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COLLEGE OF HOME ECONOMICS
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ABSTRACT

THE EFFECT OF BAKING TEMPERATURE ON THE QUALITY
CHARACTERISTICS OF ANGEL CAKES

by Doha A. Elgidaily

This investigation was primarily designed to deter-

O

I

mine the effect of the baking temperatures of 177°, 191

204°

, and 218°C. on the quality characteristics of angel
cakes. Data obtained from sensory evaluation and numerous
objective measurements of the quality characteristics were
correlated to achieve the secondary objective of this study
which was to assess the validity of objective measurements
that could be performed in laboratories with limited equip-
ment.

Cakes were prepared from commercial one-step cake
mixes and each of the four variables of oven temperature was
replicated four times. The specific gravity and pH of the
cake batter were determined as indications of control of all
variables except the oven temperature. Time-temperature
relationships were continuously recorded during baking from
potentiometer leads positioned 2.5 and 5.0 cm. from the
bottom of each cake pan.

The cakes were evaluated by a six-member panel using

a 7-point numerical scale qualified with descriptive terms.

Doha A. Elgidaily

The objective measurements included index of volume, percent-
age of weight loss during baking, moisture determinations,
percentage of sand retained, compressibility as determined
by penetrometer and the Kramer shear-press readings, tensile
strength, and tenderness.

The temperatures within the cake rose at a rate
dependent on the oven temperature with the slowest rate of
temperature rise recorded for the 1770C. oven. The differ-

o

ences in the maximum internal temperatures of 98.00, 99.5 ,

100.00, and 100.4%. reached by the cakes baked at 177°,

0 O

191 , 204 , and 2180C., respectively, were very highly sig-
nificant.

The statistical analyses of sensory evaluations
indicated very highly significant differences for texture,
tenderness, moistness, and color of the crumb scores among
the cakes baked at the four oven temperatures. Cakes of
light, Open texture were produced at the 1770 and 191°C.
baking temperatures as compared to the compact texture of
cakes baked at the two other oven temperatures. The optimum
moistness of angel cakes as well as the desirable white
color of the crumb were secured at baking temperatures not
higher than 2040C.

Statistical differences were indicated by objective
measurements. Index of volume measurements showed a very

highly significant and continuous decrease as the baking

temperature increased. Cakes with more Open texture were

Doha A. Elgidaily

produced at baking temperatures of 1770 and 1910C. according
to the results of the sand retention test. Penetrometer
measurements indicated cakes were more compressible when
baked at 1770 and 191°C. The shear-press measurements for
compressibility based on maximum force and area—under-the-
curve, showed more force was necessary to compress cakes
baked at 2180C. as compared with cakes baked at the three
other oven temperatures. The same trend was indicated by
the tenderness measurements for the shear-press based on
area-under-the-curve, showing that cakes baked at tempera-
tures higher than 2040C. required more force to be sheared.

No significant differences among cakes baked at the
four oven temperatures were indicated by the percentages of
weight loss during baking, percentages of moisture, tender—
ness values based on maximum force, and tensile strength
measurements.

Very highly significant relationships existed
between texture scores and tenderness scores, moistness
scores, and index of volume measurements. Very highly sig-
nificant correlations were also indicated between the tender—
ness scores and index of volume measurements, and compress—
ibility based on the maximum force readings of the shear—
press. Area-under—the—curve tenderness values determined by
the shear—press showed a very highly significant relationship
with shear-press measurements for compressibility based on

on both maximum force and area—under-the—curve values.

Doha A. Elgidaily

The highly significant correlation found between the
sand retention test and texture scores of angel cakes, indi-
cated the validity of this test to measure texture of angel
cakes. Because of the high standard deviations, however,
the reliability of this test is questioned.

The very highly significant relationship between
shear-press values for compressibility as indicated by max-
imum force and area—under-the-curve, tenderness scores and
the penetrometer values, indicated the penetrometer was a
valid instrument for determining compressibility of angel
cakes. .

According to the results of this investigation,
baking temperatures of 1770 and 191°C. were more satisfac-
tory for baking angel cakes than baking temperatures of 2040
and 218°C. Thick layers developed in cakes baked at 2040

and 218°C. as a result of a partial collapse of the struc—

ture after they were removed from the oven.

THE EFFECT OF BAKING TEMPERATURE ON THE QUALITY

CHARACTERISTICS OF ANGEL CAKES

BY

Doha Abdel-Rahman Elgidaily

A PROBLEM

Submitted to
the Dean of the College of Home Economics
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Institution Administration

1967

ACKNOWLEDGMENTS

The most sincere appreciation is eXpressed to Dr.
Kaye Funk for the generous help, direction, and guidance
given throughout the study. Without her never failing
encouragement and great patience, this investigation would
not have been completed. To her, the writer wishes to
acknowledge her indebtedness.

Grateful appreciation is due to Miss Katherine Hart
for her guidance and encouragement during the past two years.
Also, the writer appreciates the financial support which
made this investigation possible. Gratitude and acknowledg-
ment are also expressed to Mrs. Mary Ellen Zabik for her
interest, advice, and helpful suggestions in carrying out
this study.

The writer is thankful to Miss Mary Morr, Mrs.
Martha Kaiser, Miss Mary Ann Boyle, Miss Jenny Taylor, Miss
Sylvia Pantelas, and Mrs. Doris Lawrence, who served as
taste panel members for scoring the angel cakes prepared

in this study.

******

ii

TABLE OF CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . . . . . .
REVIEW OF LITERATURE . . . . . . . . . . . . . . . . .

Baking Temperatures for Angel Cakes . . . . . . .
Rates of Temperature Rise During Baking . . . . .
Determination of Doneness . . . . . . . . . . . .
Effect of Baking Temperature on Quality
Characteristics . . . . . . . . . . . . . . . .
Early investigations . . . . . . . . . . . . .
Other reports . . . . . . . . . . . . . . . .
Sensory Evaluation of Quality Characteristics . .
Objective Measurements of Quality Characteristics.
Volume . . . . . . . . . . . . . . . . . . . .
Moisture . . . . . . . . . . . . . . . . . . .
Cell structure . . . . . . . . . . . . . . . .
Ink prints and photography . . . . . . . .
Sand retention test . . . . . . . . . . .
Compressibility . . . . . . . . . . . . . . .
Devised instruments and penetrometers . .
Kramer shear—press . . . . . . . . . . . .
Tensile strength . . . . . . . . . . . . . . .
Tenderness . . . . . . . . . . . . . . . . . .

EXPERIMENTAL PROCEDURE . . . . . . . . . . . . . . . .

Design of Experiment . . . . . . . . . . . . . . .
Preliminary Investigations . . . . . . . . . . . .
Method of Preparation . . . . . . . . . . . . . .
Baking and Storage Procedure . . . .
Objective Measurements of Cake Batter . . . . . .
Specific gravity of batter . . . . . . . . . .

pH of batter . . . . . . . . . . . . . . . . .
Subjective Evaluation of Baked Cakes . . . . . . .
Preparation of Samples . . . . . . . . . . . . . .
Sensory Evaluation . . . . . . . . . . . . . . . .
Objective Measurements . . . . . . . . . . . . . .
Index of volume . . . . . . . . . . . . . . .
Moisture of cake . . . . . . . . . . . . . . .
Percentage of weight loss during baking .
Moisture determinations . . . . . . . . .

iii

Page

24

24
25
25
26
29
29
29
3O
3O
3O
33
33
34
34
34

Page

Structure of the cell . . . . . . . . . . . . 35

Compressibility of cake . . . . . . . . . . . 36

Penetrometer measurements . . . . . . . . 36

Kramer shear-press measurements . . . . . 36

Tensile strength . . . . . . . . . . . . . . . 38

Tenderness of cake . . . . . . . . . . . . . . 39

Analysis of Data . . . . . . . . . . . . . . . . . 41

RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . 42

Objective Measurements of Cake Batter . . . . . . 42

Specific gravity of batter . . . . . . . . . . 43

pH of batter . . . . . . . . . . . . . . . . . 43

Rates of Temperature Rise During Baking . . . . . 43
Time-temperature relationships recorded

2.5 cm. from the bottom of the pan . . . . . 45
Time-temperature relationships recorded

5.0 cm. from the bottom of the pan . . . . . 47

Maximum internal temperatures of cakes . . . . 49

Subjective Evaluation of Baked Cakes . . . . . . . 52

Sensory Evaluation . . . . . . . . . . . . . . . . 52

Texture . . . . . . . . . . . . . . . . . . . 53

Tenderness . . . . . . . . . . . . . . . . . . 55

Moistness . . . . . . . . . . . . . . . . . . 57

Color of the crumb . . . . . . . . . . . . . . 59

Objective Measurements .‘. . . . . . . . . . . . . 61

Index of volume . . . . . . . . . . . . . . . 61

Moisture of cake . . . . I . . . . . . . . . . 64'

Percentage of weight loss during baking . 64

Moisture determinations . . . . . . . . . 65

Percentage of sand retention . . . . . . . . . 66

Compressibility . . . . . . . . . . . . . . . 69

Penetrometer measurements . . . . . . . . 69

Kramer shear—press measurements . . . . . 71.

Tensile strength measurements . . . . . . . . 75

Tensile strength of body slices . . . . . 75

Tensile strength of end slices . . . . 2 . 76

Validity of Objective Measurements . . . . . . . . 83

SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . . 85

LITERATURE CITED . . . . . . . . . . . . . . . . . . . 90

APPENDIX . . . . . . . . . . . . . . . . . . . . . . . 95

iv

TABLE
1.

10.

11.

12.

LIST OF TABLES

Page

Specific gravity values of angel cakes baked
at four oven temperatures . . . . . . . . . . 44

pH values of angel cakes baked at four oven
temperatures . . . . . . . . . . . . . . . . . 45

Data and statistical analyses for the
maximum internal temperature recorded for
angel cakes baked at four oven temperatures . 50

Data and statistical analyses of sensory
scores for texture of angel cakes baked
at four oven temperatures . . . . . . . . . . 54

Data and statistical analyses of sensory
scores for tenderness of angel cakes baked
at four oven temperatures . . . . . . . . . . 56

Data and statistical analyses of sensory
scores for moistness of angel cakes baked
at four oven temperatures . . . . . . . . . . 58

Data and statistical analyses of sensory
scores for color of the crumb of angel cake
baked at four oven temperatures . . . . . . . 60

Data and statistical analyses of index of
volume of angel cakes baked at four oven
temperatures . . . . . . . . . . . . . . . . . 62

Percentage of weight loss during baking
angel cakes at four oven temperatures . . . . 65

Percentage of moisture of angel cakes
baked at four oven temperatures . . . . . . . 66

Data and statistical analyses for percentage
of sand retained by angel cakes baked at
four oven temperatures . . . . . . . . . . . . 67

Data and statistical analyses of penetrometer
measurements of angel cakes baked at four
oven temperatures . . . . . . . . . . . . . . 7O

TABLE

13.

14.

15.

16.

17.

18.

19.

Page

Data for statistical analyses of Kramer

shear-press measurements for compress—

ibility, expressed as maximum force,

of angel cakes baked at four oven

temperatures . . . . . . . . . . . . . . . . . 72

Data and statistical analyses of Kramer

shear—press measurements for compress—

ibility, eXpressed as area-under-the-

curve, of angel cakes baked at four

oven temperatures . . . . . . . . . . . . . . 74

Data and statistical analyses of Kramer

shear—press measurements for tensile

strength of body slices of angel cakes

baked at four oven temperatures . . . . . . . 77

Data and statistical analyses of Kramer

shear-press measurements for tensile

strength of end slices of angel cakes

baked at four oven temperatures . . . . . . . 78

Data and statistical analyses of Kramer

shear-press measurements for tenderness,

eXpressed as maximum force, of angel

cakes baked at four oven temperatures . . . . 80

Data and statistical analyses of Kramer

shear—press measurements for tenderness,

eXpressed as area—under-the-curve,

of angel cakes baked at four oven

temperatures . . . . . . . . . . . . . . . . . 82

Summary of correlation coefficients

calculated from sensory evaluation and

objective measurement data of angel cakes

baked at four oven temperatures . . . . . . . 99

vi

LIST OF FIGURES

FIGURE Page

1. Positions of potentiometer leads during
baking of angel cakes at four oven
temperatures . . . . . . . . . . . . . . . . . 27

2. Sequences for cutting and evaluating the
slices of angel cakes according to four
rotation plans . . . . . . . . . . . . . . . . 31

3. Compressibility measurements of angel cakes
using the Kramer shear—press . . . . . . . . . 37

4. Tensile strength measurements of angel
cakes using the Kramer shear-press . . . . . . 4O

5. Average rates of temperature rise as
measured 2.5 cm. from the bottom of the
pans used for baking angel cakes at four
oven temperatures . . . . . . . . . . . . . . 46

6. Average rates of temperature rise as
measured 5.0 cm. from the bottom of the
pans used for baking angel cakes at four
oven temperatures . . . . . . . . . . . . . . 48

vii

INTRODUCTION

Angel cakes are one of the most delicate desserts
which are usually liked for their fragile texture and subtle
flavor. However, at the present time the Optimum oven tem-
perature for baking angel cakes is not clearly defined.

Angel cake formulas appearing in the recipe books
published many years ago, recommended low oven temperatures
of 1350 to 1630C. for baking the cakes. It was theorized
that hot oven temperatures would toughen the egg white pro—
teins during baking and cakes with poor quality characteris-
tics would result.

In more recent years, some angel cake formulas have
suggested baking temperatures ranging from 1770 to 2189C.
with the resultant adjustment in baking time. Indications
are that cakes of increased volume, moistness, and tender-
ness result when temperatures ranging from 1770 to 2180C.
are used although the top crust of the cakes may be cracked
and/or burned when baked at the high oven temperatures.

Thus, oven temperatures ranging from low to high
have been recommended for baking angel cakes. The effect
of these baking temperatures on the quality characteristics
of angel cakes has not been elucidated. Therefore, the

primary objective of this study was to define the effect

of baking temperatures of 1770, 1910, 2040

, and 2180C. on
the quality characteristics of angel cakes.

Quality characteristics may be determined by sensory
evaluations and objective measurements. Methods used for
objectively measuring the quality characteristics of angel
cakes are numerous. Some measurements have been made using
instruments devised by research workers within their labora-
tories. Fabricated instruments, such as a penetrometer and
the Kramer shear-press have also been used. The accuracy
and precision of these instruments may vary greatly as do
the cost and availability. Therefore, to aid researchers
and/or classroom instructors in assessing quality character—
istics of cakes with available instruments in laboratories
with limited equipment, a secondary objective of this study

was to correlate data from numerous Objective measurements

and sensory evaluations.

REVIEW OF LITERATURE

Baking Temperatures for Angel Cakes

The conflicting reports which appear in the litera-
ture concerning the most satisfactory oven temperature for
baking angel cakes, leave some doubt as to the selection of
the most desirable baking temperature. According to Lowe's
report (36), there is no "best" temperature as acceptable
angel cakes may be baked over a range of temperatures.

Early workers (6, 22, 35, 42) recommended the use of
low oven temperatures to bake angel cakes of high quality.
In more recent years, moderate to high oven temperatures
have been advocated to obtain angel cakes with increased

volume, moistness, and tenderness (16, 40).

Rates of Temperature Rise During Baking

The rates of temperature rise during the cooking of
baked products have been measured by various techniques.
Read (52) used specially designed thermometers to measure
the temperatures at the center and just below the surface of
loaves of bread. However, it was necessary to open the oven

door to read the thermometers at regular time periods.

Stout and Drosten (54) used thermometers to measure
time-temperature relationships during the baking of bread at
oven temperatures ranging from 2000 to 250°C. The plotted
time-temperature curves for the optimumly baked loaves
showed a rapid rise in temperature during the first one-
third of the baking period, a slow rise for the next period,
and a practically constant temperature for the last one-
third of the baking period.

Cakes reached a maximum temperature of 98.30C. when
baked at an oven temperature of 182°C., according to a study
by Hall (21). A maximum indicating thermometer was used in
the experiment.

In his investigation of the influence of altitude on
characteristics of angel cakes, Barmore (5) used a single
junction thermocouple lead from a Leeds and Northrup poten—
tiometer to measure the internal temperature of cakes at a
point 1.5 cm. from the bottom of the pan during baking at

O, and 180°C. When the max-

Oven temperatures of 1380, 163
imum internal temperatures of cakes baked at the three tem-
peratures were compared, Barmore noted the temperatures of
cakes baked at 1380 and 1630C. were the same. The highest
baking temperature resulted in an increased of approximately
20C. in the internal temperature of the cakes.

Iron constantan thermocouples, enclosed in glass

sheaths, were used to measure the internal temperatures of

angel cakes by Reed, Floyd, and Pittman (53) in their study

of the effect of baking pans on the temperature of baking
and the tenderness of angel cake. Round pans, 10 in. in
diameter, were used in the experiment. Maximum internal
temperatures recorded were 104°, 105°, 107°, 108°, and
110°C. for cakes baked in tin, aluminum, Russian iron,
enamel, and glass pans, respectively, without center tubes.
The maximum temperatures recorded for cakes baked in tin,
aluminum, and Russian iron pans with center tubes were 1020,

O, and 1080C., respectively.

103

Looft (35) indicated internal temperatures of angel
cakes increased from 30 to 50C. as the baking temperature
increased from 1500 to 1700C. However, the maximum temper—
ature reached by the cakes during baking was dependent on
the baking time. Her study showed the 96°C. internal tem—
perature of Cakes baked at 1500C. for 80 min. was only 1°C.
higher than the internal temperature of cakes baked for
65 min. at the same temperature.

Miller and Derby (39) advocated the use of a multi-
point recorder to determine temperature changes in the oven
and at various locations within cake batters during baking.
Measuring changes which occur in cake batters during baking
are useful aids in comparing the effects of different ingre-

dients or mixing techniques on the internal characteristics,

according to the report.

Determination of Doneness

The browness of the crust has traditionally been
used as an indication of the doneness of angel cakes (6, 42).
Limited attempts have been made to define doneness by time-
temperature relationships.

Bread was evaluated for doneness after baking for
various periods of time in a study by Stout and Drosten (54).
The data were examined in reference to time-temperature rela—
tions recorded during baking. The authors suggested an
internal temperature of 100°C. must be maintained within the
loaf of bread for a period of 10 min. to adequately bake the
bread. They further concluded that oven temperatures should
be regulated to permit maintenance of an internal tempera-
ture of 100°C. within the loaf of bread for the prescribed
time period without excessive browning of the crust.

Looft (35), in her study on the Optimum baking tem-
perature for angel cakes, removed cakes from the oven when
they had reached and maintained their maximum temperature
for 2.5 min. Lowe (36) suggested that continuing the baking
too long after the maximum temperature had been reached
would bind more water and, therefore, increase the toughness

of angel cakes.

Effect of Baking Temperature on
Quality Characteristics
Baking temperature is an important factor in baking
high quality angel cakes. However, few workers have specif-
ically designed studies to investigate the effect of oven

temperatures on quality characteristics.

Early investigations

In their reports, Barton (6) and Mortenson (42)
recommended oven temperatures ranging from 1490 to 177°C. to
bake angel cakes with good volume and acceptable texture.
These workers assumed baking temperatures above 177°C. would
toughen the egg white proteins.

Halliday and Noble (22) advised baking angel cakes
at an oven temperature of 149°C. for 1-1/2 hr. They I
believed egg white coagulated at a low temperature would be
more tender than that coagulated at a higher temperature.
The Institute of American Poultry Industries bulletin (28)
also advocated low oven temperatures ranging from 1490 to
163°C. to bake tender angel cakes of good volume.

Barmore (4) suggested oven temperatures of not less
than 149°C. nor greater than 177°C. for baking angel cakes.
Cakes baked at oven temperatures between 1490 and 163°C.
were "dry-tasting," while cakes baked at oven temperatures
between 1630 and 177°C. were "moist," according to the

report. Tenderness of the cakes did not decrease at these

higher baking temperatures. However, volume increased as
the baking temperature increased.

To study the effect of high oven temperatures on
tenderness of angel cakes, Barmore (5) baked a series of
cakes at oven temperatures ranging from 1380 to 180°C. In
contrast to the expected results, Barmore found tenderness
and volume of cakes increased as the baking temperature rose.
Because the maximum internal temperature of the cake did not
increase appreciably in proportion to oven temperature used
for baking, Barmore suggested the use of these high oven
temperatures did not toughen the egg white proteins.

In her study of the optimum baking temperature for

angel cakes, Looft (35) investigated the effect of oven tem-

0 O O

peratures of 140°, 150 , 160 , 170 , and 180°C. on the
quality characteristics. Contrary to Barmore's findings (4),
the cakes baked at the lower oven temperatures, although
they lost more moisture during baking, felt and tasted more
moist than cakes baked at the higher oven temperatures. The
volume of the cakes increased as the baking temperature tem-
perature increased but tenderness decreased when the cakes
were baked at the higher temperature. From the results of
her study, Looft concluded an oven temperature of 150°C. was
most desirable for baking angel cakes.

Hellickson (26) reported a project undertaken to

determine the correct procedure for baking angel cakes. She

recommended a baking temperature of 149°C. to consistently

produce light, moist, tender angel cakes. Burke and Niles
(11) found the moisture loss during baking of cakes in a
177°C. oven was less than in cakes baked at 163°C. Cakes
baked at 177°C. were judged superior in volume and quality
characteristics. The crusts, however, had more cracks than
the crusts of cakes baked at 163°C.

Grewe and.Child (19) used an oven temperature of
154°C. in their study on the effect of acid potassium
tartrate on the quality characteristics of angel cakes.
Hunt and St. John (27) baked satisfactory angel cakes pre-
pared from the thick and thin portion of egg whites at an
oven temperature of 163°C.

In their investigation of the effect of pan mate-
rials On the tenderness of angel cakes, Reed, Floyd, and
Pittman (53) used an oven temperature of 163°C. The
investigators concluded the thermal efficiencies of the
aluminum, enamel, glass, Russian iron, and tin pans used in
the study, affected the maximum internal temperatures of the
cakes and hence, the tenderness. A low internal cake temper-
ature yielded a more tender product as measured by breaking
strength. Ranked in order of decreasing tenderness, were
cakes baked in tin, aluminum, Russian iron, enamel, and

'\

glass pans.

10

Other reports

 

In 1943, Miller and Vail (40) studied the quality

0

characteristics of angel cakes baked at 177°, 191 , 204°,

0, and 232°C. Their results showed volume and tenderness

218
increased with the increase in baking temperature from 1770
to 218°C. Cakes baked at 204° and 218°C. received the high-
est palatability scores. The investigators concluded the
most satisfactory baking temperatures for angel cakes were
204° and 218°C. for 35 and 30 min., respectively.

Dudgeon (16), in 1947, recommended a moderate baking
temperature of 163°C. for angel cakes. When higher tempera-
tures were used to bake the cakes, deep cracks developed in
the top crust. However, the interior of the cakes was moist,
tender, and delicate.

Reported research studies of angel cakes conducted
by Carlin and.Ayres (12, 13) and Harns.gtual. (23), used a
baking temperature of 177°C. to study the effect of added
ingredients or egg white quality on the quality characteris-
tics of angel cakes. More recent studies on angel cakes
undertaken by Funk, Zabik, and Downs (18) and Brown and
Zabik (10) used a baking temperature of 177°C. in a forced
convection oven to produce satisfactory angel cakes. Com-
mercial cake mixes (2) recommend baking temperatures ranging
from 1770 to 191°C. and directions given on the package sug-

gest cracks usually develop on the top surface of the cake

during baking.

11

Sensory Evaluation of Quality
Characteristics

According to Griswold (20), sensory evaluation is
essential to most food eXperiments because the important
questions of how a food tastes, smells, looks, and feels to
the ultimate consumer can only be answered in this way.
Sensory evaluation is, however, subject to human judgment
which is individual and not always consistent.

Boggs and Hanson (8) reported panel evaluation is
usually desirable for evaluating food acceptability not as
an entity in itself, but as a basis for correlation with
objective measurements. Funk, Zabik, and Downs (18) stated
sensory evaluations are essential to validate objective
measurements.

Several systems are available for sensory evaluation.
As reported by Griswold (20), numerical scoring of product
characteristics is the most frequently used test to evaluate
food quality. The numerical scale may or may not be qual—
ified with descriptive adjectives. However, descriptive
adjectives are helpful to the judge while he is evaluating
a product.

Meyer (38) reported numerical scoring of product
characteristics is useful for obtaining a basis by which
changes caused by preparation methods can be evaluated.

Qualities commonly evaluated in baked products are appearance,

12

color, aroma, flavor, tenderness, moistness, and general
acceptability.

From an extensive review of the literature, Amerine,
Pangborn, and Roessler (1) concluded careful selection of
judges is essential to achieve maximum discrimination among
the products subject to evaluation. Some form of screening
is helpful to eliminate judges who are unable to discrimi-
nately evaluate food products.

The size of the panel needed for sensory evaluation
of a food product varies with the sensitivities of the
judges as well as the range in acceptability of the product.
According to Lowe (36), small expert panels of four to ten
members are satisfactory for laboratory studies.

Amerine, Pangborn, and Roessler (1) inferred the
influence of health, age, sex, and smoking on panel perfor-
mance is not critical. However, the results of the sensory
panel performance may be influenced by emotional factors,
interest, motivation, knowledge, comparison of results,
adjustment to the test situation, and memory.

Many factors such as environment, sample preparation,
serving conditions, and the number of samples served may
influence the results of the sensory evaluation (1). Envi—
ronmental factors may be controlled with the use of spe-
cially designed taste panel rooms. Controlling such factors
as sample temperature, size, and identification are essen-

tial. Samples are best identified by a code rather than by

13

the name of the treatment. The number of samples served at
one time is dependent on the nature of the food product
being tested and the method of scoring. More samples can be
tasted at a session if the flavor is bland rather than
strong. Also, more samples can be effectively evaluated at
a session if a simple method of scoring is used rather than
a complex scoring method.
Objective Measurements of Quality
Characteristics
Objective measurements of quality characteristics
generally offer more possibility for accuracy and precision
than do subjective evaluations. Therefore, to evaluate dif-
ferences among several variables, many investigators subject
food products to a series of objective measurements. Com-
monly used measurements include volume, moisture, cell

structure, compressibility, tensile strength, and tenderness.

Volume

The volume of baked products may be determined by
seed displacement. This method, as described by Binnington
and Geddes (7), involves the displacement of a free-flowing
solid material such as various types of seeds. Cake volume
has been determined according to this method by many re-

searchers (12, 13, 23, 27, 32, 35, 46).

14

Brown and Zabik (10) measured the volume of angel
cakes baked in 15-1/2 x 4 x 4-in. pans before the cooled
cakes were removed from the pans. The surface of the cake
was covered with Saran before rape seeds were carefully
poured onto the cake. The volume of the cake was calculated
as the difference between the milliliters of seed measured
with the cake in the pan and the milliliters of seed which
the empty pan held.

Because volumetric measurements by seed displacement
methods damaged the fragile structure of sponge cakes, Platt
and Kratz (49) devised a method for determining an index to
volume of baked products using a planimeter. After the out—
lines of representative slices of the cake were drawn on
sheets of paper, a planimeter was used to determine the area
within each outline. The results from several measurements
were averaged for the index to volume of the cake. This
method has subsequently been used by other research workers

(40, 44).

Moisture

Brown and Zabik (10) determined the percentage of
moisture in angel cakes by drying 2-gm., shredded samples to
a constant weight in a vacuum oven at 900 to 100°C. and 29
in. of mercury. These research workers found no significant
differences in the percentage of moisture of angel cakes

prepared from liquid and spray-dried egg albumens.

15

Volatile losses occurring during baking have been
calculated from the difference in the weight of the cake
batter and the baked cake. Kraatz (32) found volatile
losses increased as baking time at a given temperature
increased. According to the results of her study on baking
times and temperatures of angel cakes, cakes baked at 150°C.
for 45 min. lost 13.2 per cent moisture while cakes baked at
170°C. for 25 min. lost only 10.2 per cent moisture.

In a study reported by Miller and Vail (40), angel
cakes baked at 177°C. for 40 min., 191°C. for 35 min., 204°C.
for 30 min., 218°C. for 25 min., and 232°C. for 21 min. lost
43.1, 36.7, 33.3, 32.9, and 30.6 per cent in weight during

baking, respectively.

Cell structure

The cell structure or texture of baked products may
be studied from permanent recordings made by ink prints or
photography. Sand retention tests offer a quantitative
measurement of the size of pores of baked products.

Ink_prints and photography. Mohs (41) used a paste-

 

like mixture of lamp black and oil to moisten the cut sur-
face of bread. The slice was then pressed upon a piece of
unsized paper to give an impression of the cell structure
and shape of the bread. Child and Purdy (15) made ink
prints of cake slices using stencil ink which was trans—

ferred to the cut surface of the cake by means of a soft

l6

brush. The surface of the cake was then pressed upon a
piece of paper.

In their report, Platt and Kratz (49) noted only
fair success in obtaining ink prints of sponge cake slices
because the delicate grain of the product did not lend it—
self to this treatment. Therefore, they used photography
to obtain permanent records of their baking studies, as did
Harrel (24) and Heald (25). The shape and grain of baked
products were recorded by Cathcart (14) by passing light
through a thin slice of the product which had been placed
on a sheet of photographic projection paper.

Contact prints, made from thin slices of a baked
product, were suggested in a study by Matejovsky (37).

The slice was placed between two glass plates, the lower of
which was covered with a piece of filter paper which had
been soaked in a 75 per cent solution of glycerine in water.
The slice was then taken to a dark room and transferred to
a piece of photographic paper. After exposure to a source
of illumination, the photographic paper was developed in the
usual manner. A number of prints were collected and used as
a basis of comparison in analysis. A scale of porosity was
developed using numbers from one to ten to denote increasing
size of pores and this scale permitted accurate and easy
comparison of results, according to the report.

Sand retention test. Because photographic records

 

do not give results which can be measured quantitatively,

l7

Swartz (55) developed a sand retention test to estimate the
grain of baked products. For this determination, a weighed
piece of cake is placed on a board set at a 400 or 450 angle
and sand is sifted over it. The piece of cake is then
rotated to permit sand that is not retained in the pores to
fall off. The sample is reweighed and the percentage of
sand retained is calculated. If the grain of the product is
coarse, more sand is retained than if the grain is fine,
according to the report. The amount of sand retained was
also influenced by the location from which the sample was
taken, moisture content of the product, and the manner of

adding the sand, according to the report.

Compressibility

 

Many of the methods described by various investiga—
tors for measuring compressibility of a baked product are
based on the same principle. A sample of a given product is
subjected to a specified weight for a given period of time.
The amount of depression is measured. The instrument con-
structed for measuring compressibility obeys Hooke's law in
that the strain produced is in proportion to the strain
producing it.

Devised instruments andjpentrometers. Making use of
the above principle, one of the early devices for compressi-
bility was developed by Katz as reported by Powers and

Simpson (50). The descent of a weighed plunger, as it

18

compressed the baked product for a period of 3 min., was
indicated by means of a pointer. Platt (48) developed a
similar device by attaching a plunger to the bottom of one
pan of a large analytical balance. The depression of the
plunger into a slice of bread was recorded in millimeters
by the pointer on the balance. Similar instruments were
devised and used by Miller and Vail (40), and Powers and
Simpson (50) for compressibility measurements.

Bailey (3) also devised a compressibility tester
by allowing an object of known weight to rest on a prism
of bread for a period of time. Owen and Van Duyne (44)
determined compressibility of cakes using a devised com-
pressometer. This instrument, which was similar to that of
Platt (48), had been modified by attaching a small electric
motor which raised the platform holding the cake sample at
a uniform rate.

King, Whiteman, and Rose (30), and King, Morris and
Whiteman (31) measured the compressibility of cakes using a
penetrometer. The amount of depression produced by the disc
was recorded in centimeters on the scale machined on the
moveable post which held the disc. Paul, Batcher, and Fulde
(46), using a Precision Universal Penetrometer fitted with a
flat disc, determined compressibility of cake by measuring
the distance the crumb was flattened by the known weight of

the disc over a specified period of time.

l9

Kramer shear-press. The Kramer shear-press was

 

developed to measure the tenderness of fruits and vegetables
(33). The basic unit of the shear-press consists of a
piston moving at a predetermined rate of speed, powered by
a hydraulic drive system. The applied force is measured by
compression of a proving ring dynometer. A sensitive pres-
sure gauge, connected to the proving ring and through an
amplifier to a recording device, provides a continuous
recording of time-force curves to indicate the force re—
quired to compress a food product.

In a review article, Kramer (34) stated the shear-
press could be used to measure quality characteristics, such
as compressibility, of baked products. Funk, Zabik, and
Downs (18) investigated the use of the shear-press to mea-
sure compressibility of angel cakes of three degrees of
toughness. The plunger from the succulometer cell and the
fixed-blade upper assembly of a standard shear-compression
cell were used to measure the compressibility of cake sam-
ples. Very highly significant correlations between the two
different sets of Kramer shear-press measurements of com-
pressibility and sensory evaluations of tenderness were
obtained in this investigation.

Brown and Zabik (10) measured compressibility of
angel cakes prepared with albumen processed in five differ—
ent ways, using the Kramer shear-press and statistically

significant differences were found. Parks, Zabik, and Stine

20

(45) obtained no significant differences among five vari-
ables of chocolate cakes when the Kramer shear-press was

used to measure compressibility.

Tensile strength

 

Platt and Kratz (49) developed one of the first and
most widely used procedures for determination of tensile
strength of cake. In this procedure, they suspended an
hourglass—shaped cake sample, which measured 3.8 cm. across
the center, from one end by a clamp. A small container was
hung from a clamp on the opposite end of the cake sample.
The investigators allowed water to flow into the container
at a constant rate of 200 gm. per min. until the total
weight caused the cake sample to break or tear across the
center section. Tensile strength was calculated from the
total weight consisting of the combined weights of the con-
tainer, water, lower clamp, and cake sample, divided by the
area of the break.

Barmore (4K 5), Kraatz (32), Looft (35), and Miller
and Vail (40) devised similar instruments to measure tensile
strength of angel cakes. In her study of the effect of
baking temperature on characteristics of angel cakes, Looft
(35) found no significant correlations between tenderness
scores and tensile strength measurements. Nevertheless, in
studies conducted by Briant and.Williams (9), Jordan, Barr,

and Wilson (29), and Feet and Lowe (47), high correlations

v,‘

21

were obtained between sensory evaluation and tensile
strength of yellow cakes as measured by similar devised
instruments.

Tensile strength of angel cakes was measured by Reed,
Floyd, and Pittman (53). However, sand rather than water
was used with the instrument described by Platt and Kratz
(49). Pyke and Johnson (51) used a similar procedure to
that of Platt and Kratz (49) for tensile strength determina-
tions. The instrument was modified to reduce the potential
danger of accidental damage to the cake samples by using
flat pieces of wood, rather than metal clamps to grip the
cake samples.

Funk, Zabik, and Downs (18) used a specially de—
signed attachment for the Kramer shear-press to measure the
tensile strength of hourglass—shaped angel cake samples.

The attachment was designed from the instrument described
by Platt and Kratz (49). Readings of the ram upstroke were
obtained by rewinding the chart—drive cable of the shear-
press. Very highly significant correlations between the
shear-press measurements of tensile strength and sensory
evaluations of tenderness were obtained in the study when
calculations were based on the maximum force, but no corre-
lation was found when calculations were based on area-under—
the-curve.

Brown and Zabik (10) measured the tensile strength

of angel cake slices in their study on the functional

22

properties of heat treated liquid and Spray-dried albumen.
No significant differences among cake samples were obtained
in this study.

In their study on the substitution of foam spray-
dried acid whey solids for buttermilk solids in chocolate
cake, Parks, Zabik, and Stine (45) found no significant dif-
ferences in tensile strength among the five cake variables
included in the study. These workers used the Kramer shear-
press method as described by Funk, Zabik, and Downs (18)
with the modification of a more sensitive electronic recorder

for the shear-press.

Tenderness

 

The objective measurement of tenderness is complex,
according to Griswold (20), because it must reflect the
action of teeth in cutting, shearing, tearing, grinding, and
squeezing. Hence, compressibility and tensile strength mea-
surements may be determined as an indication of tenderness
(20).

The Kramer shear-press equipped with the standard
shear-compression cell, was used by Funk, Zabik, and Downs
(18) to measure tenderness of angel cake samples. The corre—
lations calculated from shear—press measurements and sensory
evaluations of tenderness were very highly significant.

Brown and Zabik (10) also measured tenderness of angel cake

23

samples using the Kramer shear-press. However, no signif-
icant differences were found among cakes prepared from

albumen processed in five different ways.

EXPERIMENTAL PROCEDURE

The primary purpose of this study was to investigate
the effect of baking temperatures of 177°, 191°, 204°, and
218°C. on the quality characteristics of angel cakes. The
quality characteristics were determined by sensory evalua-
tion and objective measurements. A secondary purpose was to
assess the validity of objective measurements which could be
made in laboratories with limited equipment by correlating

apprOpriate combinations of data obtained by sensory evalua-

tions and/or objective measurements.
Design of the Experiment

Angel cakes were prepared from a common lot of
household-size packages of commercial, one-step cake mix.1
To provide sufficient slices of cake for sensory evaluation
and objective measurements, two cakes were required for each
replication. Therefore, the contents of two packages were
combined for each batch of cake batter which was divided

into two equal portions for baking. Each of the four vari-

ables of baking temperature was replicated four times.

 

1General Mills, Inc., Minneapolis, Minnesota.

24

25

Preliminary Investigations

The procedure for mixing the cake was established
through preliminary investigations. The directions of the
manufacturer of the cake mix were followed after weights,
given in ounces, and measures, given in cups, had been con-
verted to grams and.milli1iters, respectively.

The baking time for each of the four oven tempera-
tures was also established by preliminary investigations.
Doneness of the cakes was determined according to the
directions given on the package. When the cracks which
developed in the top of the cake felt "dry to touch," the
cakes were removed from the oven. Baking times of 44, 39,
'35, and 32 min. were defined for the oven temperatures of

O O

177 , 191 , 204°

, and 218°C., respectively.
Method of Preparation

For each batch of cake, 650 ml. of distilled water
at 15°C. were poured into a 20-qt. mixing bowl for a Hobart
mixer, Model A-200. After weighing 850 gm. of cake mix on
a 5-kg. capacity torsion balance, it was added to the water.
With the mixer setaflzspeed one, the mixture was blended for
30 sec. using the whip attachment. After the sides and
bottom of the bowl were scraped with a rubber spatula, mix-
ing was continued at the same speed for an additional 30 sec.

The sides and bottom of the bowl were again scraped before

26

the mixture was whipped at speed three for 4-1/2 min. To
insure accurate timing, a GraLab timen,Model 171 was used.
The specific gravity and pH were determined to insure

uniformity of the cake batter.
Baking and Storage Procedure

Using 685 gm. per pan, the cake batter was poured
into two tared, ungreased 16 x 3-1/4 x 4—in. aluminum pans.
To dispell any large air pockets, a metal spatula was used
to cut through the batter five times in a lengthwise direc-
tion.

Time-temperature relationships were continuously
recorded during baking with a lZ-point Brown Electronic
Potentiometer high-speed recorder. Two iron constantan
thermocouples were suspended into the cake batter and held
in place by clamping to an aluminum bar which spanned the
longitudinal center of the baking pan (Figure l). The
potentiometer leads were positioned 2.5 and 5.0 cm. from the
bottom of the baking pan.

Mean progressive time-temperature relationships were
determined for each baking temperature. The initial temper-
ature recordings from each of the two points within each of
the eight cakes baked at each of the four oven temperatures

0

of 177°, 191 , 204°

, and 218°C., were averaged. At 5-min.
intervals throughout the baking period, temperature record-

ings from each of the two points were averaged. The final

27

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d

BROWN Ff! '

 

  

.6.

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“.‘o‘.‘

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at ,1
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FIG. 1 Positions of potentiometer leads during baking of
angel cakes at four oven temperatures.

28

5-min. interval of the baking period was reduced in length
for l to 3 min. for the baking times of 44, 39, and 32 min.\
so the maximum temperature reached within each Cake was
included in the averages. :

Two institutional heavy-duty Hotpoint ovens, Model
HJ225, equipped with Honeywell Versatronic Controllers were
used for baking the Cakes. The upper deck was‘used to bake
cakes at 1770 and 191°C. for 44 and 39 min., respeCtively,
while the lower deck was used to bake cakes at 204°_and
218°C. for 32 and 30 min., respectively. DuringRbaking,
oven grids were set on medium and the dampers were half
Open. The two cakes representing one replication were baked
simultaneously, in the same preheated oven. All baking at
each of the four oven temperatures was completed before
resetting the oven controller to a different temperature.

Immediately after baking, the potentiometer leads
were carefully removed. The cakes were then inverted and
cooled in the pans for 1-1/2 hr. After the cakes were
removed from the pans, they were allowed to cool for an
additional 30 min. on wire racks. The cakes were then coded,
wrapped in Saran, put into polyethylene bags, and frozen at

-23.3°C.

29

Objective Measurements of Cake Batter

Control over all conditions of the study except the
variable of oven temperature was necessary. As measures of
control, the specific gravity and pH of the cake batter were

determined.

Specific gravity of batter

 

The specific gravity of the batter of each replica-
tion was determined according to the method of Platt and
Kratz (49). The technique used in this study involved a
comparison of the average weight of one-third cup of cake
batter to the average weight of one-third cup of distilled
water at 25°C. The cake batter was carefully spooned into
the one-third cup measure, leveled with a spatula and weighed
to the nearest 0.1 gm. on a Mettler balance, model P-1000.
The Specific gravity was computed by dividing the weight of
the cake batter by the weight of the distilled water. One
determination of specific gravity was made from the batter

of each replication.

pH of batter

 

The pH of the cake batter was determined using a
Beckman Zeromatic pH meter equipped with calomel and glass
electrodes. The batter used to measure the specific gravity
was divided into two portions, duplicate readings of the pH

were recorded and then averaged.

30

Subjective Evaluation of Baked.Cakes

The investigator subjectively evaluated the appear—
ance of each cake prior to preparing it for freezer storage.
The color of the top, sides, and bottom, texture of the
sides, and appearance of cracks which developed on the top
of each cake were evaluated using descriptive terms (Appen-

dix).
Preparation of Samples

All cakes were sliced in the frozen state using a
Hobart slicer, Model 410, set at 70. Slices of cake were
designated for sensory evaluation and objective measurements
according to randomly devised rotation plans developed for
each of the four replications of the variables (Figure 2).
The four rotation plans permitted evaluation of samples from
different positions within the cake by panelists and the
objective measurements. All frozen slices of cake were
individually re-wrapped in Saran and placed in polyethylene
bags. They were stored in a -23.3°C. freezer until subse-

quent thawing and evaluation.
Sensory Evaluation

A circle, 5.25 cm. in diameter, was cut from the
center of each frozen slice of cake designated for sensory

evaluation using the previously described rotation plan

31

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33

(Figure 2). The cake sample was wrapped in Saran and placed
on a white, paper plate which had previously been coded with
a random number. Samples were allowed to stand at room tem-
perature for 1—1/2 hr. to thaw and come to room temperature
before evaluation. Two samples from each of three replica-
tions were randomly presented at each session to each of the
six, trained, panel members. Tap water, at room temperature,
was served with the samples.

A numerical scale was used to evaluate the cakes for
texture, tenderness, moistness, and color of the crumb. The
scoring range was from 1 to 7, with 1 indicating the poorest
and 7, the highest quality. Descriptive terms for the
values of l, 4, and 7, aided the panelist in the evaluation.
The score card and instructions to the taste panel are

included in the Appendix.
Objective Measurements

Several objective measurements were used to evaluate
the quality characteristics of angel cakes. These included
measurements of volume, moisture, cell structure, compress-

ibility, tensile strength, and tenderness.

Index of volume

 

The index of volume for each replication was deter-
mined by averaging readings of three slices from each of the
two cakes comprising a replication. Slices were taken from

the center and a distance half-way between the center and

34

both ends of the cake (Figure 2). The index of volume was
made as outlined by Platt and Kratz (49). Defrosted cake
slices were placed on sheets of paper and carefully traced.
The area was measured by tracing the outline of the cake
slice with a K & E Compensating Polar Planimeter. Each trac-
ing was repeated three times, the readings were averaged,

and converted to square centimeters.

Moisture of cake

 

The percentage of weight loss during baking was
calculated as an indication of the moistness of the cakes.
The percentage of moisture in the cakes was also determined.

Percentage of weight loss during baking. All cakes

 

were weighed to the nearest gram before they were removed
from the baking pans. The percentage of weight lost during

baking was calculated according to the formula:

Weight loss, in_grams

Weight of batter, in grams X 100

 

The percentages of weight loss of the two cakes representing
one replication were averaged.

Moisture determinations. Cake moisture was deter—

 

mined according to the A.O.A.C. method, 16-3 (b) (43). The
designated, frozen cake slices were defrosted at room tem-
perature for 1-1/2 hr. After removing the Saran wrapping
from the slice, duplicate, shredded samples from each of the

two cakes which comprised a replication, were weighed in

35

tared aluminum-foil dishes to the nearest 0.0000 gm. using

a Mettler balance, Model H15. The samples were dried for

5 hr. at 900 to 100°C. and 28 in. of mercury. Dried samples
were cooled for 30 min. in a dessicator before reweighing.
Four values were averaged to determine the moisture content

of each replication.

Structure of the cell

 

While in the frozen state, a circle, 5.25 cm. in
diameter, was cut from the center of each slice of cake
designated for sand retention in the rotation plan (Figure 2).
The samples were re-wrapped in Saran and allowed to thaw at
room temperature for 1-1/2 hr. The samples were then weighed
to the nearest 0.00 gm. using a Torbal torsion balance,

Model PL-800. According to the method of Swartz (55),
approximately 1 tsp. of sand was sprinkled over each piece
of cake which had been placed on a 45°, inclined plane. The
device holding the cake sample was revolved twice. The sam-
ple was then reweighed and the percentage sand retention was

calculated using the formula:

Weight of sand retained X 100
Original weight of sample

 

Duplicate measurements were averaged to indicate the struc-

ture of the cells of the cake.

36

Compressibility of cake

 

Compressibility was measured with a Precision
Universal Penetrometer and a Kramer shear-press. For both
measurements, circles of cake 5.25 cm. in diameter, were cut
from frozen cake slices. Each sample was re-wrapped in
Saran and allowed to defrost at room temperature for 1-1/2
hr.

Penetrometer measurements. A flat disc, weighing

 

25.5 gm., was positioned on the surface of the cake sample.
The disc was allowed to compress the sample for a 30-sec.
period and the amount of compressibility was eXpressed in
millimeters. The values from two samples from each replica-
tion were averaged.

Kramer shear-press measurements. Compressibility of

 

cake samples was determined according to the method of Funk,
Zabik, and Downs (18) using the plunger of the succulometer
cell of the Kramer shear-press, Model SP12, equipped with an
electonic recorder, Model E2EZ. The 100-1b. electronic prov—
ing ring at a range of 5 1b. and a pressure of 25 1b. was i
used. A circular sample of cake, 5.25 cm. in diameter and
2.00 cm. in thickness, was depressed on a wooden plate
placed on the support plates at the base of the main column
of the shear-press. Each cake sample was depressed to a
uniform thickness of 1.16 cm. during a 30-sec. downward

stroke of the plunger (Figure 3). Compressibility was

37

 

FIG. 3 Compressibility measurements of angel cakes using
the Kramer shear-press.

38

calculated by multiplying the maximum force reading on the
recorded curve times the range used.

Area-under-the-curve was calculated for the shear-
press measurement. Each curve was carefully cut out and
weighed on a Mettler balance, model H15, to the nearest
0.0000 gm. A conversion factor of 174.2 for changing the
gram-weight to area had previously been determined (18) by
weighing multiple squares varying in area and taken from
random locations on similar chart paper. Two values, deter-
mined as weight times conversion factor, were averaged for

the compressibility of each replication.

Tensile strength

Tensile strength of all end slices of cake as well
as body slices designated in the rotation plan (Figure 2)
was determined using a specially designed attachment for the
Kramer shear-press, according to the method of Funk, Zabik,
and Downs (18). Acco clamps, No. 325, were modified by sub-
stituting light weight springs and flattening the indented
edge to reduce possible damage to cake samples. A set screw
was also added to further regulate the force placed against
the cake samples. The clamps were attached to a U-shaped
base plate and an upper assembly just large enough to attach
to the proving ring. The 100-1b. electronic proving ring,
the l-lb. range, and 25-lb. pressure were used. A reading

on the ram upstroke was obtained by rewinding the chart—drive

39

cable of the shear press (Figure 4). Samples of cake were
cut from frozen cake slices, 2.00 cm. thick, with an hour-
glass-shaped cutter measuring 2.54 cm. across the center.

The width of the break was measured with vernier calipers.

The formula

Maximum graph reading X Range
Area of the break (in cm‘)

was used to calculate tensile strength. The results of three
measurements were averaged to determine the tensile strength
of the cake body of each replication. Tensile strength
values of end slices represent an average of the four end

slices of each replication.

Tenderness of cake

 

The standard shear-compression cell of the Kramer
shear-press was used to measure tenderness of the cakes.
For this measurement, the lOO-lb. proving ring, a range of
50-lb. and 25-lb. of pressure were used. The cake samples,
5.39 cm. square and 2.00 cm. thick, were weighed to the
nearest 0.00 gm. using a Torbal torsion balance, Mbdel
PL-800. The cake samples were sheared during a 30-sec.
downstroke of the upper assembly of the shear-compression
cell. Between all tenderness measurements, the cell was
washed in tepid water and dried with unheated forced air.

Tenderness was calculated as:

Maximum graph reading X Rangg
Sample weight

 

 

 

a
._ .
90 ..

HO 1|
‘.-~ . 4,‘
‘> ,, - a"

FIG 4. Tensile strength measurements of angel cakes
the Kramer shear—press.

 

41

The area-under-the—curve was also calculated using the

previously outlined procedure.
Analysis of Data

The data obtained were analyzed for variance using
the RAND Routine (Option 1) for the CDC 3600 computer at
Michigan State University. Duncan's Multiple Range Test
(17) was used to pinpoint further the sources of significant
differences.

Correlation coefficients were determined for all
possible combinations of sensory evaluations and objective
measurements using a BASTAT Routine for the CDC 3600 com—
puter. Means and standard deviations were calculated using

a special program for the CDC 3600 computer.

RESULTS AND DISCUSSION

This study was undertaken to determine the effect of

baking temperatures of 1770, 1910, 2040

, and 218°C. on the
quality characteristics of angel cakes, as measured by
sensory evaluation and numerous objective measurements. The
investigation included two phases: .(1) a study of the
effect of oven temperatures on quality characteristics of
angel cakes in an attempt to define the most desirable bak-
ing temperature for the product, and (2) assessment of
validity of simple objective measurements, as would be avail-
able in laboratories with limited equipment, by correlating
appropriate data obtained by objective measurements and
sensory evaluations.

Tables of averages, grand averages, standard devia-
tions, as well as the statistical analyses, accompany the
discussion of the results. A table of the correlation coef-

ficients calculated from apprOpriate combinations of the

data is included in the Appendix.
Objective Measurements of Cake Batter

To insure uniformity of the cake batter, two objec-
tive measurements were used. The specific gravity and the

pH were determined.

42

43

Specific gravity of batter

The specific gravity of each batch of cake batter is
presented in Table 1. Analysis of variance showed highly
significant differences in specific gravity measurements
among the cake batters produced for the four variables of
oven temperature. Significant differences existed among the
four replications of each variable. Examination of the data
showed variations in the specific gravity occurred only dur-
ing the first two days of cake preparation. Therefore,
eXperimental errors involving the use of the balance explain

variances which occurred.

pH of batter

 

The pH values of each batch of angel cake batter
along with grand averages and standard deviations for each
variable are presented in Table 2. Analysis of the data
showed no significant differences in pH values of cake
batters. The average pH value for all cakes was 6.2.

Rates of Temperature Rise
During Baking

Potentiometer leads were placed at two points within
each cake. Mean progressive time-temperature relationships
were plotted for the eight cakes baked at each of the four

0

oven temperatures of 1770, 191 , 204O

, and 218°C.

44

TABLE 1 Specific gravity values of angel cakes baked at
four oven temperatures

 

 

Means, grand averages, and standard deviations

 

 

 

Oven Temperatures
Replication 177°C. 191°C. 204°C. 218°C.
a
l .35 .37 .35 .38
2 .35 .36 .35 .37
3 .35 .36 .35 .36
4 .34 .35 .35 .35
Grand average .35 .36 .35 .37
Standard deviation .005 .008 .000 .013

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 0.00027 8.02**
Replicates 3 0.00016 4.59*
Error 9 0.00003
Total 15

 

 

 

 

a O 0
Each value represents one determination.

*Significant at the 5% level of probability.

**Significant at the 1% level of probability.

45

TABLE 2 pH values of angel cakes baked at four oven
temperatures

 

Means, grand averages, and standard deviations

 

 

 

Oven Temperatures

Replication 177°C. 191°C. 204°C. 218°C.

1 6.2a 6.3 6.2 6.2

2 6.3 6.3 6.2 6.3

3 6.2 6.3 6.2 6.2

4 6.2 6.1 6.2 6.2
Grand average 6.2 6.3 6.2 6.2
Standard deviation 0.05 0.10 0.00 0.05

 

 

 

 

 

aEach value represents an average of two determinations.

Time-temperature relationshipg
recorded 2.5 cm. from the bottom
surface of the cake pan

 

 

 

As shown in Figure 5, temperatures within the cakes
rose at a rate dependent on the oven temperature with the
slowest rate of temperature rise recorded for the 177°C.
oven. After an initial period of time, which increased as
the oven temperature decreased, the temperatures within all
cakes rose at a very rapid rate. Very rapid rates of tem—
perature rise were noted for all cakes until an internal
temperature of approximately 850C. had been reached. There—
after, the rates of temperature rise decreased.

Moisture was lost by evaporation during baking as

indicated by the percentages of weight loss (Table 9).

46

 

Oc .

100 ' 1”:fi.--“' J
90 - .1
80F .

' '1
70 _ -
" 1
60)— —
1 ,1; _
' .'
50L q; 1
I

 

q

40 Oven temperatures:

 

 

 

177°C.

30 ........... 191°C .

—-— 204°C.

_ . ---- 218°C.
2016/. A
t 1
10- a
)- -

0 I I I I I I I I L J

 

0 10 20 30 40 50
Time, in minutes

FIG. 5 Average rates of temperature rise as measured 2.5 cm.
from the bottom of the pans used for baking angel
cakes at four oven temperatures.

47

Also, gelatinization of the starches as well as the hygro—
scopic properties of sugar present in the cake batter would
determine the moisture distribution within the cake at a
particular time during the baking process. According to
Barmore (4), the endothermic process of egg white coagula-
tion in angel cakes is influenced by the ingredients present
as well as their concentration. A combination of these
factors probably account for decreases in the rates of tem-
perature rise during the latter part of the baking period.
Time—temperature relationshipg

recorded 5.0 cm. from the bottom
surface of the cakegpan

 

 

Time—temperature relationships plotted from data
recorded 5.0 cm. from the bottom surface of the cake pan
showed a very rapid rise during the first 5 min. of baking
as shown in Figure 6. For the next eight to eleven minutes
of baking, the rate of temperature rise within cakes baked
at the four oven temperatures decreased. The potentiometer
lead positioned 5.0 cm. from the bottom surface of the pan
was near the exterior of the cake batter when the baking
began. Hence, the recording reflects the temperature at the
surface of the cake batter during the initial baking period.
As the cake increased in volume during baking, the recording
from the potentiometer lead indicated a decrease in the rate

of temperature rise within the cake for a period of time.

48

 

 

 

 

 

 

c.
l I I j l T l l l l
100 '— ’I -—i
/ / .4"
90 - -
80 - -
70 _ ..
‘ 1
60 *- -
' j
50 - -
' Oven temperatures: ‘
40
— 177°C. 1
: ”" 191O .
30 5 -
:' "" 204°C.
q
“““ 218°C.
20 1
lo - d
P H
O I I 1 I I I I J I I
0 10 20 50 ' 40 * 50

Time, in minutes

FIG. 6 Average rates of temperature rise as measured
5.0 cm. from the bottom of the pans used for
baking angel cakes at four oven temperatures.

49

Very rapid rates of temperature rise were noted for

O, and 218°C. until the internal

cakes baked at 191°, 204
temperature of the cakes reached approximately 820C. There-
after, rates of temperature rise decreased. The very rapid
rates of temperature rise for cakes baked at 1770C.,
decreased when the internal temperature of the cakes reached
approximately 770C. (Figure 6). These decreases in the
rates of temperature rise probably reflect moisture changes
and/or protein coagulation within the cake during the baking
process.

A comparison of the average time-temperature rela—
tionships recorded from the two points within each cake
shows that after the first 10 to 15 min. of baking time,
temperatures recorded at a point 2.5 cm. from the bottom of
the cake were higher than those recorded at a point 5.0 cm.
from the bottom of the cake. This was as expected because
heat within the cake would be transferred by conduction and/
or convection from the outer surfaces toward the center of
the cake.

Maximum internal temperatures
of cakes

The maximum internal temperatures recorded for the
cakes baked at each of the four oven temperatures as well as
grand averages, standard deviations, and statistical analy—

ses, are presented in Table 3. very highly significant

50

TABLE 3 Data and statistical analyses for the maximum
internal temperature recorded for angel cakes baked
at four oven temperatures

 

 

 

 

 

 

Means, grand averages, and standard deviations
Oven Temperatures

177°C. 191°C. 204°C. 218°C.

A B C D

°C. °C. °C. °C.
1 98.0b 99.3 99.5 100.8
2 98.3 99.5 100.5 100.3
3 98.0 99.5 100.3 100.0
4 97.8 99.5 99.5 100.5
Grand average 98.0 99.5 100.0 100.4
Standard deviation 0.2 0.1 0.5 0.3

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 4.244 34.86***
Replicates 3 0.077 0.64
Error 9 0.122
Total 15

 

 

 

 

Duncan's Multiple Range TestC

 

Significant at

Additional at

 

 

P g_0.001 P < 0.01 p < 0.05
B,C,D > A D > B

 

 

 

aThermocouples inserted 5.0 cm. from the bottom of the pan.

b

from the two cakes comprising one replication.

Each value represents an average of temperature readings

CValues underscored by the same line are not significantly
different (17).

*3‘:*

Significant at the 0.1% level of probability.

51

differences were found among the maximum internal tempera-
tures recorded for angel cakes.

According to further analysis using Duncan's Multi-
ple Range Test (17), a very highly significant increase
existed between the maximum internal temperatures of cakes

0, and 2180C. compared with the maximum

baked at 191°, 204
internal temperature of cakes baked at 1770C. At the 1%
level of probability, the maximum internal temperatures of
cakes baked at 2180C. were higher than those baked at 1910C.

The average maximum internal temperature of cakes
baked at 2180C. was 2.4OC. higher than average maximum inter-
nal temperatures of cakes baked at 1770C. These results
appear to agree with the findings of Barmore (5), indicating
the maximum internal temperature of cakes does not increase
in proportion to increases in oven temperatures used for
baking angel cakes.

An examination of the time—temperature data plotted
for the angel cakes (Figures 5,6), showed the maximum inter-
nal temperatures of cakes were not maintained for the final
minutes of the baking period as Looft (35) had indicated in
her study. However, Looft indicated maximum internal temper—
atures of angel cakes increased as the baking time increased.
The cakes used in this investigation were subjectively eval-
uated as done during preliminary investigations when baked
for the prescribed times. These conflicting results suggest

further investigations are needed to define doneness of

52

angel cakes as determined by maximum internal temperatures

and/or time—temperature relationships.
Subjective Evaluation of Baked Cakes

Using the form which appears in the Appendix, the
investigator subjectively evaluated the cakes after they
were baked. During baking, all cakes baked at the four oven
temperatures developed lengthwise cracks at each side of the
top. These cracks appeared deeper in cakes baked at 2040
and 2180C. than the cracks present in the tops of cakes
baked at the two other oven temperatures. After removal
from the oven, the portion of the cake between the cracks
tended to collapse in cakes baked at 2040 and 218°C. Per-
haps the rapid expansion of the air during baking produced
a delicate structure within these cakes and when they were
removed from the oven, the crust was too heavy to be sup-
ported by the cake structure. Hence, the cake partially
collapsed. The extent of collapse was dependent on the
baking temperature, being more pronounced in cakes baked at
218°C.

The color of the sides and bottom of cakes baked at

O and 1910C. was very light golden brown, while the sides

177
and bottoms of cakes baked at the two higher temperatures
tended to be golden brown in color. The color of the top

crust ranged from golden brown, to slightly dark brown, to

53

very dark brown, to burned when the cakes were baked at

O, 1910, 2040, and 2180C., respectively.

177
No differences were observed in the texture of the
sides and bottom of cakes baked at the four oven tempera-

tures. All cakes were sticky on the sides and bottom sur-

faces.
Sensory Evaluation

Texture, tenderness, moistness, and color of crumb
were the characteristics of angel cakes evaluated by a
trained taste panel to study the effects of four baking tem—
peratures. Sensory judgments were based on a 7-point scale,
indicating a range from poor to excellent quality. Scores
of all judges were averaged for each of the four quality
characteristics of each replication. Based on this average
score of the quality characteristics for each cake, grand

averages were computed.

Texture

The texture scores, grand averages, standard devia-
tions, and statistical analyses are presented in Table 4.
Analysis of variance for texture scores disclosed very
highly significant differences attributable to baking temper-
atures. Grand average texture scores were 5.0, 5.1, 4.5,

O

and 3.3 for angel cakes baked at 177°, 191 , 204°, and 218°C.,

respectively. Further analysis of the data using Duncan's

54

TABLE 4 Data and statistical analyses of sensory scores for
texture of angel cakes baked at four oven tempera-
tures

 

 

Means, grand averages, and standard deviations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

*‘k

 

 

 

Oven Temperatures
o o o o
«_ a 177 C. 191 C. 204 C. 218 C.
Replication A B C D
a
l 5.1 5.0 4.7 3.0
2 4.9 5.3 3.9 2.8
3 5.1 4.9 4.7 3.7
4 5.0 5.0 4.7 3.8
Grand average 5.0 5.1 4.5 3.3
Standard deviation 0.1 0.2 0.4 0.5
Statistical Significance
Analysis of Variance
Source of Degrees of
Variance Freedom Mean Square F Statistic
Temperature 3 2.608 24.97***
Replicates 3 0.135 1.29
Error 9 0.104
Total 15
Duncan's Multiple Range Testb
significant at Additional at
P g_0.001 P < 0.01 P < 0.05
A,B, C > D A,B 5 c

 

 

 

aEach value represents an average of two evaluations for
each of the six judges.

bValues underscored by the same line are not significantly
different (17).

*
Significant at the 0.1% level of probability.

55

Multiple Range Test (17), indicated cakes baked at 2180C.

o, and 2040C.

had poorer texture than cakes baked at 1770, 191
This difference was significant at the 0.1% level of proba-
bility. At the 5% level of probability, cakes baked at
2040C. scored lower in texture than cakes baked at 1770 and
191°C.

These findings indicated baking temperatures above
1910C. resulted in cakes poor in texture. The judges com-
mented on the texture of cakes baked at 2040 and 218°C. as
being compact in some areas as indicated by the presence of
thick layers. As previously indicated, these thick layers
probably developed within cakes baked at the two higher oven

temperatures as a result of the partial collapse of these

cakes after they were removed from the oven.

Tenderness

 

The tenderness scores for each replication of angel
cakes as well as the grand averages and standard deviations
for each of the four baking temperatures are presented in
Table 5. Analysis of variance showed very highly signifi-
cant differences in tenderness among the cakes. Cakes baked
at 1770C. received a grand average score of 6.1 for tender-
ness while grand average tenderness scores for cakes baked

0, and 2180C. were 5.8, 5.6, and 4.6, respec—

at 191°, 204
tively. Duncan's Multiple Range Test (17) exhibited a very
highly significant decrease in tenderness scores of cakes

baked at 2180C., compared with tenderness scores of cakes

56

TABLE 5 Data and statistical analyses of sensory scores for
tenderness of angel cakes baked at four oven
temperatures

 

 

Means, grand averages, and standard deviations

 

 

 

 

 

 

 

Oven Temperatures
o o o o
. . 177 C. 191 C. 204 C. 218 C.
Replication A B C D
1 6.1a 5.4 5.8 4.8
2 6.3 6.0 5.4 4.3
3 5.9 5.7 5.7 4.7
4 6.2 6.1 5.5 4.5
Grand average 6.1 5.8 5.6 4.6
Standard deviation 0.2 0.3 0.2 0.2

 

Statistical Significance

 

Analysis of Variance

 

 

 

 

 

 

 

 

Source of Degrees of
Variance Freedom Mean Square F Statistic
Temperature 3 1.792 - 26.01***
Replicates 3 0.005 0.07
Error 9 0.069
Total 15
Duncan's Multiple Range Testb

Significant at Additional at

P g_0.001 P < 0.01 P < 0.05

A,B,C, > D A > C

 

 

 

aEach value represents an average of two evaluations for
each of the six judges.

bValues underscored by the same line are not significantly
different (17).

***Significant at the 0.1% level of probability.

baked at the three other oven temperatures. The baking tem-
perature of 1770C. produced more tender cakes at the 5%
level of probability than did the baking temperature of
2040C. No significant differences in tenderness scores
existed between cakes baked at 1770 and 1910C.

The results of this study disclosed a decrease in
tenderness if the baking temperature used for angel cakes
was higher than 1910C. These results are in disagreement
with data reported by Miller and Vail (40) who indicated
tenderness of angel cakes increased with the increase in
baking temperature from 1770C. to 2180C.

Tenderness scores for angel cakes were correlated
with texture scores. The very highly significant correla—
tion coefficient (r = 0.89) indicated tender cakes had

medium-sized air cells with thin cell walls.

Moistness

 

Moistness scores, grand averages, standard devia—
tions and statistical analyses are presented in Table 6.
The analysis of variance computed from moistness scores
showed highly significant differences attributable to baking
temperatures. Further analysis of the data, using Duncan's
Multiple Range Test (17), indicated moistness scores aver-
aging 5.7, 5.5, and 5.6 for cakes baked at 177°, 191°, and

2040C., respectively, were not significantly different. A

very highly significant difference existed between the

58

TABLE 6 Data and statistical analyses of sensory scores for
moistness of angel cakes baked at four oven tempera-
turesa

 

 

Means, grand averages, and standard deviations

 

 

 

Oven Temperature
.0 o o o
. . 17: C. 191 C. 204 C. 218 C.
Replication A B C D
1 5.2 4.5 6.2 4.2
2 6.0 5.8 5.7 3.8
3 5.3 5.0 5.2 3.9
4 5.8 5.7 5.3 4.8
Grand average 5.7 5.5 5.6 4.2
Standard deviation 0.3 0.4 0.5 0.5

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 2.072 l7.92***
Replicates 3 0.281 2.43
Error 9 0.116

Total 15

 

 

 

 

. b
Duncan's Multiple Range Test

 

Significant at Additional at
P g_0.001 P < 0.01 P < 0.05

 

 

*‘ic

A,B,C, > D

 

 

 

 

a .
Each value represents an average of two evaluations for
each of the six judges.

bValues underscored by the same line are not significantly

different (1?).

*
Significant at the 0.1% level of probability.

59

moistness scores averaging 4.2 for cakes baked at 2180C. and
the moistness scores of cakes baked at the three other oven
temperatures, however.

Miller and Vail (40) reported moistness of angel
cakes increased as baking temperatures increased from 1770
to 2320C. However, cakes baked at 2320C. in their study,
were rated as soggy by the taste panel, according to the
report. Barmore (4) also found high baking temperatures
increased the moistness of angel cakes.

Moistness scores were correlated with texture scores.
The very highly significant correlation coefficient (r =
0.80) indicated optimum moistness was associated with desir-

able texture of angel cakes.

Color of crumb

 

The analysis of variance calculated from the sensory
scores of the color of crumb, showed very highly significant
differences due to baking temperatures. Duncan's Multiple
Range Test (17) indicated very highly significant differences
existed between the color of crumb of cakes baked at 1770
and 218°C. The panelists evaluated the color of crumb of
cakes baked at 1770C. as whiter in color than a similar
evaluation of color for cakes baked at 2180C. The color of
crumb for cakes baked at 1910 and 2040C. was significantly
whiter than the color of crumb of cakes baked at 2180C.

(Table 7). The panelists commented that the samples from

60

TABLE 7 Data and statistical analyses of sensory scores for
color of the crumb of angel cakes baked at four oven
temperatures

 

 

 

Means, grand averages, and standard deviations

 

 

 

Oven Temperatures
77’ o o o o
. . 177 C. 191 C. 204 C. 218 C.
Replication A B C D
1 6.53 6.3 6.2 5.0
2 5.4 6.1 5.9 5.3
3 ‘ 6.1 6.0 6.2 5.6
4 6.3 6.0 6.1 5.5
Grand average 6.3 6.1 6.1 5.4
Standard deviation 0.2 0.1 0.1 0.3

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

 

 

 

 

 

 

 

Source of Degrees of
Variance Freedom Mean Square F Statistic
Temperature 3 0.726 l6.10***
Replicates 3 0.004 0.09
Error 9 0.045
Total 15
Duncan's Multiple Range Testb

Significant at Additional at

P g_0.001 P < 0.01 ' P < 0.05

A > D B,C > D

 

 

 

**

aEach value represents an average of two evaluations for
each of the six judges.

bValues underscored by the same line are not significantly
different (17).

*
Significant at the 0.1% level of probability.

61

cakes baked at 2180C. appeared yellow. The means, grand
averages, and standard deviations of sensory scores of color
of crumb are presented in Table 7.

A general comment made by taste panel members indi-
cated samples from all four variables of baking temperature
were "Sparkling" and "glistened." This phenomenon was
further investigated and was then attributed to ingredients
contained in the cake mix and/or the bright lights under

which the cake samples were evaluated.
Objective Measurements

The numerical data from objective measurements used
to indicate the quality characteristics of angel cakes baked
at four oven temperatures were subjected to analysis of vari-
ance. Duncan's Multiple Range Test (17) was used to pin-
point significant differences disclosed by the analysis of
variance. Simple correlations were calculated for all
appropriate combinations of sensory evaluations and objec-

tive measurements.

Index of volume

 

Means, grand averages, standard deviations and sta—
tistical analyses of data for the index of volume of angel
cakes are presented in Table 8. When the data were analyzed
for variance, very highly significant differences attribut-

able to baking temperature were found in the index of volume.

62

TABLE 8 Data and statistical analyses of index of volume of
angel cakes baked at four oven temperatures

 

 

Means, grand averages, and standard deviations

 

 

 

 

Oven Temperatures

o o o o
. . 177 C. 191 C. 204 C. 218 C.

Replication A B C D
Sq.Cm. Sq.Cm. sq.Cm. Sq.Cm.
1 101.1a 101.1 97.6 75.6
2 108.2 96.7 95.5 78.6
3 108.5 98.2 92.1 83.2
4 109.0 101.6 89.9 80.7
Grand average 106.7 99.4 93.8 79.5
Standard deviation 3.7 2.3 3.4 3.2

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 529.212 40.33***
Replicates 3 2.247 0.17
Error 9 13.122

Total 15

 

 

 

 

Duncan's Multiple Range Testb

 

Significant at Additional at

 

 

p g_0.001 P < 0.01‘ P < 0.05
A,B,C > D A > B
A > C

 

 

 

a . . .
Each value represents an average of Six determinations.

bValues underscored by the same line are not significantly
different (17).

***
Significant at the 0.1% level of probability.

63

Further analysis using Duncan's Multiple Range Test (17)
showed cakes baked at 218°C. were smaller in volume than

0’ and 204°C., a difference signif-

cakes baked at 177°, 191
icant at the 0.1% level of probability. Also, very highly
significant differences were found between the index of
volume for cakes baked at 1770 and 204°C. At the 5% level
of probability, cakes baked at 1770C. had greater volume
than cakes baked at 191°C.

The grand averages of 106.7, 99.4, 93.8, and 79.5

0

sq. cm. for cakes baked at 1770, 191 , 204O

, and 218°C.,
respectively, showed a continuous decrease in the index of
volume as the baking temperature increased. These results
are in disagreement with data reported by Miller and Vail
(40) showing the volume of angel cakes increased as baking
temperatures increased from 1770 to 218°C. Volume of cakes
prepared from a basic recipe, was indicated by the area of
a slice of cake in their study.

The index of volume was correlated with texture
scores. The very highly significant correlation coefficient
(r = 0.86) suggested that an increase in the index of volume
was associated with an open texture of the angel cake sam—
ples. As the index of volume decreased, judges evaluated
the texture of the cake samples as more compact.

The correlation coefficient (r = 0.90) calculated
for the index of volume and tenderness scores showed tender-

ness of the cake increased as the volume increased. Samples

64

from cakes with a high index of volume broke easily and were
easily chewed by the judges.

The volume of the cakes increased as the baking time
increased according to the very highly significant correla-
tion coefficient (r = 0.92) calculated for this relationship.
Apparently, the long baking time permitted complete expansion
of the air before proteins coagulated and starches gelatin-

ized to form a stable structure for the cakes.

Moisture of cake

 

As an indication of the moistness of the cakes, the
percentages of weight loss during baking were calculated.
The percentages of moisture in the cakes was also determined.

Percentage of weight loss during baking. Mean per-
centages of weight loss from angel cakes during baking ranged
from 10.8 per cent to 11.31 per cent (Table 9). Analysis of
variance showed no significant differences among the cakes
baked at four oven temperatures.

These results do not agree with data reported by
Looft (35). According to her report, cakes baked at higher
temperatures lost less moisture during baking than cakes
baked at lower temperatures.

A significant negative correlation coefficient
(r = -0.51) was found between percentages of weight loss
during baking and moistness scores. These results do not
support comments made by the panelists indicating cakes

baked at an oven temperature of 218°C. were too moist.

65

TABLE 9 Percentage of weight loss during baking angel cakes
at four oven temperatures

 

 

Means, grand averages, and standard deviations

 

Oven Temperatures

 

 

 

Replication 177°C. 191°C. 204°C. 218°C.
% %. 96 %

1 10.88a 10.73 10.08 11.31

2 10.95 10.65 10.73 10.95

3 10.37 10.88 10.51 10.80

4 10.73 10.58 10.81 10.73
Grand average 10.73 10.71 10.51 10.95
Standard deviation 0.26 0.13 0.33 0.26

 

 

 

 

 

a . .
Each value represents an average of two determinations.

Moisture determinations. The mean percentages of

 

moisture, grand averages, and standard deviations are pre—
sented in Table 10. Analysis of variance showed no signif—
icant differences in the moisture content among cakes baked
at the four oven temperatures. The moisture content for all
angel cakes included in this study averaged 42.60 per cent.
The percentages of moisture were correlated with
sensory scores of moistness and the percentages of weight

loss during baking. Neither correlation was significant.

66

TABLE 10. Percentages of moisture of angel cakes baked at
four oven temperatures

 

 

Means, grand averages, and standard deviations

 

 

 

 

Oven Temperatures
Replication 177°C. 191°C. 204°C. 218°C.
%» % 76 %
1 39.90a 44.09 44.42 41.95
2 44.51 42.18 43.04 42.70
3 44.30 43.58 38.46 43.92
4 39.73 44.39 40.87 43.50
Mean 42.11 43.56 41.70 43.02
Standard deviation 2.65 0.98 2.61 0.87

 

 

 

 

 

a I I
Each value represents an average of four determinations.

Percentgge of sand retention

 

Samples from cakes baked at 177°, 191°, 204°, and

218°C. retained an average of 102.99, 83.72, 81.72, and
60.32 per cent, respectively, of the sand sprinkled over
them to measure the coarseness of the grain (Table 11).
Analysis of variance showed the differences among the four
variables were highly significant; ‘When Duncan's Multi-
ple Range Test (17) was used for further analysis of the
data, very highly significant differences existed between
samples of cake baked at 1770 and 218°C. The percentage of
sand retained by cakes baked at 1770C. was significantly
larger than the percentage of sand retained by cakes baked
at 191°C. and at 204°C. While no significant differences

existed in the percentage of sand retained by cakes baked

67

TABLE 11 Data and statistical analyses for percentage of
sand retained by angel cakes baked at four oven

 

 

 

 

 

 

 

 

 

 

 

temperatures
Means, grand averages, and standard deviations
Oven Temperatures

o o o o

. . 177 C. 191 C. 204 C. 218 C.
Replication A B C D

% % % %
1 87.85a 79.90 82.32 43.86
2 108.41 90.16 94.20 60.66
3 123.28 80.63 82.42 66.70
4 92.40 84.17 67.92 70.06
Grand average 102.99 83.72 81.72 60.32
Standard deviation 16.15 4.68 10.76 11.64

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 1217.707 ll.55**
Replicates 3 217.724 2.07
Error 9 105.415
Total 15

 

 

 

 

Duncan's Multiple

Range Testb

 

Significant at

Additional at

 

 

p g_0.001 p < 0.01 p < 0.05
A > D B,C > D
A > B,C

 

 

 

a O 0
Each value represents an average of two determinations.

bValues underscored by the same line are not significantly
different (17).

**Significant at the 1% level of probability.

68

at 1910 and 204°C., both of these cakes retained a signif-
icantly higher percentage of sand than cakes baked at 218°C.

The correlation coefficient (r = 0.70) showed a
highly significant relationship between the percentage of
sand retained and the texture scores. Cakes with a more
open structure, as indicated by high texture scores,
retained more sand than cakes with a compact structure which
received low texture scores. The very highly significant
correlation coefficient (r = 0.87) between the percentage
of sand retained and the index of volume support this con-
clusion.

Swartz (55) used butter cakes to develop the sand
retention test. In butter cakes, a coarse-grained product
denotes poor quality and the product is characterized by
large pores which retain a high percentage of sand. In
angel cakes, however, Funk, Zabik, and Downs (18) noted the
pores decreased in size as the quality of the cake decreased.
The results of this study support this conclusion since more
sand was retained by cakes receiving high texture scores.

According to the results of this study, the sand
retention test is a valid measurement for determining the
texture of angel cakes. The high standard deviations sug-
gest irregularities of the grain of cake samples from the
four variables of baking temperature. The texture of the

angel cakes varied within a slice of cake and hence, the

69

location from which the sample was taken would influence the

amount of sand retained.

Compressibility

 

The compressibility of angel cakes was determined by
two instruments. The penetrometer and the Kramer shear-
press, with the appropriate attachment, were used.

Penetrometer measurements. Means, grand averages,

 

standard deviations, and statistical analyses of the pene-
trometer measurements of compressibility are presented in
Table 12. When the data were analyzed for variance, very
highly significant differences existed among the cakes baked
at four oven temperatures. Duncan's Multiple Range Test
(17) indicated very highly significant differences existed
between cakes baked at 1770 and 218°C. The lower baking
temperature produced more compressible cakes than the 218°C.
baking temperature. At the 1% level of probability, cakes
baked at_218°C. were less compressible than cakes baked at
191° and 204°C. There was a significant decrease in the
compressibility of cakes baked at 204°C. when compared with
those baked at 177°C. No significant differences existed in
compressipility between cakes baked at 177° and 191°C. or at
191° and 204°C.

When the penetrometer values were correlated with
texture scores, a very highly significant correlation coef-

ficient (r = 0.87) was found. This correlation suggests

70

TABLE 12 Data and statistical analyses of penetrometer
measurements of angel cakes baked at four oven

 

 

 

 

 

 

temperatures
Means, grand averages, and standard deviations
Oven Temperatures
o o o o
. . 177 C. 191 C. 204 C. 218 C.
Replication A B C D
mm. mm. mm. mm.
1 13.7a 7.7 13.9 0.5
2 14.7 11.9 4.7 0.8
3 14.5 6.5 9.3 1.0
4 14.7 14.2 8.7 3.7
Grand average 14.4 10.1 9.2 1.5
Standard deviation 0.5 3.6 3.8 1.5

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 115.196 l4.20***
Replicates 3 5.197 0.64
Error 9 8.114
Total 15

 

 

 

 

Duncan's Multiple Range Test

b

 

Significant at
P g 0.001

Additional at

 

P < 0.01

P < 0.05

 

A > D

 

B,C > D

A > C

 

 

a . .
Each value represents an average of two determinations.

bValues underscored by the same line are not significantly
different (17).

***Significant at the 0.1% level of probability.

71

that as the size of the pores of angel cakes increase, the
cake becomes more compressible. Apparently the open texture
characterized a fragile cake which was easier to compress
than cakes characterized by a close, compact texture.

The very highly significant correlation coefficient
(r = 0.88) between the penetrometer values and the index of
volume emphasizes the relationship between the Open texture
and the compressibility of the cakes. As the index of
volume increased, the cakes were more easily compressed.

The correlation coefficient (r = 0.93) between pene-
trometer values and tenderness scores was very highly signif-
icant. The compressibility of cakes increased as the tender-
ness increased.

Kramer shear:press measurements. Values for Kramer

 

shear-press measurements for compressibility were exPressed
as maximum force and area-under-the-curve. Means, grand
averages, standard deviations, and statistical analyses for
shear-press measurements expressed as maximum force are pre-
sented in Table 13. When the data were analyzed for vari-
ance attributable to baking temperature, very highly signif-
icant differences existed. Further analysis of the data
using Duncan's Multiple Range Test (17) indicated cakes
baked at 177° and 191°C. required less force to compress
them, at the 0.1% level of probability, than cakes baked at
218°C. Highly significant differences existed in the force

required for compressibility between cakes baked at 204° and

72

 

 

 

 

 

 

TABLE 13 Data and statistical analyses of Kramer shear-press
measurements for compressibility, eXpressed as _
maximum force, of angel cakes baked at four oven
temperatures

Means, grand averages, and standard deviations
Oven Temperatures
o o o o

. . 177 C. 191 C. 204 C. 218 C.
Replication A B C D #—
Lb.force Lb.force Lb.force Lb.force

1 0.24a 0.58 0.31 2.54

2 0.20 0.41 0.68 2.45

3 0.21 0.55 0.63 1.44

4 0.24 0.35 0.63 1.16

Grand average 0.22 0.47 0.56 1.90

Standard deviation 0.02 0.11 0.17 0.70

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 2.270 16.13***
Replicates 3 0.111 0.79
Error 9 0.141

Total 15

 

 

 

 

b

Duncan's Multiple Range Test

 

Significant at
P g_0.001

Additional at

 

P < 0.05

 

,A,B < D

 

C < D

 

 

a I I
Each value represents an average of two determinations.

bValues underscored by the same line are not significantly

different (17

***Significant at the 0.1% level of probability.

).

73

218°C. There were no significant differences in the force

°, and 204°C.

required to compress cakes baked at 177°, 191

A very highly significant negative correlation coef-
ficient (r = -0.87) existed between tenderness scores of
cakes and the force needed to compress them. This correla-
tion suggested that as angel cakes increased in tenderness,
they needed less force to compress them.

The volume of the cakes decreased as the values of
compressibility based on maximum force, increased, according
to the very highly significant negative correlation coeffi-
cient (r = -0.89) calculated for this relationship. The
increase in the maximum force required to compress cakes of
low volume is perhaps due to the presence of thick layers
which developed in cakes baked at 2040 and 218°C.

A very highly significant negative correlation coef-
ficient (r = -0.87) was found between the shear-press and
penetrometer measurements of compressibility. The cakes
which required less force, as indicated by the shear-press
measurements, were more compressible, as shown by penetrom-
eter measurements.

Grand averages for area—under-the-curve values of
compressibility were 0.32, 0.66, 0.69, and 2.28 sq. cm. for

0, and 218°C., respectively.

cakes baked at 177°, 191°, 204
Means for each cake along with the standard deviations and
statistical analyses are presented in Table 14. When ana-

lyzed for variance, very highly significant differences

74

TABLE 14 Data and statistical analyses of Kramer shear-press
measurements for compressibility, expressed as
area—under-the-curve, of angel cakes baked at four

oven temperatures

 

 

Means, grand averages, and standard deviations

 

 

 

 

 

 

 

 

Oven Temperatures
o o o o
. . 177 C. 191 C. 204 C. 218 C.
Replication A B C D

Sq.Cm. Sq.Cm. Sq.Cm. Sq.Cm.

1 0.33a 0.79 0.44 2.81

2 0.31 0.57 0.85 3.01

3 0.32 0.77 0.76 1.86

4 0.31 0.50 0.72 1.45
Grand average 0.32 0.66 0.69 2.28
Standard deviation 0.00 0.15 0.18 0.75

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 3.099 19.9l***
Replicates 3 0.153 0.98
Error 9 0.156
Total 15

 

 

 

Duncan's Multiple Range Testb

 

 

Additional at
P < 0.01

Significant at
P g_0.001

 

P < 0.05

 

A,B,C < D

 

 

 

a I I
Each value represents an average of two determinations.

bValues underscored by the same line are not significantly

different (17).

***Significant at the 0.1% level of probability.

75

attributable to baking temperatures were found. Duncan's
Multiple Range Test (17) showed very highly significant
differences existed only between cakes baked at 218°C. and
those baked at the three other oven temperatures, indicating
the largest amount of force was required to compress cakes
baked at 218°C .

The correlation coefficient (r = 0.99) between
values for compressibility based on maximum force and area-
under-the-curve showed a very highly significant relation-
ship. As the maximum force for compressibility increased,
the area-under-the-curve increased accordingly.

A very highly significant negative correlation coef-
ficient (r = -0.88) was also indicated between area-under-
the-curve values for compressibility and the penetrometer
readings. The cakes which were more compressible as shown
by the penetrometer required less force to compress them as

indicated by the shear—press.

Tensile strepgth measurements

The Kramer shear-press was used to measure tensile
strength of body and end slices of the angel cakes. Values
for these measurements are expressed as the maximum force
required to break hourglass-shaped samples of cake.

Tensile strength of body slices. Analysis of vari-
ance for tensile strength of the body slices of the angel

cakes showed no significant differences attributable to

76

baking temperatures. Among replications of the four vari-
ables, however, significant differences existed (Table 15).
Visual differences were apparent in the cake samples. As
mentioned previously, thick, compact layers developed in the
cakes baked at 204° and 218°C. when they were removed from
the oven. The thick, compact layers caused by partial col-
lapse of the cake structure, determined the location of the
break. Cake samples in which the layer was present tended
to pull apart very easily. Also, as noted by Funk, Zabik,
and Downs (18), difficulties were encountered in performing
the tensile strength measurements. Although every attempt
was made to prevent it, a few cake samples were damaged
while clamping them in position for the measurement.

The tensile strength of body slices of angel cakes
was correlated with tenderness scores, index of volume, and
compressibility as determined by the penetrometer and shear-
press. No significant correlations resulted.

Tensile strength of end slices. The analysis of

 

variance indicated significant differences in end slices of
cakes baked at different oven temperatures (Table 16). At
the 1% level of probability, end slices of cakes baked at
218°C. broke easier than the end slices of cakes baked at
191°C., according to analysis using Duncan's Multiple Range
Test (17). End slices from cakes baked at 177°C. had less
tensile strength, at the 5%.1evel of probability, than those

baked at 191°C. Means, grand averages, and standard

77

TABLE 15 Data and statistical analyses of Kramer shear—press
measurements for tensile strength of body slices of
angel cakes baked at four oven temperatures

 

 

 

 

 

 

 

 

 

 

 

 

 

Means, grand averages, and standard deviations
Oven Temperatures
o o o o

. - 177 C. 191 C. 204 C. 218 C.

Replication A B C D
Lb.force Lb.force Lb.fogce Lb.force
/Cm. /cm. /cm. /cm.

1 0.030a 0.033 0.027 0.037

2- 0.020 0.028 0.027 0.025

3 0.020 0.025 0.024 0.012

4 0.024 0.023 0.018 0.023
Grand average 0.024 0.027 0.024 0.024
Standard deviation 0.005 0.004 0.004 0.010

Statistical Significance
Analysis of Variance

Source of Degrees of
Variance Freedom Mean Square F Statistic
Temperature 3 0.00001150 0.56
Replicates 3 0.0001025 4.99*
Error 9 0.00002
Total 15

 

 

 

 

a . .
Each value represents an average of three determinations.

*Significant at the 5% level of probability.

78

TABLE 16 Data and statistical analyses of Kramer shear-press
measurements for tensile strength of end slices of
angel cakes baked at four oven temperatures

 

 

Means, grand averages, and standard deviations

 

 

 

 

Oven Temperatures
. .. 177°C. 191°C. 204°C. 218°C.
Replications A B C D

Lb.fogce Lb.force Lb.foEce Lb.force

/Cm. /cm.2 /cm. /cm.2

1 0.030a 0.049 0.038 0.024

2 0.034 0.042 0.033 0.023

3 0.035 0.038 0.039 0.033

4 0.025 0.043 0.041 0.040

Grand average 0.031 0.043 0.038 0.030

Standard deviation 0.005 0.005 0.003 0.008

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F. Statistic
Temperature 3 0.000149 4.29*
Replicates 3 0.0000132 0.38
Error - 9 0.00003
Total 15

 

 

 

 

Duncan's Multiple Range Test

 

Additional at
P < 0.01

Significant at
P g 0.001

 

P < 0.05

 

D < B A < B

 

 

 

a O I
Each value represents an average of four determinations.

*Significant at the 5% level of probability.

79

deviations for Kramer shear-press measurements of tensile
strength are presented in Table 16.
These results indicate the baking temperature of

o and 218°C. yielded end cake slices with almost equal

177
tensile strength. The end slices from all cakes, regardless
of the baking temperature, were free from the thick, compact
layers which were present in body slices of cakes baked at

2040 and 218°C. Here again, some cake samples were damaged

as they were placed in the apparatus.

Tenderness measurements

The analysis of variance showed no significant dif—
ferences in tenderness of angel cakes baked at four oven
temperatures (Table 17). The grand averages of 2.44, 2.34,

2.27, and 2.46 lb. force/gm. for cakes baked at 177°, 191°,

0, and 218°C., respectively, are presented in Table 17

204
along with mean values for each replication and the standard
deviations.

Significant differences were found between replica-
tions, according to the analysis of variance. The thick,
compact layers present in part of the cake slices may
explain the differences between replications.

Maximum force values for tenderness were correlated

with maximum force and area-under-the-curve values for com-

pressibility. Neither correlation was significant.

80

 

 

 

 

 

 

TABLE 17 Data and statistical analyses of Kramer shear-
press measurements for tenderness, eXpressed as
maximum force, of angel cakes baked at four oven
temperatures

Means, grand averages, and standard deviations

Oven Temperatures
Replication 177°C. 191°C. 204°C. 218°C.
Lb.force Lb.force Lb.force Lb.force

. /gm - /gm . /gm . /gm
1 2.17a 2.46 2.15 2.07
2 3.10 2.40 2.94 2.72
3 2.17 2.16 1.97 2.51
4 2.31 2.34 2.01 2.55
Grand average 2.44 2.34 2.27 2.46
Standard deviation 0.45 0.13 0.46 0.28

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 0.032 0.52
Replicates 3 0.312 4.96*
Error 9 0.063

Total 15

 

 

 

a C 0
Each value represents an average of two determinations.

*Significant at the 5% level of probability.

81

Mean values, grand averages, and standard deviations
for area-under-the-curve values for tenderness, as well as
statistical analyses are presented in Table 18. When the
area-under-the—curve tenderness values were analyzed for
variance, very highly significant differences attributable
to baking temperatues were found. Further analysis of the
data using Duncan's Multiple Range Test (17) showed very
highly significant differences in tenderness between cakes
baked at 218° and those baked at 1770 and 204°C. The baking
temperatures of 1770 and 204°C. produced more tender cakes
than did the 218°C. baking temperature. Cakes baked at
191°C. were more tender at the 1%leve1 of probability, than
cakes baked at 218°C. The tenderness values for cakes baked

0, and 204°C. were not significantly different.

at 177°, 191
The area-under-the-curve tenderness values are not
in agreement with maximum force values for tenderness.
Examination of the shear—press data indicated the recorded
maximum force required to shear samples of cake increased as
the baking temperature increased. However, the average
weight of the samples showed values of 8.63, 10.25, 10.15,
and 13.75 gm. as the baking temperature increased from 177°,

0

191 , 204°

, and 218°C., respectively. Sample weight was an
integral part of the formula for calculating maximum force
while it was not reflected in area-under-the-curve values.
Apparently, weight increased in the same ratio as did the

recorded maximum force readings on the graph.

TABLE 18

82

press measurements,
area-under-the-curve,
oven temperatures

Data and statistical analyses of Kramer shear-
for tenderness,

expressed as
of angel cakes baked at four

 

 

Means, grand averages,

and standard deviations

 

 

 

 

Oven Temperatures
o o o o
- . 177 C. 191 C. 204 C. 218 C.
Replication A B C D

Sq.Cm. .Sq.Cm. Sq.Cm. Sq.Cm.

1 2.29a ‘3.48 2.46 5.32

2 $3.15 3.17 4.13 7.02

3 2.28 3.35 2.88 4.02

4 2.13 3.07 2.77,, 4.63

Mean 2.46 3.27 3.11 5.25
Standard deviation 0.46 0.18 0.69 ' 1.30

 

 

 

 

 

Statistical Significance

 

Analysis of Variance

 

 

Source of Degrees of

Variance Freedom Mean Square F Statistic
Temperature 3 5.785 l6.48***
Replicates 3 1.351 3.85
Error 9 0.351
Total 15

 

 

 

 

Duncan's Multiple Range Testb

 

Significant at Additional at

 

p g_0.001 p < 0.01 p < 0.05

 

A,C < D B < D

 

 

 

a . .
Each value represents an average of two determinations.

bValues underscored by the same line are not significantly
different (17).

***Significant at the 0.1% level of probability.

83

Very highly significant correlation coefficients
(r = 0.91 and r = 0.93) existed between area-under-the-curve
values for tenderness and maximum force and area-under-the
curve values for compressibility, respectively. These corre-
lations suggested as the force needed to shear the cake
increased, the force needed to compress it also increased.

A negative correlation coefficient (r = —0.84)
showed a very highly significant relationship between pene-
trometer values and area-under-the-curve values for tender-
ness. This correlation indicated cakes which were less
compressible by the penetrometer, needed more force to be
sheared by the shear-press. This indicates the penetrometer
is a reliable test for measuring compressibility of angel

cakes.

Validity of Objective Measurements

The percentage of weight loss during baking and the
percentage of moisture were determined as indications of the
moistness of the angel cakes. Both of these objective mea-
surements indicated no significant differences among the
cakes baked at four oven temperatures. However, sensory
evaluations of moistness indicated significant differences
attributable to baking temperatures. When the percentages
of moisture were correlated with moistness scores, the corre-
lation was not significant. The percentages of weight loss

and moistness scores showed a significant correlation.

84

Because the two measurements agree in their assessment of
the moistness of the cake, they are considered valid. Per-
haps the judges were influenced by other factors such as
texture and tenderness of the cake samples in their evalua—
tions of moistness.

The highly significant relationship found between
the percentage of sand retained and the texture scores of
angel cakes suggests the sand retention test is a valid
measurement to determine the texture of angel cakes. How-
ever, the high standard deviations of the test values as
presented in Table 11, point out some limitations of this
test. The location from which the samples are taken, moist—
ness of the cake, manner of adding the sand, as well as the
interpretation of the test results must be considered.

The penetrometer values showed very highly signif-
icant correlation coefficients with the shear press values
for compressibility expressed as maximum force and area-
under-the-curve, and tenderness scores as well as area—under-
the-curve values for tenderness. Therefore, under the condi-
tions of this study, the penetrometer is a valid instrument
for compressibility measurements of angel cakes.

The validity of the Kramer shear-press for measuring
the quality characteristics of angel cakes has been assessed.
Funk, Zabik, and Downs (18) determined that the shear-press
could be used for measurements of compressibility, tensile

strength, and tenderness to define quality characteristics.

SUMMARY'AND CONCLUSIONS

The primary purpose of this study was to investigate
the effect of the baking temperatures of 177°, 191°, 204°,
and 218°C. on the quality characteristics of angel cakes as
measured by sensory evaluations and objective measurements.
A secondary purpose was to assess the validity of objective
measurements which could be performed in laboratories with
limited equipment by correlating appropriate data obtained
from these measurements with Kramer shear-press data and
sensory evaluations.

Cakes were prepared from household-size packages of
commercial cake mix following the one-step procedure sug-
gested by the manufacturer. Ingredients were weighed or
measured to the nearest gram or milliliter. To provide
sufficient slices for sensory evaluations and objective mea-
surements, the contents of two packages were combined for
mixing and then the batter was divided into two equal por-
tions for baking. The specific gravity and pH of the cake
batter were determined as indications of control of all
variables except the oven temperature. Time-temperature
relationships were continuously recorded during baking from
potentiometer leads positioned 2.5 and 5.0 cm. from the

bottom of each cake pan. Each variable was replicated four

times.

85

86

After the cakes had been cooled and weighed to
determine losses during baking, they were wrapped in Saran,
put into polyethylene bags and frozen at -23.3°C. until
needed for subsequent evaluation. The cakes were sliced
from the frozen state for sensory evaluation and objective
measurements.

The cakes were evaluated by a six-member, trained
taste panel using a 7-point numerical scale. Descriptive
terms aided the panelists in their evaluations. Objective
measurements were index of volume, percentages of weight
loss during baking, moisture determinations, percentage of
sand retained, compressibility as indicated by penetrometer
and Kramer shear—press readings, tensile strength, and
tenderness.

Highly significant differences were present in the
specific gravity measurements of the cake batter. These
differences are probably attributable to exPerimental errors.
No significant differences were found in the pH values of
the cake batter.

The temperatures within the cakes rose at a rate
dependent on the oven temperature with the slowest rate of
temperature rise recorded for the 177°C. oven. Grand aver—

0

age maximum internal temperatures of 98.00, 99.5 , 100.00,

and 100.4°C. were recorded for cakes baked at temperatures

of 177°, 191°, 204°

, and 218°C., respectively. The differ—
ences in the maximum internal temperatures were very highly

significant.

87

The statistical analyses of sensory evaluations
indicated very highly significant differences for texture,
tenderness, moistness, and color of the crumb scores among
the cakes baked at the four oven temperatures. Cakes of
light, open texture were produced at the 1770 and 191°C.
baking temperatures as compared with the compact texture of
cakes baked at the two other temperatures. Tenderness of
cakes decreased when cakes were baked at temperatures higher
than 191°C. The optimum moistness of angel cakes as well as
the desirable white color of the crumb were secured at bak-
ing temperatures not higher than 204°C.

Statistical differences were indicated by objective
measurements. Index of volume measurements showed a very
highly significant and continuous decrease as the baking
temperature increased. Cakes with more open texture were
produced at baking temperatures of 1770 and 191°C. according
to the results of the sand retention test. Penetrometer
measurements indicated cakes were more compressible when
baked at 1770 and 191°C. The shear-press measurements for
compressibility based on maximum force and area-under-the-
curve, showed more force was necessary to compress cakes
baked at 218°C. compared with the three other oven temper-
atures. The same trend was indicated by the values of
tenderness measurements for the shear-press based on area-
under-the-curve, showing that cakes baked at temperatures

higher than 204°C. required more force to be sheared.

88

No significant differences among cakes baked at the
four oven temperatures were indicated by the tenderness
values of the shear—press based on maximum force, tensile
strength measurements by the shear-press, percentages of
moisture in the cake, and percentages of weight loss during
baking.

Very highly significant relationships existed
between texture scores and moistness scores, tenderness
scores, and index of volume measurements. Very highly sig-
nificant correlations were also indicated.between the tender-
ness scores and index of volume measurements and compress-
ibility measurements based on the maximum force readings of
the shear-press. Area-under-the-curve tenderness values
determined by the shear-press showed a very highly signifi-
cant correlation with shear-press measurements for compress-
ibility based on both maximum force and area-under—the-curve
values.

The highly significant correlation found between the
sand retention test and texture scores of angel cakes sug-
gested the validity of this test to measure texture of angel
cakes. Because of the high standard deviations, however,
the reliability of this test is questioned.

The very highly significant relationships between
shear-press values for both maximum force and area-under—the—

curve measurements of compressibility, tenderness scores and

89

the penetrometer values indicated the penetrometer was a
valid test to determine compressibility of angel cakes.

According to the results of this investigation,
baking temperatures of 1770 and 191°C. were more satisfac-
tory for baking angel cakes than baking temperatures of 2040
and 218°C. Thick layers developed in cakes baked at 2040
and 218°C. as a result of a partial collapse of the struc-
ture after they were removed from the oven. The top crust
of these cakes was deeply cracked and the surface was very
dark brown to burned. Perhaps the crust was too heavy to
be supported by the delicate structure of the cakes and'
hence, the cakes collapsed when they were removed from the
oven.

Further research seems to be needed in the two fol-
lowing areas: (1) an investigation to clearly define done-
ness of angel cakes as determined by maximum internal tem-
perature reached by the cake and/or time—temperature rela-
tionships, and (2) further analysis to determine the factors

influencing sensory evaluations of angel cakes.

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LITERATURE CITED

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Principles of Sensory Evaluation of Food. New Ybrk:
Academic Press Inc., 1965.

Anon. General Mills, Inc. General Offices,
Minneapolis, Minnesota.

Bailey, L.H.: A simple apparatus for measuring the
compressibility of baked products. Cereal Chem.
7:340, 1930.

Barmore, M.A.: Baking angel food cake at any altitude.
Colorado Agric. Exper. Sta. Tech. Bul. 13, 1935.

Barmore, M.A.: The influence of various factors
including altitudes in the production of angel
food cake. Colorado Agric. EXper. Sta. Tech. Bul.
15, 1936.

Barton, J.: Angel food for Easter. Pacific Rural
Press 135:376 (March), 1938.

Binnington, D:S., and Geddes, W.F.: An improved wide-
range volume-measuring apparatus for small loaves.
Cereal Chem. 15:235, 1938.

Boggs, M.M., and Hanson, H.L.: Analysis of foods by
sensory difference tests. Advances in Food Res.
2:219, 1949.

Briant, A.M., and Williams, A.R.: Whole egg sponge
cakes. J. Home Econ. 48:420, 1956.

Brown, S.L., and Zabik, M.E.: Effect of heat treat-
ments on the physical and functional properties of
liquid and spray dried egg albumen. Food Tech.
21:87, 1967.

Burke, E.A., and Niles, K.B.: A study of seasonal

variation in egg white performance. U.S. Egg and
Poultry Mag. 42:542, 1936.

90

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Carlin, A.F., and.Ayres, J.C.: Storage studies on
yeast—fermented dried egg white. Food Tech.
5:172, 1951.

Carlin, A.F., and.Ayres, J.C.: Effect of the removal
of glucose by enzyme treatment on the whipping
properties of dried albumen. Food.Tech. 7:268,
1953.

Cathcart, W.H.: Photo-records as applied to cake.
Cereal Chem. 16:423, 1939.

Child,.A.M. and Purdy, D.I.: Method for graphic
record of texture, volume, and contour of cakes.
Cereal Chem. 3:57, 1926.

Dudgeon, E.: How to make angel food cake. Country
Gentleman 117:128 (April), 1947.

Duncan, D.: Multiple F. Test (J. Biometric Soc.
2:3, 1955.

Funk, K., Zabik, M.E., and Downs, D.M.: Comparison
of shear-press measurements and sensory evalua—
tions of angel cakes. J. Food Sci. 30:729, 1965.

Grewe, E., and Child, A.M.: The effect of acid
potassium tartrate as an ingredient in angel cakes.
Cereal Chem. 7:245, 1930.

Griswold, R.M. The ExPerimental Study of Foods.
Boston: Houghton Mifflin Co., 1962.

Hall, H.: Cake temperature while baking, and its
effect on starches of cake flours. Baker's
Helper, p. 340 (Feb. 1), 1930.

Halliday, E.Gq and Ndble, I.T.: Hows and whys of
cooking. Chicago: Univ. of Chicago Press, 1933.

Harns, J.V., Sauter, E.A., McLaren, E.A., and
Stadelman, W.J.: The use of angel food cake to
test egg white quality. Poultry Sci. 31:1083,
1952.

Harrel, C.G.: Some basic principles of photography
as applied to cereal work. Cereal Chem. 7:313,
1930.

Heald, W;L.: A practical method of photographing
bread. Cereal Chem. 6:69, 1929.

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92

Hellickson, A.H.: "A" is for angel food. American
Home 13:497 (May). 1935.

Hunt, L.W. and St. John, J.L.: Angel food cake from
the thick and thin portions of egg white. U.S.
Egg and Poultry Mag. 38:46, 1932.

Institute of American Poultry Industries: Angel food
cake. Publication 17. H.E. Chicago, Ill.

Jordan, R., Barr, A.T., and.Wilson, M.L.: Shell eggs:
quality and prOperties as affected by temperature
and length of storage. Purdue Agric. EXper. Sta.
Bul. 612, 1954.

King, F.B., Whiteman, E.F., and Rose, W.G.: Cake
making quality of eggs as related to some factors
in egg production. Cereal Chem. 13:703, 1936.

King, F.B., Morris, H.P., and Whiteman,E.F.: Some
methods and apparatus used in measuring the quality
of eggs for cake making. Cereal Chem. 13:37, 1936.

Kraatz, E.: Angel cake. III. The Optimum baking time
and temperature. M.S. Thesis, Iowa State College,
1938.

Kramer, A., Guyer, R.B., and Rodgers, H.P.: New shear
press predicts quality of canned lima beans. Food
Engin. 23:112, 1951.

Kramer, A.: The shear press, a basic tool for the
food technologist. The Food Scientist 5:7, 1961.

Looft, M.G.: Angel cake. II. The optimum baking
temperature. M.S. thesis, Iowa State College,
1937.

Lowe, 8.: Experimental Cookery. 4th ed. New York:
John Wiley and Sons, Inc., 1955.

Matejovsky, C.: A practical and simple method of
recOrding the form and porosity of baked products.
Cereal Chem. 15:471, 1938.

Meyer, L.H.: Food Chemistry. New York: Reinhold
Publishing Corporation, 1960.

Miller, B.S., and Derby, R.I.: Devices useful for
judging what occurs in a cake during baking.
Cereal Sci. Today 9:386, 1964.

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93

Miller, E.L., and Vail, G.E.: Angel food cakes made
from fresh and frozen egg whites. Cereal Chem.
20:528, 1943.

Mohs, K.: Size of the pores in baked bread. Cereal
Chem. 1:149, 1924.

Mortenson, L.: Angel food - queen of cakes.
Successful Farming 31:12 (Feb.), 1933.

Official methods of analysis of the association of
Official Agricultural Chemists. Washington:
Association Of Official Agricultural Chemists,
1950.

Owen, R.F. and Van Duyne, F.O.: Comparison of the
quality of freshly baked cakes, thawed frozen
baked cakes, and cakes prepared from batters which
had been frozen. Food Res. 15:169, 1950.

Parks, M.S., Zabik, M.E., and Stine, C.M.: substitu-
tion of foam spray-dried acid whey solids for
buttermilk solids in chocolate cake. Mich.
Agric. Exper. Sta. Quarterly Bul. 49 p. 43
(August), 1966.

Paul, P., Batcher, O.M., and Fulde, L.: Dry mix and
frozen baked products. I. Dry mix and frozen
cakes. J. Home Econ. 46:249, 1954.

Peet, L.J., and Lowe, B.: Starting baked products in
cold versus preheated ovens. Iowa Agric. EXper.
Sta. Res. Bul. 213, 1937.

Platt, W.: (Staling of bread. Cereal Chem. 7:39, 1930.

Platt, W., and.Kratz, P.D.: Measuring and recording
some characteristics of test sponge cakes. Cereal
Chem. 10:73, 1933.

Powers, L.B., and Simpson, J.I.: Effect of soy flours
on rate of staling in plain cake. Food Res.
12:449, 1947.

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physical measurements upon fresh and stored eggs
and their behavior in the preparation and baking of
cake. Poultry Sci. 20:125 (March), 1941.

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94

Read, 0.8.: The baking temperature of bread. Iowa.
Acad. of Sci. 37:231,l930.

Reed, S.J., Floyd, E.V., and Pittman, M.S.: Effect
of pan on temperature of baking and tenderness of
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Swartz, V.W.: Two further simple objective tests for
judging cake quality. Cereal Chem. 15:247, 1938.

APPENDIX

96

EVALUATION SHEET FOR SUBJECTIVE EVALUATION

OF ANGEL CAKES

 

Date:
Oven temperature: Baking time: Replication NO.:
ATTRIBUTES CAKE A OR C CAKE B 0R D

 

Appearance of the cake:
Cracks: Slightly deep
Very deep

Collapse:

 

Color:

Top: Golden brown
Dark brown
Very dark brown
Burned

Sides and bottom:
White
Light golden

Golden brown

 

 

Texture of the sides and bottom:
Dry
Moist

Sticky

 

 

 

 

97

ANGEL CAKE TASTE PANEL

GENERAL INSTRUCTIONS

1. YOu have been provided with a written schedule of dates
and times the panel will meet. Cake samples will be
available at 10 A.M. in the taste panel room of the
Institution Administration Department. YOu may evaluate
your samples at your convenience between 10 and 11 A.M.

2. Please refrain from smoking, eating, or drinking for one-
half hour prior to evaluation. Please do not give any
facial or vocal reactions as you evaluate your sample.

3. The samples are coded with random numbers and are pre-
sented in a randomized fashion. Please start with the
sample in the upper left-hand corner of the tray and
proceed toward the right. The lower row should be
evaluated in the same order.

4. Each sample is to be evaluated on a separate score sheet
using a 7-point scale, a score of 7 being the highest
given. Four attributes are to be judged. Descriptive
terms for the scores of 7, 4, and l are given to help in
your evaluation. Quality characteristics for standard
and below standard angel cakes are also listed for each
attribute.

5. Place a check, using a red pencil, in the block which
most nearly fits your evaluation of each quality char—
acteristic of the sample. Score each sample indepen—
dently of others. .§§_SURE THE PLATE CODE MATCHES THE
SCORE CARD.

6. You may rinse your mouth between sample evaluations with
the water provided.

************

Texture. Please break the cake sample in half. Evaluate
the texture of the sample on the freshly broken surface
of the cake.

Tenderness. Evaluate the tenderness of the sample by
breaking or tearing AND masticating.

 

Moistness. Evaluate the sample on the basis of your first
impression of mouth feel.

 

Color. Evaluate the color of the sample on a freshly broken
surface.

BE SURE YOU HAVE RECORDED YOUR EVALUATION OF FOUR QUALITY
CHARACTERISTICS FOR EACH CAKE SAMPLEt PLEASE WRITE IN (OR
UNDERLINE) descriptive terms when scores of 4 or lower are
given to indicate the reason for the score.

98

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99

TABLE 19 Summary of correlation coefficients calculated
from sensory evaluation and objective measurement
data of angel cakes baked at four oven temperatures

 

 

 

. . Correlation
Relationship Coefficient

Tenderness scores/Texture scores . . . . . . . . 0.89***
Moistness scores/Texture scores . . . . . . . . 0.80***
Index of volume/Texture scores . . . . . . . . . 0.86***
Index of volume/Tenderness scores . . . . . . . 0.90***
Index of volume/Time of baking . . . . . . . . . 0.92***
Percentage of weight loss/Moistness scores . . . -0.51*
Percentage of moisture/Moistness scores . . . . -0.03
Percentage of moisture/Percentage of weight loss -0.08
Percentage of sand retention/Texture scores . . 0.70**
Percentage of sand retention/Index of volume . . 0.87***
Penetrometer measurements/Texture scores . . . . 0.87***
Penetrometer measurements/Index of volume . . . 0.88***
Penetrometer measurements/Tenderness scores . . 0.93***
Compressibility, maximum force/Tenderness

scores . . . . . . . . . . . . . . . . . . . -0.87***
Compressibility, maximum force/Index of volume . -0.89***
Compressibility, maximum force/Penetrometer

measurements . . . . . . . . . . . . . . . . -0.87***
Compressibility, area-under-the-curve/

Compressibility, maximum force . . . . . . . 0.99***
Compressibility, area-under-the—curve/

Penetrometer measurements . . . . . . . . . -0.88***
Tensile strength of body slices/Tenderness

scores . . . . . . . . . . . . . . . . . . . 0.00
Tensile strength of body slices/Index of volume -0.09
Tensile strength of body slices/Penetrometer .

measurements . . . . . . . . . . . . . . . . -0.07
Tensile strength of body slices/Compressibility,

maximum force . . . . . . . . . . . . . . 0.21
Tensile strength of body slices/Compressibility,

area-under-the-curve . . . . . . . . . . . 0.17
Tenderness, maximum force/Compressibility,

maximum force . . . . . . . . . . . . . . . 0.07
Tenderness, maximum force/Compressibility,

area-under-the-curve . . . . . . . . . . . . 0.10
Tenderness, area-under-the-curve/Compressibility

maximum force . . . . . . . . . . . . . . . 0.91***
Tenderness, area-under-the-curve/Compressibility

area-under-the-curve . . . . . . . . . . . . 0.93***
Tenderness, area-under-the-curve/Penetrometer

measurements . . . . . . . . . . . . . . . . -0.84***

 

*Significant at the 5%.level of probability.
**Significant at the 1% level of probability.
***Significant at the 0.1% level of probability.

MICHIGAN STATE UNIVERSITY
COLLEGE OF HOME ECONONHCS
EAST LANSING, MICHIGAN

M.S. 1967
ELIGIDAILY, Doha A.

The Effect of Baking Temperature

‘ on the Quality Characteristics of
I Angel Cakes

Elgidaily, Doha Abdelwfinhmnn

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