ABSTRACT

EFFECT OF TWO METHODS OF DRY HEAT COOKERY
ON PALATABILITY AND COOKING LOSSES OF
SEMITENDINOSUS MUSCLE OF BEEF ROUND

by Anne Louise Douglas Shaw

This investigation compared the effects of conventional oven—
roasting and a combination of internal radial heating and conventional
roasting on the palatability, yield, and rate of heat penetration in
semitendinosus muscles,comparable in shape and weight, from six
pairs of U. S. Choice steer beef rounds.

A thermal rod used in the radial-conventional method consisted
of an electric wire mounted in a hollow, stainless steel rod 12 inches
in length and O. lZS-inch in diameter. The extended wire was termi-
nated at each end with a small clamp used to connect the rod into an
auxiliary electric circuit. Roasts were split lengthwise to the sample
radius for insertion of the rod.

For both roasting methods, a controlled air temperature of
149°C was maintained throughout cooking. In addition, a powerstat,
set at 20 per cent, controlled the voltage entering the thermal rod in
the radial-conventional method, Time-temperature data during roast-
ing and cooling were obtained from thermocouples positioned at sample
depths of 0. 25-inch, 0. 75-inch and 1.0 inch for the radial conventional
method and at depths of O. 25-inch, 0.75-inch and radius for the con-
ventional method. Cooking periods were terminated in the radial-

conventional method when all positioned potentiometer leads registered

Anne Louise Douglas Shaw

a minimum internal temperature of 800C and in the conventional
method when the lead positioned at the radius registered a minimum
internal temperature of 800C.

The results of this study indicate that method of cooking does
affect palatability, cooking losses, and rate of heat penetration in
semitendinosus beef muscle.

Total cooking losses and volatile losses were lower and drip
and volume losses were higher in radial-conventional roasts than in
conventional roasts.

With the exceptions of tenderness and residual connective tissue,
palatability scores for all factors judged were comparable for the
two cooking methods. Conventionally cooked samples were signifi-
cantly more tender and had less residual tissue.

Total cooking time for the radial-conventional method was
approximately half that required for the conventional method and in
both methods the rate of rise in internal temperature decreased as the
internal temperature of the roast increased.

Radial-conventional roasts exhibited a faster rate of heat trans-
fer at all times during the cooking period. Both methods exhibited
the phenomenon that rate of heat penetration decreases as muscle
coagulation proceeds.

This study indicates that the radial-conventional cooking method
has potential as an acceptable means of cooking semitendinosus muscle
of beef round. Modifications of procedure are suggested which might
increase tenderness, lessen residual connective tissue, and further

improve juicine s s .

EFFECT OF TWO METHODS OF DRY HEAT COOKERY
ON PALATABILITY AND COOKING LOSSES OF
SEMITENDINOSUS MUSCLE OF BEEF ROUND

By

Anne Louise Douglas Shaw

A THESIS

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

MAST ER OF SCIENCE

Department of Institution Administration

1964

 

.. .2 i: ‘r’ 7

,;/"<—'(

AC KNOW LED GM ENTS

Sincere and grateful appreciation is extended to Dr. Grace
Miller for her patient encouragement, her invaluable assistance
and counsel, and her friendship through the duration of this
investigation.

Special thanks are expressed to Dr. Grace Miller, Miss
Mary Morr, Miss Doris Downs,» Miss Grace Masuda, Miss
Zenovia Lukianchuk and Mrs. Beverley Wilkinson for their partici-
pation on the taste panel.

The author is thankful to Mr. Lyman J. Bratzler for his
help in procuring and dissecting the beef rounds and to Dr. William

Baten for his assistance with the interpretation of the statistical
data of this study.

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

ii

TABLE OF CONTENTS

Page

INTRODUCTION.................. ...... 1
REVIEWOFLITERATURE.................. 4
Factors Affecting Cooking Losses in Meat . . . . . . . 4
CompositionofMeat............... 4
Grade....................... 5

Weight and surface area . . . . . . . . . . . . . 6
Aging............. ...... 6

Cooking method, temperature, time . . . . . . . 7

Factors Affecting Rate of Heat Penetration. . . . . . . 9
Compositionofmeat............... 9

Weight and surface area . . . . . . . . . . . . . ll
Aging.......................11

Initial temperature of the meat. . . . . . . . . . 11

Cooking method, temperature, time . . . . . . . 12

Factors Affecting Palatability Characteristics. . . . . 14
Aromaandflavor ..... .......... 14
Appearance and texture. . . . . . . . . . . . . . 16
Tenderness............... ..... 19
Juiciness..................... 24

Methods of Evaluating Palatability . . . . . . . . . . . 27
Subjective evaluation . . . . . . . . . . . . . . . 27

Objective evaluation. . . . . . . . . . . . . . . . 29
Combination subjective and objective evaluation . 30

METHOD OF PROCEDURE . . . . . . . . . . ........ 32
Procurement of Samples . . . . . . . . . . . . . . . . 32
EquipmentUsed..................... 33
Measuring and weighing. . . . . . . . . ..... 33
Roasting...................... 34
Slicing....................... 35

Objectivetesting................. 35

iii

TABLE OF CONTENTS - Continued

Page

Preliminary Investigations ....... . . . . . . . . 35
Powerstat setting. . ....... . . . . . . . . 39
Thermocouple placement. . . . . . . . . . . . . 40
Preparation of samples for subjective testing . . 40
Preliminary taste panel . . . . . . . . . . . . . 42
Preparation of samples for objective testing . . 42
Preroasting Preparation . . . . . . . . . . . . . . . . 43
Preparation of raw roasts . . . . . . . . . . . . 43
Cooking temperature . . . . . . . . . . . . . . . 44
CookingProcess.................... 45
Conventional method . . . . . . . . . . . . . . . 45
Radial-conventional method . . . . . . . . . . . 45
Treatment After Roasting. . . . . . . . . . . . . . . . 45
Treatment of roasts before chilling . . . . . . . 46
Treatment of roasts after chilling . . . . . . . . 46
Evaluation of Samples. . . . . . . . . . . . . . . . . . 46
Subjective testing. . . . . . . . . . . . . . . . . 46
Objective testing . . . . . . . ..... . . . . . 47
Heatpenetration................. 48

Analysisofthedata................ 48

RESULTSANDDISCUSSION ................. 50

Palatability ........ . . . . . . . . . . . . . . . 50
Aromaandflavor. . . . . ..... . . . . . . . 51
Color and texture. ..... . . . . . . . . . . . 52
Juiciness..................... 54
Tenderness.................... 56

CookingLosses..................... 59
Total cooking losses . . . . . . . . . . . . . . . 61
Driplosses.................... 61
Volatile losses ..... . . . . . . . . . . . . . 61
Volume losses . . . . . . . . ..... . . . . . 62

pH....................... ..... 63

Heat Penetration . . . . . . . . . . . . . . . . . . . . 64

SUMMARY AND CONCLUSIONS. . . . . . . . . . . . . . . . 72
LITERATURECITED...... ..... 77

APPENDIX , , , 85

C O O O O O O C O 0 O O O O O O O O O 0 Q 0 0

iv

TABLE

10.

11.

LIST OF TABLES

Average palatability scores for seven judges for six
samples for two methods of cooking. . . . . . . . .

Analyses of variance of aroma and flavor scores for
twomethodsofcooking. . . . . . . . . . . . . . .

Analyses of variance of color and texture scores for
twomethodsofcooking. . . . . . . . . . . . . . .

Average press fluid yields and grand average juici-
ness scores 0 O O O O O O O O O O O O O O O O O O O 0

Analyses of variance of press fluid yields and juici-
ness scores for two methods of cooking . . . . . .

Grand average scores for softness, friability,
residual tissue, and tenderness, and mean shear
values for two methods of cooking . . . . . . . . . .

Analyses of variance for softness, friability,
residual tissue, and tenderness scores, and shear
force values for two methods of cooking . . . . . .

Correlation coefficients for all possible combi-
nations of softness, friability, residual tissue, and
tenderness scores, and Warner Bratzler shear
measurements....................

Mean per cent cooking and volume losses of six
replications for two methods of cookery . . . . . .

Analyses of variance of cooking and volume losses
for twomethodsofcookery. . . . . . . . . . . . .

Mean percentages for volume loss, changes in
linear measurements and total weight loss for two

methodsofcookery. .. .. . . . . .. . . . ..

V

Page

51

52

54

55

55

56

58

58

60

6O

62

LIST OF TABLES - Continued

TABLE

12.

13.

14.

15.

l6.

17.

18.

19.

Page
Weight of rounds, muscle weight, maximum linear
measurements of muscles, and trimmed sample
weight......................... 86
Average palatability scores of seven judges for six
replications for two cooking methods . . . . . . . . 87
Average press fluid yields and shear force values
of cooked samples for six replications for two cook-
ing methOdSO O O O O Q 0 O O O O O C O O O I O O O O O 88

Cooking weight losses for six roasts for two methods
ofcookery......................

Volume loss for six roasts for two methods of
cookery I I O O O C O C O I O I O O O O O O O O O O O O

Determinations of pH for raw and cooked samples
and the change in pH for six roasts for two methods
Of COOking. O O O O O O O O O O O O O O O O O O C O O 0

Changes in the rate of heat penetration for five
replications, for three sample depths for the radial-
conventional cooking method. . . . . . . . . . . . .

Changes in the rate of heat penetration for five repli-

cations, for three sample depths for the conventional
cookingmethod........ ............

vi

89

9O

91

92

93

LIST OF FIGURES

FIGURE Page
1. Thermal rod and sample roast. . . . . . . . . . . . 36
2. Splitting the raw roast . . . . . . . . . . . . . . . . 36
3. Inserting the thermal rod . . . . . . . . . . . . . . 37
4. Tyingtherawroast................. 37
5. Positioning potentiometer leads: 3 = 0. 25-inch,
b and _c_ = 0. 75-inch and 1.0 inch from surface; _d_ =
attached to thermal rod . . . . . . . . . . . . . . . 38
6. Connecting thermal rod in auxiliary circuit; 2 =
potentiometer lead for oven temperature record,

3: connection of rod to circuit . . . . . . . . . . . 38

7. Location of samples for objective and subjective
evaluation of cooked roasts . . . . . . . . . . . . . 41

8. Average time-temperature relationships during
cooking for three sample depths for two cooking
methods....................... 65

9. Average rate of heat penetration: Min/0C rise for
three sample depths for the radial-conventional
cookingmethod................... 68

10. Average rate of heat penetration: Min/0C rise for

three sample depths for the conventional cooking
method 0 O O O O O O 0 0 O O O O O O O O O O O O O O O 69

vii

IN TROD UC TION

One of the primary concerns of all food service operators is
the production and service of quality food at a price satisfactory to
the consumer and commensurate with an adequate operational profit
percentage.

Because of the nutritional and satiety values of meat and the
popularity it enjoys in the human diet, meat has become a daily
necessity for every food service menu. Moreover, due to the cost
of procurement and losses incurred in preparation and service, cuts
of meat suitable for roasting represent a larger initial cost per
sliceable portion than do cuts which are acceptable for menu items
requiring cubed or ground meat.

Cuts of meat are classified as tender and less tender, depend—
ing upon the location in the carcass and the amount of exercise the
muscles have received. In addition, varying degrees of tenderness
result from inherent differences in the type and extent of connective
tissue present. Less tender cuts have a greater proportion of
collagen and/or elastin than do tender cuts and are usually considered
less desirable for roasting, broiling, or pan-broiling. Studies have
shown that collagen can be softened and made more tender by the
application of heat in the presence of moisture. Consequently, less
tender cuts of meat are usually cooked by moist heat methods such
as braising, boiling, or steaming.

If a food service operator could utilize less tender, less expensive
cuts of beef for roasting, and produce products of acceptable yield and

palatability which could be sold at a price satisfactory to both the

consumer and the operation, the resultant mutual gains would be
invaluable. Moreover, if economies in time required for roasting
could be effected, more efficient use of available equipment could
be made.

The primary objective of this study was to investigate the effect
of a combination of internal radial heating and conventional oven roast-
ing on the yield and palatability of semitendinosus muscle of beef
round. Matching muscles from paired rounds were conventionally
roasted as a control. Internal radial heat was applied by means of
a specially constructed thermal rod installed in a closed electrical
circuit. The rod was horizontally positioned in the center of the meat,
and heat was transmitted directly from the rod to the sample.

With heat being simultaneously available from two sources, the
thermal rod and the oven, it was anticipated that total cooking time
might be shorter for the radial-conventional method than for the
conventional method alone. If this was a valid premise, it was
expected that the radial-conventional method might decrease drip
and evaporation losses, and increase total yield. In addition, the
inherent moisture of muscle tissue held within the cells requires both
heat and time to effect evaporation. The increased total heat per unit
of time reacting with moisture within the muscle tissue might permit
sufficient softening of the collagen to create desirable tenderness
in the product,

Research has shown that heat transferred from the cooking
medium to the product being cooked does not necessarily penetrate
all foods of similar classification at the same rate. In beef, dif-
ferences due to heredity, feed, exercise, and age may cause varia-
tions in the type and amount of fat, muscle tissue, bone, connective
tissue, and moisture present. A roast cut from one carcass may

contain proportionately more or less of any of these elements than a

similar roast from another carcass of the same grade. Tissue density,
shape, and surface area of raw roasts of similar weight may also
differ markedly. Moreover, it is conceivable that factors related to
sample composition and physical structure may be more important
determinants of cooking time required for a specified degree of done-
ness than initial roast weight. For this reason, it was questioned
whether the present system of minutes per pound is a valid means for
estimating roasting time for meat.

. The second objective of this study, therefore, was to examine
the resultant heat penetration data and investigate the potential for
using such data as a more accurate basis for predicting roasting time

for the semitendinosus muscle of beef round.

REVIEW OF LIT ERAT URE

Factors Affecting Cooking Losses In Meat

Cooking losses in meat include both drippings and volatile losses.
Numerous studies have been conducted to determine factors which
contribute to an increase or decrease in these cooking losses. Factors
which are known to influence cooking losses are: composition of
meat, grade, weight and surface area, aging, and cooking method,

temperature and time.

Composition of meat

 

An early study conducted by Grindley and Mojonnier (35) showed
that both water and fat accounted for the weight loss in roasted meats.
Grindley, McCormack, and Porter (34) observed the major portion of
weight loss in rrieat resulted from evaporation of water during cooking.

Lowe (48) reported that the ratio of evaporation loss to dripping
loss is higher for lean meat than for fat meat. The findings of
Alexander (3) are in agreement with this statement. She found that
dripping losses for rib roasts cooked in a 1250C oven to an internal
temperature of 580C varied from 3. 7 per cent for the well-fattened
Choice grade to 0. 4 per cent for the leaner Canner grade. Evaporation
losses for these roasts ranged from 6. 5 per cent for the Choice grade
to 10. 9 per cent for the Canner grade.

Thille, Williamson, and Morgan (79) studied rib roasts cooked
at 210°C to an internal temperature of 650C. Their data revealed
greater total cooking losses for fat-surfaced roasts than for lean-
surfaced roasts with volatile losses greater in the latter than in the

former.

According to Paul and Bratzler (62), steaks from semi-
membranosus muscle, cooked in deep fat at 147°C to an internal
temperature of 630C, had lower cooking losses than steaks from the

adductor muscle cooked in an identical manner.

Grade

 

An increase in the grade of meat usually results from an in—
crease in fat content. This being true, cuts from carcasses of higher
grade usually have greater cooking losses (48).

Two grades of sirloin butt were studied by Dunnigan (32). His
results showed that the composition of meat had a direct influence on
cooking weight losses, with leaner roasts yielding lower total cooking
losses. Alexander and Clark (4) found that rib roasts from higher
grade beef usually showed greater dripping losses and smaller volatile
losses than similar roasts from lower grade beef. Masuda (54) re-
ported no significant differences in volatile losses or total cooking
losses attributable to grade, but average dripping losses at 900C
internal temperature for Good and Choice grade roasts were signifi-
cantly higher than those for Commercial grade roasts. No significant
difference was found between the average dripping losses of Good
and Choice grade roasts cooked to 90°C.

In another study, Day (28) roasted longissimus dorsi muscles of
Good, Commercial, and Utility grades of beef. Her data showed no
significant differences attributable to grade in average total cooking
losses, volatile losses, or drip losses. Choice and Good grade beef
rounds were cooked to an internal temperature of 90°C by Aldrich and
Lowe (2). They found high losses for all cuts, but noted no significant

differences between grades .

Weight and surface area

 

McCance and Ship (55) cooked pieces of top round beef weighing
50, 400,. and 1500 grams each, at 100°C in steam. Regardless of
sample size, total per cent losses of water were the same. The
results of Cline e_t a1. (21) are in agreement with these findings.
Marshall, Wood, and Patton (53) roasted 5-, 10-, and 15-pound cuts
of Choice top round of beef. They found the size of the roast did
affect the total per cent cooking losses. Losses for the 5-pound roasts
were significantly greater than for the 10- and l5-pound roasts at all
degrees of doneness except rare.

Two studies (43,49) have shown that compact pieces of meat with
smaller surface areas have less cooking weight losses than pieces of
similar weight which have irregular shapes and greater surface areas.
Thin, flat roasts, however, require a shorter cooking time per pound

than thick, blocky roasts.

45233

Research conducted by Moran and Smith (57) using top round,
bottom round, and loin roasts ripened 3, 7, and 16 days showed that
with longer aging periods cooking losses decreased. A study con-
ducted at Iowa State College (42) showed beef roasts with a longer
ripening period exhibited lower weight losses when cooked in air than
when cooked in steam, fat, or water.

According to Alexander and Clark (5) the cooking losses and time
required to cook lamb and mutton were decreased with increased

ripening periods. Hanson gt a_L_l. (40) reported similar findings in their

study of New York dressed broilers held at 1.7OC.

Cooking method, temperature and time

 

Lowe (48) states that the method of cooking influences not only
the total but also the relative proportions of the different constituents
lost during cooking.

Clark and Van Duyne (18) compared cooking losses resulting
from top round beef roasts cooked in a pressure saucepan with similar
samples roasted in the oven to an internal temperature of 820C. They
observed significantly greater losses in drip and total cooking losses
in the roasts cooked in the pressure saucepan than in the oven roasts.

Several investigators (21, 59) have reported that low internal
temperatures of meat at the beginning of the cooking period result in
increased cooking losses. However, Lowe and co-workers (49) found
that cooking losses for frozen cuts of meat were not always greater
than those of defrosted meat.

Morgan and Nelson (58) reported that skewered meat yielded
smaller and less consistent decreases in total shrinkage of meat than
unskewered roasts. The total loss of weight in skewered roasts
averaged 27. 3 per cent as compared with 31. 5 per cent for unskewered
roasts. The results of other investigators support these findings
(13, 21).

Cooking losses of meats roasted in covered and uncovered pans
have been compared by several investigators (35,46, 55). 7 Findings
from these studies indicate that weight losses are greater when meats
are roasted in covered pans than when cooked in open pans.

The question of whether high cooking temperatures increase or
decrease cooking losses has been investigated by many research
workers. Lowe (48) states that, in general, when cooking temperature
is increased cooking losses also increase. Child and Satorius (17)

roasted semitendinosus beef. muscles at oven temperatures of 125,

150, 175, and 2000C to an internal temperature of 580C. They con-
cluded that with increased oven temperatures rate of evaporation was
accelerated and greater cooking losses resulted. A similar study
(47) using standing rib roasts seared at 2500C for 20 minutes and
cooked at temperatures ranging from 110 to 1750C, showed that
average total cooking losses increased in proportion to rise in oven
temperature. Total average cooking losses varied from 13. 52 per
cent in roasts cooked at 110°C to 22.49 per cent in roasts cooked at
175°C.

Using very low oven temperatures, Bramblett it a}. (10) found
that beef'cooked at 630C had a lower percentage of cooking losses and
a higher percentage of moisture content than beef cooked at 680C.
The results of other studies (19. 20, 21) are in agreement with these
findings.

Lowe (48) states that if other conditions are standardized, the
more well-done meat is cooked the greater the cooking losses.
According to Child and Fogarty (16), who cooked semitendinosus
muscles of beef round at an oven temperature of 150°C to internal
temperatures of 58 and 750C, the higher the internal temperature was,
the greater were the cooking losses. Earlier meat studies (35,47)
also indicated an increase of cooking losses with an increase in degree
of doneness.

Aldrich and Lowe (2) cooked pot roasts from Choice and Good
grade beef rounds, rump on, at an oven temperature of 150°C to an
internal temperature of 900C. An additional hour of cooking after the
internal temperature reached 900C increased the average total weight
loss 38.9 per cent, the average volatile loss 27. 2 per cent, and the
average volume loss 25. 3 per cent.

In another investigation (79), rib roasts of beef cooked at 2100C

. 0 .
to an internal temperature of 65 C showed m01sture losses were

directly proportional to the length of roasting time. Paul and Bratzler
(62), in their study of steaks from semimembranosus and adductor
muscles cooked in deep fat, found a high positive correlation between

cooking time and cooking losses.

Factors Affecting Rate of Heat Penetration

The time required for cooking meat is often stated in minutes per
pound. However, the extreme variability of meat coupled with the
many interdependent factors influencing heat transfer make it difficult
to forecast the exact time required for cooking. Major factors which
influence cooking time required for meat will be reviewed under the
headings of composition of meat, weight and surface area, aging, initial

temperature of meat, and cooking method, temperature and time.

Compo sition of meat

 

Because of variances in thermal conductivity and heat capacity
in all matter, the rate and extent of heating of any given material is
dependent upon the nature of the product itself. Also, the rate of
heating may be affected by the consistency and homogeneity of the
product (30).

Lowe (48) filled pint jars with lean beef, lean pork, fat pork,
and suet to obtain data on the rate of heat penetration in muscular and
fatty tissue. The four jars were placed in a processing container
and heated in boiling water and steam for 3 hours. Temperatures
were recorded by thermometers inserted through rubber corks in the
lids of the jar and processor to the center of the jar. Data showed
the rate of heat penetration was greatest in the lean beef and decreased
in the order of lean pork, fat pork, and suet. Thille, Williamson and

Morgan (79) studied the rate of heat penetration into balls of beef fat.

10

They observed that as the fat liquified upon heating, the heat pene-
tration rate increased. They suggested that surface fat of meat tends
to increase the rate of heat penetration due to its early melting in

the cooking process, whereas, interior fat remains solid for a longer
period of time and may retard the rate of heat penetration.

Towson (80) cooked paired prime beef ribs at 125 and 200°C to
an internal temperature of 630C. Temperatures were recorded at 4
points in each roast during cooking: (a) the center which was 2 inches
from either cut surface of the longissimus dorsi muscle, (b) 0. 5 inch
below the chine bone, (c) 0. 5 inch from the cut surface of the lean, and
(d) 0. 5 inch below the surface of the fat over the top of the roast. Data
showed that when the exterior fat layer was deeper than 0. 5 inch, so
the thermometer bulb was embedded in the fat, the heat penetrated the
0.5 inch layer of fat more slowly than the 2 inches of lean. In their
study of rate of heat penetration in roasts, Thille, Williamson, and
Morgan (79) reported fat covered roasts required 23.4 minutes per
pound as compared to 19. 3 minutes per pound for lean roasts.

Cline and associates (21) studied six different kinds of roasts
from 450 cuts of beef to determine how different methods of cooking
affect the quality and palatability of beef. Roasts were cooked to an
internal temperature of 570C in a 1250C oven. They reported that
boneless roasts took longer to cook than cutswith bone. Prime rib
roasts required 24 minutes per pound, unboned rump 23 minutes per
pound, and two cuts from the chuck 18 minutes per pound. Sirloin
tip roasts, and the heel of the round, with no bone, cooked in 33 and
29 minutes per pound respectively. Contrary to this, other investi-

gators (79) have reported bone to be a poor conductor of heat.

ll

WeiQt and surface area

 

Lowe (48) states that as the size of a piece of meat increases,
its weight increases in greater ratio than its dimensions. This being
true, if other conditions are standardized, larger cuts such as roasts
and hams will require fewer minutes per pound for cooking than
smaller similar cuts. 1

T0p round roasts weighing 5, 10, and 15 pounds were cooked by
Mar shall, Wood, and Patton (53). Analyses of these data indicated
that as size and degree of doneness increased, total cooking time also
increased. However, fewer minutes per pound were required for
cooking the larger roasts. Thille gt a_1. (79) reported a longer heating
period per unit of weight was necessary for lean-surfaced roasts even

though they were equal to or larger-than fat- surfaced roasts.

{isles

According to Alexander and Clark (5), from their work with
mutton and lamb, increased ripening periods after slaughter shortened
cooking time. Hanson e__t a_._l. (40) found that heat penetration was more
rapid as post mortem changes in broilers progressed.

Steaks from semimembranosus and adductor muscles were cooked
in deep fat by Paul and Bratzler (62) to study the effect of lengthened
storage periods. For the semimembranosus steaks, increased storage
tended to increase cooking losses but decrease cooking time. In the
adductor, steaks cooking losses were not altered significantly with in-

creased storage, but cooking time was decreased slightly.

Initial temperature of the meat

 

A longer cooking time is required when the initial temperature
of meat is low than when it is high. Meat still frozen at the beginning

of a cooking period requires a longer cooking time because part of the

12

heat is being used to melt the ice before the temperature can be raised
above the freezing temperature of the meat (48).

The effect of four methods of defrosting meats and of the manner
and temperature of cooking upon weight loss and palatability of roasts
was studied by Lowe and associates (49). A longer cooking time was
required for frozen cuts of meat than for comparable cuts which were

thawed .

Cookinginethod, temperature and time

 

If the temperature of different cooking mediums is the same,
time required for cooking depends to a great extent upon the rate of
heat transfer in the particular medium being used (48).

Harrison (42) reported that cooking time for beef was shortest
in water followed by fat, steam, and air, respectively. Cover (22)
compared the cooking times required for similar roasts cooked in a
water bath and in an oven of the same temperature. The time required
to reach the desired internal temperature was less than 3 hours in the
water bath and more than 23 hours in the oven.

Twelve top round beef roasts, weighing 5 pounds each, were
cooked in the pressure saucepan or oven roasted to an internal
temperature of 82°C by Clark and Van Duyne (18). Roasts cooked in
the pressure saucepan required two-thirds less time than those cooked
in the oven. According to a study by Visser e_t al. (82), roasts cooked
in deep fat had shorter and steeper time-temperature curves than did
comparable roasts cooked in the oven. At a given temperature, heat
conductivity of liquid fat was approximately six times that of air.

The use of skewers to reduce cooking time has been investigated
by several workers (13, 23, 58). Morgan and Nelson (58) compared the
cooking times required to reach a given interior temperature by

skewered and unskewered two—rib standing beef roasts. Their findings

13

showed that the rate of cooking increased from 30 to 45 per cent when
nickel-plated copper skewers were used. Similar results were found
when Cover (23) cooked paired round, arm-bone chuck, and standing
rib roasts of beef to an internal temperature of 800C in a 1250C oven,
one with and the other without skewers. Skewers decreased both
cooking time and cooking losses.

Lowe (48) pointed out that the higher the cooking temperature,
the more rapidly a piece of meat will reach a definite temperature,
for, with a higher temperature at the surface, the more rapidly heat
will penetrate into the interior of meat.

In annearly experiment, Latzke (47) roasted standing ribs of
beef to the same degree of doneness at different oven temperatures.

She found the rate of heat penetration per pound of raw meat increased
in proportion to the rise in external temperature. Cline, Loughead,
and Schwartz (20) studied the effect of two roasting temperatures, 257
and 3110F, on the palatability of beef roasts. In all cases, the time
per pound required for roasting was lessened by the higher oven
temperature.

Cooking meat rare requires a shorter time than cooking it
medium or well done if all other conditions are standardized (48).
Latzke (47) found that roasts cooked in a 125°C oven to different degrees
of doneness required varying average minutes per pound. The rare
beef roasts required 14.19 minutes, the medium 16.44 minutes, and
the well-done 22, 91 minutes.

According to a recent study by Marshall gt a}. (53), roasts cooked
to 70 and 80°C in a 93°C oven exhibited wide differences in rate of heat
penetration. Roasts cooked to these same internal temperatures at
higher oven temperatures, 107 and 121°C, showed less variation.
Roasts cooked to 600C showed the most uniform rates of heat penetration

among oven temperatures used in the experiment,

14

Factors Affecting Palatability Characteristics

"Regardless of the nutritional excellence and adaptability of
meat and meat products as an item of the diet, meat will be con-
sumed in adequate and increasing quantities only if it appeals to and
is accepted by the consumer on the basis of its palatability or taste
characteristics (84). "

The palatability of cooked meat depends upon six major qualities:
aroma, flavor, appearance, texture, tenderness, and juiciness.
These, in turn, are affected by one or more of the following factors:
composition of the meat, grade, aging, and method and extent of

cooking.

Aroma and flavor

 

Meat flavor and aroma are difficult to separate because many of
the flavor properties are the result of odor sensations. Raw meat
flavor is weak, salty, and blood-like. True meaty flavor is developed
during cooking and is thought to arise from chemical changes in the
muscle fiber protein. Many of the flavor components of cooked meat
are water-soluble, but some may be found in the water-insoluble

nitrogenous fraction from muscle fibers (84).

Grade. The effect of carcass grade on aroma and flavor has
been reported by numerous investigators. In comparing longissimus
dorsi muscles of Good, Commercial, and Utility grades, Day (28)
reported significant differences in flavor and aroma of the cooked
meat due to grade. Griswold (36) studied the effect of different methods
of cooking beef round of Commercial and Prime grades. Large dif-
ferences were found between animals within a grade but, on the whole,
palatability scores were higher for beef rounds of Prime than of

Commercial grade. Statistical analysis conducted by Masuda (54)

15

showed the average aroma and flavor scores from Commercial grade
beef to be significantly higher than those from Good and Choice grade
roasts. Lowe e_t 31' (49) compared Choice, Good, and Commercial
grade rib roasts. Highest scores for aroma and flavor were obtained
from the Choice grade.

In her study of the palatability of two grades of sirloin butts,
Dunnigan (32) cooked Choice and Utility grade sirloin butts, with and
without bone, at an oven temperature of 150°C to an internal tempera-
ture of 70°C. Scores for aroma and flavor were significantly higher
for Choice roasts than for Utility roasts. Barbella and associates (6)
cooked 728 beef rib roasts to study the effect of fatness and other
factors on flavor and juiciness of beef. They observed that the lean
meat from wellwfed animals was very superior in flavor to meat from
poorly-fed animals. Other investigators (11, 76) have reported that

with increased degree of finish there is an increase in flavor scores.

Aging. Cooked unaged beef is quite metallic and astringent
and lacks typical beef flavor. True beef flavor is fully developed by
approximately 8 days' aging; as the beef becomes more tender during
aging, the bouquet develops (84).

The effect of storage conditions on the palatability of beef was
investigated by Paul, Lowe, and McClurg (64). Paired rounds of Good
grade steer were stored and checked at intervals up to 18 days. The
flavor and aroma improved up to the 9th day, but thereafter scores for
these characteristics decreased with increased aging of the meat.
These decreases were attributed to the development of gameness in
the lean, and rancidity in the fat. A similar study by Griswold and
Wharton (37) reported that meat aged 37 days had somewhat stronger

aroma and flavor than meat aged nine days.

16

Harrison (41) studied the histological, physical, and organo—
leptic changes in beef during the ripening period. She found that at
temperatures of 34 and 36°F, the first ten days of ripening yielded
the greatest improvement in palatability. A musty odor and a high

flavor developed between 20 and 30 days of aging.

Method and extent of cooking. Twelve comparable top round

 

beef roasts were cooked in the pressure saucepan or roasted in the
oven to an internal temperature of 82°C by Clark and Van Duyne (18).
Results indicated that more palatable meat was obtained in the oven
than in the pressure saucepan, Judges preferred the flavor of the
lean and fat of the oven roasted meat. Cline and associates (21)
reported lower flavor and aroma scores for tender beef cuts cooked
with added water in a 125°C oven than for comparable oven roasted
cuts. Griswold (36), in comparing the effect of different cooking
methods, found beef round roasted at 121°C scored high in flavor and
acceptability. Similar findings were reported by Stech and West (77).
Latzke (47) seared standing rib roasts at 250°C for 20 minutes
and then cooked them at various temperatures from 110 to 175°C.
The medium-done roasts cooked at an oven temperature of 125°C
gave a product with maximum desirability of flavor, Aldrich and
Lowe (2) found that an additional hour of cooking at 150°C, after the
internal temperature of beef round pot roasts reached 90°C, decreased
the scores for aroma and flavor. According to Weir (84), an increase
in the sulfury flavor component results from this additional holding

period.

Appearance and texture

 

Crist and Seaton (26) reported that appearance ranked first in
importance according to their judges' scores . Brady (9) concluded

from his study of factors influencing tenderness and texture of beef,

17

that texture is dependent upon the size of the bundle of muscle fibers,
and the greater the number of fibers in a bundle, the finer the texture.
This conclusion is substantiated in part by the fact that longissimus
dorsi muscles which are considered to have good texture have been
shown to have more fibers of a similar diameter per primary bundle

than do muscles of less desirable texture such as the semitendinosus

(7).

223513. According to Masuda (54), the average appearance
scores for roasts of Commercial and Good grades were significantly
higher than for roasts of Choice grade. No significant differences in
texture were found attributable to grade. Day (28) reported that judges
found little difference between grades in appearance or texture.

An earlier study by Satorius and Child (72) showed no significant
difference between medium and good grades in the external appearance
of longissimus dorsi and adductor muscles cooked to 58°C at a 150°C
oven temperature. However, a significant difference was found

between the two grades in the external appearance of the raw muscle.

2919;. According to Weir (84) the color of cooked, uncured,
lean meats depends to a great extent upon the nature and amount of
myoglobin derivatives and decomposition products present. Pigment
changes that occur during cooking also help determine the final color
of cooked meats; these changes being determined by the type, length,
and temperature of cooking. Visual color changes occurring in meat
are related to temperature as follows: below 60°C, little or no color
change; 65-700C, decreasing pinkness to 70°C; at 759C, complete
loss of pinkness.

The fat portion of meat changes very little in color during cook-
ing except for surface browning which increases the attractive

appearance of meat. Fat decomposition and poly'rnerization with

18

carbohydrate and protein decomposition products cause this surface
browning. The greenish iridescence on the surface of cut cooked meat
is caused by the refraction of light in the thin layer of fat spread over 1

its surface by slicing (84).

Methpd and extent of cooking: Winegarden e_t a_._l. (86) studied the

 

physical changes occurring in connective tissue of beef during heating.
Results showed that strips of connective tissue softened, shortened in
length, decreased in width, and increased in thickness during heating.
These changes occurred together, and as cooking time increased and

temperature of heating was elevated, the degree of changes increased.

Bramblett and associates (1‘0) cooked five muscles from six pairs
of Standard grade beef rounds, one of each pair at 630C for 30 hours,
and the other at 680C for 18 hours. Taste panel scores for texture and
appearance were higher for meat cooked at the lower temperature than
for meat cooked at the higher temperature.

In studying the effect of extent of cooking on palatability and
edible portion of Good and Choice beef rounds, Aldrich (1) found that
cooking for an additional hour after the internal temperature reached
900C resulted in lower average appearance scores than cooking only
to 900C. Data from a similar study (53) showed that appearance tended
to be scored lower as the degree of doneness increased.

Lukianchuk (51) compared the effect of two methods of dry heat
cookery on palatability and cooking losses of paired semimembranosus
muscles of beef round. Taste panel members scored the texture of
conventionally roasted samples slightly higher than those cooked in
deep fat, although statistical analysis of these data indicated no
significant difference in texture attributable to cooking method.

An early study by Morgan and Nelson (58) revealed that meat from
unskewered roasts was drier and less appetizing in appearance than

meat from skewered roasts. Roasts cooked well-done in covered pans

19

did not differ in interior appearance from roasts similarly cooked in

uncovered pans .

Tenderness

 

The most important palatability factor in the acceptance of beef,
as determined by consumer studies, is tenderness (84). Many factors

both ante-mortem and post-mortem, influence the tenderness of beef.

Composition of meat. Lowe (48) states that collagen affects the

 

tenderness of meat to a greater extent than elastin because the ratio
of elastin to collagen is small. Collagen is converted, to gelatin by
heat in the presence of water, whereas, little change occurs in elastin.

The effect of intramuscular fat on tenderness of meat has been
studied by many investigators. Helser, Nelson and Lowe (43) reported
that betters-fattened animals yield more tender meat than less-fattened
ones. Contrary to this, Hankins and Ellis (39) reported no significant
cor relation between the fat content and tenderness of cooked longissimus
dorsi muscles. They concluded that variations in tenderness are
caused mainly by factors other than fat content.

Instudying the comparative tenderness of samples from eight
muscles of Good grade beef, Ramsbottom and Strandine (70) found no
relationship between the amount of fat within the muscle and shear force
values of raw or cooked samples. They concluded that the relative
amounts of collagenous and elastic connective tissue in the muscle in—

fluenced the tenderness of the cooked muscle.

 

Age, sex, and grade. Brady (9) believes that the texture of
meat is an indication of tenderness, and the finer the texture, the
more tender the meat. His data demonstrated that with an increase
in the age of the animal there is an increase in the diameter of muscle

fibers. ~ A mean diameter of 58. 8 microns was reported for the same

20

muscle in yearling steers as compared with 70. 9 microns for mature
cows.

Hiner and Hankins (44) studied animals ranging in age from 2.5
to 5.5 years to determine the effect of animal age on tenderness of
meat. Increases in animal age were accompanied by decreases in
tenderness. The findings of MacKintosh and co-workers (52) sub-
stantiate these results.

Satorius and Child (74) roasted cuts from six steers graded high-
medium to good and from seven cows graded good, to an internal
temperature of 58°C in a 150°C oven. Tenderness measurements by
the Minnesota modification of the Warner Bratzler shear apparatus
showed that meat from steers was much more tender than meat from
cows. Shear force required for steers was 18 pounds as compared to
28 pounds for cows.

Day (28) reported differences in tenderness attributable to grade,
significant at the 1% probability level, for longissimus dorsi muscles
of Good, Commercial and Utility grades of beef. Average tenderness
scores for roasts from tender cuts of Commercial, Good, and Choice
grade beef cooked by Masuda (54) revealed that Choice grade roasts
were significantly more tender than Commercial and Good grade roasts.
No significant difference in tenderness was found between the average

scores of Commercial and Good grade roasts.

Animal and muscle variations, Weir (84) states that among

 

muscles in any one animal there is a wide variation in tenderness.
In general, muscles containing the largest amount of connective tissue
are the least tender, and those with the smallest amount are the most
tender.

Noble, Halliday, and Klaas (60) investigated the tenderness of
cooked beef by means of a slightly modified New York Testing Labora-

tory Penetrometer. With one exception, rib cuts of beef were one

21

and one-half times more tender than first round cuts from the same
animal. Ramsbottom and Strandine (70) studied 25 representative
beef muscles from three commercially graded Good carcasses cooked
in 121, 1°C lard to an internal temperature of 76.70C. Shear tests
with the Warner Bratzler machine showed a significant variation in
tenderness from muscle to muscle. Bramblett and associates (10)
reported significant differences in shear values among five muscles
of Standard grade beef round cooked by two different methods.

In her study, Griswold (36) found no significant differences
between shear values of semimembranosus and biceps femoris muscles
of beef round. Contrary to this, Mitchell (56) concluded that the inner
round is more tender than the outer round. Examination of 12 rounds
indicated that inside muscles contained much smaller percentages of

elastin and collagen than outside muscles.

Aging. Lowe (48) reported that Lehmann was one of the first
persons to measure the increase of tenderness of beef during aging.

In his work with flank and loin muscles, he showed that aging increased
tenderness. When meat is held at 0.50C after slaughter, there is a
decrease in tenderness during the first 24 hours while rigor mortis
sets in, and then a gradual increase in tenderness (84).

In 1944, Paul at a1. (64) studied the changes in histological struc-
ture and palatability of beef during 1. 70C storage over a 4-day period.
They observed that the greatest increase in tenderness of small beef
cuts coincided with their observed increase in frequency of fiber
breakdown.

According to Moran and Smith (57), alteration in the protein of
muscle fiber is the most important change during the first few days
after death during the disappearance of rigor. Several days after death
rigor is completely resolved and any further increase in tenderness

is due mainly to the softening and swelling of the collagen. In contrast

22

to this Wierbicki e_t a_L_1. (85) believe that connective tissue changes
cannot account for the tenderness produced by aging. From their
experiments, Birkner and Auerbach (7) concluded that aging has no

apparent effect upon elastic fibers.

Freezing. Regarding the tenderizing of beef by freezing, there
is no unanimity of opinion. In their work with steaks, Pearson and
Miller (65) found freezing by itself did not increase tenderness, whereas
frozen storage brought about a decrease in tenderness. Ramsbottom
(69) reported that frozen storage at —23.30C or lower for as long as
7 years did not significantly affect the tenderness of beef steaks.
Paul and Child (63) observed no significant difference in the tenderness
of meat which was frozen at —180C and meat which was not frozen.
Hiner and Hankins (44) studied paired short loins of beef and
observed that freezing had more tenderizing effect than storage at 34°F.
They reported that beef frozen at 20°F was approximately 12 per cent
more tender and beef frozen at ~10 or -40°F was 18 per cent more
tender than beef ripened at 34°F. No significant difference in the
tenderizing effect was found between loins frozen at -40°F and those

frozen at ~100F,

Method and extent of cooking; Cover (23) studied the effect of

 

metal skewers on cooking time and tenderness of beef. She found
that the use of skewers in paired round-bone chuck roasts decreased
the tenderness of the cooked product. Conversely, Morgan (58)
found that skewered roasts were more tender than those cooked without
skewers.

Lukianchuk (51) studied semimembranosus muscles of beef and
reported no significant differences attributable to cooking method for
softness, friability, residual tissue, general tenderness, or shear

force.

23

In another study, Clark and co-workers (18) compared the effect
of oven roasting and pressure saucepan cookery on palatability of beef
muscles. No differences were detected by a mechanical shear stress
apparatus or by subjective evaluation of tenderness in semimembranosus
and adductor muscles of beef round cooked by either method.

Cooking time and tenderness of meat cooked in a water bath and
in an oven of the same temperature were compared by Cover (22).

Both subjective and objective evaluations indicated roasts cooked in the
oven were more tender than roasts cooked in a water bath. She con-
cluded that "moist heat" in the sense of added moisture is not necessary
for making tough meat tender. The results reported by Griswold (36)
are in agreement with these findings.

Lowe (48) pointed out that cooking time rather than cooking
temperature is the factor which determines tenderness in meat. Child
and Satorius (17) studied the effect of various oven temperatures on
the tenderness of roasted beef muscles. Semitendinosus muscles
heated to an internal temperature of 58°C at oven temperatures of 125,
150, 175, and 200°C did not differ in shear force values. Bramblett
it a_._1, (10) reported beef cooked at 63°C as compared with beef cooked
at 68°C was more tender.

In another study, Cover (25) investigated the relationship between
oven temperature and meat tenderness, Constant oven temperatures of
125 and 225°C were used to roast meat to an internal temperature of
800C. These data revealed roundw-bone chuck and rump roasts of beef,
and half ham roasts of pork were more tender when cooked at 125°C
than when cooked at 225°C. Cover concluded that the tenderizing effect
noted in samples roasted at the lower temperature probably did not
result from oven temperature alone, but from the combined effect of

longer cooking period and lower cooking temperature.

24

According to a more recent statement by Weir (84), two
changes occur during the cooking of meat: the muscle fibers become
tougher, and the connective tissue becomes more tender. Although
these two occurrences are dependent upon both time and temperature,
the time factor is more important for collagen softening while the
temperature factor appears to be more important for muscle fiber
toughening.

In studying the effect of cooking time on pot roasts from beef
round, Aldrich and Lows (2) reported that an additional hour of cook-
ing after the internal temperature of the roasts reached 90°C resulted
in a slight increase in tenderness as shown by panel scores and shear
force readings.

Satorius and Child (72) studied the effect of coagulation at three
stages of doneness on shear force values. They reported that with
increased internal temperature semitendinosus beef muscles become
more tender until 75°C was reached when the meat then was found to
be less tender than that cooked to 67°C. They conclude that during
the first two stages of coagulation, to 58°C and to 67°C, the effect of
hydrolysis is evidently greater than that of increased density from
coagulation; while in the last stage, to 75°C, the reverse is true.
Noble, Halliday and Klaas (60) concluded from penetrometer readings

that toughening occurred during heating from 61 to 75°C.

Juicine ss

Juiciness of cooked meat may be separated into two effects: the
first is the impression of wetness during the first chews produced by
the rapid release of meat fluids; the second is one of sustained juici-
ness apparently due to the slow release of serum and to the stimulating

effect of fat on salivary flow,

25

Composition of meat. Noble, Halliday, and Klaas (60) reported

 

that beef rounds yielded more juice than standing rib roasts when both
cuts were cooked to 61°C at an oven temperature of 149°C. Harrison
(42) reported that, of the muscles included in her study, roasts from
the psoas major muscle were most juicy and those from the semi-
tendinosus muscle were the least juicy. Variation in juiciness from
muscle to muscle was also found by Paul, Lowe, and McClurg (64),

Using a pressometer to measure the press fluid in standing and
rolled rib roasts of beef, Child and Esteros (15) concluded that standing
rib roasts contained a larger quantity of juice than the rolled rib roasts.
The findings of Alexander and Clark (4) are in agreement with this con-
clusion.

Well-marbled meat from mature animals with a relatively high
degree of finish is juicier than that from young animals with less
marbling (84). Stech and West (77) studied differences in eating quality
factors of beef from 18- and 30—month old steers. Although age dif-
ference did not affect juiciness significantly, anterior locations of
semimembranosus, adductor, and longissimus dorsi muscles scored
higher for juiciness than posterior locations.

Thille, Williamson and Morgan (79) cooked beef rib roasts at
210°C to an internal temperature of 65°C, Their data showed that fat-
surfaced beef roasts were less dry than lean-surfaced roasts,

Barbella e1: a_1_l. (6) used 728 rib roasts to study the relationships of
flavor and juiciness to fatness and other factors. They observed a
rapid increase in juiciness with increased fatness up to 22. 5 per cent
and more slowly thereafter to 42. 5 per cent. After a 42. 5 per cent
fatness level was reached, there was no increased juiciness attribut-

able to fatness .

Grade. Several investigators (1, 28, 54) have reported findings

on the relationship between carcass grade and juiciness. Masuda (54),

26

studying Choice, Good, and Commercial grades of beef, found no
significant differences in juiciness attributable to grade. Day (28),
using beef of Good, Commercial, and Utility grades, came to the same
conclusion. According to Aldrich (l), the amount of press fluid found
in Choice rounds was slightly higher than that found in Good rounds.
Contrary to this, Vail and O'Neill (81) reported cooked Choice grade
rolled rib, round, and clod cuts of beef yielded appreciably less

press fluid than similar Good grade cuts.

Aging. Changes which are noticeable during aging, according
to Lowe (48), are increased tenderness, change in flavor, and increase
in case with which juice may be pressed from the meat. Weir (84)
states that tenderness and juiciness are closely related; the more
tender the meat, the more quickly the juices are released by chewing,
and the more juicy the meat appears.

Harrison (41) reported little variation in juiciness scores of
roasts stored 1 to 20 days. Juiciness scores decreased after 30 days
of aging. She concluded that evaporation of the fluids in the raw roasts
during storage was great enough to affect the juiciness scores of the
cooked roasts. According to Paul (61), during the first few days of
storage there is a reduction in press fluid, followed by a sharp in-

crease between the 9th and 18th day of ripening.

Method and extent of cooking. Morgan and Nelson (58) reported

 

skewered roasts were more juicy than unskewered roasts when cooked
at the same oven temperature and to the same internal temperature.
Cover's (23) findings were in agreement with this.

Cline and co-workers (21) used 450 cuts of beef to study the effect
of cooking methods on palatability of meat. They reported that searing
does not increase the juiciness of cooked meat. Clark and Van Duyne

(18) reported that meat cooked in the pressure saucepan to an internal

27

temperature of 80°C was considered too dry by the judges. The results
of Lukianchuk's study (51) showed that for both subjective and objective
evaluations, conventionally roasted samples were juicier than those
cooked in deep fat.

Child and Satorius (17) studied the effect of exterior temperature
on the juiciness of beef. They concluded that external temperatures
do not affect either the amount of press fluid or the juiciness scores of
comparable cuts of meat cooked to the same internal temperature.
Contrary to these findings, Cline e_t 3.1: (21) reported that high oven
temperatures decrease the juiciness of roasts. In their study,
Bramblett e_t a}. (10) noted that meat cooked at 68°C for 18 hours
yielded less press fluid and lower scores for juiciness than meat cooked
at 630C for 30 hours.

Aldrich and Lowe (2) found that an additional hour of cooking after
the internal temperature of pot roasts reached 90°C decreased the
juiciness of the product. In a 1938 study, Satorius and Child (74)
reported that semitendinosus beef muscle, roasted to an internal
temperature of 67°C, had more press fluid than comparable cuts
roasted to 75°C. This difference was not evident when internal
temperatures were increased from 58 to 670C. Noble, Halliday, and
Klaas (60) also found that cooking to a lower internal temperature
(61°C) yielded juicier meat than cooking to a higher internal tempera-

ture (750C).
Methods of Evaluating Palatability

Sulljective evaluation

 

Lowe (48) states that the acceptance or rejection of a food is based
largely on the stimulus given the sense organs of an individual. Sight,

smell, taste, and touch are the more important senses in food evaluation.

28

According to Weir (83), taste panels are of two main types,

(a) the specialized research panel designed to determine differences
in treatments and the magnitude of the difference of preference; (b) the
consumer panel designed to indicate a preference and/or the degree of
preference for the samples being evaluated.

There are many types of sensory tests given to panel members.
These may be ranking tests, scoring tests, triangle tests, paired
sample tests, and others (48). Numerous investigators (24, 27,48,75)
have described the procedure and discussed the advantages and disad-
vantages of one or more of these methods of evaluation.

Lowe (48) states that none of the methods for determining sensory
differences is entirely satisfactory because: (a) with some methods, no
evaluation of the particular gradation of quality is obtained, (b) all tests
are not applicable to all products, and (c) evaluations may be compara-
tive rather than absolute. According to Boggs and Hanson (8), the
following factors affect the accuracy of results: (a) characteristics
evaluated, (b) cooking of the sample, (c) quality of the foods, (d) reference
standards, and (e) replications.

Weir (83) suggests that the following points be remembered:

(a) when sampling meat for tenderness, judges should be given a

sample from the same relative position each time, (b) the temperature
of the meat at the time of testing should always be the same, (c) samples
should be large enough to allow judges to recheck the samples if they
wish.

Dove (31) recommends air conditioned rooms for testing to prevent
odors of paint, coffee, smoke or other aromas from influencing judges'
decisions. According to Peret (66) china, silver and glass utensils
should be used in testing to assure optimum results. Other investigators
(33) stress the importance of isolating judges, one from another, to

assure accurate results.

29

At a symposium on Accepted Testing Methodology, held in
Chicago in 1953 (67), Dr. H. Schlosberg, Brown University, reported
that the best or only way to obtain more stable and sensitive measure-
ments of response is to increase the size of the panel. The problem
of planning organoleptic tests to increase the validity and accuracy
of panel scores has been discussed by Crist and Seaton (26), Lowe

and Stewart (50), and Dove (31).

Objective evaluation

 

Meat quality is determined by the total effect of its physical and
chemical characteristics. Since certain organoleptic properties of
meat are obviously dependent upon physical characteristics, attempts

have been made to measure some physical characteristics objectively.

Tenderness. Several mechanical devices have been developed

 

to determine values related to tenderness. These instruments, the
Warner-Bratzler shear machine, the recording strain-gauge denture
tenderometer, the New York Testing Laboratory penetrometer, and
others, have been described by Bratzler, Warner, and MacKintosh
(12), Winkler (87) and Proctor gt a_1. (68). In general, either the force
required to cut or shear through a piece of meat, or the amount of
work done in cutting or shearing through a piece of meat, is measured
by these instruments.

A review by Schultz (75) outlines the advantages and disadvantages
of some of the instruments and methods. Hurwicz and Tischer (45)
studied the problems encountered with the Warner-Bratzler shear
machine and pointed out some of the inherent errors.

According to Doty (29), the following statements can be made
concerning methods for evaluating objective tenderness: (a) samples
to be tested must be of uniform size, (b) testing must be done at a

single temperature, (c) several replicate tests must be run on each

30

sample, and (d) results obtained on raw beef are of little value as an
indication of tenderness of cooked meat. Doty further states that if
these general precautions are observed, shear or other objective
tenderness measurements on cooked meat may correlate quite well
with taste panel evaluations of tenderness. Several investigators

(2, 73) have found a high degree of correlation between taste panel

tenderness scores and shear force values.

Juiciness. Since the liberation of meat fluids during chewing
is responsible for the sensation of juiciness, an objective evaluation
of juiciness can be determined by an estimate of the expres sable fluid
from meat (29). In 1934, Child and Baldelli (14) designed equipment
to determine the fluid expressed from cooked meat under 200 p. s.i.
This they called a pressometer. In 1943, Tanner, Clark, and Hankins
(78) adapted an hydraulic press to determine the fluid expressed from
cooked meat at 2500 p. s.i.

Doty (29) pointed out that for some types of cooked meats a fair
index of organoleptic juiciness is obtained by these methods, but
because juiciness is apparently due to the fat concentration and dis-
tribution, this is generally not so. Child and Esteros (15) and Day
(28) reported significant correlation between taste panel juiciness
scores and pressometer readings. Aldrich (1) found good correlation
between the percentage of press fluid determined by a pressometer
and judges' scores for juiciness in muscles from Good and Choice
grade beef rounds cooked to 900C. Tanner e_t a_l. (78) found no corre-

lation between juiciness scores and hydraulic press fluid values.

Combination of subjective and objective methods

 

Due to the shortcomings of both subjective and objective tests
when used separately, many workers have used a combination of the

two methods for determining food acceptability.

31

Halliday (38) recommended the use of a combination of subjective
and objective methods for food testing. The same recommendation
was made by Dove (31) who stated that ". . . in order to judge the
merit and range of use of each and every objective test, we must hunt
out a scientific basis for our judgment by developing a method of
measuring the subjective responses. " Other investigators (50) believe
that objective tests for organoleptic qualities must measure those

characteristics which are correlated with acceptability.

METHOD OF PROCEDURE

To compare the effect of two methods of dry heat cookery on
palatability, cooking losses, and rate of cooking, twelve semi-
tendinosus muscles from six pairs of U. 5. Choice grade steer beef
rounds, rump on, were used. One muscle from each pair was con-
ventionally roasted whereas the matching muscle was cooked by a
combination of internal radial heating and conventional roasting.
Procedures used for the preparation, roasting, and subjective and
objective evaluations of the samples were developed through pre-

liminary investigations in the laboratory.
Procurement of Samples

Paired steer rounds, weighing approximately 70 to 80 pounds
per round, were purchased from the Farmer Peet Packing Company
and delivered to the Michigan State” University animal husbandry meat
laboratory. Six days after slaughter, the semitendinosus muscles
were dissected from the rounds, the surface fat removed, and the
muscles trimmed to provide roasts as comparable as possible in shape
within a weight range of 1300 to 1500 grams. Trimmed samples were
individually wrapped in Tite freezer paper, assigned code numbers
from a table of random numbers, marked for identification of the
anterior and posterior ends, blast frozen and stored at ~20°C until
defrosted prior to cooking. Storage periods for the samples ranged
from 91 to 105 days. Information regarding weight of rounds, weight
of muscles, muscle linear measurements, and trimmed sample weight

is given in Table 12, the Appendix.

32

33

Equipment Used

With the exception of the thermal rod assembly, standard
institutional roasting equipment was used throughout the study.
In addition, certain pieces of special laboratory equipment were used

to facilitate accurate collection of data.

Measuringfiand weighing

 

The device used for measuring the length, width, and depth of
the raw and cooked test samples consisted of two vertical 18-inch
rulers which were numbered from the bottom to the top. Connecting
the two vertical rulers was a horizontal 24-inch ruler with numbers
reading from left to right. The left vertical ruler was secured on a
metal foot and could stand alone; the horizontal ruler could be moved
up and down and the right vertical ruler could be moved toward or
away from the left ruler.

To determine length, the sample was placed between the verti-
cal rulers and the right vertical ruler was adjusted so that the rulers
touched both ends of the sample at the longest point. Anterior,
middle, posterior, and maximum measurements were taken for the
width and depth of each sample. To determine width, the sample
was turned so that the vertical rulers touched both sides at the desired
locations. To measure sample depth, the horizontal ruler was
lowered until it touched the sample at the designated locations and
leveled to the same inch marking of both vertical rulers. Length
and width measurements were read from the horizontal ruler, whereas
depth measurements were read from the vertical rulers. All linear
measurements were recorded to the nearest 0.125-inch. I

A large Pyrex cylinder, two lOOO-milliliter graduate cylinders,
a rubber hose, a clamp, and a lZ-inch thermometer with a temperature

0 _
range of -20 to 100 C were used for volume measurements.

34

A torsion balance, with a capacity of 4. 5 kilograms, was used
to determine the weights of the raw and cooked samples, the roasting
pans, racks, and drippings. Readings were recorded to the nearest
gram.

An 8-point Minneapolis Honeywell Electronik Multipoint
Recorder, Type 153, with a chart drive of 10 inches per hour, was
used to record data relevant to internal oven temperature, thermal
rod temperature during the cooking period, and time-temperature

relationships of the roasts throughout the cooking and cooling periods.

Roasting

The thermal rod used for the internal heating of roasts was
designed by and procured through the Food Service Industry Research
Center at Michigan State University. The unit consisted of an electric
wire mounted in a hollow, unpolished, stainless steel rod 12 inches in
length and 0. 125-inch in diameter. The wire extended 6 inches beyond
either end of the rod and was terminated with small clamps used for
inserting the rod in an auxiliary electric circuit controlled by a power-
stat.

For this study, the raw meat was split lengthwise to a depth
equal to the radius of the sample, the thermal rod horizontally inserted,
and the roast tied securely with heavy cotton cord. The sample was
placed on racks in a roasting pan, with the split in a lateral position,
and the entire assembly placed in a preheated oven. The clamps of
the thermal unit were connected to the auxiliary circuit and, when
current was applied, electrical energy transmitted as heat energy
penetrated the sample.

The thermal rod used in this research and the consecutive steps

in the procedure for splitting the raw sample, inserting the rod, tying

35

the sample, positioning the sample, and connecting the rod in the
auxiliary circuit are illustrated in Figures 1 through 6.

Standard aluminum roasting pans, 17. 25 inches long, 11. 25
inches wide, and 2.25 inches deep, were used for both cooking methods.
Since single unit wire racks to fit these dimensions were not available,
each pan was equipped with two overlapping 10. 5 inch square wire
racks supported by 0. 5 inch legs.

The lower deck of a 2-deck thermostatically controlled Hotpoint
roasting and baking oven, Model No. HJ. 225 with an air cushion
bottom, was used throughout the study. Special fabrication included

interior lighting and two single-pane glass windows.

Slicing
A Hobart electric slicer, Model No. 410 positioned at no. 12

setting, was used to obtain slices 0. 25-inch thick for the taste panel

evaluation.

Objective te sting

 

Three pieces of standard objective measuring equipment were
used in this study. A Beckman zeromatic pH meter, Model No. 9600
with glass electrode, was used to determine the pH of both raw and
cooked samples. A Warner Bratzler shear apparatus and a Carver
laboratory press were used to evaluate tenderness and juiciness of

the cooked samples, respectively.

Preliminar y Inve stigations

To determine procedures for the conventional and radial-
conventional roasting methods, twelve crosscuts of U. S. Choice grade

beef round, similar in weight and shape to the actual test samples,

 

Figure 1.

Figure 2.

36

Splitting the

 

raw roast.

 

Figure 3. Inserting the thermal rod.

 

Figure 4. Tying the raw roast.

38

 

Figure 5. Positioning potentiometer leads: _a_ = 0.25-inch, b and g =
0.75 and 1. 0-inch from surface; _d_ = attached to thermal rod.

 

Figure 6. Connecting thermal rod in auxiliary circuit: 3 = potentiome-
ter lead for oven temperature record, _f_ = connection of
rod to circuit.

39

were cooked and evaluated. Data from preliminary trials were used
to establish the powerstat setting for thermal control of the rod and
thermocouple placement for the time-temperature records during
roasting. Methodology for the preparation of samples for subjective
and objective testing was developed. Samples from the roasts were

used for preliminary taste panel instruction.

Power stat s etting

 

Dial settings of 20, 30, 40 per cent, and a combination of 20
and 30 per cent were experimented with to determine a powerstat
setting which would provide the maximum rod voltage which could be
used without charring the adjacent muscle tissue. In this study power-
stat settings of 20, 30, and 40 per cent reduced 110 volt current to
22, 33, and 44 volts, respectively. In each trial, the deck oven was
preheated to- and maintained at 1490C during roasting, with the upper
and lower grids set on medium and the damper half closed.

When a powerstat setting of 30 or 40 per cent was used the inner
tissue became charred during roasting and moisture loss was excessive.
Experimentation with an initial setting of 30 per cent during the first
half of the roasting period and a reduced setting of 20 per cent for the
remainder of the roasting period produced similar results. Further
work in which a setting of 20 per cent was used throughout the roasting
periodgave a product in which the inner tissues were not discolored
and moisture loss was comparable to conventionally roasted samples.
From these data is was decided that a constant power stat setting of
20 per cent was most suitable for the radial-conventional roasting

method.

40

The rmocouple plac em ent

 

Conventional roasting. During preliminary study, one thermo-

 

couple was positioned at a depth equal to the sample radius (1. 5
inches) for determination of the end cooking temperature for con-
trolled doneness. A second thermocouple was mounted in the oven

to record internal oven temperatures throughout the roasting period.
Since rate of heat penetration in raw and coagulated tissue may differ,
simultaneous continuous records of time—temperature relationships
for different depths of sample tissue seemed desirable. ~ For collection
of these data, additional thermocouples were positioned at 0.75 and

0.25 inches from the sample surface.

Radial-conventional roasting: Experimentation with thermo-

m

 

couple placement for this method required consideration of the depth
of tissue between the two heat sources. Mathematical calculations of
the distance to be penetrated before heat from the two sources met,
placed the contact point at approximately 1.0 inch from the surface.
Accordingly, one thermocouple was used to determine end cooking
temperature for controlled doneness at the estimated sample radius,
a second to record the temperature of the thermal rod during roast-
ing, and a third to record internal oven temperature during roasting.
Two additional thermocouples were positioned at depths of 0.75 and
0.25 inches from the sample surface to collect data basic to the

determination of rate of heat penetration in raw and coagulated tissue.

Preparation of samples for subjective testing

 

Cooked roasts were removed from the refrigerator after storage
0 . . . .
for 15 hours at 4 C. Usmg the Hobart electric slicer, 16 slices

were removed from the anterior end of each sample as shown in Figure

7. The first 2 slices were reserved for press fluid determinations;

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42

the remaining 14 slices were used as samples for the seven taste
panel members. Two slices from a conventionally roasted sample
and two slices from a radial-conventionally roasted sample were

arranged on coded plates and covered with Saran.

Preliminary taste panel

 

Taste panel members were presented slices of beef from both
conventionally and radial-conventionally cooked samples. The evalu-
ators were asked to consider each roast without reference to the
other. Factors to be scored were aroma, color, texture, flavor,
juiciness, softness, friability, residual connective tissue, and tender-
ness. A copy of the score card is included in the Appendix, page 87.

Judges were asked to cut a 0. 50 to 0.75-inch square piece
from the center of one slice from each roast sample and to count the
number of chews required for complete mastication. They recorded
the number of chews for each sample and also assigned a numerical
tenderness score. From these evaluations, an individual "chew
range" table was developed for and used by each judge for scoring

samples for tenderness throughout the study.

Preparation of samples for objective testing

 

Raw samples for pH determinations were obtained from a 0. 5-
inch slice removed from the posterior end of each roast. The location
from which cooked samples were taken is shown in Figure 7.

Procedures for obtaining objective test data were developed as

follow 3 .

21:1. Readings of pH were recorded for slurries of both raw and
cooked samples. Twenty grams of sample were chopped finely,

placed in a Hotpoint electric blender with 100 ml. of distilled water

43

of known pH, and blended for three minutes. The resultant mixture
was strained through a fine sieve into two 20 ml. beakers to permit

duplicate readings for each sample.

Press fluid. The first two slices removed from the anterior

 

end of the cooked sample (Figure 7) were wrapped immediately in
Saran, coded, frozen, and stored at -200C until completion of the
experiment. Samples were removed from the freezer and defrosted
at room temperature (23 to 250C) before press fluid determinations

were made.

Shear. After the 16 slices for taste panel evaluation and press
fluid determination were removed, a distance of 3-inches was
measured and the sample was cut vertically straight with a sharp
knife. A core 1. 0-inch in diameter, cut parallel to the fibers, was
removed from the center of each muscle. Each core was wrapped in
Saran, coded, frozen, and stored at ~200C until completion of the
experiment. Prior to shear testing, the cores were removed from

the freezer and defrosted at room temperature (23 to 250C).
Preroasting Preparation

A schedule was formulated whereby samples were cooked twice
weekly for a period of 3 weeks. On each cooking day, one roast was
cooked by the conventional method and one roast was cooked by the
radial-conventional method. Methods used for the cooking of samples
were assigned according to a randomized arrangement of right and left

muscles from the six pairs of rounds.

Preparation of raw roasts

 

Wrapped samples were removed from the freezer, placed on an

. . . . 0
aluminum tray, and defrosted in a reach-1n refrigerator at 4 C for a

44

period of 48 hours. On the morning they were cooked, defrosted

raw roasts were removed from the refrigerator, unwrapped, and a
posterior portion removed for objective determination of pH. The
ends of the roasts were cut vertically straight and the net weight and
linear measurements of the trimmed sample were recorded. Volume
was determined by the displacement method in 8 to 100C water.

Although samples cooked conventionally were not split hori—
zontally, each was tied firmly in five places with heavy cotton cord.
The gross weight of the roasting pan and racks was recorded, the
sample placed on the racks in the roasting pan, and the combined
weight of the pan, racks, and sample recorded- Three potentiometer
leads for recording data pertinent to time-temperature relationships
during cooking and cooling were positioned in the sample at depths
of 0.25-inch and 0.75-inch from the sample surface, and at the
sample radius.

Each of the samples cooked radial-conventionally was split
lengthwise, the thermal rod inserted horizontally, and the sample tied
with heavy cotton cord (Figures 2, 3 and 4). The gross weight of
the roasting pan and racks was recorded, the sample positioned on
the racks in the roasting pan and the combined weight of the pan,
racks, and sample recorded. Three potentiometer leads were placed
at depths of 0. 25-inch, 0.75—inch, and 1.0 inch from the sample

surface (Figure 5).

Cooking temperature

 

For both the conventional and radial-conventional methods, the
deck oven was preheated to 1490C, and the thermostat adjusted
throughout the cooking period to maintain a controlled air temperature
of 149°C. In addition, a constant setting of 20 per cent was main-

tained on the powerstat for the radial—conventional method.

45

Cooking Pr oc e s 5

Conventional method

 

When the internal temperature of the raw defrosted sample
reached 10°C the sample and assembled apparatus were placed in
the center of the preheated oven, and the oven door closed tightly.
Each sample was cooked to an internal temperature of 80°C, as
determined by the thermocouple positioned at the radius, then re-
moved from the oven and cooled in the roasting pan at room tempera-
ture to 700C. Then the thermocouples were removed, the strings

cut, and the roast allowed to stand for 15 additional minutes.

Radial-conventional method

 

When the internal temperature of the raw defrosted sample
reached 10°C the sample and assembled apparatus were placed in
the preheated oven as shown in Figure 6. The thermal rod was
connected to the electrical circuit, the oven door closed tightly, and
the powerstat set at 20 per cent.

When all potentiometer leads positioned in the sample reached
a minimum internal temperature of 80°C, the thermal rod was dis-
connected from the electrical circuit, the roast removed from the
oven and cooled in the roasting pan at room temperature to 700C.
Then the thermocouples were removed, the strings cut, the thermal

rod removed, and the roast allowed to stand for 15 additional minutes.
Treatment After Roasting

Data from the cooked samples were collected both before chilling

on the day of cooking and on the day after chilling.

46

Treatment of roasts before chilling

 

Following the specified cooling period, the combined weight of
the pan, rack, and drip; and the net weight of the sample were re-
corded. Linear measurements and volume by displacement in 45 to
50°C water were recorded. The roast was then wrapped in Saran,
coded, the anterior and posterior ends marked for identification, and
refrigerated overnight at 40C.

The weight in grams of the drippings was recorded. This weight
was obtained by subtracting the known weight of the pan and racks

from the total weight of the pan, racks and drippings.

Treatment of roasts after chilling

 

The day after the roasts were cooked, samples for objective
and subjective evaluation were removed according to procedures

described under Preliminary Investigations.
Evaluation of Samples

Nine palatability characteristics of the samples were evaluated
subjectively by a seven member taste panel. Measurements of pH,
press fluid, and tenderness were determined objectively. Panel
scores, objective measurements, and cooking loss data were analyzed
statistically. Data pertaining to rate of heat penetration for each

method of cooking were studied.

Subjective testing

 

At consecutive testings each judge was presented with two slices
from the same relative position in each roast. Samples were scored
for aroma, color, texture, flavor, juiciness, softness, friability,

residual connective tissue, and tenderness. Scores were based on a

47

seven point numerical scale. A score of 7 indicated excellent quality;
a score of 1 represented unacceptable quality. The judges con-
sidered descriptive terminology on the score sheet when assigning a
numerical score for each palatability factor. Additional written
comments by the judges were tabulated and included in the interpre-

tation of the data.

Objective te sting

 

The pH of raw samples was taken the day of cooking; the pH of
cooked samples the day after cooking. Objective measurements of
press fluid and tenderness were made after completion of the cooking

schedule .

p_I-_i_. Slurries for pH determinations were prepared as described
in the Preliminary Investigations. Duplicate readings, taken on the
Beckman zeromatic pH meter, were averaged. Change in pH between

the raw and cooked sample was calculated for each replication.

Press fluid. Two samples, each weighing 12 to 14 grams, were

 

cut from the cooked, defrosted slices from each roast, individually
weighed and placed between felt pads. Each sample was subjected

to a pressure of 15,000 pounds per square‘inch for 10 minutes in a
Carver laboratory press. After pressing, samples were separated
from the pads and reweighed. Per cent press fluid was calculated by
dividing the difference between the initial and pressed weights by the
initial weight of the sample and multiplying the resulting value by 100.
Per cent press fluid yields for each replication and averages for each

cooking method were determined.

- Shear. Objective measurements of tenderness were determined
by the Warner-Bratzler shear apparatus which measures pounds of

force required to cut through a cylinder of muscle of definite diameter.

48

Four shear readings were taken from each defrosted 1.0 inch diameter
core. These readings were totaled and averaged for each roast and

grand averages for each cooking method were calculated.

Cooking losses. Volume loss was calculated and converted to

 

percentage of initial sample volume. Total cooking, drip, and

volatile losses were determined for each roast and these values
changed to percentages based on the raw weight of the sample. Changes
in linear measurements effected by cooking were calculated and
converted to percentages of initial sample measurements. Mean per

cent linear changes were determined for each cooking method.

Heat penetration

 

During the cooking and cooling periods, progressive time-
temperature relationships at three sample depths were recorded.
For the radial-conventional method, these depths were 1.0 inch,
0.75-inch, and 0. 25-inch respectively. For the conventional method
these depths were the radius, 0. 75—inch, and 0. 25-inch respectively.
Rates of heat penetration, expressed as minutes per 0C rise, were
calculated from the mean progressive time-temperature relationships
at designated intervals for internal temperature for each depth for

each method of roasting.

Analysis of the data

 

Analysis of variance was the statistical measure used to evalu-
ate objective data pertaining to total cooking loss, drip loss, volatile
loss, volume loss, shear, press fluid, and change in pH to determine
differences attributable to method of cooking.

For the subjective data, panel scores for each replication were

averaged for each palatability factor to minimize variance due to

49

judges. Analysis of variance, based on the mean taste panel scores,
was computed for each palatability factor to determine differences
due to method of cooking.

Correlation coefficients were determined for all possible com-
binations of softness, friability, residual connective tissue, tender-
ness, and shear measurement. In addition, per cent press fluid yield

and subjective juiciness were correlated.

RESULTS AND DISCUSSION

The primary objective of this study was to compare the effects
of conventional oven— roasting and a combination of internal radial
heating and conventional oven- roasting on the palatability and yield
of semitendinosus muscles from Choice grade steer beef rounds.
Samples were tested both subjectively and objectively and the resultant
data were analyzed statistically to determine differences attributable
to cooking method. I

A secondary objective was to examine the heat penetration data
and investigate the potential for using such data as a valid basis for
predicting roasting time for semitendinosus muscle of beef round.
Mean progressive time-temperature relationships were collated to

determine differences in rate of heat penetration due to cooking method.

Palatability

Subjective evaluations of aroma, flavor, color, texture, juici—
ness, softness, friability, residual connective tissue, and tenderness
were made by a panel of seven judges. The scoring scale range was
from 7 to 1, indicating excellent to unacceptable quality, respectively.
Judges considered descriptive terminology on the scoresheet when
assigning a numerical score for each palatability factor.

Average palatability scores for each replication appear in
Table 13, the Appendix. Judges' numerical scores for each palatability
factor were totaled and averaged for each roast and grand averages
for method of cooking were computed. Grand averages, based on six
replications for each method of cooking, for each characteristic

evaluated are summarized in Table 1.

50

51

Table 1. Grand average palatability scores1 of six samples for two
methods of cooking.

 

Palatability Method of Cooking

 

 

Characteristic Conventional Radial-Conventional
Aroma 5. 1 4. 8
Flavor 5 . 0 4 . 9
Color 4. 3 3. 6
Texture 4.6 4. 7
Juiciness 4. 2 4. 7
Softness 4.4 4.4
Friability 3 . 0 2. 9
Residual Tissue 5.0 4.6
Tenderness 4.6 4, 2

 

lHighest possible score, 7 points.

Aroma and flavor

 

Grand mean palatability scores for aroma were 5. 1 and 4.8 for
the conventional and radial-conventional methods, respectively.
Descriptive terminology checked by judges ranged from a fair, faint
aroma to a rich and meaty aroma. Analysis of variance computed
on the mean aroma scores revealed no significant differences attribu-
table to method of cooking or to animal. The aroma of the drip was
noted by the investigator, For all replications, the aroma was full,
rich, and meaty.

Very little difference in flavor was detected by the judges.

The grand average flavor score for the conventional samples was

5.0 as compared to 4.9 for the radial-conventional samples. A score
of 5 indicated good, full flavor. No significant differences in flavor
were found by analysis of variance of mean scores. The flavor of

the drippings was also noted by the investigator. Drippings from

the radial-conventional roasts were always full, rich and meaty with

52

a strong but acceptable salty taste. Although drippings from the
conventional roasts had a full meaty flavor, a slightly charred taste
was usually present.

The analyses of variance of aroma and flavor scores are given

in Table 2.

Table 2. Analyses of variance of aroma and flavor scores for two
methods of cooking.

 

 

 

 

m m

Source of M.S. Values
Variance D. F. Aroma Flavor
TOTAL 11 .

ANIMAL 5 0. 02 0. 05
METHOD 1 0. 22 0. 01
ERROR 5 0.10 0. 06

 

 

Color and texture

The external appearance of whole roasts varied slightly between
the two methods of cooking. The exteriors of the conventional
samples were slightly darker than the radial-conventional roasts and
sometimes appeared almost charred in a few places.

In judging samples for color, panel members noted that the
color of radial-conventional roasts was not typical of well-done meat.
The pink areas tended to be toward the outer edge of the sample
rather than the center, but location was not consistent among repli-
cations. Mean panel scores for color varied from 2. 9 to 4. 2, indi—
cating a range of poor to desirable color for the radial-conventional
samples. The grand mean score for color was 3.6 which indicated a

mean evaluation of fair to good.

53

Grand average color score for the conventional method was
4.6 showing that judges tended to rate these samples higher than
the radial-conventional samples. Mean color scores for individual
roasts ranged from 3.6 to 4.7, fair to desirable. In three of the
conventional samples, a few judges noted that the color was slightly
pink and not typical of well-done meat.

Analysis of variance of the mean color scores revealed no
significant differences in color attributable to animal or to method
of cooking.

A slight iridescence was observed on the surface of samples
from both methods of cooking. According to Weir (84), this is caused
by the refraction of light in the fat layer spread by slicing. Both
Masuda (54) and Lukianchuk (51) reported similar observations.

Color of the drippings was noted by the investigator. Drippings
from the radial-conventional roasts were a rich, red-brown color.
During the cooling period, an orange-brown liquid seeped from the
roasts. Drippings from the conventional roasts were very dark
brown. During cooling, little if any liquid seeped from the roasts.
These differences may be due to the longer cooking period required
for the conventional roasts during which the drippings would tend to
become more concentrated through evaporation.

Textures of the radial—conventional and conventional roasts
were judged very similar. Grand mean texture scores were 4. 7 and
4.6 respectively. These scores denote judgments of fair to good.

Several judges described the pink areas of the radial-conventional
roasts as spongy. A few samples were reported to have considerable
amounts of noticeable thick connective tissue. Considering that the
semitendinosus muscle is a less tender beef cut this is not an unusual

observation.

54

Analyses of variance of the average texture scores revealed no
significant differences attributable to animal or to method of cooking.
A summary of the analyses of variance of color and texture mean

scores is given in Table 3.

Table 3. Analyses of variance of color and texture scores for two
methods of cooking,

Source of M.S. Value
Variance D. F. Color Texture

 

 

 

TOTAL 11

ANIMAL 5 0.08 0. 05
METHOD 1 1,47 0. 01
ERROR 5 0. 38 0. 05

 

Juiciness

Judges indicated only a slight preference for the juiciness of
the radial—conventional samples as compared to the conventional
samples. Grand mean scores were 4.7 and 4.2 respectively. Panel
members described all samples as juicy or as neither juicy nor dry.

Objective evaluation of juiciness revealed that radial-conventional
samples were more juicy than conventional samples. Mean per cent
press fluid yields were 40.46 and 37.23, respectively. , Per cent
press fluid yields for each replication are given in Table 14, the
Appendix.

Mean per cent press fluid yields and grand average juiciness
scores for both methods are given in Table 4.

No significant differences due to animal or to method of cooking
were found by analysis of variance of mean juiciness scores. Analysis

of variance of press fluid yields revealed no significant differences

55

Table 4. Average press fluid yields and grand average juiciness

 

 

scores.
Cooking Method % Press Fluid Juiciness Score
Conventional 37. 23 4. 2
Radial-Conventional 40. 46 4. 7

 

1Highest possible score, 7 points.

attributable to animal, but press fluid was greater (5% level of prob-
ability) in the radial-conventional samples than in the conventional
samples. The analyses of variance of juiciness scores and press

fluid yields for two methods of cooking are presented in Table 5.

Table 5. Analyses of variance of press fluid yields and juiciness
scores for two methods of cooking.

 

 

 

Source of M. S . Values

Variance D. F. % Press Fluid Juiciness Score
TOTAL 11

ANIMAL 5 13.29 0. 29
METHOD 1 31.42* 0.80
ERROR 5 4.13 0. 24

 

3::
Significant at 5% level of probability.

The positive correlation (r = . 559) found between mean juici-
ness scores and press fluid yields approached the 5% level of

probability (r = .576).

56

Tenderness

 

Grand average scores for softness, friability, residual con-
nective tissue, and tenderness, and average shear values for the two
methods of cooking are given in Table 6. Shear values of cooked

samples for each replication are shown in Table 14, the Appendix.

Table 6. Grand average scores1 for softness, friability, residual
tissue, and tenderness and mean shear values for two
methods of cooking.

 

 

 

m m m
Cooking Soft- Residual Tender- Shear
Method ness Friability Tissue ness (lb)
Conventional 4.4 3.0 5.0 4.6 17.19
Radial-Conventiona14.4 2.9 4.6 4.2 19.35

 

1Highest possible score, 7 points.

Grand mean scores for softness were identical for the two
methods of cooking. Mean softness scores for individual samples
ranged from 3. 9 to 4. 7. In most instances, judges marked the
descriptive term "neither hard nor soft. " Analysis of variance re-
vealed no significant difference in softness attributable to animal or
to method of cooking.

Subjective evaluation of friability revealed that conventional
roasts were rated only slightly higher than radial-conventional roasts.
Grand mean score for the radial-conventional samples was 2. 9 as
compared to 3. 0 for the conventional samples. The descriptive term
for a score of 3 was “slightly friable. " Differences in friability due
to animal or to cooking method were not statistically significant.

In judging residual connective tissue, mean sample scores

ranged from 4. 0 to 5. 3. Grand mean scores were 4. 6 for the

57

radial-conventional roasts and 5. 0 for the conventional roasts.
Analysis of variance showed that residual connective tissue was
significantly less (1% level of probability) in the conventional roasts
than in the radial-conventional roasts. The smaller amount of
residual connective tissue in the conventionally cooked roasts was
probably due to increased conversion of collagen to gelatin during
the longer cooking time required for this method.

Tenderness ratings were subjectively determined by the number
of chews required to completely masticate a sample of definite size.
Grand mean scores for tenderness were 4.6 for the conventional
samples and 4. 2 for the radial-conventional samples. Conventional
samples were most often described as tender, whereas radial-con-
ventional samples were most often scored as slightly tough. Analysis
of variance of mean tenderness scores revealed a significant differ-
once at the 5% probability level attributable to animal, and at the 1%
level of probability attributable to method of cooking.

Objective determinations of tenderness showed that conventional
roasts were more tender than radial-conventional roasts. Mean
shear values were 17.19 and 19. 35 respectively. However, analysis
of variance for average shear readings showed no significant differ-
ences attributable to animal or to method of cooking.

The analyses of variance for softness, friability, residual
connective tissue, tenderness and shear force are summarized in
Table 7.

The relationships between mean subjective scores for softness,
friability, residual connective tissue, and tenderness and objective
shear force measurements were studied. The correlation coefficients
determined for all possible combinations of these factors are surn-

marized in Table 8.

58

Table 7. Analyses of variance for softness, friability, residual
connective tissue, and tenderness scores, and shear force

values for two methods of cooking.

 

 

 

M.S. Value
Source of Soft- Residual Tender— Shear
Variance D. F. ness Friability Tissue ness Force
TOTAL 11 . . . .
ANIMAL 5 0.08 0.13 0.15 0.17* 11,49
METHOD 1 0.00 0.05 0.52** 0.52M< 13.82
ERROR 5 0.07 0.04 0.03 0.02 5.40

 

*
Significant at 5% level of probability.

M:
Significant at 1% level of probability.

 

 

Table 8. Correlation coefficients for all possible combinations of
softness, friability, residual tissue, and tenderness scores
and Warner Bratzler shear measurements.

Correlation

Relationship Coefficient

Softness/Friability . 182

Softness/Residual Tissue . 153

Softness/Tenderness . 148

Softness/Warner Bratzler Shear -. 091

Friability/Residual Tissue -. 007

Friability/Tenderness . 790**

Friability/W arner Bratzler Shear -. 399

Residual Tissue/Tenderness . 855*96

Residual Tissue/Warner Bratzler Shear —.441

Tenderness/Warner Bratzler Shear -.656*

 

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

59

Significant positive correlations (1% probability level) were
found between subjective evaluations of friability and tenderness,
and between subjective evaluations of residual connective tissue and
tenderness. Since it is known that the conversion of collagen to
gelatin during cooking decreases the amount of connective tissue in
cooked beef muscle and increases the ease with which muscle fibers
can be separated, it seems reasonable to expect these relationships
might be true. However, since the correlation coefficients obtained
between subjective evaluations of friability and objective shear
measurements and between subjective evaluations of residual con-
nective tissue and objective shear measurements were not significant,
the extent to which friability and residual connective tissue influence
tenderness remains in doubt.

A negative correlation, significant at the 5% level of prob-
ability, was found between subjective tenderness scores and objective
shear measurements. Correlation coefficients for all remaining

relationships studied were not significant.
Cooking Losses

Percentages based on raw weight of sample, were calculated
for total, drip, and volatile losses. Volume loss was converted to
percentage of initial sample volume. Per cent total, drip, volatile,
and volume losses for six replications for each cooking) method are
recorded in Tables 15 and 16, the Appendix. Mean per cent values
for cooking and volume losses for each cooking method are recorded
in Table 9.

Analyses of variance were computed for total, drip, volatile
and volume losses to determine differences due to method and animal.

Results of these analyses are summarized in Table 10.

60

Table 9. Mean per cent cooking and volume losses of six replications
for two methods of cookery.

 

Method of Cooking

 

 

Losses Conventional Radial-Conventional
% %
Total cooking 30.111 26. 32
Drip 2. 14 3. 37
Volatile 27. 97 22. 94
Volume 28.51 30.25

 

lAverages based on six replications.

Table 10. Analyses of variance of cooking and volume losses for
two methods of cookery.

 

 

 

Source of M.S. Values

Variance D. F. Total Drip Volatile Volume
TOTAL 11 .

ANIMAL 5 6.64 0.21 8.8 31.83
METHOD 1 43.13=¢< 4.54** 75.76** 9.05
ERROR 5 3.08 0.19 3.11 32.14

 

>:<
Significant at the 5% level of probability.
>:<>:<
Significant at the 1% level of probability.

61

Total cooking losses

 

The average total cooking loss was 30. 11 per cent for con-
ventionally roasted samples and 26. 32 per cent for radial-conven-
tionally roasted samples. The conventionally cooked roasts had
significantly greater total cooking losses then the radial-conventionally
cooked roasts (5% level of probability). The average total cooking
time was 64. 5 minutes for the radial-conventional samples compared
with 125. 6 minutes for the conventional samples. Since, on the
average, conventionally roasted samples required 48.6 per cent
more cooking time than radial-conventional samples, it is probable
that cooking time as well as method influenced total losses and also

the ratio of drip to volatile losses.

Drip losses

 

The average per cent drip loss was 2. 14 for conventionally
roasted samples and 3. 37 for the samples cooked by the radial-
conventional method. Analysis of variance showed no significant
differences attributable to animal, but drip losses were significantly
greater (1% level of probability) for the radial-conventional samples
than for the conventional samples. The shorter cooking period and
the additional surface area which resulted from cutting the sample to
insert the thermal rod could account in part, for the greater drip

loss in the radial-conventional samples.

Volatile los ses

 

Mean volatile losses for conventional roasts and for radial-
conventional roasts were 27.97 and 22. 94 per cent respectively.
Analysis of the data showed the higher amount of volatile loss from

the conventional roasts was significant at the 1% level of probability.

62

The greater part of volatile loss is from evaporation of water.
Inasmuch as volatile loss was calculated on the basis of total weight
loss minus weight of drippings, the longer cooking time required
for the conventional method may have influenced evaporation of

drippings as well as sample moisture.

Volume losses

 

Average volume losses for the conventional roasts and for the
radial-conventional roasts were 28. 51 and 30.25 per cent,
respectively. Analysis of variance for per cent volume loss indicated
no significant differences among samples due to animal or method of
cooking.

Mean percentages for volume loss, changes in linear measure-
ments and total weight loss for the two methods of cookery are shown

in Table 11.

Table 11. Mean percentages for volume loss, changes in linear
measurements, and total weight loss for two methods of

 

 

 

 

cookery.
Method
Conventional Radial-Conventional
% %
Volume loss 28. 511 30.25
Shrink in length 9. 61 9. 05
Shrink in width 2. 35 2. 35
Gain in depth 21.04 18.31

Total weight loss 30.11 26. 32

 

1 . . .
Averages based on 81X replications

Lowe (48) states that during cooking the shrink in volume in

muscles of beef round is never as great as the decrease in weight.

63

Data in Table 11 indicate this to be true for conventional roasts, but
not for roasts cooked by the radial-conventional method. Lukianchuk
(51) had similar results. Her conventionally cooked samples had
greater mean total weight loss than mean volume loss, but samples
cooked in deep fat did not.

According to Lowe (48), during cooking meat shrinks along the
length of the fibers and in width but may gain in the third dimension
until cooked extremely well done. The data from both methods used

in this experiment support this premise.

pH

Determination of pH for raw and cooked samples, based on the
average of two readings, and the change in pH for six replications
for each cooking method are shown in Table 17, the Appendix. The
pH of raw samples used for both cooking methods ranged from 5. 5 to
5.8.

Winkler (87) studied the relationship between pH and tenderness
in meat and reported toughness in raw meat to be maximum at pH
5.0 to 6. 0. Since the semitendinosus muscle is usually classified as
a less tender portion of the beef carcass, the pH values of the raw
test roasts in this study were in accord with Winkler's findings.

In all cases cooked roasts were slightly more alkaline than raw
roasts. The pH of samples roasted by either method varied from 5. 8
to 6. 0. Changes in pH brought about by cooking ranged from 0. 2 to 0. 3
for the conventionally roasted samples and from 0. 2 to 0.4 for the

radial-conventionally roasted samples .

64
Heat Penetration

Due to difficulty in obtaining accurate potentiometer recordings
during one day of cooking, results and discussion of data pertaining
to rate of cooking are based on five replications for each method.

Data pertaining to time-temperature relationships during cook-
ing were obtained from potentiometer leads positioned at three depths
from the surface of the sample: 0.25-inch, 0.75-inch, and sample
radius (approximately 1. 5 inches) for the conventional method and
0. 25-inch, 0.75-inch, and l. 0 inch for the radial-conventional method.
The lead positioned with depth equal to the sample radius was used
to determine the end of the cooking period for the conventional method.
For the radial-conventional method all leads were required to reach
a minimum of 80°C before samples were removed from the oven.

Average initial sample temperatures for depths of 0. 25-inch,
0.75-inch, and the radius were 13.4, 10.0, and 9.40C, respectively.
Mean progressive time-temperature relationships during cooking for
three sample depths and two methods are shown in Figure 8. All
curves for roasts cooked by the radial-conventional method were
somewhat steeper and considerably shorter than the comparable curves
for conventionally roasted samples. The internal temperature of
samples cooked by the radial-conventional method increased steadily
and rapidly throughout cooking. Although the rise in temperature for
samples cooked by the conventional method was much slower, the
rate of rise was steady until an internal temperature of 50°C was
reached; thereafter the rate of rise decreased continuously.

Roasts cooked conventionally required nearly twice as much
time to reach an end cooking temperature of 80°C as those cooked by
the radial-conventional method. Average cooking time was 126. 5 minutes

for conventionally roasted samples compared with 64. 5 minutes for the

65

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66

radial—conventional samples, a difference of 61. 1 minutes for roasts
of comparable size, shape, and composition. It seems reasonable
to expect that by adding a second heat source, the thermal rod,
cooking time would be decreased. Furthermore, by locating the

rod horizontally at the radius of the roast and simultaneously apply-
ing heat to the interior as well as the exterior of the roast, the depth
of tissue which the heat from each source must penetrate before they
meet is reduced.

As was expected, the mean end cooking temperatures of con-
ventional roasts at depth locations 0. 25-inch and 0. 75-inch from the
sample surface exceeded the internal temperature at the radius;
91.4°c for the o. 25-inch depth and 86.00C for the o. 75-inch depth.
In the samples roasted by the radial-conventional method, however,
mean end temperatures for the 0. 25-inch and 0. 75—inch depth loca-
tions were 79. 3 and 81. 80C, respectively.

Variations in end cooking temperatures at similar depths among
replications were apparent in both methods. Inherent differences in
the samples, changes in linear measurements brought about by
evaporation and coagulation of the tissue, and experimental error in
the placement of the potentiometer leads appeared to contribute
appreciably to variations among replications within method.

At the end of the cooking period roasts were removed from the
oven and allowed to stand at room temperature until the temperature
of the lead which had determined the end of the cooking period had
cooled to 700C. The internal temperature rise of roasts after
removal from the oven was similar for both methods, varying only
from 0 to 20C among replications within each method.

Progressive changes in the mean rate of heat penetration during
cooking, expressed as minutes per degree Centigrade rise at 10-

degree intervals from 20 to 800C, for two cooking methods at three

67

sample depths are shown in Figures 9 and 10. Changes in rate of
heat penetration for each replication for each method are given in
Tables 18 and 19, the Appendix.

After an internal temperature of 350C was reached, the mean
heat penetration curves for radial-conventional roasts at sample
depths of 0. 75-inch and 1.0 inch were similar in shape and showed
a steady decline in rate of penetration throughout the remainder
of the cooking period. Although the rate of heat penetration was
initially high at the 0. 25-inch sample depth, there was a steady
moderate decrease until the temperature of the sample at this depth
reached 600C. From 60 to 70°C the rate decreased sharply but
after the sample reached 700C there was a slight increase in rate
of heat penetration (see Figure 9).

Variations in mean heat penetration rates for all sample depths
studied were more pronounced in conventionally roasted samples than
in radial-conventional samples. Rate of heat penetration was steady
at the 0. 75-inch depth to a temperature of 500C. Thereafter there
was a sharp decrease throughout the remainder of the cooking period.
Curves for the 0. 25-inch depth and radius depth were similar in out-
line. There was a rapid rise in rate to a temperature of 40°C and
then a steady decline thereafter. The 0.25-inch depth showed a sharp
decrease in rate between temperatures of 40 and 500C and a very sharp
decline between temperatures of 70 and 800C. As was anticipated
because of their proximity to the source of heat, the initial rise in
rate of heat penetration was highest at the 0. 25-inch depth and lowest
at the radius depth. Throughout most of the cooking period the rate
was generally highest at the 0. 25-inch depth and lowest at the radius
depth. The rates of heat penetration at internal temperature inter-
vals between 60 and 700C and 70 and 80°C were similar at all sample

depths .

68

Min/0C rise

60

70 80

 

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1.50-

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2.75<

3.00.

 

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Protein
Coagulation

Key:
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" 1.0 inch

 

 

 

 

Rare

 

 

 

Medium

 

Well-done

 

 

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30 40 50

 

60

 

 

70 80

Figure 9. Average rate of heat penetration: Min/0C rise for three
sample depths for the radial-conventional cooking method.

 

o 69
Min/ C rise
0 20 30 40 50 60 70 80

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MALI 1

 

 

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C 0 20 30 40 50 60 70 80

Figure 10. Average rate of heat penetration: Min/0C rise for three
sample depths for the conventional cooking method.

70

Lowe (48) states that according to Sprague and Grindley internal
temperatures ranging from 55 to 65°C represent rare beef; those
ranging from 70 to 800C denote well-done beef. For comparison of
rate of heat penetration for the two cooking methods used in this
study, temperatures of 50, 60, 70, and 80°C were chosen as indicative
of the following degrees of doneness: beginning of muscle coagulation,
rare, medium, and well-done. The comparative ranges in minutes
per degree Centigrade rise between stages of doneness for the three
sample depths for the two cooking methods are illustrated in Figures
9 and 10.

Except between temperatures of 70 and 80°C at the 0. 25-inch
location in the radial-conventional samples, at all depths measured
there was a decrease in rate of heat penetration as the state of muscle
coagulation was approached and a continuous decline throughout the
remainder of the cooking period. This phenomenon is attributed to
the fact that evaporation and muscle coagulation which occur during
cooking are endothermic processes. Consequently, less heat is
available for elevation of muscle temperature.

For each sample depth measured, the rate of rise in temperature
for radial-conventional roasts exceeded that of the conventional roasts.
These results were anticipated due to the additional heat source in
the radial-conventional method. At the exterior surface of each
sample there is a layer of immobile air which acts as an insulator
between the heat source and the sample. It is believed that when the
surrounding oven air is put in motion by the heat energy applied, the
insulating air layer gradually becomes thinner and the temperature of
the meat at the surface increases. Between the thermal rod and the
sample surface there is a very much thinner insulating air layer.

As a result, heat from the rod is more easily transferred to the meat.

In addition, without considering the effect of the insulating air layer,

71

metal is a better conductor of heat than air and thus heat transfer
could be more efficient. Considering both of these factors, at any
given time there should be a greater amount of heat within the radial-
conventional samples and, consequently, the rate of heat penetration

within the samples would exceed that of the conventional samples.

SUMMARY AND CONCLUSIONS

The objectives of this study were to compare the effects of
conventional oven- roasting and a combination of internal radial heat-
ing and conventional roasting on the palatability and yield of semi-
tendinosusmuscles from paired U. S. Choice steer beef rounds, and
to investigate the potential for using heat penetration data as a valid
basis for predicting cooking time for semitendinosus muscle of beef
round. Procedures used for the preparation, roasting, and sub-
jective and objective evaluations of the samples were developed
through preliminary investigations in the laboratory.

Semitendinosus muscles were dissected, cleared of surface
fat, and trimmed as comparable as possible in shape within a weight
range of 1300 to 1500 grams. Individual raw roasts were wrapped,
frozen, and stored at ~20°C until defrosted for testing.

Prior to cooking, each sample was defrosted and weighed.

. ,Data pertaining to linear and volumetric measurements were recorded.
Roasts cooked by the radial-conventional method were split length-

wise to a depth equal to the sample radius, the thermal rod inserted
horizontally, and the roast tied securely with heavy cotton cord.

Roasts cooked conventionally were tied in'a like manner. Potentiometer
leads were positioned at three depths as measured from the surface of
the roast: 0.25-inch, 0.75-inch, and sample radius for the conven-
tional method, and 0. 25-inch, 0. 75-inch, and 1. 0 inch for the radial-
conventional method. Six replications, for each cooking method were
performed.

For both methods, the deck oven was preheated to 1490C, and

this air temperature maintained throughout the cooking periods.

72

73

In the radial-conventional method a powerstat, set at 20 per cent,
was used to reduce the current entering the thermal rod to 22 volts.
All roasts were cooked to an internal temperature of 80°C. In the
conventional samples internal end temperature was determined by
the thermocouple positioned at the radius; in the radial-conventional
samples all potentiometer leads in the roasts were required to
reach a minimum temperature of 80°C before the roast was removed
from the oven. Samples roasted by either method were cooled at
room temperature to 70°C before the leads (conventional samples)
and the leads and thermal rod (radial-conventional samples) were
removed. All samples were allowed to stand 15 additional minutes
before objective data for cooked roasts were recorded.

A seven member taste panel scored all samples for aroma,
flavor , color, texture, juiciness, softness, friability, residual
connective tissue, and tenderness. Measurements of pH, press fluid
and shear were determined objectively. Total cooking, drip, volatile,
and volume losses were recorded for each roast. Data pertaining
to rate of heat penetration were studied to evaluate differences attribut-
able to cooking method.

Grand average palatability scores for conventionally roasted
samples were higher for aroma, flavor, color, friability, residual
tissue and tenderness than for comparable grand averages for radial-
conventional samples. A very slight preference was recorded for
the texture of the radial-conventional samples although several judges
described areas of some samples as spongy. Grand mean softness
scores were identical for the two cooking methods.

Statistical analyses revealed no significant differences in aroma,
flavor, color, friability, texture or softness attributable to method of

cooking.

74

Judges favored the juiciness of the radial-conventional samples.
Samples were described as juicy or as neither juicy nor dry. Mean
per cent press fluid yield was higher for the radial-conventional
samples than for the conventional samples. Analysis of variance of
mean juiciness scores revealed no significant differences attributable
to animal or method of cooking. Statistical analysis of per cent press
fluid values however revealed significant difference due to method of
cooking. A positive correlation coefficient determined for juiciness/
per cent press fluid approached the 5% level of significance.

Grand mean scores for tenderness favored the conventionally
roasted samples. Conventional samples were most often scored as
tender, whereas radial-conventional samples were most often scored
as slightly tough. Analysis of variance of mean tenderness scores
revealed highly significant differences in tenderness attributable to
method of cooking. Analysis of variance also showed that residual
connective tissue was significantly less (1% level of probability) in
conventional samples.

All cooked samples had slightly higher pH values than raw
samples. However, changes in pH brought about by cooking were not
significant for method.

Conventionally cooked roasts had significantly greater total
cooking losses than samples cooked by the radial-conventional method.
Analysis of variance of the data showed drip losses in the radial-
conventional samples were significantly greater (1% level of probability)
than drip losses in the conventional samples, whereas volatile losses
were significantly greater (1% level of probability) in conventional
roasts than in radial-conventional roasts.

Mean volume loss was higher for radial-conventional samples
than for conventionally roasted samples. Conventional samples had

higher total weight losses than radial-conventional samples.

75

Roasts cooked by the radial-conventional method revealed greater
volume loss than weight loss whereas for the conventional roasts
this relationship was reversed.

Positive correlation coefficients, significant at the 1% prob-
ability level, were found between friability/tenderness and residual
connective tissue/tenderness. A negative correlation coefficient,
significant at the 5% level of probability, was found between Warner
Bratzler shear/tenderness.

In all replications, the conventional roasting required approxi-
mately twice the cooking time required for radial-conventional
roasting, and, irrespective of method, rate of temperature rise
generally decreased as muscle coagulation progressed.

Mean end cooking temperatures at the three lead depths showed
a smaller range in the radial-conventional samples than in the con-
ventional samples. The ranges of internal temperature rise during
the cooling periods were comparable for both cooking methods.

No appreciable difference in rates of heat penetration was noted
at the three sample depths in the radial-conventional method whereas
the rates of heat penetration at the three sample depths in the con-
ventional method showed greater variance from each other. Rate of
heat penetration at all depths in the radial-conventional samples was
faster at any given time than in the conventional samples.

Within the limits of this investigation the following conclusions
are indicated:

1. With the exception of tenderness and residual connective
tissue, semitendinosus samples cooked by a combination of radial
heating and conventional roasting compared favorably with similar
samples cooked conventionally for all palatability factors scored.

2. Per cent total cooking losses were decreased by use of the

radial-conventional method. Although per cent drip losses were

76

higher in the radial-conventional method, per cent volatile losses

were lower than in the conventional method. Because of the shorter
cooking period and the split surface in the radial-conventional samples
there was more opportunity for drippings to form and remain. With
the longer cooking period more evaporation could occur and conse-
quently higher volatile losses'were evident in the conventional samples.
Volume losses were higher in the radial-conventional samples. It is
conceivable that the increased total heat within the radial-conventional
samples could account, in part , for volume losses exceeding those of
the conventional samples.

3. Total cooking time was reduced nearly 50 per cent by use of
the radial-conventional method. Because of the increased heat avail-
able from two sources, heat transfer to and through the muscle tissue
was more rapid in this method.

4. The theory that rate of heat penetration decreases as muscle
coagulation progresses is strongly supported by this study. In both
cooking methods, minutes per degree Centigrade rise increased as
samples approached the beginning of muscle coagulation and continued
to increase as muscle coagulation progressed.

The results of this study show that the radial-conventional
method has potential as an acceptable means for cooking semitendinosus
muscle of beef round. If a means could be devised to insert the thermal
rod without splitting the roast, more moisture might be retained by
the samples and sample tenderness might consequently be increased.
Furthermore, if radial-conventional samples were cooked at a slightly
lower oven temperature it is reasonable to expect both cooking time
and cooking losses would increase slightly but it is also likely that

tenderness would increase and residual connective tissue decrease.

10.

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APPENDIX

85

86

Table 12. Weight of rounds, muscle weight, maximum linear measure-
ments of muscles, and trimmed sample weight.

 

 

 

 

Weight Weight Maximum Linear Trimmed
Left Rump On Muscle Measurements (in.) Sample
Round (lb. ) (gm. ) Length Width Depth (gm. )
1 79.6 1571 13.50 4.13 2.63 1247
2 84.5 1966 13.38 4.75 3.13 1256
3 76.0 1567 13.00 4.00 2.63 1174
4 70.2 1532 12.75 3.75 2.88 1149
5 72.4 1426 13.00 3.88 2.63 1131
6 79.0 1652 13.88 3.88 2.75 1118
Right
Round
1 77.0 1535 13.63 3.88 2.63 1170
2 76.2 1875 13.25 4.63 3.00 1294
3 76.1 1560 12.25 4.13 2.75 1204
4 67.2 1499 12.50 4.13 2.75 1179
5 70.8 1425 12.38 3.88 2.63 1152
6 75.0 1653 14.13 4.00 2.75 1209

 

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89

Table 14. Average press fluid yields and shear force values of cooked

samples for six replications for two cooking methods.

 

Press Fluid

Shear Force

 

Method of Cooking (70) (1b.)
Radial-conventional 44.631 19.58 7'

41.00 19.01

39.60 18.13

42.03 23.90

39.34 16.40

36.18 19.05

Average 40.46 19. 35

Conventional 37.46 12. 62

39.39 18.27

40.97 17.38

38.00 19. 25

35.07 14.22

32.47 21.45

Average 37.23 17.19

 

1Based on 2 determinations.

2Based on 4 determinations.

90

 

 

Table 15. Cooking weight losses for six roasts for two methods of
cookery.
Method of Raw Cooked Total Total Drip Volatile
Cooking Weight Weight Loss Loss Loss Loss
(gm.) (gm.) (gm.) (‘70) (‘70) (‘70)
Radial- 1247 920 327 26.22 3.69 22.53
conventlonal 1256 936 320 25.48 4.06 21.42
1174 854 320 27.26 2.90 24.36
1179 878 301 25.53 3.31 22.22
1152 872 280 24. 31 3.47 20.83
1209 857 352 29.12 2.81 26. 30
Average 1203 886 317 26.32 3.37 22.94
Conventional 1170 814 356 30.43 2.22 28.21
1294 960 334 25.81 2.09 23.73
1204 846 358 29.73 2.82 26.91
1149 814 335 29.16 2.00 27.15
1131 767 364 32.18 2.21 29.97
1118 745 373 33. 36 1.52 31.84
Average 1178 825 353 30.11 2.14 27.97

 

91

Table 16. Volume loss for six roasts for two methods of cookery.

 

 

 

 

Method Volume in Milliliters Volume
of Raw Cooked Loss
Cooking Sample Sample Change (%)
Radial-
conventional 1110 745 365 32. 88
1238 790 448 36.19
1140 850 290 25.44
1100 800 300 27. 27
1020 770 250 24. 51
1080 700 380 35.19
Average 1115 776 339 30.25
Conventional 1080 725 355 32. 87
1120 890 230 20. 54
1080 728 352 32.59
1125 880 245 21.78
1030 740 290 28.16
1025 665 360 35.12

Average 1077 771 305 28.51

 

92

Table 17. Determinations of pH for raw and cooked samples and the
change in pH for six roasts for two methods of cookery.

 

 

 

Method of pH Readings Change
Cooking Raw Samples Cooked Samples in pH
Radial-
conventional 5 . 6 l 5 . 8 0. 2
5.5 5.8 0 3
5.8 6.0 0.2
5.7 5. 0 2
5.6 6.0 0.4
5.6 5.8 0.2
Conventional 5 . 6 5 . 8 0. 2
5 5 5.8 0 3
5.8 6.0 0 2
5 7 5.9 0 2
5 7 5.9 0 2
5.7 5.9 0 2

 

1Based on 2 readings.

93

Table 18. Changes in the rate of heat penetration for five replications,
for three sample depths for the radial-conventional cooking
method.

 

 

Radial-Conventional Method Samples
(Min./OC rise)

0
Temperature C Replications Mean

 

0. 25-inch Depth

 

 

 

 

 

Initial - 20 .4 .3 .3 .1 .2 .26
20-30 .7 .2 .4 .5 .2 .40
30-40 .6 .5 .6 .6 .3 .52
40-50 1.0 .7 .8 .6 .4 .70
50-60 1.1 1.3 .9 .7 .9 .98
60-70 1.2 2.0 2.0 1.1 1.7 1.60
70-80 1.5 1.5 1.5 1.2 1.7 1.48

0.75-inch Depth

Initial-20 .8 1.1 1.1 1.0 1.4 1.08
20-30 .7 .6 4 .4 .6 .54
30-40 .8 .6 6 .5 .6 .62
40-50 1.0 .7 .7 .6 .7 .74
50-60 1.1 .9 .9 .8 .9 .92
60-70 1.3 1.0 1.2 .9 1.1 1.10
70-80 1.4 1.6 1.4 1.5 1.4 1.46

1-inch Depth

Initial - 20 .4 .9 .6 .4 1.0 .66
20-30 .6 .7 .4 .5 .8 .60
30-40 .6 .6 .6 .4 .6 .56
40-50 .8 .7 .7 .5 .8 .70
50-60 .1 .8 .7 .5 .7 .76
60-70 .3 .9 .9 .6 1.1 .96
70-80 .5 1.1 1.5 .9 1.4 1.28

 

94

Table 19. Changes in the rate of heat penetration for five replications,
for three sample depths for the conventional cooking method.

 

 

 

ConventionalOMethod Samples
(Min./ C rise)

0
Temperature C Replications Mean

 

0.25-inch Depth

 

 

 

 

 

Initial - 20 .1 .8 .6 1 5.4 1.08
20-30 .1 .9 .5 2 3.7 .74
30-40 .3 .9 .6 2 2.5 .50
40-50 .5 1.3 1.2 .4 5.2 1.04
50-60 .6 1.7 1.4 1.6 5.9 1.18
60-70 .7 1.8 2.6 4.0 9.6 1.92
70 -80 .9 2.6 3.2 8.0 16.4 3.28

0.75-inch Depth

Initial-20 .8 .8 1.1 .9 1.5 1.02
20-30 1.1 .9 1.1 .7 1.2 1.00
30-40 .9 1.2 1.2 .7 1.0 1.00
40-50 .8 1.6 1.2 1.0 .7 1.06
50-60 1.2 1.8 2.0 1.1 1.0 1.42
60-70 2.2 2.7 2.2 3.1 1.7 2.38
70-80 2.0 4.1 2.7 4.1 1.6 2.90

1.50-inch Depth (radius)

Initial - 20 2.0 2.0 2.1 1.9 3.0 2.20
20-30 1.0 1.2 1.2 .9 1.7 1.20
30-40 1.0 1.2 1.2 .9 1.1 1.08
40-50 1.2 1.3 1.4 1.1 1.4 1.28
50-60 1.4 1.8 1.8 1.6 1.4 1.60
60-70 1.9 2.2 2.1 3.2 1.8 2.24
70 -80 2.5 4.0 3.0 3.8 2.2 3.10

 

 

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