

 

Parent
Flour

 

 

 

' Gluten Hashing

 

 

 

l 1
Crude Starch
Gluten + U.S.

 

 

 

 

 

 

J Fractionation by pH

 

 

 

I , I l
4.7 5.6 5-8/ 5.1
Insal. Insol. 5-' ‘ $01..
_ Insol. .

 

 

Figure 1. Overall fractionation scheme for parent soft
wheat flours.

53

fresh every 2-3 days, and stored at room temperature.
Hand-washing was done under a continuous stream of buffer
(ca. 70 ml/min) until the wash water squeezed from the gluten
appeared clear. Between 8-10 min. of washing time accom-
plished this. The starch-water solubles material was passed
through a U.S. Standard Sieve No. 80 (W.S. Tyler Co., Mentor,
OH) having 177 micron openings (80 mesh), in order to remove
particles of gluten. The gluten sediment remaining on the
screen was combined, after rinsing with buffer, with the
gluten ball obtained. Gluten was allowed to relax overnight
under refrigeration, was then frozen and freeze-dried. The
starch-water solubles material was frozen in thin layers in
aluminum foil pans and also freeze-dried. A Stokes Model
2003F2 freeze dryer (F.J. Stokes Co., Philadelphia, PA) was
used for all freeze-drying. Only slight heating was used

in order to prevent heat damage. All freeze-dried starch-
water solubles material and gluten were stored at -10°C.

Approximately 5100 g of each flour were separated.

Grinding of Fractions

Starch + water-solubles material and gluten were ground
in a Udy Cyclone Sample Mill Model 3010-030 (Udy Co., Fort
Collins, CO) equipped with a 40-mesh screen (470-micron
openings). The mill was carefully cleaned between sample

grindings by forcing air through the screen, blades and air

filter.

54

Fractionation of Gluten byng
Glutens were fractionated using a slight modification
of the method of Shogren et a1. (1969). A flow diagram
(Figure 2) shows the fractionation process. Ground gluten
was divided into 5 batches for fractionation. Between
95-135 9 (depending on flour type) was wetted with distilled
water and scissored into 2856 m1 of 0.005 N lactic acid
placed on a magnetic stirrer. Stirring was continued at a
moderately fast speed for 5 hr after all the gluten had been
added. The solubilized gluten was then stored under
refrigeration overnight and fractionated over a 2—day period.
The solubilized gluten was adjusted to pH 4.7 with 0.1 N
Na2C03 and then centrifuged for 20 min at 1,000 x g. The
supernatant, pH 4.7-soluble material, was decanted and
adjusted to pH 5.6 with 0.1 N Na2C03 and centrifuged for
20 min at 1,000 x g. The precipitate from this, and each
subsequent centrifugation, was resuspended in 0.005 N lactic
acid, and then neutralized to pH 6.1 with 0.1 N Na2C03. The
pH 5.6-soluble supernatant was adjusted to pH 5.8 with
0.1 N NaZCO3, and then centrifuged for 20 min at 1,000 x g.
The 5.8-soluble supernatant was adjusted to pH 6.1 with
0.1 N Na2C03, but not centrifuged, since preliminary studies
produced insignificant amounts of pH 6.1-insoluble material.
All centrifugation was done in an IEC B-20A refrigerated
centrifuge (Damon/IEC Division;Needham Hts., MA) having a

6x250 ml capacity. The rpm setting was calculated to

55

 

Freeze-dried
Crude Gluten

l

Solubilized

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Gluten
(3) I.4.7
1
pH 4.7- pH 4.?-
Insoluble Soluble
® I.s.s
l
H 5.6— pH 5.6-
Insoluble 7 Soluble
G) I.“
7 ' l
Insoluble Soluble
® I06.1

 

 

 

pH 6.1-
I pl.SolubleIC)

 

H 60‘-
Insoluble

 

 

(3 = NEUTRALIZED AND FREEZE-DRIED

E, = ADJUSTED TO CORRESPONDING pH
AND CENTRIFUGED

C) = FREEZE-DRIED

Figure 2. Scheme for fractionation of gluten by pH,
following solubilization in 0.005 N lactic acid.

56

deliver a force of 1,000 x g to the center of the centrifuge
bottle. Refrigeration was set at 0°C.

All pH adjustments were made with a Fischer Accumet
Model 810 pH meter (Fischer Scientific Co., Pittsburgh, PA),
equipped with a universal glass electrode, a calomel
reference electrode and an automatic temperature compensation
probe. A two-point standardization was made daily with
pH 7.0 and pH 4.0 standard buffer solutions. Solutions and
suspensions being adjusted were stirred constantly with a
magnetic stirrer.

Neutralized, precipitated fractions were subsequently
frozen in thin layers and freeze-dried. Weights of unground
fractions were taken in order to calculate recoveries."
Percentage of each fraction recovered was calculated as

follows:

% gluten fraction =

Weight of individual gluten fraction x 100
Sum of weights offall gluten fractions

These values were corrected to a dry-weight basis following
moisture determinations. Gluten fractions were ground in
the Udy Cyclone Sample Mill as previously described.
Observations regarding appearance of fractions prior to and

after freeze-drying were also noted.

57

Protein Content

Protein contents of fractions and whole flours were
determined in duplicate using a slight variation of AACC
Method 46-13 (1983), a standard micro-Kjeldahl procedure.
Sample size varied with sample type. A 50-mg sample size
was used for whole flours and starch-water solubles frac-
tions. For whole gluten and all gluten subfractions, a
ZO-mg sample size was used, due to their high protein
contents. Approximately 50 ml of distillate was collected
in 10 m1 of boric acid. Methyl red-bromcresol green was
used as an indicator in the sample titrations. Percentage

nitrogen was calculated as follows:
% N =

(ml HCl - ml blank) x normality x equiv. wt. N
x 100
sample wt. (mg)

Percentage nitrogen was then multiplied by a 5.7 conversion
factor to give total protein. This factor was used for all
flour fraction calculations. Protein contents were converted

to a dry-weight basis.
Moisture Content

Moisture contents of flours and flour fractions were
determined in duplicate using a modification of AACC Method
44-40 (1983). Sample size was determined by sample type,

58

since some fractions were limited in quantity. One-g samples
of whole flours, starch-water solubles fractions, pH 4.7-
insoluble and pH 6.1-soluble gluten fractions were used.

For whole gluten fractions, 0.5-9 samples were used; only
0.2-g of the pH 5.6-insoluble and pH 5.8/6.1-insoluble

gluten fractions were available. Samples were dried under

a partial vacuum (ca. 25 mm Hg) between 95 and 100°C for

6 hrs., cooled in a desiccator, and then re-weighed. Per-

centage moisture was calculated as follows:
% Moisture =

Wet sample wt. - Dry sample wt. 100
_ Wet sample wt. x .

Flour Reconstitutions

According to the method of Shogren et al. (1969), gluten
fractions were reconstituted singly with the starch-water ~
solubles fraction, and additionally flours were reconsti-
tuted having all fractions in their original proportions.
All flours were reconstituted to their original protein
contents. No interchanges between fractions of varietal

flours were made.

Calculations

 

The following equations, used to calculate reconstitution
of flours, were developed by the author. Percentage of

starch-water solubles and percentage of gluten were

59

back-calculated from their protein contents and that of the
parent flour as follows:

1) a (x + y) = bx + cy

where a - percentage protein in flour

b

percentage protein in gluten

percentage protein in starch + water-
solubles

C

x = amount of gluten
y = amount of starch + water-solubles
x+y = amount of flour

2) % gluten = _x_

x+y . 100

3) % starch + water-solubles = _1_.. 100
x+y
A flour was reconstituted from whole crude gluten and starch +
water-solubles using these proportions.
Amount of protein (9) supplied by each gluten fraction
was calculated on a moisture-free basis as follows:

4) amt. (g) protein in fraction =

 

Amt. (g) fraction x Amt. ( ,grotein

100 g crude gluten l g raction
Recovery of gluten protein after fractionation was calculated
as:

5) % Recovery =

Sum ofgprotein from fractions(g) x 100
Amt. (g) protein per 100 g crude gluten

60

Thus, loss of protein, or error from gluten fractiona-
tion can be expressed as:

6) % loss of protein = 100 - % Recovery

The total amount of gluten required for reconstituting
the a11-fractions-in-their-original proportions flours
was increased by the percent loss of protein for three of
the four flours. Augusta, Frankenmuth, and Tecumseh flours
were, thus adjusted 4.99, 4.38, and 5.61%, respectively.
For Hillsdale, an adjustment of 3.76% was necessary to obtain
the correct flour protein content, rather than the 3.66%
calculated protein loss. Calculations for the amount of each

fraction required were made as follows:

7) Amt. (g) of fraction =

Amt. (g) gluten fraction

100 g crude gluten x total amt. of gluten

required

The single gluten fraction flours were calculated
algebraically using Eq. 1. Thus, the amount of gluten
added to flours varied with fraction type, but protein
contents were fixed. Since all calculations were made on
a moisture-free basis, amounts of fractions to be weighed
were converted back to an "as-is" basis. A 20% random
sampling of the reconstituted flours (made following dry
blending and humidification) was analyzed for Kjeldahl
nitrogen as in the previously described method. The actual

protein contents, plus the corresponding calculated protein

61

contents and error values are reported in the Appendix.
Additional calculations were made in order to determine
the percentage of total gluten protein contributed by each
gluten fraction, and the percentage of total flour protein
contributed by each flour fraction. Percentage of gluten

protein supplied by each fraction was calculated as follows:

8) Percentage of gluten protein =

Amt. (g) protein/100 g crude gluten (eq. 4) x 100
Total amt. (g) protein per 100 g crude gluten

Percentage of total flour protein supplied by each flour

fraction was calculated as:

9a) Amt.(g) protein supplied by each gluten fraction

per 100 g flour =

T3 gluten ggluten fract. -x g protein
0 g flour 9 crude gluten 1 g gluten fract.

b) Amt. (g) protein supplied by starch + water-solubles=

 

Amt. (g) starch + w.s. x Amt. (g)protein
00 g flour 1 g starch + w.s.

c) Percentage of total flour protein supplied by each
fraction =

g protein supplied by flour fraction

9 protein supplied by all fractions x ‘00

Dry Blending
Appropriate fractions were dry blended by first mixing

thoroughly by hand until the material appeared homogeneous.

62

The mixture was then stirred in an electric blender for 6
min at low speed. The material was scraped from the sides
of the container, and again mixed briefly by hand. Finally,
the material was mixed on the high speed setting of the

electric blender for l min.

Humidification of Flours

Moistures of dry blended flours were adjusted into the
range for normal flours in a large fermentation cabinet
(National Manufacturing, Lincoln, NE). Temperature was
maintained at 85°F; a humidity setting of 80 was used.
Flour samples were spread evenly in foil pans and stirred
every hr. to expose bottom layers of flour to moist air.
Flours were left ~4.5 hrs. Moistures were determined in
duplicate on humidified flours using the previously described
method. All flours were brought to between 10.1 - 12.8%
moisture. Final flour moistures are provided in the
Appendix. Humidified flours were stored in glass jars
with a layer of parafilm inside and outside the lid to

prevent moisture loss.

Final Sample Materials

The final sample materials used in the baking test for
pastry consisted of the parent (original) flour plus six
reconstituted flours for each varietal flour. The six
reconstituted flours included: whole crude gluten, all

fractions reconstituted-in-their-original proportions (A.F.R.),

63

pH 4.7-insoluble, pH 5.6-insoluble, pH 5.8/6.1-insoluble

and pH 6.1 soluble. The names given to these flours refer
to the type of gluten fraction used in their reconstitution;
all reconstituted flours contained the starch + water-
solubles fraction. These six, plus the parent flours,

are referred to, henceforth, as reconstitution types.
Baking Test for Pastry

Experimental Design

Test bakes for pastry were completely randomized.
Samples were assigned random numbers from a table of ten
thousand random digits. Mixing and baking orders were the

same. Each flour sample type was baked in triplicate.

Ingredients
A commercial shortening - Hyscor all purpose vegetable

shortening (P.V.O. Foods, Inc., St. Louis, MO) containing
fully refined and partially hydrOgenated soybean and
cottonseed oils - was used. The shortening contained no
emulsifiers. A stock 6.98% salt solution was prepared to
deliver the correct amount of water and salt. All ingredi-
ents were weighed before beginning the experiment.
Humidified flours were weighed into plastic bags; these
were then double-bagged to prevent moisture loss. The salt
solution was agitated prior to the weighing of each aliquot

into culture tubes. The tubes were tightly capped. A11

64

ingredients were stored in a refrigerator (3-4OC).

Formula

A lean, low-fat formula was used to place maximum stress
on the flour. The amount of flour used was based on the
amount of reconstituted flour available. Actual amounts
used for each flour type are given in the Appendix. Formula

percentages of each ingredient are given in Table 2.

Table 2. Pie dough formulation

 

Ingredient Formula (%)I
Flour ' 100
Shortening 41
Salt solution (25.8)
Water 24
Salt 1.8

 

1Based on flour weight.

MixingProcedure

A slight modification of the method of Miller and
Trimbo (1970) was used. Chilled shortening (8-12°C) was
added in small pieces to chilled flour and blended in a
Kitchen Aid Model K5-A mixer (Hobart Mfg. Co., Troy, OH),
equipped with a flat beater attachment, for 1 min at speed 6

(ca. 200 rpm). The sides of the bowl were scraped, then

65

the salt solution (5-12°C) was added. Mixing was continued
for l min. at speed 6 (ca. 200 rpm). Doughs were placed

in plastic zip-lock bags and refrigerated. Ten to eleven
samples were mixed on one day, and then rolled and baked the
following day. The resting period for the doughs was
21.5-24.5 hrs. (time elapsed between end of mixing and end

of rolling).

Baking Procedure

Doughs were removed from the refrigerator for 13-15 min.
prior to rolling, to soften dough slightly and facilitate
handling. Dough temperatures averaged 12.5°C during
rolling. Doughs were flattened slightly and placed between
two sheets of parchment paper and rblled with a wooden
rolling pin on a wood board. One eighth-inch rolling
guides were used. Doughs were cut into square wafers (ca.
5 cm x 5 cm). Using a specially designed tool, each wafer
was pricked with 9 equally-spaced holes. Wafers were baked
on stainless steel cookie sheets (1/8-inch thick) in a
4-tray rotary oven (Rotary Hearth Test Baking Ovens,
National Manufacturing Co., Lincoln, NE) at 450°F (12°F) for
13 min. After removal from oven, cookie sheets were placed

on wire cooling racks.

Physical Testing Procedures

 

Crust Shrinkage. The areas of 4 wafers were measured

before and after baking for each sample (except 20-g test

66

bakes, where only 2 wafers were available). Crust shrinkage
was calculated as:
% shrinkage =

Area before baking - Area after baking x 100
Area before baking

Flakiness. The height of a stack of 4 wafers was used

 

as an index of flakiness. For 20-g test bakes, the values
obtained from the height of 2 wafers were doubled, such that
comparison could be made with other samples.

Surface Blistering. Observations of surface blistering,
as a measure of gluten strength, were made subjectively. A
scale of 1.0 - 5.0 in increments of 0.5 was used. A
description of this scale is shown in Figure 3.

BreakingStrengtn. Breaking strength was measured
using an FTC-Kramer Texture-Test system (Model T-2100-C)
equipped with a Model FTA-lOO force transducer and a Model
CA-l single-blade shear cell (Food Technology Corp.,
Rockville, MD). Blade thickness was about l/B-inch. Prior
to shearing, wafers were measured for width and thickness
of area to be sheared. Samples were tested between 55-70
min. after removal from the oven. Four wafers were broken
for each test (except 20 9 test bakes, where only one wafer
was available). Following each test, debris was removed
from the blade and base sample holder with a small brush.

Breaking strength was calculated as follows:

67

Figure 3. Scores used for evaluating surface blistering.
1.0 = Very slight; 3.0 = moderate; 5.0 = Very
high.

68

 

 

....

 

' =04. mud-a. ....

 

69

‘95 force = Transducer x Range x Reading

cm2 broken cm‘ broken x 100

Surface browning. Differences in browning reaction
were measured using a Hunterlab Model 025-2 Color Difference
Meter (Hunter Associates Laboratory, Inc., Reston, VA). The
"L", "a“, and "b" values obtained represent reflectance
ranges from black to white (0 to 100, L value), green to
red (-a to +a), and blue to yellow (-b to +b). The instru-
ment was standardized with a yellow tile (Standard No.
C2-15327) with assigned values of L = 78.5, a = -3.2, and
b = +23.4. 1Enough sample was placed in the glass holder to
cover the aperture of the unit. Three readings were taken
for each determination by rotating the glass container

one-third.
Statistical Analyses of the Data

Using Mstat (Michigan State University, 1982), a two-
factor factorial analysis of variance was performed to
determine if any significant differences existed in the
main effects of flour variety, and type of reconstituted
flour, for the mean values of flakiness, crust shrinkage,
surface blistering, breaking strength and surface browning
("L", "a" and "b"). Values for both crust shrinkage and
redness ("a") were coded +5.0 in order to eliminate negative
values during analysis of variance. Reported means are

decoded. Significant interactions between main effects for

70

these dependent variables were also determined. When
significant differences were found among flour variety
means, or means for type of reconstituted flour, the Duncan‘s
multiple range test of the ranking subprogram of Mstat was
used to compare and rank them. When a significant inter-
action between main effects was found, a least significant
difference (LSD) value was determined, also using Mstat.
Correlations among individual dependent variables,
between the dependent variables and flour protein content,
and between dependent variables and the percentage of each

gluten fraction obtained were also determined with Mstat.

RESULTS AND DISCUSSION

Flour Composition

The moisture and protein contents of the parent flours
are shown in Table 3. Moisture contents of the parent
flours varied by less than 0.5% (with a relative difference
of 4.00%). Protein contents ranged from 8.01 to 10.83%.

The normal ranges of protein and moisture contents
for pastry flours is 8.0 - 8.5%, and 13.0 - 13.5%, respec-
tively (Preonas et al.,l967; Pyler, 1973). Matz recom-
mended a lower range for protein contents of 7.0 - 8.5%.

An extended range of 8.0 - 9.8% protein and 12.0 - 14.0%
moisture.was stated by Tsourides (1968)as being ideal for

pie baking.
Flour Fractionations

Gluten Washing

The calculated percentages of crude gluten and starch +
water-solubles obtained by gluten washing, and their
respective protein contents are given in Table 4.
Calculated gluten percentages ranged from 12.30 to 15.48;
since these values are higher than their corresponding flour

protein contents, incomplete starch removal is indicated.

71

72

 

 

 

 

 

 

Table 3. Moisture and protein contents of parent soft
wheat varietal flours.
Parent flour Moisture1 Protein1
% (%, dry basis)
Augusta 11.09 8.01
Hillsdale 10.79 8.08
Frankenmuth 10.91 9.01
Tecumseh 11.24 10.83
1n = 2
Table 4. Percentages by weight and protein content of crude
gluten and starch + water- solubles obtained by
gluten washing 50ft wheat flours.
Fraction Weight (%)1 Protein Content (%)2
Varietal .
flour Crude Starch + Crude Starch +
gluten water- gluten water-
solubles solubles
Augusta 12.30 87.70 55.56 1.33
Hillsdale 12.50 87.50 56.14 1.21
Frankenmuth 13.45 86.55 59.02 1.24
Tecumseh 15.48 84.52 60.97 1.65

 

1Back-calculated using Eq.

2 _

n - 2; expressed on a dry basis.

1; expressed on a dry basis.

73

Dill and Alsberg (1924) reported percentage values of
8.52 and 8.80 for a soft white winter flour; values for soft
red winter flours ranged from 8.96 to 11.12%. Higher values
were reported for hard wheat flours. Fisher and Halton
(1936) recovered 6.85, 12.36, and 12.29% dry gluten for
respective weak, medium and strong flours. A yield of 21.5%
gluten (14% moisture basis, m.b.) was recovered by Walden
and McConnell (1955) from a hard red spring flour. Sollars
(1956) obtained yields of 12.6, 9.9, and 8.6% (14% m.b.)
from respective hand-kneaded, mechanically-kneaded and acetic
acid-extracted doughs. An extremely wide range of 9.0-27.2%
dry gluten was obtained by Greenaway and Watson (1975) for
hard red spring, hard-red winter, and white wheats; with
their automatic method, a range of 7.1 to 16.6% dry gluten
was obtained for the same flours.

The protein contents of whole crude glutens ranged from
55.56 to 60.97%. Similarly, the lower protein contents of
these glutens, as compared with those commercially obtained,
and those obtained experimentally by other researchers,
confirm the incomplete removal of starch. Protein contents
of commercial samples of vital gluten have been reported as
76.3 and 77.8% by Kissell and Yamazaki (1975). Gluten
protein contents of 76.0 and 77.7% were reported by Dill and
Alsberg (1924) for a soft red winter flour; glutens from the
soft white winter flours had protein contents ranging from

74.4 to 78.5%. The weak, medium and strong flours of Fisher

74

and Halton (1936) had respective gluten protein contents of
83.5, 86.6 and 84.6%. A gluten protein content of 59.8%
(14% m.b.) was reported for the hard red spring wheat of
Walden and McConnell (1955). The hand-kneaded, mechanically-
kneaded, and acetic acid-extracted glutens of Sollars-(1956)
had respective protein contents of 40.4, 64.3 and 66.4%.
Thus, the values of Table 4 are comparable to those reported
in the fractionation-reconstitution studies of Walden and
McConnell (1955) and Sollars (1956). Values of 80.0, 82.0
and 83.0 were obtained for white, hard red winter and hard
red spring flour glutens, respectively, by Greenaway and
Watson (1975).

As the protein contents of the parent flours increased,
the protein contents of the crude glutens obtained also
-increased (Table 4). Protein contents of the starch +
water-solubles fraction ranged from 1.21 to 1.65%, and

thus, varied little.

Fractionation by pH (Isoelectric Precipitation)

The gluten fractions, obtained by solubilizing gluten
in dilute lactic acid and adjusting to various pH levels,
differed in their recoveries and protein contents.
Recoveries and protein contents also differed among the
varietal flours. In preliminary studies with both bread
and cake flours, insignificant amounts of the pH 6.1-insolu-

ble gluten fraction of Shogren et a1. (1969) were recovered.

75

Thus, the pH 5.8-soluble material was not centrifuged
following adjustment to pH 6.1. No pH 6.1-insoluble
material precipitated from Augusta gluten. Small amounts
of pH 6.1-insoluble gluten settled without centrifugation
from Hillsdale and Frankenmuth suspensions. Tecumseh was,
however, particularly aberrant. Large amounts of pH 6.1-
insoluble material settled.

As compared with the other varieties, Tecumseh has a
complex parentage, very similar to that of Arthur soft red
winter wheat. One of the crosses for Tecumseh consisted of
Purkof, a semihard red winter wheat (Everson et al., 1974).
Since the hard winter wheats used by Shogren et a1. (1969)
similarly contained appreciable amounts of pH 6.1-insoluble
material, possibly the inclusion of a semihard variety in
the pedigree of Tecumseh influences the type of protein, as
characterized by isoelectric precipitation.

The pH 6.1-insoluble material, obtained without centri-
fugation, was combined with the pH 5.8-insoluble gluten
from the corresponding flour. Thus, this fraction is
referred to as pH 5.8/6.1-insoluble gluten. Only Augusta
is primarily pH 5.8-insoluble material.

Percentage Recoveries of Gluten Fractions. The relative
amount of each gluten fraction obtained is shown in Table 5,
and in the form of pie graph in Figure 4. The relative
amounts of each fraction obtained varied greatly with

parent varietal flour. Augusts had a much higher percentage

76

Table 5. Percentage by weight of each gluten fraction
recovered by precipitating at various pH levels.

 

Fraction Weight (%)1’2

 

Gluten fraction
Augusta Hillsdale Frank. Tecumseh,

*1;

pH 4.7-insoluble 60.99 38.85 45.18 48.13
pH 5.6-insoluble 2.27 5.90 3.73 2.10
pH 5.8/6.1-insoluble 6.10 16.66 14.45 14.25
pH 6.1-soluble 30.68 38.59 36.65 35.52

 

1Expressed on a dry basis.

2Pooled from 5 batches of gluten fractions.

of pH 4.7-insoluble material (60.99%) and a far lower
percentage of the pH 5.8/6.1-insoluble material (6.10%); as
was previously noted, no pH 6.1-insoluble material was
present in this varietal-flour. Although Hillsdale had a
protein content similar to AuguSta, its fractionation
pattern resembled that of the higher protein flours. As
protein content increased from that of Hillsdale to Tecumseh,
the percentage of pH 4.7-insoluble material obtained
increased from 38.85 to 48.13%. The percentages of other
fractions decreased as flour protein content increased; the
pH 5.6-insoluble material decreased by more than half, from

5.90 to 2.10%.

77

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.e weaned
Lap. NV ..0nea a. me Ann. epv Ana. mv ..enea 8. me. fine. epv
.Fomea F.e\m.m .Penea F.e\m.m
Aum.mev
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Aam.mmv Aao.emv
Aup.mev .Pom P.e .Pom P.e
.FOnea A.e
IumZDUuh Ikazzwxz<mu
Aam.mv Aae.epv Aum.~v
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78

Protein Content. The protein contents of the various
fractions are shown in Table 6, and in the form of a bar
graph in Figure 5 (the starch + water-solubles fraction is
also shown). As the pH of the gluten fraction increased,
protein content similarly increased. Protein contents
ranged among varietal flours from 21.00 to 36.39% for
pH 4.7-insoluble gluten, from 66.33 to 69.33% for pH 5.6-
insoluble gluten, from 74.82 to 78.24% for pH 5.8/6.1-
.insoluble gluten, and from 77.01 to 79.89% for the 6.1-
soluble gluten. No trend was noticed between protein content
of the parent flour, and those of the gluten fractions.

Shogren et a1. (1969) reported values of 16.3 and 25.2%
for the pH 4.7-insoluble fractions of two hard winter wheat
flours. Protein contents of 76.5 and 74.8, 78.1 and 76.7,
79.2 and 78.3, 62.1 and 61.7, were reported for the pH 5.6-
insoluble, pH 5.8-insoluble, pH 6.1-insoluble, and pH 6.1-
soluble fractions, respectively. V

Percentgge of Total Gluten Protein Supplied by Each
Gluten Fraction. The part of total gluten protein contributed
by each gluten fraction is given in Table 7, and in the form
of pie graphs in Figure 6. Gluten protein recoveries and
losses are also provided. The pH 4.7-insoluble gluten
ranged from 14.5 to 39.9% among the varieties; ranges were
from 2.4 to 7.0%, 8.3 to 22.2%, and 44.0 to 52.9% for the
pH 5.6-insoluble, pH 5.8/6.1-insoluble and pH 6.1-soluble

glutens, respectively. The data for percentage of gluten

79

Table 6. Protein contents of gluten fractions obtained
from varietal flours by precipitating at various
pH levels.1

 

Protein Content (%)2
Gluten fraction

 

 

Augusta Hillsdale Frank. Tecumseh
pH 4.7-insoluble 36.39 21.00 31.07 34.43
pH 5.6-insoluble 66.96 66.34 68.42 69.33
pH 5.8/6.1-insoluble 75.97 74.82 76.75 78.24
pH 6.1-soluble _ 79.74 77.01 78.48 79.89

 

1n=2.

2Nx5.7; expressed on a dry basis.

Table 7. Percentage of total gluten protein contributed by
each gluten fraction, obtained by precipitating
at various pH levels.1 ' ‘

 

Percentage of Total Gluten Protein (%)2
Gluten fraction

 

 

Augusta Hillsdale Frank. Tecumseh
pH 4.7-insoluble 39.9 14.5 23.8 27.2
pH 5.6-insoluble 2.7 7.0 4.3 2.4
pH 5.8/6.1-insoluble 8.3 22.2 18.8 18.3
pH 6.1-soluble 44.0 52.9 48.7 46.5
Total recovery 94.9 96.6 95.6 94.4
Gluten protein loss 5.1 3.4 4.4 5.6

 

1Expressed on a dry basis.

2Calculated using Eq. 8.

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Protein contents of flour fractions obtained b
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I = insoluble, S = soluble, Sr+ us a starch + water-,§1ub195f°c‘p‘t“‘°"

by pH.

Figure 5.

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82

contributed by each fraction mirrored the pattern of the
percentage by weight of fraction data; thus, Augusta was
again the aberrant flour. Gluten protein contributed by pH
4.7-insoluble gluten again increased with flour protein
content among the Hillsdale, Frankenmuth and Tecumseh
varietal flours. Again, the gluten protein contributed by
the other fractions decreased as protein content of these
flours increased. Recoveries of gluten protein ranged from
94.4 to 96.6%, and, therefore, percent gluten protein losses
ranged from 3.4 to 5.6%. Percentage gluten protein losses
increased as flour protein content increased for Hillsdale,
Frankenmuth and Tecumseh. Augusta was again the exception.
Percentaggof Total Flour Protein Supplied by Each Flour
Fraction. 'Table 8 shows the percentage of total flour
protein contributed by each flour fraction. Figure 7
illustrates this in the form of pie graphs. Among the
varieties, the pH 4.7-insoluble gluten ranged from 13.0 to
35.6%, whereas ranges of 2.2 to 6.2%, 7.4 to 19.9% and 39.3
to 47.4% were calculated for the pH 5.6-insoluble, pH 5.8/6.1-
insoluble and pH 6.1-soluble glutens, respectively. The
starch + water-solubles fraction ranged from 12.4 to 15.3%
of the total flour protein. The relationship between parent
flour protein and that contributed by the gluten fractions
to the total flour protein is the same as mentioned in the'
above percentage of total gluten protein discussion. The

total protein contributed by the starch + water-solubles

83

Table 8. Percentage of total flour protein contributed by
each flour fraction obtained by gluten washing
and pH fractionation.

Percentage of Total Flour Protein (%)2

 

Flour fraction
Augusta Hillsdale Frank. Tecumseh

A

pH 4.7-insoluble 35.6 13.0 21.8 24.9
gluten

pH 5.6-insoluble 2.4 6.2 4.0 2.2
gluten

pH 5.8/6.1-insolub1e 7.4 19.9 17.2 16.7
gluten

pH 6.1-soluble 39.3 47.4 44.7 42.6
gluten

Starch + water- 15.3 13.5 12.4 13.6
solubles

Flour protein 95.7 97.0 96.2 95.1
recovery

L

1Expressed on a dry basis.

ZCalculated using Eq. 9 (values corrected for flour protein

losses).

84

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85

increased with increasing flour protein among the Hillsdale,
Frankenmuth and Tecumseh varieties. Augusta was anomalous
once more.

The percentage of total flour protein data of two hard
winter wheats reported by Shogren et a1. (1969) differed
greatly from the data shown in Table 8. After correcting
for flour protein losses for comparison purposes, the values
obtained by these workers were 8.5 and 4.8, 20.7 and 19.9,
23.0 and 22.1, 24.5 and 27.9, 8.4 and 11.1, 14.8 and 14.2
for the pH 4.7-insoluble, pH 5.6-insoluble, pH 5.8-insoluble,
pH 6.1-insoluble, pH 6.1-soluble and starch + water-solubles
fractions, respectively. Thus, the pH 5.8-insoluble and
pH 6.1-insoluble fractions combined accounted for-47.5 and
50.0% of the total flour protein of these two hard wheat
flours. As compared with the data for soft wheat flours in
Table 8, significantly less flour protein was contributed by
the pH 4.7-insoluble fraction, whereas significantly more
flour protein was contributed by the pH 5.6-insoluble
fraction of the hard wheat flours. The greatest differences
between flour protein distribution patterns of the soft wheat
flours (Table 8) and the hard winter wheat flours of Shogren
et a1. (1969) were in the combined values of the pH 5.8-
insoluble and pH 6.1-insoluble fractions (~2.5 times higher
in the hard wheat flours) and in pH 6.1-soluble fraction

(~4.0 times higher in the soft wheat flours).

86

Flour Protein Recoveries. Flour protein recoveries
ranged from 95.1 to 97.0% (Table 8). Shogren et a1. (1969)
recovered 97.4 and 100.3% of the flour protein. Recoveries
of 94.0, 94.8, and 88.1% flour protein were attained in the
respective hand-kneaded, mechanically-kneaded and acetic
acid-extracted flour separations of Sollars (1956). Sollars
and Rubenthaler (1975) achieved a 99% recovery of flour
protein. 1

Observations on theAppearance of Gluten Fractions. The
characteristic appearance of gluten fractions following
precipitation was in agreement with observations of Shogren
et a1. (1969). The pH 4.7-insoluble material contained
noticeable starch and bran particles not removed during
gluten washing, and lacked any cohesiveness or elasticity.
When neutralized to pH 6.1, the material became compact
clots. The pH 5.6-insoluble material was a slightly sticky,
tough and elastic precipitate. 'There was no evidence of bran
particles, but some starch appeared with this fraction. It
became a compact, feathery precipitate upon neutralization
to pH 6.1. Both the pH 5.8-insoluble and pH 6.1-insoluble
materials were very sticky and extremely extensible before
and after neutralization to pH 6.1. The pH 6.1-soluble
material, which was in solution following fractionation, was
extremely sticky and gum-like when partially freeze-dried.
Thin strands could be formed due to its extremely extensible

character. Following freeze-drying, the pH 5.6-insoluble

B7

material had a greasy feel, indicating that more flour lipid
may have been partioned with this fraction. Glutenin was
described by Dimler (1963) as being tough, elastic, and
rubbery, with resistance to stretching, whereas gliadin has

a sirupy extensible nature, with the ability to flow. Thus,
the pH 5.6-insoluble fraction had characteristics similar to
those of glutenin, in contrast with the pH 5.8/6.1-insolubles
fraction and the pH 6.1-soluble fraction, which both
resembled gliadin in character.

The gluten fraCtions separated from hard wheat flours by
Shogren et a1. (1969) were characterized by starch-gel
electrophoresis. The electrophoretic patterns obtained by
these workers are consistent with the viscoelastic properties
of the fractions obtained in this study. The pattern for the
pH 4.7-insoluble gluten protein contained significant amounts
of protein too large to enter the gel (glutenins), whereas
only trace amounts of the gliadins were present. In
contrast, the pH 6.1-soluble gluten proteins contained a
high gliadin concentration, but only traces of glutenin.
Thus, these workers asserted that gliadins increased, and
glutenins decreased as the pH of each gluten fraction

increased.

88

Flour Reconstitutions

As stated previously, final flour protein (a 20% random
sampling) and moisture contents are provided in the
appendix. Error values ranged between 1.29 to 2.95%. The
reconstituted flour of Finney (1943) had a protein content
identical to that of the original flour. Walden and
McConnell (1955) reported an experimental protein value of
14.5% as compared with the 14.9% calculated protein value
(ca. 2.68% error). The reconstituted flours of Sollars
(1958a) contained 6.39 and 6.09% protein as compared with the
respective 6.04 and 6.21% protein values of the original
flours; thus, error values would be 5.79 and 1.93%, respec-

tively.
BakingyTest for Pastry

Results for each dependent variable will first be

discussed separately. Analyses of variance tables for each

of these dependent variables are provided in the appendix.
Correlations among dependent variables, between the dependent
variables and flour protein content, and between the dependent
variables and percentage of gluten fraction present, will
follow. Lastly, the effect of fractionation/reconstitution
procedures on pastry textural characteristics, and implica-

tions of the data, will be discussed.

89

Flakiness

 

Significant differences in the flakiness of pastry wafers
were found among varietal flours and reconstitution types at
a= 0.01. Interaction between the main effects was signifi-
cant at a=0.0S.

Table 9 shows the means for flakiness of pastry wafers
baked from the varietal parent and reconstituted flours
(interaction). These results are depicted as bar graphs in
Figure 8. Pastry wafers from Tecumseh.parent flour were
significantly more flaky than all other types, except those
baked from Tecumseh pH 6.1-soluble reconstituted (reconst.)
flour. Conversely, the pastry wafers baked from pH 5.6-
insoluble reconst. flour were significantly less flaky than
all other types.

Means ranged from 2.0 to 3.4 cm. Ostrander et a1. (1971)
also used height of a stack of 4 wafers as an index to
flakiness. They reported a range of values from 1.89 to
2.31 cm for a soft wheat all-purpose flour baked with, and
without, elaidinized lipid. These workers rolled their doughs
to a 3.4 mm thickness as compared with a 3.2 mm (l/8-inch)
thickness used by the author.

Flakiness means for each reconstitution type are provided
in Table 10; they are shown as a bar graph in Figure 9.
Pastry wafers from the parent flours were significantly more
flaky than all others, except those from pH 6.1-soluble

reconst. flours. Wafers baked from the pH 5.6-insoluble

90

Table 9. Flakiness of pastry wafers baked from varietal
parent and reconstituted flours

 

Height of a stack of 4 wafers (cm)
Reconstitution

 

type
Augusta Hillsdale Frank. Tecumseh

 

Parent Flour 2.7 2.9 2.9 3.4
Whole crude gluten 2.5 2.6 2.4 2.6
A.F.R.2 2.6 2.6 2.8 3.0
pH 4.7-insoluble 2.3 2.3 2.3 2.4
pH 5.6-insoluble 2.2 2.3 2.2 2.0
pH 5.8/6.1-insoluble 2.8 2.7 2.5 2.9
pH 6.1-soluble 2.7 2.6 2.9 3.2

 

1n=3, standard error=0.ll. LSD=0.32 at a=0.05.

2All fractions reconstituted in original proportions.

91

  

 

  

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94

reconst. flours were significantly less flaky than all
other types, except those from pH 4.7-insoluble reconst.
flours. Among the single fraction reconst. flours, flaki-
ness increased with pH, with the exception of the pH 4.7-
insoluble reconst. type. Thus, it appears that flakiness
of pastry increases with a probable increased gliadin-to-
glutenin ratio.

Lowe (l943) stated that some gluten strength and
development allows formation of dough layers that enable
steam retention; the steam then forces the doUgh layers
apart. The greater flakiness of pastry wafers baked from
the higher pH single fraction flours suggests that they
have more gluten strength and development. This is in
agreement with Shogren et al. (l969), who observed higher
loaf volume in bread baked from the higher pH flours.

Flakiness means for varietal flours are given in Table
ll, and shown as a bar graph in Figure 9. Pastry wafers
baked from Tecumseh flours were significantly more flaky -
than those baked from the other varietal flours. No

differences were seen among the other flours.

Crust Shrinkage

Significant differences in the crust shrinkage of pastry
wafers were found among varietal flours and reconstitution
types at a=0.0l. Also significant at a=0.0l was the

interaction between main effects.

95

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96

Means for crust shrinkage of pastry wafers baked from
varietal parent and reconstituted flours (interaction) are
provided in Table l2. In Figure l0, they are presented in
the form of a bar graph. Tecumseh whole flour exhibited the
most crust shrinkage, and was significantly different from
Augusta, Hillsdale and Frankenmuth A.F.R. flours, Augusta-
whole gluten, Augusta pH 6.l-insoluble, Hillsdale pH 5.8/6.1-
insoluble, and all varietal pH 4.7-insoluble and pH 5.6-
insoluble reconst. flours.) All varietal pH 4.7-insoluble
and pH 5.6-insoluble reconst. flours yielded less shrunken
pastry than all other flours, with the exception of Augusta
A.F.R., Augusta pH 6.l—soluble and Hillsdale pH 5.8/6.l-
insoluble reconst. flours.“ Of these, Augusta pH 4.7-
insoluble pastry wafers were the least shrunken.

These crust shrinkage means ranged from 0.8 to l4.3%.
Miller and Trimbo (l970), by varying dough formulations and
treatments, observed 0-35% crust shrinkage in pastry. With
a l0.6% flour protein content and 40% vegetable shortening
(based on flour wt.) in the formula, a crust shrinkage of
8% was found by these workers. Miller and Trimbo (l970)
noted that thickening of pastry strips accompanied crust
shrinkage; this occurrence was also observed by the author.

Crust shrinkage means for each reconstitution type are
given in Table l0, and illustrated in Figure ll. Overall,
pastry wafers baked from parent flours displayed the most

crust shrinkage; they were significantly different from all

97

Table 12. Crust shrinkage of pastry wafers baked from
varietal parent and reconstituted flours.

 

Crust Shrinkage (%)

 

 

Reconstitution
Type
Augusta Hillsdale Frank. Tecumseh

Parent Flour 11.4 10.3 9.2 14.3
Whole crude gluten 7.2 9.3 11.5 12.0
A.F.R.2 3.1 7.5 8.1 9.9
pH 4.7-insoluble 0.8 3.7 3.2 1.8
pH 5.6-insoluble 4.5 3.9 2.4 1.8
pH 5.8/6.1-insolub1e 9.1 5.4 9.3 9.9
pH 6.1-soluble 4 1 10.1 12.8 10.2

 

1n=3; Standard error=1.22; LSD=4.S9 at a=0.01.

2All fractions reconstituted in original proportions.

 

98

    
  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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100

others, except those baked from whole crude gluten and pH
6.1-soluble reconst. flours. Pastry baked from pH 4.7- ‘
insoluble reconst. flours had significantly less shrinkage
than other types.

Crust shrinkage of pastry wafers progressively decreased
as the pH of the fraction decreased among the single fraction
reconst. flours. Consistent with flakiness results, this
also seems to indicate that less gluten strength or develop-
ment was present in the lower pH fractions of probable higher
glutenin content. These results suggest that a higher
gliadin ratio in flour could contribute to greater crust
shrinkage in pastry.

“Crust shrinkage means for varietal flours are shown in
Table 11. Pastry wafers baked from Augusta flours exhibited
significantly less shrinkage than Frankenmuth and Tecumseh
flours. Hillsdale flours were not significantly different

from those of the other varieties.

Surface Blistering Scores

Significant differences were found among the reconstitu-
tion types at a=0.01. No significant differences were found
among varietal flours. Interaction between main effects was
not significant.

Surface blistering score means of pastry wafers baked
from varietal parent and reconstituted flours (interaction)

are provided in Table 13, and in the form of bar graphs in

101

Table 13. Surface blistering Scores of pastry wafers baked
from varietal parent and reconstituted flours.

 

Surface Blistering Score2

Reconstitution

 

type Augusta Hillsdale Frank. Tecumseh

 

 

Parent Flour 2.0 2.7 2.0 2.0
Hhole crude gluten 2.8 3.2 2.7 2.2
A.F.R.3 4.0 4.7 4.2 4.7
pH 4.7-insoluble 1.7 2.0 2.0 2.0
pH 5.6-insoluble 2.5 2.2 2.0 1.7
pH 5.8/6.1- 4.0 2.7 2.7 3.3
insoluble

pH 6.1-soluble 4.7 4.3 4.7 4.3
1

n=3, Standard error=0.31, LSD=0.87 at a=0.05.
21=very slight, 5=very high

3All fractions reconstituted in original proportions.

102

Figure 12. The pastry wafers with the highest surface
blistering score means were those baked from Augusta and
Frankenmuth pH 6.1-soluble reconst. flours, and those baked
from Tecumseh and Hillsdale A.F.R. flours. Pastry wafers
from Tecumseh pH 5.6-insoluble and Augusta pH 4.7-insoluble
reconst. flours had the lowest surface blistering scores.
The range for means was 1.7 to 4.7.

Among the surface blistering score means for reconsti-
tution type (Table 10; Figure 13), pastry wafers from the
pH 6.1-soluble reconst. and A.F.R. flours were significantly
more blistered than all other types. Again, for the single
fraction reconst. flours, as the pH increased, the surface
blistering score similarly increased. Hith surface blister-
ing as an indicator of gluten strength, these results are
consistent with those for flakiness and Crust shrinkage.
Thus, the probable higher gliadin ratio of the higher pH
gluten fractions is once more indicated as contributing
more gluten strength.

Surface blistering score means for varietal flours are
given in Table 11 and displayed in Figure 13. Overall,
Augusta and Hillsdale had higher mean scores than Franken-

muth and Tecumseh. However, the difference is insignificant.

Breaking Strength
Significant differences in the breaking strength of

pastry wafers were observed among varietal flours and

103

 

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105

reconstitution types at a=0.01. A significant interaction
between main effects was found at a=0.05.

Means for breaking strength of pastry wafers baked from
varietal parent and reconstituted flours (interaction) are
provided in Table 14 and illustrated as bar graphs in
Figure 14. Frankenmuth pH 6.1-soluble reconst. flour yielded
pastry wafers with the highest breaking strength, signifi-
cantly higher than all varietal parent and pH 5.8/6.1-
insoluble reconst. flours, and also higher than many other
pastry types. Tecumseh parent flour, oddly, yielded pastry
' with the lowest breaking strength. Since this varietal flour
had the highest protein content, pastry baked from it would
be expected to have a higher breaking strength. Thus,
among the parent flours, the breaking strengths of pastry
wafers were not determined by floUr protein content. Of
these parent flours, Frankenmuth yielded pastry with the
highest breaking strength. Other researchers (Denton et al.,
1933; Miller and Trimbo, 1970) reported an increase in
breaking strength with increased flour protein content.

The range of means was between 1.1 to 2.9 lbs force/cm2
broken. Miller and Trimbo (1970) reported a Kramer Shear
Press value of 240 lbs force for pastry baked from a dough
containing 40% shortening (based on flour wt.) and an all-
purpose flour having a protein content of 10.6%. This shear
value seems comparatively high. A pastry containing 50%

shortening and all-purpose flour was reported by Stinson and

106

Table 14. Breaking strength of pastry wafers baked from
varietal parent and reconstituted flours.

 

 

 

Breaking S§rength
(1b force/cm broken)
Flour type
Augusta Hillsdale Frank. Tecumseh

Parent Flour 1.4 1.3 1.8 1.1
Whole crude gluten 1.4 1.6 2.3 1.8
A.F.R.2 2.2 2.7 2.0 1.9
pH 4.7-insoluble 2.4 2.6 2.3 1.5
pH 5.6-insoluble 1.3 1.8 2.2 1.4
pH 5.8/6.1- 1.6 1.5 1.9 1.7

insoluble
pH 6.1-soluble 2.8 2.3 2.9 2.3

 

1

n=3; Standard error=0.22; LSD=0.63 at 0.05.

2All fractions reconstituted in original proportions.

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108

Huck (1969) as having a shear press value of 20.7 lb/g. The
use of multiple blade test cells, and differences in the
areas of pastry samples sheared could account for the discrep-
ancy between literature values and those of the present study.
Breaking strength means for each reconstitution type are
given in Table 10 and depicted as a bar graph in Figure 15.
Pastry baked from pH 6.1-soluble reconst. flour had a
significantly higher breaking strength than the other types,
with the exception of A.F.R., and pH 4.7-insoluble reconst.
flours. Though not significantly different from the pH 5.6-
insoluble, pH 5.8/6.1-insolub1e or whole crude gluten reconst.
flours, the pastry baked from parent flours had the lowest
breaking strength of all reconstitution types. The relation—
ship between breaking strength and pH of the fraction used in
the single fraction reconst. flours was not linear as for
crust shrinkage and surface blistering scores. The flours
with extremes of pH, that is 4.7 and 6.1, yielded the toughest
pastry wafers. If the pH 4.7-insoluble reconst. flour is
excluded, breaking strength does decrease with decreasing pH.
The pH 4.7-insoluble fraction contained noticeable amounts of
bran particles and starch not removed during gluten washing,
thus more of the fraction was required in reconstituting to
the original protein content of the flour. A larger amount
of weaker gluten could possibly have contributed to greater
gluten strength or development, quantitatively. However,

flakiness, crust shrinkage, and surface blistering of pastry

109

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110

from the pH 4.7-insoluble reconst. flour indicated less
gluten strength within this fraction.

Breaking strength means for the different varietal flours
are provided in Table 11, and illustrated in Figure 15.
Pastry baked from Frankenmuth flours had a significantly
higher breaking strength than those from Augusta and Tecumseh
flours. Breaking strength means for Hillsdale flours were not
significantly different from those of the other varietal

flours.

Crust Surface Browning

As previously stated, lightness, redness and yellowness
values, obtained from a Hunter Color Difference meter, were
used to detect differences in surface browning. The values
will first be discussed separately, the interpreted as
descriptions of the browning reaction.

Lightness. Significant differences in the lightness
mean values of pastry wafers were found among the reconsti-
tution types at a=0.01. Differences among varietal flour
means were insignificant. Interaction between main effects
was significant at 9:0.01.

Table 15 gives the lightness value means of pastry wafers
baked from varietal parent and reconstituted flours; these
are also shown in Figure 16. Pastry baked from Augusta
parent flour had the lightest surface; it was significantly

lighter than all varietal pH 4.7-insoluble and pH

111

Table 15. Lightness values of pastry wafers baked from
varietal parent and reconstituted flours.

 

 

 

Lightness2
Reconstitution
type
Augusta Hillsdale Frank. Tecumseh
Parent Flour 71.7 69.2 68.7 69.3
Whole crude gluten 57.9 60.4 60.4 64.7
A.F.R.3 60.8 66.1 63.9 65.5
pH 4.7-insoluble 55.5 59.4 58.1 54.6
pH 5.6-insoluble 46.8 56.2 53.7 49.2
pH 5.8/6.1— 66.5 62.7 .60.3 65.5
insoluble

pH 6.1-soluble 69.8 61.0 65.6 65.9

 

1n=3, Standard error=1.91, LSD=7.20 at o=0.01.

2A5 determined by Hunter Color Difference ("L" value,
0 (black) to 100 (white)).

3All fractions reconstituted in original proportions.

112

 

 

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113

5.6-insoluble reconst. flours, all varietal whole crude
gluten reconst. flours (except Tecumseh), Augusta A.F.R.,
Hillsdale pH 6.1-soluble, plus Hillsdale and Frankenmuth

pH 5.8/6.1-insoluble reconst. flours. Augusta pH 5.6-
insoluble reconst. flour yielded the darkest pastry; it was
significantly darker than all others, except those baked
from Frankenmuth and Tecumseh pH 5.6-insoluble reconst.
flours. .Means ranged from 46.8 to 71.7.

Lightness mean values for reconstitution types are
provided in Table 16, and illustrated in Figure 17. Pastry
wafers baked from parent flours were significantly lighter
than those baked from all other flour types. The pH 5.6-
insoluble reconst. flours yielded the darkest pastry wafers;
they were significantly darker than those from all other
reconstitution types. With the exception of the pH 5.6-
insoluble reconst. flours, as pH decreased among the single
fraction reconst. flours, the pastry wafers yielded were
darker. Lightness value means for varietal flours are given
in Table 17 and depicted as a bar graph in Figure 17.
Pastries from Hillsdale flours were lightest, and those
from Augusta were darkest. However, the slight differences
were insignificant.

Redness. Reconstitution type means for redness were
significantly different at a=0.01. Varietal flour means were
not significantly different. A significant interaction

between main effects was found at a=0.01.

114

Table 16. Lightness, redness and yellowness value means for
reconstitution types. .

 

 

 

Reconstitution Lightness3'4 Redness!”6 Yellowness7'8
type

Parent flours 69.7a ’ -0.6d 20.2b

Hhole crude 60.8c 2.8b’c 21.5a
gluten

A.F.R.9 64.1b’c 2.4° 21.6a

pH 4.7- 56.9d 3.8b 21.0a
insoluble

pH 5.6- 51.4e 6.2a 20.9‘1b
insoluble

pH 5.8/6.1- 63.8b’c 2.1c 21.7a
insoluble

pH 6.1-soluble 65.6b 1.9c 21.7a

1

Means having the same superscript are not significantly
different at d=0.01.

2As determined by Hunter Color Difference.

3"L" values = 0 (black) to 100 (white).

4n=12; Standard error=0.95; LSD=3.60.

5"a" values; negative values indicate greenness.
6n=12; Standard error=0.30; LSD=1.15.

7"D" values.

8n=12; Standard error=0.21; LSD=0.79.

9All fractions reconstituted in original proportions.

 

 

 

 

 

 

 

 

 

 

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116

Table 17. Lightness, redness agd yellowness value means
for varietal flours. ’2

 

 

Varietal Lightness3’4 Redness?"6 Yellowness7’8
flour

Tecumseh 62.1a 2,53 21.0b,c

Frankenmuth 61.5a 2.8a 21.9a

Hillsdale 62.1a 2.3a 21.4“;b

Augusta 61.3a 3.0a 20.7c

 

1Means having the same superscript are not significantly
different at a=0.01.

2As determined by Hunter Color Difference.
3"L" values=0 (black) to 100 (white).
4n=21; Standard error=0.72; LSD=2.04.

5"a" values.

6n=21; Standard error=0.23; LSD=0.65.

7

"b" values.

8n=21; Standard error=0.l6; LSD=0.59.

117

Redness value means of pastry wafers baked from varietal
parent and reconstituted flours are shown in Table 18, and
as a bar graph in Figure 18. Augusta pH 5.6-insoluble
reconst. flour yielded pastry with the highest redness
value; pastry from this flour had a significantly redder
surface than pastry samples from all other flour types,
except Augusta pH 4.7-insoluble, Augusta whole crude gluten,
and pH 5.6-insoluble reconst. flours from the other wheat
varieties. Pastry baked from Augusta parent flour was the
least red; in fact, the negative value indicates a greenish
hue to this pastry type. Augusta parent flour pastry was
significantly less red (and more green) than pastry from
all other types, except Augusta pH 5.8-insoluble, Augusta
pH 6.1-soluble, Tecumseh whole crude gluten reconst., and
all varietal parent flours. Mean values ranged from -1.2 to
6.9 (+).

In Table 16 and Figure 19, redness value means for each
reconstitution type are shown. The pastry wafers baked
from the pH 5.6-insoluble reconst. flours had significantly
redder crust surfaces than those baked from other reconsti-
tution types. As with lightness values, when the pH 5.6-
insoluble reconst. flours were excluded, pastry wafers
were increasingly red as pH of the single fraction reconst.
flours decreased. Pastry baked from the parent flours was
significantly less red and more green than that from other

types.

118

Table 18. Redness values of pastry wafers baked from
varietal parent and reconstituted flours.

 

Redness2

Reconstitution

 

 

type
Augusta Hillsdale Frank. Tecumseh
Parent Flour -l.2 -0.7 -0.4 -0.1
Hhole Crude gluten 4.6 3.0 2.2 1.4
A.F.R.3 3.4 1.5 2.2 2.5
pH 4.7-insoluble 5.3 2.0 3.6 4.2
pH 5.6-insoluble 6.9 5.2 6.1 6.7
pH 5.8/6.1- 1.4 1.8 3.6 1.7
insoluble
pH 6.1-soluble 0.2 3.3 2.4 1.6

 

In=3, Standard error=0.61, LSD=2.29 at a=0.01.

2As determined by Hunter Color Difference ("a" values);
negative values indicate greenness.

3All fractions reconstituted in original pr0portions.

119

 

 

 

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PF=parent flour, HG=whole crude gluten, AFR=a11

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121

Varietal flour redness value means are provided in
Table 17 and depicted as a bar graph in Figure 19. Pastries
from Augusta flours were the most red; those from Hillsdale
were the least red. These differences were insignificant,
however.

Yellowness. Significant differences in the yellowness

 

value means of pastry wafers were found among both recon-
stitution types and varietal flours at o=0.01. A signifi-
cant interaction between main effects was found at a=0.01.
Yellowness value means of pastry wafers baked from
varietal parent and reconstituted flours are shown in
Table 19, and as a bar graph in Figure 20. Frankenmuth
pH 6.1-soluble reconst. flour yielded pastry wafers that had
the most yellow surface color; pastry baked from this flour
was significantly more yellow than Hillsdale and Tecumseh
pH 4.7-insoluble reconst., Augusta andTecumseh pH 5.6-
insoluble reconst., Augusta pH 5.8-insoluble reconst.,
Augusta pH 6.1-soluble reconst., and all varietal parent
flours. Pastry baked from Augusta pH 5.6-insoluble reconst.
flour had the least yellow surface color, and was signifi-
cantly different from pastries baked from all other flours,
except those from Hillsdale and Tecumseh pH 4.7-insoluble
reconst., Augusta and Tecumseh pH 5.6-insoluble reconst.,
Augusta pH 6.1-soluble reconst., and all varietal parent

flours. Mean values ranged from 19.0 to 23.1.

122

Table 19. Yellowness values of pastry wafers baked from
varietal parent and reconstituted flours.1

 

Yellowness2

Reconstitution

 

 

Type
Augusta Hillsdale Frank. Tecumseh
Parent Flour 19.7 19.7 20.7 20.5
Whole Crude gluten 21.5. 21.6 21.5 21.3
A.F.R.3 21.6 21.4 21.7 21.5
pH 4.7-insoluble 21.6 20.5 22.1 20.0
pH 5.6-insoluble 19.0 22.4 21.4 20.8
pH 5.8/6.1- 20.9 22.3 22.4 21.3
insoluble
pH 6.1-soluble 20.6 21.6 23.1 21.4

 

1n=3, Standard error=0.42, LSD=1.57 at a=0.01.
zAs determined by Hunter Color Difference ("b" values).

3A11 fractions reconstituted in original proportions.

123

 

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124

Yellowness mean values for each reconstitution type
are provided in Table 16, and illustrated in Figure 21. The
parent flours yielded pastries that were significantly less
yellow than those baked from all other reconstitution types,
except the pH 5.6-insoluble reconst. flours. Pastries baked
from the pH 5.8/6.1-insoluble reconst. flours were the most
yellow; however, these were only significantly different
from pastries baked from the parent flours. Among the
single pH fraction reconst. flours, no relationship was
seen between pH and'resulting yellowness of the pastry crust
surface.

Yellowness mean values for varietal flours are shown in
Table 17, and as a bar graph in Figure 21. Pastry wafers
baked from Frankenmuth flours had significantly more yellow
crust surfaces than those from Tecumseh and Augusta flours.
Augusta flours yielded pastry wafers having the least yellow
crust surface; these wafers were significantly less yellow
than those from Hillsdale and Frankenmuth flours.

Differences in Browning Reaction. Among the reconstitu-
tion types, the lightness and redness values, especially the
latter, differentiated most consistently between browning
reactions on the various pastry crust surfaces. Although
highly significant differences were found among the yellow-
ness values, all pastry types had yellowish surfaces, and
the range of values was not as wide as for the redness and

lightness values. Redness and lightness values followed the

125

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126

same pattern, and the relationship was linear, with the
exception of two values. That is, as lightness decreased,
redness increased, with the exception of pastries from
A.F.R. flours; these were more red, but not as dark as those
from pH 5.8/6.1-insoluble reconst. flours. Thus, as the
pastry surfaces underwent browning during baking, lightness
values decreased and redness values increased. Since red is
a component of the color brown, this seems logical. The
ranking of flours based on reconstitution type in order of
increasing browning was as follows: parent, pH 6.1-soluble
reconst., A.F.R., pH 5.8/6.1-insoluble reconst., whole crude
gluten reconst., pH 4.7-insoluble reconst., and pH 5.6-
insoluble reconst. Thus, the lower pH gluten fractions,
when reconstituted into flours, yielded the pastry with the
most brown crust surface. With the exception of the pH 5.6-
insoluble reconst. flours, as the pH of the singly reconst.
flours increased, the browning reaction of these flours
decreased. It, thus, appears that the higher glutenin-
containing fractions contributed to greater crust surface
browning than did those fractions higher in gliadins. The
pH 4.7-insoluble fraction may have produced less browning in
pastry due to the presence of some starch + water-solubles
material. Hater-soluble protein would have accounted for
part of the protein used in reconstitution; the water-
soluble proteins possibly contribute less browning than the

gluten proteins. The pH 5.6-insoluble gluten fraction had

127

a more greasy feel; additional flour lipid in this fraction
could possibly have enhanced the browning reaction in
pastry.

No significant differences were seen in lightness and
redness values among the varietal flour means. aAlthough
significant differences were found among yellowness varietal
flour means, it appears that crust browning differences
among varietal flours were insignificant. Since the
varietal flours used in this study differed in protein
content, these results are in agreement with Smak (1972);
this author stated that positive correlations between

browning and protein content were variety-dependent.
Correlations AmonggDependent Variables

Correlations among the textural characteristics of pastry
wafers are shown in Table 20. Flakiness was positively
correlated with both crust shrinkage and surface blistering
scores; crust shrinkage, however, was not significantly
correlated with surface blistering scores. Miller and Trimbo
(1970) stated that the pie crusts that exhibited the most
flakiness had also exhibited the most crust shrinkage and
thickening during baking.

Breaking strength was not significantly correlated with
flakiness or crust shrinkage, but was positively correlated
with surface blistering scores. Matthews and Dawson (1963)

found negative correlations between flakiness scores and

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129

breaking strength values (r=-0.83 to -0.99 at a=0.01).
Miller and Trimbo (1970) found all combinations of flakiness
and tenderness in pie crusts and concluded that "flakiness
is not a requisite for tenderness."

Lightness values were positively correlated with flaki-
ness, crust shrinkage and surface blistering scores; light-
ness values were negatively correlated with those for
redness. Redness values were negatively correlated with
flakiness and crust shrinkage. Yellowness values were
positively correlated with breaking strength.

The pastry wafers having greater flakiness and crust
shrinkage and, thus, probably more gluten development,
appear to have undergone less browning, as indicated by
lightness and redness values. Overall, flakiness, crust
shrinkage, surface blistering and browning reaction were
reliable indicators of gluten strength and development in

pastry wafers. Breaking strength was inconsistent.

Correlations Between Dependent Variables

and Flour Protein Content

Table 21 shows correlations between the textural
characteristics of pastry and flour protein content. An
extremely high correlation was found between flakiness and
flour protein content (r=0.96 at a=0.01). A pie crust baked
from a high protein flour was found by Miller and Trimbo

(1970) to be very flaky as compared with pie crust baked

130

Table 21. Correlations coefficients of flour protein
content and percentage of gluten fractions with
textural characteristics of pastry wafers.

 

 

 

Source Flour Protein Percentage of Gluten
Content1 Fractions Obtained?

Flakiness 0.96 n.s.

Crust shrinkage 0.81 n.s.

Surface blistering -0.82 n.s.

score

Breaking strength -0.503 0.58
Lightness 0.443 n.s.

Redness n.s. n.s.
Yellowness n.s. n.s.

1

n=4; n.s.=not significant at d=0.01.

2n=l6 (compared with all single fraction reconstituted
flour values); n.s.=not significant at d=0.05.

3Significant at a=0.05

131

from starch, but no protein. Crust shrinkage was positi—
vely correlated with flour protein content; this is also in
agreement with Miller and Trimbo (1970).

Both surface blistering score and breaking strength
were negatively correlated with flour protein content.
Surface blistering would be expected to be greater in flours
of higher protein content, since it indicates gluten
strength. Also, pastry wafers baked from the higher protein
flours would be expected to have higher breaking strengths,
due to the potential for greater gluten development. Denton
et al. (1933) and Miller and Trimbo (1970) found an inverse
relationship between tenderness and flour protein content
(a positive correlation between breaking strength and flour
protein content). The breaking strength means for varietal
flours had a pattern similar to that of the values for the
parent flour, that is, Frankenmuth pastry was the toughest,
and Tecumseh pastry, the most tender. Thus, Tecumseh flour
was particularly anomalous with regard to breaking strength.
Hhen Tecumseh is excluded from the varietal flour mean data,
the relationship between flour protein content and breaking
strength is a positive correlation. That the negative
correlation found among all four varieties is only signifi-
cant at a=0.05, reflects this. Therefore, it appears that
the correlation between flour protein content and breaking

strength of pastry wafers is variety dependent.

132

Lightness values were positively correlated with flour
protein content, indicating that increased protein quantity
did not increase crust surface browning, but rather the
contrary. This finding is consistent with the positive
correlations found between lightness and the flakiness,
crust shrinkage and surface blistering scores of pastry
‘wafers; these positive correlations suggested that greater
gluten development concurred with less crust surface browning.
Redness and yellowness values were not significantly

correlated with flour protein content.

Correlations Between Pastry Textural Characteristics and

Flour Fractionation Patterns

Among the single fraction reconst. flours, only breaking
strength of pastry wafers was positively correlated (r=
0.58 at a=0.05) with the percentage of each gluten fraction
obtained during fractionation. This means that an increase
in the yield of a gluten fraction c0incided with increased
breaking strengths of pastry wafers baked from flour reconsti-
tuted from that gluten fraction alone. For example, the
pastry wafers baked from pH 6.1-soluble reconst. flours
had higher breaking strengths as compared with those wafers
baked from pH 5.6-insoluble reconst. flours; among all
varietal flours, a much greater percentage of pH 6.1-
soluble material was yielded as compared with pH 5.6-

insoluble material. The pH 4.7-insoluble reconst. flours

133

baked into pastries having higher breaking strengths;
significantly larger amounts of pH 4.7-insoluble material
were yielded from each varietal flour. Thus, the amount of
gluten having gliadin-to-glutenin ratios that resulted in

more tender pastry wafers, was small.

Effect of Fractionation/Reconstitution Procedures_gn

Pastry Textural Characteristics

Finney (1943) stated that "for a wheat-flour fraction-
ating technique to be of value, each of the fractions must
retain its original characteristics to the extent that when
a flour is reconstituted and the usual baking ingredients
added it will yield a dough and loaf of bread identical
(within experimental error) with that obtained from the
original flour." In this case, textural characteristics of
pie pastry baked from the whole crude gluten and A.F.R.
flours should approximate those of the corresponding parent
flour. By comparing the whole crude gluten and A.F.R. flours
with the parent flours, the effect each fractionation
procedure (gluten washing vs. isoelectric precipitation)
has on textural characteristics of pastry can be seen.

From Figures 8 and 9, it can be seen that the flakiness
of pastry wafers baked from A.F.R. flours more closely
resembled those of the parent flours. Neither the whole
crude gluten nor the A.F.R. flours yielded pastry wafers as

flaky as those baked from the parent flours. However, the

134

isoelectric precipitation process appears to have partially
restored the gluten functionality as defined by flakiness.

Crust shrinkage in pie pastry baked from the whole crude
gluten and A.F.R. flours was lower than in pastry baked
from the parent flours (Figures 10 and 11). The isoelectric
precipitation process in this case caused a far greater
deviation from crust shrinkage values of the parent flour.
This seems inconsistent with the flakiness results..

Surface blistering scores, shown in Figure 12 and 13,
were higher in the two reconstituted flours, as compared
with the parent flour. The A.F.R. flours received much
higher surface blistering scores than either the whole crude
-gluten or parent flours, however. This is inconsistent with
the crust shrinkage results when both are viewed as measures
of gluten strength.

Breaking strength values (Figures 14 and 15) were higher
in both reconstitution types as compared with the parent
flours. The A.F.R. flours deviated the most with regards
to this variable.

Lightness values were significantly lower in both
reconstitution types as compared with the parent flours
(Figures 16 and 17), the greater difference being between
the whole crude gluten and parent flours.

Redness values were greatly affected by both fractiona-
tion processes (Figures 18 and 19). Pastry baked from the

parent flours had a greenish hue (-a values). A reddish

135

hue was detected on the surfaces of the pastry wafers baked
from the whole crude gluten and A.F.R. flours. The whole
crude gluten flours yielded pastry wafers with higher
redness (+a) values, thus differing more from the pastry
baked from the parent flours.

Yellowness values were significantly higher in pastry
baked from both reconstitution types as compared with that
baked from the parent flours (Figures 20 and 21); these
values were just slightly, and not significantly, higher in
the A.F.R. flours, when compared to the values from whole

crude gluten flours.

These lightness, redness and yellowness results indicate
that both fractionation processes resulted in greater crust
surface browning in pie pastry. As compared with the parent
flours, the whole crude gluten flours differed more in this
respect. The isoelectric precipitation procedure appears to
have reduced the surface browning potential somewhat.

Overall, the whole crude gluten flours provided a better
model of the parent flour. The crust shrinkage, surface
blistering score, and breaking strength results were more
similar to those of the parent flours. The A.F.R. flours
served as a better model with regards to flakiness and
crust surface browning results.

The fractionation and reconstitution procedures did have
an effect on the textural characteristics of pie pastry.

Using a doughing step in the reconstitution procedure

136

(followed by lyophilization and grinding) could possibly
restore the properties of the parent flour. Then again,

the deleterious effect of a doughing step on cake structure,
when combined with lyophilization and grinding (Donelson

et al., 19608), suggests that differences in pastry baked

from reconstituted flours so treated could be greater.
Implications of the Data

The quantity and quality of protein in pastry flours
have a tangible effect on the textural characteristics of
pie pastry. From the correlation data, it can be seen that
the quantity of protein influences the flakiness, crust
shrinkage, surface blistering score, breaking strength and
lightness of pastry wafers. The reconstitution type data
shows that the quality of protein, as varies by gliadin-to-
glutenin ratio; also influences these factors, plus the
redness values of pastry wafers. The influence that the
gluten fraction type used in the single fraction reconst.
flours had on these textural characteristics, especially
flakiness and crust shrinkage, indicates that gluten
development does occur in pie pastry. The amount and type
of gluten, as determined by both flour variety and reconsti-
tution type, were probably largely responsible for the
statistical differences found among types of pastry. The
higher glutenin-containing flours (lower pH) yielded pastry

that was less flaky, less shrunken, less blistered, with a

137

darker crust color. However, the pH 5.6-insoluble reconst.
flour pastry was more tender than pH 4.7-insoluble reconst.
flour pastry. Since the flour lipid was not extracted
prior to fractionation this, too, could have influenced
textural characteristics. The pH 5.6-insoluble gluten
fraction had a noticeable greasy feel. Frazier et al.
(1981) stated that the bound flour lipid was located with
the high molecular weight glutenin. Possibly the flour lipid
precluded the full extent of gluten development that might
otherwise have occurred in the pH 5.6-insoluble reconst. flour
dough.

Fractionation and reconstitution procedures themselves
affect the textural properties of pie pastry. In this
study, the properties of the parent flour were not restored
within experimental error upon reconstitution. The
additional fractionation by pH (isoelectric precipitation)
step, in many cases, further changed the resultant textural

properties of pie pastry.

SUMMARY AND CONCLUSIONS

The purpose of this study was to investigate the
functionality of soft wheat flour, particularly gluten
quantity and quality, in pie pastry, using fractionation/
reconstitution techniques. In fractionating the soft wheat
flours, gluten was first washed out, and subsequently
fractionated by pH (isoelectrically precipitated).
Fractionation patterns of four varietal flours were
compared. Flours were reconstituted to their original
protein contents from whole crudegluten, and from the
gluten fractions singly and all in their original pr0por-
tions for the four varietal flours. Pie pastry was baked
from these reconstituted, plus their parent, flours, and the
textural characteristics - flakiness, crust shrinkage,
surface blistering, breaking strength and crust surface
browning (as lightness, redness and yellowness) were
measured. The effects of both flour variety and reconstitu-
tion type on these textural characteristics were reported.

As the protein content of the flours increased, so did
the percentage of gluten yielded and its corresponding
protein content. Fractionation of gluten by pH revealed

different patterns among the four varieties; Augusta was

138

139

particularly anomalous in this regard. For the other three
varietal flours, as the flour protein content increased,
the percentage by weight of each gluten fraction obtained,
the percentage of total gluten protein and total flour
protein contributed by each gluten fraction increased for
the pH 4.7-insoluble material, and decreased for the other
gluten fractions. Observations on the appearance of gluten
fractions revealed that the lower pH fractions had the
characteristic appearance of glutenin, whereas the higher
pH fractions had an appearance characteristic of gliadin.

Results of the baking test for pastry indicated that
reconstitution did not restore the original properties of
the parent flours. Flakiness, crust shrinkage, surface
blistering, breaking strength and crust surface browning were
affected by both fractionation procedures. The isoelectric
precipitation procedure generally contributed greater loss
of the original flour properties.

Among the single pH fraction reconstituted flours, as pH
increased, flakiness, crust shrinkage and surface blistering
scores in pastry increased, whereas crust surface browning
decreased. Breaking strengths were higher in the pastries
baked from the pH 4.7-insoluble and pH 6.1-soluble reconst.
flours (the extremes of pH), and highest in the latter.

Flakiness was found to be positively correlated with
flour protein content, crust shrinkage and surface blister-

ing scores. Both flakiness and crust shrinkage were

 

 

140

negatively correlated with crust surface browning.

Significant differences among varietal flours for
flakiness and crust shrinkage could be attributed to
differences in flour protein content. Breaking strength
was found to be truly flour variety-dependent, since the
highest protein flour yielded pastry having the lowest
breaking strength. Among the other varietal flours, breaking
strength could be positively correlated with flour protein
content.

Overall, these data suggest that flour selection may be
an important determinant of the textural characteristics of
pastry. Additionally, higher protein flours may be used in
pie doughs without undesirable toughness in pastry.

In the opinion of the author, among the parent flours,
Tecumseh yielded pastry with the most desirable characteris-

tics. Pastry wafers baked from Tecumseh parent flour were

the most flaky, which is a favorable attribute. However,
crust shrinkage was appreciably higher in this pastry type
which is undesirable.

Surface blistering scores were more desirable in pastry
from the reconstituted flours as compared with any parent
flour; an intermediate score of $3.0 would be ideal. Hith
higher scores the surface blisters were burst. Among the
parent flours, Hillsdale had the surface blistering score

closest to the ideal. The score for Tecumseh was acceptable.

141

Strangely, the Tecumseh parent flours yielded the pastry
with the lowest breaking strength. This pastry was not too
fragile to make handling or serving a problem.

Crust surface browning was most desirable in the A.F.R.
flours. Lightness values varied little among the parent
flours. The Tecumseh parent flours yielded the most red
wafers. Thus, even with the higher crust shrinkage the
other desirable attributes of Tecumseh parent flour pastry
made this type the most desirable.

In future investigations in the fractionation/reconsti-
tution of soft wheat pastry flours, electron microscopy of
pie doughs and pie pastry could possibly reveal additional
information on the functionality of flour components. That
pastry is a low moisture product would be advantageous for
this type of work. Also, it remains to be determined what
conditions are necessary for full restoration of the
original flour properties, as determined by functionality
in pastry, upon flour fractionation/reconstitution.

Agronomic studies, such as varying the level of nitrogen
fertilization in order to alter protein contents within a
variety, followed by pastry baking of the flours, could
reveal much to the wheat growers. The effect on pastry of
flours milled from wheats grown on different plots may also

be of interest.

APPENDIX

142

 

 

 

Table 22. .Agronomic and compositional data of varietal
soft wheats.
Wheat 1983 Yield] Test Wt.2 »Total Wheat Total Wheat
Variety (Bu/acre) (lbs/bu) ProteinZ-B Ash2-3
(%) (76)
Augusta 69.3 58.3 9.05 1.53
Hillsdale 68.9 60.7 9.50 1.57
Frankenmuth 67.0 60.6 10.17 1.68
Tecumseh 54.3 62.4 11.55 1.72
1Dr. E. Everson, Dept. Crop and Soil Science, Michigan '
State University, East Lansing, MI

2Soft Wheat

3Reported 0

Quality Laboratory, Wooster, OH.

n a 14% moisture basis.

 

 

 

Table 23. Experimenfial milling data for varietal soft
wheats. 1

Wheat Break Straight -Flour Flogr
Variety Yield Grade Protein3 Ash

% % % %
Augusta 34.1 76.7 7.9 0.40
Hillsdale 29.4 76.0 8.1 0.36
Frankenmuth 31.5 76.1 9.0 0.41
Tecumseh 27.6 77.7 10.6 0.40
1Soft Wheat Quality Laboratory, Wooster, OH.

2Allis-Chalmer milled flours.

3Reported o

n a 14% moisture basis.

143

Table 24. Experimental milling and baking data fgr
varietal soft wheats and their flours.

 

 

 

Wheat Variety ESI2 Friability3 Cookie Diameter
(%) (%) (cm)

Augusta 10.5 27.9 17.8

Hillsdale 11.6 27.0 17.8

Frankenmuth 10.6 26.5 18.1

Tecumseh 9.2 27.1 18.2

1

Soft Wheat Quality Laboratory, Wooster, OH.

2Endosperm separation index (Yamazaki and Andrews, 1982).

3Percentage of flour obtained from break and reduction
rolls as compared with total amount of stock fed into
rolls (Andrews, 1986).

Table 25. Standard pie dough formulations used in the
baking test for pastry.

 

Standard (9)

 

Flour Types

 

Flour Shortening Salt 1
solution
Augusta and Tecumseh 20 8.2 5.2
5.6-insoluble
Frankenmuth 44 18.0 11.4
5.6-insoluble
All varieties - whole 50 24.6 15.5
crude gluten
Augusta 5.8-insoluble 70 28.7 18.1
All others 100 41.0 25.8

 

16.98% salt

144

Table 26. Final moisture contents of humidified reconsti-
tuted flours.

 

Moisture (%)
Reconstitution

 

 

type
Augusta Hillsdale Frank. Tecumseh
Whole Crude gluten 11.19 11.76 10.13 10.73
All Fractions 11.18 12.02 10.23 11.19

Reconst.
pH 4.7-insoluble 11.82 10.41 10.15 10.66
pH 5.6-insoluble 10.38 10.09 12.78 10.86
pH 5.8/6.1- 11.33 10.14 10.78 11.72

insoluble

pH 6.1-soluble 12.56 ~ll.51 10.55 10.62

 

n=2.

Table 27. Protein contents of reconstituted flours.1

 

 

 

Protein (%) Error2
Flour Type (%)
Experimental Calculated

Hillsdale pH 6.1 7.85 8.08 2.85
soluble

Frankenmuth pH 4.7- 9.25 9.01 2.66
insoluble

Frankenmuth whole 9.27 9.01 2.89
crude gluten

Tecumseh pH 4.7- 10.97 10.83 1.29
insoluble

Tecumseh All 10.51 10.83 2.95

Fractions Reconst.

 

]n=2; 20% random sampling.
2Error % = Calculated - Experimental
( ) Calculated x 100

145

Table 28. Analysis of variance for flakiness.1

 

 

Source of Degrees Sum of Mean F Probability
Variation of Squares Square Value
Freedom
V 3 0.77 0.258 6.59 .000
R 6 5.91 0.985 25.14 .000
VxR 18 1.40 0.078 1.99 .026
Error 56 2.19 0.039

 

1V=flour variety, R=reconstitution type.

Table 29. Analysis of variance for crust shrinkage.1

 

 

Source of Degrees Sum of Mean F Probability
Variation of Squares .Square value
Freedom
v 3 95.20 31.732 7.13 .000
R 6 836.31 139.384 31.30 .000
VxR 18 254.73 14.152 3.18 .000
Error 56 249.35 4.453

 

1V=flour variety, R=reconstitution type.

146

Table 30. Analysis of variance for surface blistering
scores.

 

 

Source of Degrees Sum of Mean F Probability.
Variation of Squares Square Value
Freedom
V 3 0.96 0.321 1.13 .346
R 6 83.53 13.922 48.73 .000
VxR 18 7.99 0.444 1.55 .105
Error 56 16.00 0.286

 

1V=f10ur variety, R=reconstitution type.

Analysis of variance for breaking strength.1

 

 

Table 31.
Source of Degrees Sum of Mean F Probability
Variation of Squares Square Value
Freedom
V 3 2.67 0.890 6.00 .001
R 6 11.53 1.921 12.95 .000
VxR 18 4.85 0.270 1.82 .045
Error 56 8.31 0.148

1

V=flour variety, R=reconstitution type.

147

Table 32. Analysis of variance for lightness ("L").1

 

 

Source of Degrees Sum of Mean F Probability
Variation of Squares Square Value
Freedom
V 3 11.21 3.737 0.34
R 6 2618.19 436.364 39.88 .000
VxR 18 517.20 28.733 2.63 .003
Error 56 612.73 10.942

 

1V=flour variety, R=reconstitution type.

Table 33. Analysis of variance for redness ("a").1

 

 

Source of Degrees Sum of Mean F Probability
Variation of Squares Square Value
Freedom
V 3 4.87 1.622 1.46 .235
R 6 303.75 50.626 45.57 .000
VxR 18 66.63 3.702 3.33 .000
Error 56 62.21 1.111

 

1V=flour variety, R=reconstitution type.

148

Table 34. Analysis of variance for yellowness (“b").1

 

 

Source of Degrees Sum of Mean F Probability
Variation of Squares Square Value
Freedom
V 3 15.79 5.264 10.09 .000
R 6 22.13 3.689 7.07 .000
VxR 18 28.36 1.575 3.02 .000
Error 56 29.22 0.522

 

1V=flour variety, R=reconstitution type.

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