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5-1963

The Effects of Cooking Temperature and Stage of Doneness on Some Factors in Broiled Beef

Carmencita Salvosa Utah State University

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Recommended Citation Salvosa, Carmencita, "The Effects of Cooking Temperature and Stage of Doneness on Some Factors in Broiled Beef" (1963). All Graduate Theses and Dissertations. 4839. https://digitalcommons.usu.edu/etd/4839

This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. THE EFFECTS OF COOKING TEMPERATURE AND STAGE OF

DONENESS ON SOME FACTORSby IN BROILED BEEF

Carmencita Salvosa

A thesis submitted in partial fulfillment of the requirements for the degree

of

MASTER OF SCIENCE

in

Food and Nutrition

.

UTAH STATE UNIVERSITY· Logan,1963 Utah ii

ACKNOWLEDGMENT

I wish to express my deepest gratitude to my major professor,

Dr. Margaret B. Merkley, for her patience, untiring personal interest and efforts without which I would still be working on this thesis now.

To Dean Phyllis Snow and Dr. Ethelwyn B. Wilcox, I am grateful for their generous help and suggestions throughout the study.

To Taylor Instrument Company, I would like to express my appreciation for the loan of the multipoint potentiometer and the special thermometer.

To Dr. Rex Hurst I would like to express my thanks for help in the statistical analyses.

I am indebted to all my friends for their true spirit in international friendship.

Carmencita Salvosa iii

TABLE OF CONTENTS

Page

INTRODUCTION

REVIEW OF LITERATURE

Thiamine Retention

Thiamine retention after broiling 5

Soluble Proteins . 6

Denaturation 6 Effects of heat on nutritive value of proteins

Weight Losses

Stage of cookery 9 Cooking temperature 10

Tenderness 10

Cooking time and temperature 11 Internal temperature 11

Press Fluid 12 Cooking of Meat 14

METHOD OF PROCEDURE 15

Preliminary Tests 15 Selection of Meat 16 Preparation for Cooking 17 Broiling 17 Chemical Tests 18

Preparation for sampling 18 Thiamine 19 Soluble proteins 19 iv

TABLE OF CONTENTS (Continued)

Page

Physical Tests 19

Weight losses 19 Moisture 19 Tenderness 19 Press fluid 19 Flavor test for preference 20

Other Tests 20

RESULTS AND DISCUSSION 21

Thiamine Retention 21

Effect of cooking temperature 21 Effect of cooking time 30 Effect of thickness of steaks 30

Soluble Proteins . 33

Effect of cooking temperature 33 Effect of cooking time . 33 Effect of degree of doneness 35

Weight Loss 35

Effect of cooking temperature 35 Effect of degree of doneness 37

Moisture Retention 37

Effect of cooking temperature 37 Effect of degree of doneness 37

Tenderness Scores 38

Effect of cooking temperature 38 Effect of degree of doneness 38 Effect of different muscles 38

Press Fluid 41 v

TABLE OF CONTENTS (Continued)

Page

Effect of cooking temperature 41 Effect of degree of doneness 43 Effect on tenderness 43 Effect on weight loss 43

Flavor 45 Cooking Time 46 Rate of Heat Penetration 46 Statistical Analyses 49

SUMMARY. 50

LITERATURE CITED 53

APPENDIX 61 vi

LIST OF TABLES

Table Page

1. Thiamine content of beef round and sirloin (mg/100 gm wet basis) 4

2. Results of preliminary tests on charcoal broiler 16

3. Effect of temperature on some factors in top sirloin steaks cooked rare 29

4. Thiamine retention as r elated to cooking time and stage of doneness 31

5. Effect of degree of doneness on some factors in top sirloin steaks broiled at 350° F 32

6. Tenderness values for r ectus femoris and vastus lateralis muscles 40

7. Juiciness as related to cooking temperatures 41

8. Press fluid as related to tenderness 44

9. Press fluid as related to weight loss 44

10. Average scores of four judges for flavor test 45

11. Cooking temperature as related to degree of doneness and cooking time 47

12. Time table for broiling sirloin steaks 62

13. Effect of temperature on some factors in top sirloin steaks cooked rare 63

14. Top sirloin steaks cooked at 350° F 66

15. Hedonic scale 68 vii

LIST OF FIGURES

Figure Page

1. Thiamine retention in top sirloin steaks cooked rare at three temperatures . 28

2. Thiamine retention in top sirloin steaks cooked to three degrees of doneness at 350° F 28

3. Soluble protein retention in top sirloin steaks cooked rare at three temperatures 34

4. Soluble protein retention in top sirloin steaks cooked to three degrees of doneness at 350° F 34

5. Weight loss in top sirloin steaks cooked rare at three temperatures 36

6. Weight loss in top sirloin steaks cooked to three degrees of doneness at 350° F 36

7. Moisture in top sirloin steaks cooked to three degrees of doneness at 350° F . 39

8. Shear force values in top sirloin steaks cooked to three degrees of doneness at 35 0° F 39

9. Press fluid in top sirloin steaks cooked rare at three temperatures 42

10. Press fluid in top sirloin steaks cooked to three degrees of doneness at 350° F 42

11. Heat curves representing temperatures of each of the three thermocouples 48 viii

LIST OF PLATES

Plate Page

1. One inch thick top sirloin steaks cooked rare at three temperatures 22

2 . One inch thick top sirloin steaks cooked to three degrees of doneness at 350° F . 23

3. One and one- half inch thick top sirloin steaks cooked rare at three tempe ratures . 24

4 . One and one-half inch thick top sirloin steaks cooked to three degrees of doneness at 350° F 25

5. Two inch thick top sirloin steaks cooked rare at three temperatures . 26

6. Two inch thick top sirloin stea ks cooked to two degrees of doneness at 350° F 27 viii

LIST OF PLATES

Plate Page

1. One inch thick top s irloin steaks cooked rare at three temperatures . 22

2. One inch thick top strloin steaks cooked to three degrees of doneness at 350° F 23

3. One and one-half in h thick top sirloin steaks cooked rare at three temperatures 24

4 . One and one-half inch thick top sirloin steaks cooked to three degrees of doneness at 350° F 25

5. Two inch thick top sirloin steaks cooked rare at three temperatures . 26

6. Two inch thick top sirloin steaks cooked to two degrees of doneness at 350° F . 27 INTRODUCTION

Broiling is cooking tender cuts of meat by radiant heat from hot coals ,

a gas flame, or an electric element. Steaks and chops for broiling a r e from

1 to 2 inches thick.

Broiling as a method of cooking meat is not new, but the directions for

the process are the result of individual trial and err or testing and are often

in conflict. Current interest in indoor and outdoor broiling, particularly in

Western United States , emphasizes the need for better information. There

is no measuring device for surface heat during broiling and thus little re­ search on the relationship of surface temperature, degree of doneness and

cooking time. Little has be en done to investigate the effect of a change in rate of heat transfer on the physical and che mical reactions which occur dur­ ing broiling.

Although some work has been done on the effects of different cooking methods on weight losses, tenderness, palatability, a nd thiamine content of beef, no reports were found relating cut of meat, t emperature at the surface of the meat, and degree of doneness to other factors during broiling.

The existing literature c ontained r elatively little information on changes produced in broiled beef. Most of the data available were indefinite, lacking precise information regar ding time and temperature. Timetables for broil­ ing, like roasting, varied in directions given and frequently stated the time 2 of cooking in minutes per pound. At best this can serve only as a poor guide because the amount of fat and bone present, the state of the meat, whether solid or ground, the amount of connective tissue present, and the thickness of the meat influence the rate of heat penetration.

This initial study was conducted on beef using charcoal as the source of heat, since the heat of the charcoal could be controlled at different tempera­ tures. A high, medium and low temperature were used for cooking and the meat was cooked to three degrees of doneness (rare, medium and well-done).

In this research a potentiometer devised by Taylor Instrument Company to measure the temperature at the surfaces of the meat and internally was used. Thus it was possible to accurately measure the temperature.

An experimental model of a coil-type thermometer was also made by

Taylor Instrument Company and its use offered, for the first time, the pos­ sibility of determining the temperature at the surface of the meat.

The purpose of this study was to investigate the relationship of surface temperature during broiling to stage of doneness and to cooking time on the following factors in broiled sirloin steaks: thiamine retention, soluble pro­ tein content, weight loss, moisture retention, changes in tenderness, juici­ ness and flavor. It was hoped that the findings might be of use in the develop­ ment of a thermometer to be used for broiling much as oven and meat thermometers are used now for roasting meats. Also, an attempt was made to develop time-temperature charts for use in broiling. 3

REVIEW OF LITERATURE

Thiamine Retention

A review of literature indicated a wide variation in the thiamine content of raw beef. Cover et al. (1944, 1947) stated that since many cuts of meat contained a large number of muscles, muscle variation could not be excluded.

They added that animal variation may account for some of the differences.

Table 1 shows the results of some studies on the thiamine content of beef round and sirloin.

Arnold and Elvehjem (1939), Rice and Beuk (1945), and Beadle et al.

(1943) concluded that the rate and extent of destruction were related both to the time and temperature of healing or cooking.

Schweigert et al. (1944) and Lushbough et al. (1959) reported that thia­ mine and pyridoxine were more readily destroyed by heat processing or standard cooking procedures than were other B-vitamins.

Lushbough et al. (1962), in their work on thiamine retention in meats after various heat treatments, stated that if the maximum amount of thiamine were to be retained in meat, cooking or processing should involve the use of the lowest temperatures a nd shortest times possible. Thiamine content of beef round cooked to the same degree of doneness at three temperatures de­ creased significantly at tbe highest temperature. 4

Table 1. Thiamine content of beef round and sirloin (mg/100 gm wet basis)

Round Sirloin Reference Raw Cooked Raw Cooked

Mickelsen et al. (1939a) 0. 450a

Waisman and Elvehjem (1941) 0.900a 0. 450a

Cheldelin a nd Williams (1942) 0. 063

Campbell et al. (1946) 0. 030 0. 039

Watt and Merrill (1950) 0. 080 0. 070

National Livestock and Meat Boa rd (1950) 0. 080

Leverton a nd Odell (1958) o. nb

Dawson e t a l. (1959) 0. 19- 1. 20c

Noble a nd Gomez (1960) 0. 102a 0. 084a aM01sture tree. brat- free. 'Tat-free; average for loin, rib and round. Thiamine retention after broiling

The existing literature contained relatively little information on the thiamine retention in broiled beef.

According to Mickelsen et al. (1939b), Cover et al. (1944), and Tucker et al. (1946) thiamine retention was related to degree of doneness.

Farrer (1955) stated that although shorter cooking time and lower cook­ ing temperatures favored thiamine retention, a combination of high tempera­ ture and short time might lead to smaller losses than found with lower temperatures and longer cooking times.

The National Livestock and Meat Board (1950) stated that thiamine had a retention of 80 percent in broiling. Morgan (1960) in reviewing the effects of home preparation on the nutrient content of foods of animal origin reported a retention of 60 to 86 percent.

In sirloin steaks pan broiled to a well-done stage for 18 minutes,

Campbell et al. (1946) reported that 13 percent of the thiamine was lost in cooking. The cooking temperature and internal temperature at doneness were not given.

Cover and Smith (1956) studied the effect of dry heat cooking on vitamin retention in meat from beef animals of different levels of fleshing. They reported that loin and bottom round steaks broiled at 392° F for 35 minutes had thiamine retentions of 56 percent and 61 percent, respectively. Soluble Proteins

Denaturation

The effect of high temperatures on proteins is almost entirely one of denaturation. According to Bull (1949) the most generally accepted theory of protein denaturation is that of Wu who proposed that denaturation be looked upon as a change from the unique and specific structure of the native protein to the much more randomly arranged denatured form. The peptide chains in the native molecule exist in a highly ordered structure and, when the protein molecule is denatured, this precise folding of the peptide chains is destroyed.

A later definition was by Neurath et al. (1944): "Denaturation is any non-proteolytic modification of the unique structure of a native protein, giving rise to definite changes in chemical, physical, or biological properties."

This definition excludes hydrolysis of the peptide bonds.

Putnam (1953) interpreted the phenomenon in terms of a theory of pro­ tein structure. According to him, all the evidence indicates that denatura­ tion is a physical or intramolecular rearrangement rather than a chemical alteration of native protein structure and that it led to a change in specific spatial configuration without hydrolysis of primary covalent bonds.

Heat is the first known, most common, and most widely investigated denaturing agent. Among the important changes occurring in various kinds of denaturation of most proteins are the following which may be evaluated quantitatively: (1) decrease in solubility, (2) loss of biological activity, (3) increased reactivity of constituent groups, and (4) changes in molecular shape or size.

According to Putnam (1953) , the coagulation was a secondary phenom­ enon although heat-denatured proteins readily aggregated. Diminished solu­ bility was the most familiar criterion of heat denaturation, and measurement either of the amount of soluble proteins remaining or of the precipitate served as a useful quantitative index. The coagulated protein was unsuited for most physical or chemical analyses.

Anson (1945) stated that heat coagulation of isoelectric proteins took place about 600 times faster when the temperature was raised 50° F.

Mitchell et al. (1949) and Rice and Beuk (1953) found that the effect of heat on food proteins depended upon the temperature attained within the food.

A review of the literature showed only one report on the effect of heat on soluble proteins of beef muscle. Ginger et al. (1954) found that cooking caused a very marked decrease in the amount of soluble protein nitrogen present and resulted in the liberation of some free amino nitrogen.

Effects of heat on nutritive value of proteins

Some of the work on raw and cooked beef indicated that home cooking methods had little effect on nutritive value. This was observed by the follow­ ing workers: Seegers et al. (1936), Swanson and Nelson (1938), Mitchell et al. (1949), McBride et al. (1951), and Clark et al. (1955).

In a study on raw and cured pork, Beuk (1948) found that neither standard home cooking methods nor commercial heat processing methods 8 destroyed significant amounts of amino acids other than cystine. Studies of

Neilands et al. (1949) and Dunn et al. (1949) supported these findings . Sim­ ilar results were found by Griswold (1951) who also reporte d that excessive heat l owered the nutritive value of meat protein , probably by forming enzym e resistant linkages .

There were some indications that if the temperature of processing ex­ ceeded certain limits, i.e. , about 212° F, the nutritive value of meat pro­ teins was impaired more seriously. This was noted in the studies of Morgan and Kern (1934) , Seegers (1935) , Seegers and Mattill (1935) , Poling et al.

(1944), Mayfield and Hedrick (1949) , Beuk et al. (1950) , and Wheeler and

Morgan (1958) .

Rice and Beuk (1953) stated that when a reduction in protein quality occurred it could be attributed to one or more of the following causes:

1. Actual destruction of one or more of the essential amino acids.

2. Formation of inte r- or intramolecular bonds which are r esistant to digestive enzymes. This may result in the inability of the animal to digest the protein or it may be reflected only in the biological value of the fragments which are a bsorbed.

3. Alteration in the rate at which the various amino acids are r eleased from the protein, resulting in mixtures of amino acids less efficient for m etabolism and assimilation.

According to McHenry (1957) moderately cooked meat was digested and absorbed more thoroughly than raw or overcooked meat; the moderately cooked product had, ounce for ounce, a greater nutritive value. Clifford 9

(1930) also found that cooked beef was digested more rapidly than raw beef.

Results similar to those of McHenry (1957) and Clifford (1930) were found by Schroeder et al. (1961) who reported that any ordinary heating of meat improved the nutritional quality of the protein. The methods of heating used in ordinary cookery did not greatly diminish the nutritive value of meat proteins. On the other hand, prolonged high temperatures appeared to de­ crease their over-all utilization.

Weight Losses

Weight losses in meat have been studied by a number of workers. In general the higher the internal temperature of the meat or the stage of done­ ness and the higher the cooking temperature, the greater the losses.

Very little work has been done on the weight losses of beef during broiling. However, the literature showed that the factors affecting the shrinkage of meat were generally in agreement.

Stage of cookery

According to Hughes (1955), shrinkage in cooked meats started at

140° F. The higher the internal temperature of the meat or the stage of doneness, the greater the shrinkage. Similar findings were noted by the following workers: Latzke (1930), Child and Satorius (1937), Cover (1937 and

1943), Satorius and Child (1938), Tucker et al. (1946), Aldrich and Lowe

(1954), Clark et al. (1955), Cover et al. (1937 and 1962), and Visser et al.

(1960). 10

It was observed by Cover et a l. (1962) that greater weight losses were associated with drier and less tender meat.

Cooking temperature

The literature showed that weight losses were greater with higher cook­ ing temperatures. This was observed by the following workers: Cline et al.

(1930), Alexander (1930), Child and Satorius (1938), Cover et al. (1949),

Lowe (1955) , West and Wood (1959), Bramblett et al. (1959), and Lushbough et al. (1962) .

Griswold (1955) found that when the time of cooking was unusually long at the lower temperature, the weight losses during cooking were high. Lowe et al. (1952) had similar findings in their study with veal leg roasts.

Tenderness

According to Harrison et al. (1959) tenderness in cooked meat was the total effect of composition of muscle, aging before cooking, heat coagulation of muscle fiber proteins, and the changes which took pla::e in the connective tissues.

Ramsbottom et al. (1945) reported that in as much as connective tissue and fatty tissue were made more tender by cooking, the decrease in tender­ ness of muscle was associated with factors such as coagulation and denatura­ tion of muscle proteins together with varying degrees of shrinkage and hard­ ening of muscle fibers. 11

Winegarden et al. (1952) concluded that cooking steaks a nd roasts to

rare or medium-done (131 ° to 149° F) brought about little, if any, change in

the connective tissues of the muscles. At 131° F little change occurred with

short periods of heating, but with higher temper atures , physical changes

occurred rapidly. During heating, the collagenous tissues lost weight,

softened, shrank in length, and increased in thickness .

Rams bottom et al. (1945) found that collagenous tissue changed con­

siderably on cooking but elastic tissue changed less.

Cooking time and temperature

Cooking time, Cover (1941) pointed out, was one factor in determining

tenderness of meat. Experimenting with paired roasts (one roasted with a

skewer and the other without), she found that long, slow cooking of unskewered

roasts increased tenderness of meat. In a later work Cover (1943) compared the effect of extremely slow rates of heat penetr ation to tenderness of beef

r oasts. She fo und , with paired roasts , that those cooked at 17 6° F consist­

ently had lower shear values than those cooked at 257° F .

Internal temperature

Top and bottom round steaks were cooked by Clark et al. (1955) by oven-braising to 176° F, in a pressure saucepan under 10 and 15 pounds pressure to the same internal temperature, and under 15 pounds pressure to

234 ° F. Top and bottom round steaks cooked to 234 ° F were significantly more tender than those cooked to 176° F. It was concluded that the internal 12

temperatures to which meat was cooked were more important in determining

tenderness than were methods of cooking studied.

Hood et al. (1955) noted no significant differences in tenderness of biceps

femoris cuts between meat roasted to 160° F and that to 176° F. When semi­

tendinosus muscle was cooked to three internal temperatures (136°, 153°,

and 167° F) by Satorius and Child (1938) , the diameter_ of the muscle fibers

decreased and tenderness increased up to 153° F. Between 153° and 167° F

the muscle fiber diameter did not change but tenderness decreased.

Visser et al. (1960), in a study of various beef muscles cooked in deep

fat to 212° and 230° F, showed that an increa se in internal temperature

tended to increase tenderness scores, but not significantly.

Cover et al. (1962) observed that beef steaks cooked by dry heat became

less tender with increasing internal temperature. Smith (1961) found similar

results in her study on venison.

Press Fluid

On the whole, subjective juiciness and the amount of press fluid did not appear to represent quite the same thing. Satorius and Child (1938), Hall

et al. (1944), Hardy and Noble (1945) , and Gaddis et al. (1950) found no rela­

tion between press fluid and juiciness.

That temperature and l ength of cooking affect juiciness in meat was

established by Satorius and Child (19 38). Similar results were noted by

Lowe et al. (1952), Siemers and Hanning (1953) , and Bramblett et al. (1959).

However, Child and Satorius (1938) noted that semitendinosus muscle heated 13 to an internal temperature of 136° F (rare ) a t different oven temperatures did not differ in press fluid or shear force.

Although low oven temperatures during roasting usually resulted in lower cooking losses and juicier meat both cooking losses and juiciness were adversely affected if meat were held at low cooking temperatures for very long periods Griswold (1955) studied the effect of cooking beef r ound roasted at two temperatures and found that meat roasted at 300° F was superior in juiciness to that roasted at the lower temperature.

Weir (1960) stated that tenderness and juiciness were closely related; the more tender the meat, the more quickly the juices were released by chew­ ing and the juicier the meat appeared. Cooking procedure was perhaps the most important factor influencing the juic iness of cooked meat. In general, those cooking procedures that resulted in the greatest retention of fluids and fat yielded the juiciest meat. For this reason juic iness usually varied in­ versely with cooking losses.

Rare meat is juicier than well-done meat. Satorius and Child (19 38 ) found that both the total moisture and press fluid decreased with each incre­ ment in interior temperature except that there wa s no decrease in press fluid between 136° and 153° F for beef roasts . Several workers , Hall (1944),

Cover and Shrode (1955), Clark et al. (1955) , Visser et al. (1960) , a nd

Cover et al. (1962), also reported that meat becam e progressively less juicy as its internal temperature increased. 14

Cooking of Meat

Cooking of meat is accomplished when the heat necessary to achieve the desired changes has penetrated to the center of the cut being cooked.

Directions for cooking often state the time of cooking in terms of minutes per pound. Lowe (1955) stated that at best this served only as a poor guide for the following factors affected the time required to cook meat or the rate of heat penetration: (a) the method of cooking, (b) the cooking temperature, (c) weight, surface area, and the shortest distance to the center of the thickest portion of the meat, (d) degree of doneness , (e) the composition of the meat,

(f) the degree of post mortem changes, and (g) the initial temperature of the meat. It is for these reasons that cookbook directions vary greatly (See

Appendix, Table 12).

According to Tischer and Hurwicz (1957) the striation of muscles in­ fluenced heat transfer and chemical and microbiological changes. The structure of muscles was such that it conducted impulses , fluids, and gases in one direction much more readily than in another. It is well known, for instance, that diffusion through the sheath of muscle cells was much slower than it was through the length of the muscle. The structure of cells was changed after the application of heat. The changes, no doubt, influenced the passage of heat and the character and extent of chemical changes in animal tissue. 15

METHOD OF PROCEDURE

Preliminary Tests

Preliminary studies were made to determine the broiling temperatures

used in electric ovens as a guide to those which might be used with a char­

coal broiler. These studies were conducted on an electric Hotpoint r ange

(Model RB, RC, and RD, Catalogue Number 109RD6).

Four broiling temperatures (500°, 400°, 350°, a nd 300° F) at three

different distances (8, 6, and 4 inches) from the broiler were tested. The

thermometer was placed on a rack, the heat regulator set at the temperature

being tested, the broiler turned on, the door l eft open as indicated for broil­

ing, and a record made of the temperature at the broiling surface in 1 minute

intervals.

For example, with the heat regulator at 500° F and the thermometer

8 inches from the broiler, at the end of 10 minutes the temperature was

340° F; at the end of 20 minutes the temperature was 430° F; and at the end

of 30 minutes the temperature wa s 460° F. At 6 inches from the heat, the

temperatures at the end of 10, 20, and 30 minutes were 400°, 480°, and 520°

F, respectively. At 4 inches from the heat, at the end of 10, 20, and 30

minutes, the temperatures were 500°, 570°, and 580° F. These and other tests showed that it was impossible to regulate the heat at a constant temperature. 16

Since it was impossible to control the heat of the electric broiler at a given temperature, the preliminary study was done using a charcoal broiler where through manipulation of the height of the grill from the charcoal and manipulation of the coals, it was possible to keep the heat comparatively constant.

Tests were conducted to determine the internal temperatures at time of turning and at the end of the broiling period, methods of controlling surface temperature, approximate cooking time required, and to work out the defini- tions for the three degrees of doneness . The results of these tests are shown below.

Table 2 . Results of preliminary tests on charcoal broiler

Internal Color in a Degree of Final internal Amount and temperature cross section doneness temperature color of juice at turning slice

Rare 85°-90° F 135°-140° F Bright red Abundant; red

Medium 90°-110° F 155°-160° F Pink or rose Less than rare; lighter red

Well-done 11o0 -n2° F 165°-170° F Not pink Very little; yellowish

Selection of Meat

Top sirloin steaks of good grade, 1, 1 1/2, and 2 inches thick, were selected as representative of the type of steaks generally charcoal broiled. 17

They were purchased from the meat counter of a Logan supermarket either the morning of the cooking day or the night before. In the latter case the meat was loosely wrapped and stored at 40° F until needed.

Preparation for Cooking

Before cooking the width of the outer contour fat was measured in cen­ timeters.

A raw meat sample, approximately 100 grams, was cut from the bi­ ceps femoris, gluteus medius, and gluteus profundus muscles for chemical analyses. This sample was placed in a labeled 250 milliliter beaker, cov­ ered with saran wrap, and refrigerated until chemical tests could be made later in the day.

The fat was scored and the steak weighed in grams on a labeled weighed aluminum pan. The meat, covered with saran wrap to help prevent moisture loss , was kept at refrigeration temperature until ready for cooking.

Thermocouples were sewed to the top and bottom surfaces and into the center of each steak, using nylon thread and a straight needle. These thermo­ couples were attached to a multi-point potentiometer built by Taylor Instru­ ment Company. The steaks were placed in an aluminum pan over ice during the sewing and registered between 35° and 45° F at the start of broiling.

Cooking was done outdoors on a charcoal grill. Charcoal was ignited with an electric starter. It was allowed to burn until gray and then spread 18

evenly. An experimental thermometer made by Taylor Instrument Company was placed on the grill to note the temperature of cooking. The desired temperature (300°, 350°, or 400° F) was regulated by manipulation of the coals and the grill. These temperatures were chosen because they were the ones most often suggested in cookbooks (See Appendix, Table 12).

The temperatures in the preliminary tests were used to determine time of turning and degree of doneness.

The steaks broiled rare were cooked at 300°, 350°, and 400° F. Reten­ tions of thiamine and soluble proteins were greater at 350° F than at either of the other temperatures; moreover these steaks cooked at 350° were the most palatable as indicated by the scores obtained by the subjective judging, thus the medium and well-done steaks were cooked at 350° F . It was found im­ practical to cook 2-inch steaks to the well-done stage. Surface core harden­ ing, formed during broiling, prevented penetration of heat into the center of the meat and it was impossible to reach an internal temperature of 170° F even after broiling times of 120 minutes.

Chemical Tests

Preparation for sampling

Samples of the lean raw and cooked steaks, freed of visible fat and connective tissue, were each cut into 1/2 to 1 inch cubes and ground with a grinder attachment of an electric mixer. After grinding three times, samples were weighed out for analyses. All determinations were made in duplicate. 19

Thiamine

The thiochrome method as modified by Conner and Straub (1941) was

used for thiamine assays.

Soluble proteins

Soluble protein determinations were made by a modification of the

biuret method of Salwin (1954).

Physical Tests

Weight losses

Weight losses were calculated from the change in weight of the meat

during cooking and thus included losses due to both evaporation and drippings.

Moisture

Moisture was determined by drying 5 grams of the ground meat in a dehydrator for 2 hours and then in a vacuum oven for 5 hours at 208° F a nd at 22 to 25 pounds pressure.

Tenderness

Four cylindrical cores, 1 inch in diameter, were taken from the rectus femoris and vastus lateralis muscles of each cooked steak. These cores were tested for tenderness on the Warner-Bratzler shearing machine.

Press fluid

Tests for juiciness were made with 50 grams of meat from each steak.

The meat was placed in the succulometer machine and pressure was held at 20

2, 500 to 2, 550 pounds for 10 minutes to express the juice from the m eat.

The juice was measured in milliliters.

Flavor test for preference

Research showed that when judging tenderness and flavor at the same time, tenderness affected flavor. Therefore it was decided to do tests for flavor only due to the limited amount of meat.

The cores of meat used in the tests for te nderness were wrapped sep­ arately in squares of aluminum foil and tested at room temperature by four judges. Because of its flexibility, simplicity, and reliability of results , the Hedonic scale suggested by Peryam and Girardot (1952) was used for scoring. This scale has nine phrases arranged from 1. 0 (dislike extremely) to 9. 0 (like extremely). See Appendix, Table 15.

Other Tests

Total nitrogen and fat extractions were run on a ll samples included in this study. These results will be r eported at a later time. 21

RESULTS AND DISCUSSION

Basic data on the thiamine and soluble protein content , weight losses, moisture, tenderness, press fluid, and flavor of the cooked meat are given in the Appendix, Tables 13 and 14.

Colored pictures of the different thicknesses of steak.,; cooked rare a t three temperatures and those cooked to three degrees of doneness at 350° F are shown in Plates 1 to 6.

Thiamine Retention

Effect of cooking temperature

For all thicknesses, thiamine retention of the steaks cooked to the rare stage was found to be highest in those steaks cooked at 350° F (Figure 1 and

Table 3) . At 400° and 300° F there was greater destruction of the vitamin.

Average retentions of thiamine in the 1 inch thick cuts were 55 percent at

400° F, 70 percent at 350° F, and 57 percent at 300° F. In the 11/2 inch thick cuts average retentions at 400°, 350°, and 300° F were 61, 71, and

60 percent, respectively. The 2 inch thick cuts retained 51 percent at 400°,

67 percent at 350°, and 59 percent at 300° F . This is similar to the results of Lushbough et al. (1962) who found that in beef round thiamine losses were greatest at the highest temperature. 22

Plate 1. One inch thick top sirloin steaks cooked rare at thrr·ee temperatures. 23

Rare

Medium

Well-done

Plate 2. One inch thick top sirloin steaks cookec tc three degrees of doneness at 350° F. ~4

Plate 3. One and one-half inch thick top sirloin steaks cooiked rar e at hree temperatures. 24

Plate 3. One and one-half inch thick top sirloin steaks cooked rare at threJ temperatures. 25

Rare

Medium

Well-done

Plate 4. One and one-half inch thick top sirloin steaks cookredi to three degrees of doneness at 350° F . 25

Rare

Medium

Plate 4. One and one-half inch thick top sirloin steaks cooked t(J) three degrees of doneness at 350° F . 26

Plate 5. Two inch thick top sirloin steaks cooked rare at t htr ree temp(ratures. 27

Rare

Medium

Plate 6. Two inch thick top sirloin steaks cooked to two degrees of doneness at 350° F . 28

in, thick

80

Figure 1. Thiamine retention in top sirloin steaks cooked rare at three temperatures.

in. thick

80

~ra re CJmedium ~well-done

Figure 2. Thiamine retention ~ n top sirloin steaks eooked to three degrees of doneness at 350°. F. Table 3. Effect of temperature on s ome factors in top sirloin steaks cooked r a r e

Internal Final Total Soluble Press Cooking . Turning . . Thia mine Weight Moisture Shear Flavor t temperature t ' mternal cookmg protein fluid emperature . 1me r etention loss content force s core at turnmg temperature time r et ention value

min. min. per c ent percent percent percent lb. ml.

1 in. thick 400° F 85° F 12 137° F 19 55 53 31. 2 59 . 3 20.8 8.6 7. 2 350° F 83° F 11 138° F 18 70 62 22.8 63. 9 19. 1 9.8 7 . 2 300° F 85° F 15 139° F 22 57 60 23. 2 62. 0 18.8 7.5 6 . 8

1 1/2 in. thick 400° F 98° F 11 138° F 22 61 27 30.4 60. 0 21.0 6.7 7. 3 350° F 97° F 12 139° F 27 71 44 23. 6 63.4 22 . 8 9 . 2 7. 7 300° F 91°F 17 140° F 36 60 30 26.8 62.3 23. 1 7.1 6. 8

2 in. thick 400° F 86° F 22 136° F 33 51 27 29. 0 62. 6 18. 1 11. 0 6. 3 350° F 86° F 31 141° F 43 67 41 32.9 62 . 9 18.5 10.1 7. 4 300° F 87° F 32 136° F 61 59 23 25.6 59. 3 21. 7 8 .0 6.8

"' 30

Effect of cooking time

All s teaks broiled rare at 300° F required a longer cooking time than at 350° F (Table 3) and retention of thia mine was less . This agreed with the findings of Farrer (1955) which stated that both shorter cooking time and lower cooking temperatures favor thiamine retention, but a combination of high temperatures and short cooking times may l ead to smaller losses than lower temperatures for longer times.

Cooking times for all steaks at all degrees of doneness varied greatly.

At any temperature, as cooking time required to reach the same final inter­ nal temperature increased, thiamine retention decreased (See Table 4 and

Appendix, Tables 13 and 14) . This finding agrees with that of Beadle et al.

(1943) who reported that, at any temperature, the rate and extent of thiamine destruction were related to time of heating or cooking.

Effect of thickness of steaks

Degree of doneness affected the retention of thia mine in all thicknesses of steaks cooked at 350° F (See Figure 2, page 28, and Table 5, page 32). A negative correlation of -0. 59 showed that thiamine retention decreased as the stage of doneness increased. In the 1 inch thick steaks retention averaged

70 percent in the cuts cooked rare, 49 percent in the medium-done cuts, and

40 percent in the well-done cuts. Retentions in the 1 1/ 2 inch thick steaks cooked rare, medium, and well-done were 71 , 51, and 42 percent, respec­ tively. The 2 inch thick steaks had a retention of 67 percent in the cuts cooked rare and 49 percent in the cuts cooked medium-done. 31

Table 4. Thia mine r etention as related to cooking time and stage of doneness

Degree of Cooking Cooking Thiamine Thickness Sample No. doneness te mperature time retention

inches minutes percent

Rare 400° F 2 24 19 63 32 29 51 27 41 38

Rare 300° F 26 48 64 29 60 59 34 74 54

Medium 350° F 50 30 51 46 41 49 51 43 46

Medium 350° F 2 49 33 52 48 42 49 56 58 46 Table 5 . Effect of degree of doneness on some factors in top sirloin steaks broiled at 350° F

Soluble Press De ree of Internal Turnin Final Total Thiamine Weight Moisture Shear Flavor g temperature g internal cooking protein fluid retention loss content force score doneness at turning time temperature time retention value

min. min. percent percent percent percent lb. ml.

1 in. thick Rare 83° F 11 138° F 18 70 62 22.8 63.9 19 . 1 9.8 7. 2 Medium 93° F 14 150° F 38 49 43 29 . 8 57.0 20. 8 4.0 7.5 Well-done 112° F 17 173° F 52 40 28 43.1 50. 0 24. 9 2 . 0 6. 1

1 1/2 in. thick Rare 97° F 12 139° F 27 71 44 23. 6 63.4 22 . 8 9.2 7. 7 Medium 87° F 30 149° F 45 51 39 32.6 60.4 21. 3 5 . 9 7. 7 Well-done 114° F 32 172° F 51 42 28 38.6 57.9 29.2 3. 0 7. 2

2 in. thick Rare 86° F 31 141° F 43 67 41 32.9 62.9 18.5 10. 1 7.4 Medium 93° F 31 152° F 44 49 37 32 . 2 62 .7 24. 5 6 . 8 7. 3

"' 33

These results were similar to those of Mickelsen et at. (1939) , Cover et at. (1944), and Tucker et al. (1946) who noted that thiamine retention was related to stage of doneness.

It was interesting to note that for the steaks cooked rare at 350° F, the 1 inch and 1 1/2 inch cuts r etained slightly more thiamine than did the

2 inch cuts (Figure 1, page 28, and Ta ble 3, page 29) .

Soluble Proteins

Effect of cooking temperature

Under the conditions of this study retention of soluble proteins in the steaks cooked rare was found to be greatest at 350° F (Figure 3 and Table 3).

A greater rate of denaturation was observed at 400° and 300° F. Average retentions of soluble proteins in the 1 inch thick cuts cooked at 400°, 350°, and 300° F were 53, 62, and 60 percent, respectively. In the 1 1/2 inch thick cuts the retentions were 27 percent at 400° F, 44 percent at 350° F, and 30 percent at 300° F . It was observed that at the three cooking tempera­ tures, soluble protein retention was highest in the 1 inch thick cuts, probably due to shorter cooking time. The highly significant correlation of -0.58 be­ tween soluble protein retention and thickness indicated that as thickness increased, soluble protein retention decreased.

Effect of cooking time

Denaturation of proteins was greater with longer cooking time in some individual steaks. As cooking time increased soluble protein retention 34

in. thick

1

2

% " -4000 F. rnrm 3500 F. §sooo F.

F1111re 3. Soluble protein retention in top elrloln et~ cooked rare at tiu'e.!l temperaturee.

% o 10 20 so 40 so eo 7o

~rare CJmedium ~well-done

F11\lre 4. Soluble protein retention in top sirloin steaks Qooked to tiu'ee degree& of donenese at 3500 F. 35 decreased. This agreed with the findings of Mitchell et al. (1949) and Rice and Beuk (1953) who found that the effect of heat on food proteins depended not only upon the intensity but also upon the duration of the heat treatment.

Effect of degree of doneness

As in thiamine, degree of doneness was related to retention of soluble proteins. The steaks cooked to highest internal temperatures lost most soluble proteins. F igure 4 and Table 5 show that at 350° F and at all thick­ nesses steaks cooked rare had a greater amount of soluble proteins than did those cooked medium and well-done. Soluble protein retentions in the 1 inch thick cuts cooked rare, medium, and well-done were 62, 43, and 28 percent, respectively. In the 1 1/2 inch thick cuts retentions were 44 percent when cooked rare, 39 percent when cooked medium-done, and 28 percent when cooked well-done. The 2 inch thick cuts cooked rare retained 41 percent of the soluble proteins while those cooked medium-done retained 37 percent.

Weight Loss

Effect of cooking temperature

Weight loss was directly related to cooking temperature. Figure 5 and

Table 3 show that in the 1 inch and 1 1/2 inch thick steaks cooked rare, weight l osses were markedly increased at the highest cooking temperature or at 400° F. This was in agreement with the results obtained by the follow­ ing workers: Cline et al. (1930), Alexander (1930) , Child and Satorius (1938), 36

in. thick

1 1/2

2

% 15 20 25 30 35

Figure 5. Weight loss in top sirloin steaks cooked rare at three temperatures.

in. thick

11/2

2

% 0 10 15 20 25 30 35 4 45

E228rarr. c=Jmedium ~well-done

Figure 6. Weight loss in top sirloin steaks cooked to t1!ree degrees of doneness at 350° F. 37

Cover et al. (1949), Lowe (1955), West and Wood (1959), Bramblett et al.

(1959) , and Lushbough et al. (1962) .

Effect of degree of doneness

In general the higher the internal temperature of the meat or the stage of doneness, the greater the loss in weight. In the 1 inch and 1 1/2 inch thick cuts cooked to three degrees of doneness at 350° F , weight losses were increased as the internal temperatures were raised (Figure 6 and Table 5).

Weight losses in the 1 inch thick steaks cooked rare, medium, and well-done were 22. 8, 29. 8, and 43.1 percent, respectively. In the 1 1/2 inch thick cuts, weight losses were 23.6 percent in those cuts cooked rare, 32.6 per­ cent in the medium-done cuts, and 38.6 percent in the well-done cuts.

A number of workers confirmed these findings: Latzke (1930) , Child and Satorius (1937), Cover (1937 and 1943), Satorius and Child (19 38),

Tucker et al. (1946), Aldrich and Lowe (1954) , Hughes (1955) , Clark et al.

(1955) , Cover et al. (1957 and 1962), and Visser et al. (1960).

Moisture Retention

Effect of cooking temperature

Although the data show that cooking temperature affected moisture, variations were very slight.

Effect of degree of doneness

In the 1 inch and 1 1/2 inch thick cuts cooked to three degrees of done­ ness at 350° F, the total moisture tended to decrease with an increase in the 38 internal temperature (Figure 7 and Table 5). Similar findings were reported by Satorius and Child (1938) and Cover et al. (1962).

Tenderness Scores

In the shear test results, scores indicate the number of pounds required to cut or press through a 1 inch core of meat.

Effect of cooking temperature

Cooking temperature affected tenderness in the steaks cooked rare at the three temperatures. However, results in the different thicknesses were inconsistent.

Effect of degree of doneness

Tenderness scores in the 1 inch and 2 inch thick steaks cooked to three degrees of doneness at 350° F were similar to those found by Cover et al.

(1962). As the internal temperature of the m eat increased, toughness of the meat increased also.

Effect of different muscles

Table 6 shows that except for the results on tenderness of the 2 inch thick cuts cooked rare at the three different temperatures, the mean tender­ ness scores of the rectus femoris and vastus lateralis muscles were in agreement with those reported by Ramsbottom and Strandine (1948). The vastus lateralis muscle was found slightly tougher than the rectus femoris muscle. 39

in. thick

% 0 10 20 30 40 50 60 70

~rare Omedium ~well-done

Figure 7. Moisture i.n top sirloin steaks cooked to three degrees of doneness at 350° F.

in. thick

1 1/2

2

lb. 0 10 15 20 25 30

~ra re Omedium ~well-done

Figure 8. Shear force values in top s irloin steaks cooked to three degrees of donenes s at 350° F. 40

Table 6 . Tenderness values for rectus femoris and vastus lateralis muscles

Degree of Cooking Shear force Thickness doneness te mperature Rectus femoris Vastus later a lis

in. lb.

Ra r e 400° F 20.2 21. 4 350° F 18. 8 19 . 4 300° F 17 . 0 20. 6

400° F 1 1/2 17.1 24.9 350° F 22.1 23.5 300° F 22. 4 23. 9

400° F 2 18. 4 17. 3 350° F 19.2 17.9 300° F 22. 1 21. 3

Me dium 350° F 1 19. 5 22 . 2 1 1/2 20.5 22. 1 2 23. 2 25.8

Well-done 350° F 1 24. 6 25 . 2 1 1/2 28. 8 29 . 5 41

Press Fluid

Effect of cooking temperature

Only s light differences in juiciness were observed. Cooking tempera- ture affected juiciness in the 1 inch and 1 1/2 inch thick cuts cooked rare

(Figure 9 and Table 7). The amount of juice was found to be highest in those cuts cooked at 350° F . At 300° F and with a longer cooking time the juice was decreased.

Table 7. Juiciness as related to cooking t emperatures

Cooking temperature Thickness Cooking time Press fluid

in. min . ml.

19 8. 6 18 9.8 22 7.5

400° F 1 1/2 22 6.7 350° F 27 9.2 300° F 36 7. 1

The results were similar to those of Satorius and Child (19 38), Lowe et al. (19 52), Siemers and Hanning (1953), a nd Bramblett et al. (19 59), who found that juiciness in meat was influenced greatly both by the temperature and length of cooking. 42

in. thick

1 1/2

2

m l. 2 4 6

Figure 9. Press fluid in top sirloin steaks cooked rare at three t emperatures.

in. thic

1 1/2

2

ml. 0 2 4 6 10

~rar e c:::Jmedium ~well-done

Figur e 10. P ress fluid m top sirloin steaks cooked to three degrees of doneness at 350° F. 43

Effect of degree of doneness

The meat became progressively less juicy as the internal temperature was increased. This fact was noted by Satorius and Child (1938), Hall (1944),

Cover and Shrode (1955), Clark et al. (1955) , Cover et al. (1957 and 1962), and Visser et al. (1960).

In the three thicknesses of steaks cooked to three degrees of doneness at 350° F, press fluid values were found to decrease with increasing internal temperature (Figure 10 and Table 5). The 1 inch thick steaks cooked rare, m edium, and well-done had 9. 8, 4. 0, and 2. 0 milliliters of press fluid , respectively. In the 1 1/2 inch thick steaks press fluid values wer e 9. 2 milliliters when cooked rare, 5. 9 milliliters when cooked medium, and

3. 0 milliliters when cooked well-done. The 2 inch thick steaks cooked rare had 10. 1 milliliters of press fluid while thos e cooked m edium-done had

6. 8 milliliters. As the degree of doneness was increased, press fluid decr eased.

Effect on tenderness

P ress fluid was related to tenderness. As press fluid decreased, tenderness decreased. This was observed at 350° F with all thicknesses and at all three degrees of doneness with one exception, the 1 1/ 2 inch thick cuts cooked rare (Table 8).

Effect on weight loss

Table 9 shows that press fluid decreased with increasing weight loss.

This was noted in the 1 1/2 inch thick cuts cooked rare at 400° F and 350° F . 44

Table 8. Press fluid as related to tenderness

Degree of doneness Thickness Press fluid value Shear force

in. ml. lb.

Rare 9.8 19. 1 Medium 4.0 20.8 Well- done 2.0 24 . 9

Rare 1 1/2 9.2 22. 8 Medium 5. 9 21. 3 Well-done 3. 0 29.2

Rare 2 10. 1 18. 5 Medium 6.8 24 . 5

Table 9. Press fluid as related to weight loss

Degree of Cooking Press fluid Thickness Weight loss doneness te mperature value

in. ml. percent

Rare 400° F 1 1/2 6. 7 30. 4 Rare 350° F 1 1/2 9.2 23 . 6

Rare 350° F 9.8 22 . 8 Medium 4 . 0 29 . 8 Well-done 2.0 43.1

Rare 350° F 1 1/2 9.2 23. 6 Medium 5.9 32.6 Well-done 3. 0 38.6 45

The same trend was observed in the 1 inch and 1 1/2 inch thick cuts cooked to different degrees of doneness at 350° F . These results concurred with the report of Weir (1959) and Cover et al. (1962) who stated that juiciness varied inversely with cooking losses.

Average scores obtained by the subjective judging for flavor are shown in Table 10. The Hedonic scale (See Appendix, Table 15) was used to judge flavor . In the rare steaks cooked at the three different temperatures, the best score, 7. 4 (between "like moderately" and "like very much"), was given to those cooked at 350° F. Steaks cooked at 400° F scored 6. 9 or "like moderately. " Steaks cooked at 300° F scored slightly lower, 6. 8. Comments showed that the judges found the meat juicy at 350° F but drier and less tender at 300° F.

Table 10. Average scores of four judges for flavor test

Cooking Flavor score temperature Rare Medium Well-done

400° F 6.9

350° F 7.4 7.5 6.6

300° F 6.8 46

Steaks were considered best when cooked m edium- done at 350° F.

They scored 7. 5. Those cooked well-done at the same temperature received

th e lowest scor e, 6. 6 , between "liked slightly" and "like moderately."

Comments on the well-done steaks were m ade to the effect that they were

tough and very dry .

Cooking Time

There was great variation in cooking time of the individual steaks (See

Appendix, Tables 13 and 14) .

Table 11 shows the results of cooking temperature as related to degree

of doneness and cooking time. The steaks are classified according totem­

perature of cooking, thickness of the cut, and degree of doneness .

It was obser ved that the thick cuts took the longest time to reach a

definite temper ature. A highly significant corr elation coefficient of 0. 48

indicated a direct relationship between thickness of the cut and length of

cooking time.

The temperature of cooking affected cooking time. The meat r eached

the final internal temperature more r apidly at the higher temperature.

Rate of Heat Penetration

Composite heat curves are shown in Figure 11. These curves r epre­ s ent the temperatures of each of the three thermocouples in the steaks broiled to the different stages of doneness at the three temperatures. 47

Table 11 . Cooking temperature as related to degree of doneness a nd cooking time

Internal Final Total Degree of Cooking Thickness temperature Turning inte rnal cooking doneness te mperature at turning time temperature time

in. min. min.

Rare 400° F 85° F 12 137° F 19 350° F 83° F 11 138° F 18 300° F 85° F 15 139° F 22

400° F 1 1/2 98° F 11 138° F 22 350° F 97° F 12 139° F 27 300° F 91° F 17 140° F 36

400° F 2 88° F 22 136° F 33 350° F 86° F 31 141° F 43 300° F 87° F 32 136° F 61

Medium 350° F 1 93° F 14 150° F 38 1 1/2 87° F 30 149° F 45 2 93° F 31 152° F 44

0 Well-done 350° F 1 112 F 17 173° F 52 1 1/2 114° F 32 172° F 51 49

The standard deviations of temperature for the surface toward the heat source and away from the heat source were greater than for the internal temperature. For example, in the 1 inch thick r are steaks cooked at 300° F the standard deviation for the temperature away from the heat source was

25, fo r the temperature toward the heat source, 29, and for th e internal temperature, 13. 7. Other samples followed a similar pattern.

Statistical Analyses

When the first three variables , i.e., thickness , cooking temperature, and internal temperature, were compared to cooking time in the formula 2 2 2 1 , 1 , 2 , 2 , 3, 3 , 1 X 2, 1 X 3,

2 R = 0. 64 §. = 10. 35 .

The variation in cooking time was 10 minutes ; 64 percent of the total variation was accounted for by the mathematical equation while 36 percent was due to unknown factor s .

By adding five other variables, namely, raw weight, shear for ce, press fluid , soluble proteins (raw ), and thiamine (raw), to the formula 2 2 2 1, 1 2 , 2 , 3, 3 1 X 2 , 1 X 3, 4, 6, 7, 9, 11,

R2 = 0.79 §. = 8. 24.

The variation in cooking time was decreased 8 minutes , 79 percent of this variation was due to the mathematical equation. 50

SUMMARY

Studies were conducted on Good grade top sirloin steaks of beef, 1,

1 1/2, and 2 inches thick, charcoal broiled at 400°, 350°, and 300° F. The

steaks were cooked to an internal temperature of 135° to 140° Fat a ll three

temperatures. Those cooked to the medium (155° to 160° F) and well-done

(165° to 170° F) stages were broiled at 350° F . The following chemical and

physical tests were made on each: thiamine, soluble proteins , weight loss ,

moisture, tenderness, juiciness, and flavor.

For all thicknesses, thiamine retention in the steaks cooked rare was

found to be highest in those cuts cooked at 350° F . When cooked to different

degrees of doneness, thiamine retention decreased as the internal tempera­

ture increased. It was found that in some steaks destruction of the vitamin

was proportional to the time of cooking.

Like thiamine, soluble protein retention was influenced by temperature

of cooking, degree of doneness, and time of cooking. Retention of soluble proteins in the steaks cooked rare was found to be best at 350° F . When cooked to different end-point temperatures at 350° F, the steaks cooked rare had a greater amount of soluble proteins than did those cooked medium and well-done. Denaturation of proteins was greater with longer cooking time in some individual steaks. Thickness was found to be related to retention. The highest amount of soluble proteins was found in the 1 inch cuts when the 51

steaks were cooked rare at the three temperatures. When cooked to different

degrees of done ness at 350° F, the 1 inch cuts cooked rare also had the best

retention of soluble proteins.

Weight losses were related to cooking temperature and degree of done­

ness in the 1 and 1 1/2 inch cuts. At the highest cooking temperature, or at

400° F, the meat had a greater decrease in weight than when cooked at the

lower temperatures. There was a consistent increase in weight loss as the

internal temperature of the meat was increased.

In the 1 a nd 1 1/2 inch cuts cooked to three degrees of doneness at

350° F, moisture decreased with an increase in the internal temperature of

the meat.

Rare meat was more tender than medium and well-done meat. This

was noted in the 1 and 2 inch thick cuts cooked at 350° F . In the 1 1/2 inch

cuts the steaks cooked medium were more tender than those cooked rare.

However, the meat became l ess tender when cooked well-done.

Cooking temperature affected juiciness in the 1 and 1 1/2 inch thick

cuts cooked rare. The amount of press fluid was found to be highest in those

cuts cooked at 350° F. Degree of doneness was another factor related to

juiciness. The meat became progressively less juicy as its internal tem­

perature was increased. It was found that juiciness was also influenced by

tenderness and weight loss. Greater press fluid was related to more tender

meat and less loss in weight.

Flavor scores showed a preference for steaks cooked rare and medium­ done at 350° F. The lowest score was received by those steaks cooked 52 well-done at 35 0° F.

Broiling the meat rare at 350° F proved to be the best cooking tempera­ ture. Besides having the best retention of thiamine and soluble proteins , the steaks cooked at 350° F had more juice and better flavor than those cooked at 400° and 300° F .

In the statistical analyses of the results the first three variables, i.e., thickness, cooking temperature, and interna l temperature, gave an R2 of

0. 64 and a~ of 10. 35. Adding five other variables, namely, raw weight, percentage of weight loss, shear force, press fluid, and percentage of thiamine retention, resulted in R2 : 0. 79 and ~ = 8. 24.

Further research is needed to develop cooking charts for outdoor broiling and to confirm the findings in this thesis. 53

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APPENDIX Table 12. Time table for broiling s irloin steaks

Cooking Final internal temperature Cooking time Thickness temperature Rare Medium Well-done Rare Medium Well-done in. minutes National Livestock and Meat Board (1950) 1 350° F 140° F 160° F 20 25 1 1/2 350° F 140° F 160° F 30 35 2 350° F 140° F 160° F 40 45

McLean and Campbell (1952) 1 5 6 7-8 1 1/2 9 10 12-13 2 16 18 20-21 Better Homes and Ga rdens (1953) 140° F 160° F 170° F Wilmot and Batjer (1955) 110° Fa ll0° Fa 120° Fa 135° F 155° F 170° F Hughes (1955) 1 350° F 20-22 25 30 1 1/ 2 350° F 30-32 35 40 Lowe (1955) 131-149° F 149-158° F 158-176° F Armour (1956) 1 10-12 14-16 20-25 1 1/2 14-16 18-20 25-30 2 20- 25 30- 35 40-45 West and Wood (1959) 130-135° F Fowler et al. (1961) 1 15 20 30 1 1/2 25 35 2 35 50 Taylor Instrument Co. (1962) 135° F 155° F 165° F a At turning. "'"" Table 13. Effect of temperature on some factors in top sirloin steaks cooked rare

Chemical tests Sample Internal Turning Final Total Thiamine Soluble Physical tests number temperature time internal cooking retention protein Weight Moisture Shear Press fluid Flavor at turning temperature time loss retention content force value score

min. min. percent percent percent percent lb. ml. 1 inch thick 400° F 18 84° F 6 140° F 11 63.9 60.0 26.5 65.2 19.9 8.2 7. 0 21 82° F 10 141° F 18 60.0 49.7 36.6 53.2 17.6 10.6 6.8 38 84° F 14 134° F 21 44.9 45.3 41.1 55.2 25.7 6.4 7. 3 44 81° F 15 135° F 23 56.9 55.6 23.6 64.8 17.0 9.0 7. 3 35 95° F 13 136° F 23 51.4 53.2 31.3 58.0 24.0 8.8 Average 85° F ~ 12 137° F 19 55.3 53.1 31.2 59.3 20. 8 8.6 7.2 350° F 22 84° F 8 139° F 13 64.7 70.1 24. 8 62.1 16.4 13. 7 7. 0 19 82° F 10 144° F 14 79.1 65.5 18.2 66.5 17.1 10.8 6. 5 39 81° F 13 135° F 16 71. 3 52.2 23.8 63.6 21.9 9.3 6. 8 36 84° F 9 136° F 20 77.0 63.3 25.4 62.2 21. 1 9 . 7 8 . 0 45 85° F 16 135° F 27 64.8 61.4 22.6 65.2 15.4 .§.:_Q Average 83° F ~ 11 138° F 18 70.1 61. 7 22.8 63.9 19. 1 9.8 7. 3 300° F 20 79° F 9 140° F 13 66. 3 62.2 14. 8 68.4 19.2 9.0 5.8 37 91° F 11 145° F 17 45.5 65.4 37.5 56.1 27.8 5.5 5.8 55 93° F 17 135° F 23 61. 6 59.4 21.5 63.3 13.7 5.0 7. 0 47 82° F 16 141° F 25 56.8 65.4 18.7 66.5 15.3 13.4 7.5 40 81° F 22 134° F 30 54.0 45.3 20.6 55.6 17 .4 Average 85° F ~ ~ 15 139° F 22 56.8 59.8 23.2 62.0 18 .8 7.5 6.8 "' Table 13. (Continued)

Chemical tests Sample Internal Turning Final Total Thiamine Soluble Physical tests number temperature time internal cooking retention protein Weight Moisture Shear Press fluid Flavor at turning temperature time retention loss content force value score

min. min percent percent percent percent lb. ml.

!....!L.2 inches thick 400° F 16 106° F 9 140° F 17 58.7 30.3 30.9 61. 1 21.6 9.3 7.3 10 98° F 9 140° F 24 60.0 23.0 30.6 58.6 24. 1 3. 9 7.5 13 90° F 15 134° F 26 62.7 30.9 30.1 60.4 17.3 ~ 7.3 Average 98° F 11 138° F 22 60.7 27.2 30.4 60.0 21.0 6.7 7.3

350° F 17 92° F 12 139° F 20 70.5 34.3 24.1 60.7 18. 4 10.4 7.8 105° F 12 140° F 27 75.8 60.0 17.5 67 . 3 23. 8 11.8 7. 3 11 95° F 12 139° F 35 -~ 45.0 31.3 62.1 26.1 ~ §.:Jl. Average ~ 12 139° F 27 70.8 43.5 23.6 63.4 22. 8 9.2 7. 7

300° F 15 90° F 6 141° F 24 65.5 21.7 20.1 64.9 19. 1 10.9 7. 0 9 95° F 12 139° F 34 74.3 47.2 20.0 63.5 24.4 7.4 7. 3 12 89° F 30 141° F 50 43. 9 25 .5 41.5 58.5 25.9 ~ §.:Jl. Average 91°F 17 140° F 36 59 . 9 29.9 26.8 62.3 23. 1 7.1 6.8

"'"" Table 13. (Continued)

Chemical tests Sam le Internal Turnin . Final Total Thiamine Soluble . . Physical tests . p temperature g mternal cookmg We1ght Mo1sture Shear Press flmd Flavor number at turning time temperature time retention protein loss content force value score retention min. min. percent percent percent percent lb. ml.

2 inches thick 400° F 24 91° F 16 138° F 29 63.3 25.8 29.8 62.7 14. 2 10.3 6. 0 32 89° F 21 135° F 29 51. 1 31.2 22.7 64.0 20.2 12.4 6. 8 27 85° F 29 136° F 41 38.5 21.5 51.5 61.2 19.9 10.4 ~ Average 88° F 22 136° F 33 51. 1 27.1 29.0 62.6 18.1 11. 0 6.3

350° F 25 89° F 27 139° F 37 64.7 44.8 31. 0 64.3 11.9 11. 3 7.8 28 85° F 29 136° F 46 40.9 42.4 35.7 60.3 21.6 7.7 6.8 33 85° F 37 149° F 46 58.5 39.6 32 . 3 64.0 22.1 11.4 u Average 86° F 31 141° F 43 67 . 4 41.4 32.9 62 .9 18 .5 10. 1 7. 4

300° F 26 89° F 34 136° F 48 63. 6 30.0 19.1 61.3 18.1 9.5 5.8 29 86° F 33 136° F 60 58 .7 23.6 33.5 56.4 19 .2 3.5 7.2 34 85° F ~ 135° F 74 53.8 20.7 23.0 60.2 27. 8 11. 1 22 Average 87° F 32 136° F 61 58.7 23.1 25.6 59. 3 21. 7 8.0 6.8

a> "' Table 14. Top sirloin steaks cooked at 350° F

Chemical tests Internal Final Total Physical tests Sample temperature Turning internal cooking Thiamine Soluble Weight Moisture Shear Press fluid Flavor number at turning time temperature time retention protein loss content force value score retention min. min. percent percent percent percent lb. ml.

Medium-done

1 inch thick 50 98° F 14 150° F 30 51. 1 48.0 32.8 57.4 21.9 4.3 8.2 46 90° F 15 149° F 41 48.7 38 . 9 18.7 55.7 18.8 3.1 7.0 51 91°F 12 150° F 43 46. 3 43.3 35. 1 57.9 21. 7 ------4.7 -7.2 Average 93° F 14 150° F 38 48.7 42.8 29.8 57.0 20.8 4 . 0 7.5

1 1/2 inches thick 42 89° F 23 149° F 40 52.2 40.0 27.6 59.9 18 . 7 7. 7 8.2 43 89° F 27 149° F 40 48.1 36.1 35.4 60.9 19.5 5.0 8.0 41 82° F 39 150° F 56 54.6 40.0 34.4 60.5 25 . 6 !:....!!. ~ Average 87° F 30 149° F 45 51.4 38.7 32.6 60. 4 21. 3 5.9 7.7

2 inches thick 49 90° F 22 148° F 33 51. 7 45.9 28.5 63.9 25.1 7.5 7.0 48 90° F 28 151° F 42 49.5 38 . 0 33. 2 64. 6 24.2 3.6 7.0 56 99° F 44 156° F 58 45. 7 30.3 34.6 59 .4 24.1 9.2 8. 0 Average 93° F 31 l52"F 44 49. 1 36 . 9 32.2 62.7 24.5 6.8 7.3

a> a> Table 14. (Continued)

Chemical tests Sam le Internal Turnin . Final Total Thiamine Soluble . . Physical tests . P temperature g mternal cookmg Weight Mmsture Shear Press flmd Flavor number at turning time temperatur e time retention protein loss content force value score retention min. min percent percent percent percent lb. ml.

Well-done

1 inch thick 54 117° F 10 176° F 34 40.6 29.6 42. 3 50.6 22.9 1.6 6 . 5 57 110° F 29 171° F 50 37. 8 29 . 6 38 .2 52 . 0 27.8 3.7 6.8 64 110° F 12 171° F 73 41.8 26.4 51.4 46 . 3 24.0 .2.:.1. £.Jl. Average 112° F 17 173° F 52 40.0 28.4 43. 1 49.6 24. 9 2.0 6.1

1 1/2 inches thick 59 123° F 22 171° F 38 41.9 26.3 36.8 56 . 5 33.1 3. 1 7.2 60 110° F 36 174° F 53 42.4 31.6 44. 1 56.5 20.2 2.1 7.2 58 110° F 38 170° F 62 42.1 26.3 34. 7 60.7 31.6 ~ .?.:...Q Average 114° F 32 172° F 51 42.1 28 . 1 38 . 6 57.9 29.2 3.0 7. 2

0>..., 68

Table 15 . Hedonic scale

Name Date

Sample_ Sample_ Sample_ Sample_ Sample ___

Like Like Like Like Like 9 Extremely Extremely Extrem ely Extremely Extremely

Like Like Like Like Like 8 Very Much Very Much Very Much Very Much Ver y Much

Like Like Like Like Like 7 Moderately Moderately Moderately Moderately Moderately

Like Like Like Like Like 6 Slightly Slightly Slightly Slightly Slightly

Neither Like Neither Like Neither Like Neither Like Neither Like 5 Nor Dis like Nor Dislike Nor Dislike Nor Dislike Nor Dislike

Dislike Dislike Dislike Dislike Dislike 4 Slightly Slightly Slightly Slightly Slightly

Dislike Dislike Dislike Dislike Dislike 3 Moderately Moderately Moderately Moderately Moderately

Dislike Dislike Dislike Dislike Dislike 2 Very Much Very Much Very Much Very Much Very Much

Dislike Dislike Dislike Dislike Dislike 1 Extremely Extremely Extremely Extremely Extremely

Comm ents Comments Comments Comments Comments

Directions: Completely enctrcle the category which best describes your reaction to the s a mple written above the column. Then under Comments give your reasons for r ating the sample as you did. (i. e. Flavor too strong, lacks flavor, odor not pleasant, etc.)