evaluation of pork quality a thesis

COMPARISON OF WARNER-BRATZLER SHEAR,

ARMOUR TENDEROMETER, AND SENSORY

EVALUATION OF PORK QUALITY

by

SHU-SHUN JULIE YEH, B.S.

A THESIS

IN

FOOD AND NUTRITION

Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

IN

HOME ECONOMICS

Approved

Accepted

December, 1973

/9 93

ACKNOWLED GMENTS

My earnest appreciation is expressed to Mrs. Clara

M. McPherson for her advice, patience, and encouragement

throughout the study. Appreciation is also extended to

Dr. S. P. Yang and Dr. Leland F. Tribble for their service

on the committee and their valuable evaluations and sug

gestions.

Acknowledgement is expressed to Mr. Charles T.

Gaskins for his guidance in statistical analysis of data.

I am deeply indebted to the members of the sensory panel

for their cooperation and help throughout the experiment.

I am grateful to those individuals in the Department of

Animal Science who were involved with this project, for

only with their help was this study possible.

1 1

TABLE OF CONTENTS

« • ACKNOWLEDGMENTS ii

LIST OF TABLES v

LIST OF ILLUSTRATIONS vi

I. INTRODUCTION 1

Statement of the Problem 1

Purposes 3

Hypotheses 3

II. REVIEW OF LITERATURE 5

Trends in Pork Consumption 5

Factors Which Affect Pork Quality 7

Genetic Factors 7

Ration and Management 8

Sex 11

Consumer's Criteria for High Quality Pork . . 12

Mechanical Measurements of Tenderness . . . . 14

III. METHODOLOGY 18

Animals 18

Ration 18

Marbling 19

The Sample 19

Cooking Procedure 19

Sensory Evaluation 20

Warner-Bratzler Shear 22

Total Fat Content 22

iii

IV

IV. FINDINGS AND INTERPRETATION 24

Variation Caused by Treatment 24

Variation in Cooking Losses 24

Sensory Panel Evaluation 25

Objective Measures of Tenderness 25

Intramuscular Fat 26

Variation Caused by Marbling 26





Variation Caused by Sex 31





Correlation Among Tenderometer, Warner-Bratzler Shear, Sensory Tenderness Scores and Number of Chew-Counts 34

Correlation Coefficients Between

Selected Variables 35

V. SUMMARY AND CONCLUSIONS 38

LIST OF REFERENCES 41

APPENDIX 46

LIST OF TABLES

Table Page

1. Least Square Means for Variables Due to Treatment 27

2. Least Square Means for Variables Due

to Marbling 28

3. Least Square Means for Variables Due to Sex . . 33

4. Correlation Coefficients Between Tenderometer, Warner-Bratzler Shear, Sensory Tenderness and Chew-Count Scores 35

5. Correlation Coefficients Between Selected Variables 36

LIST OF ILLUSTRATIONS

Figure Page

1. Pork Roast Divided into Sections for Sampling 21

VI

CHAPTER I

INTRODUCTION

Statement of the Problem

Consumers have become increasingly sensitive to fat

in their diets, with a decided objection to pork fat (1) .

This sensitivity is attributed to an increased awareness of

the health aspects of obesity and to various dietary fac

tors associated with heart disease. In addition, there has

been an increased use of vegetable oils, which has changed

the relationship of lard prices to prices of live hogs when

compared to former years. However, consumers have demon

strated a willingness to pay a higher price for lean pork

in general (2).

Swine production is an important segment of the

agriculture of the High Plains region of Texas (3). Tra

ditionally the ration fed to swine is a corn-soybean mix

ture. In the major pork producing areas of the United

States, namely the Midwest, corn has been the most common

grain used in swine rations (4). However, in Texas, corn

is not grown in as great a quantity as grain sorghum and

wheat due to climatic conditions. In 1972, grain sorghum

production in Texas was 74 million bushels, wheat 105 mil

lion bushels, and corn 6.3 million bushels (5). Therefore,

r

it is not only convenient but also economical and agricul

turally sound to substitute sorhgum and wheat for corn in

swine rations on the High Plains. Some research has been

done to determine the effect of feeding grain sorghum upon

the quality of pork (6).

Studies have shown that hog carcasses vary widely

with respect to the proportions of fat to lean (7). Diet

has a marked influence on the ratio of fat to lean in the

carcass and particularly on the level of intramuscular fat

(8). Results of work by Harrington and Pearson give sup

port to the supposition that pork loins with low levels of

intramuscular fat tend to be somewhat tougher on the aver

age, than those with more intramuscular fat, although the

relation was not sufficiently correlated to be used for

predictive purposes (9). Other factors such as sex, feed

restrictions, and level of dietary protein intake were

shown to influence tenderness (8).

Tenderness is probably the most important factor

affecting the consumer's evaluation of meat quality and

acceptability. Various mechanical methods of measuring

tenderness have been developed and evaluated (10) . The

latest device for evaluating tenderness is known as the

Armour Tenderometer which can be used on both raw and cooked

samples (11). The Warner-Bratzler Shear Apparatus, if used

to determine tenderness on raw sample, destroys its integ

rity so the same sample cannot be tested again after cooking

Further research is needed to determine the effect

of ration, sex, and level of marbling upon the quality of

pork. Such research would be highly beneficial to both the

grain and swine producers on the High Plains of Texas.

Purposes

This study was initiated between the Departments

of Animal Science and Food and Nutrition to determine the

following:

1. the differences in pork quality which will occur as a result of feeding rations formulated with grain sorghum, wheat and corn

2. the effect on pork quality when three levels of marbling are produced by feeding the above rations

3. the effect of sex on pork quality with ration and marbling as variables

4. the relationships between Armour Tenderometer scores, Warner-Bratzler shear values, and sensory panel chew counts.

Hypotheses

The following hypotheses were tested:

1. There will be no significant differences in

the quality of the pork which can be attributed to type

of ration.

2. There will be no significant differences in

the quality of the pork which can be attributed to sex

of the animals.

3. There will be significant differences in the

quality of the pork which can be attributed to level of

marbling.

4. There will be significant relationships between

the Armour Tenderometer values, Warner-Bratzler shear values

and sensory panel chew counts.

5. The pork roasts with higher levels of marbling

will show greater intramuscular fat content when chemically

analyzed.

CHAPTER II

REVIEW OF LITERATURE

Trends in Pork Consumption

The per capita pork consumption in 1879 was estimated

to be 73 lbs.; whereas, in 1966 the USDA estimated it to be

only 58 lbs. with the exception of the drought years of

1935-36, the 1966 per capita consumption was the lowest ever

recorded, in spite of the fact that the per capita consump

tion of all meats was the second highest in the nation's

history at 170 lbs. Thus Americans are eating more meat

but less pork. There are four possible explanations for

this: 1) proliferation of alternatives; 2) increased protein

competition; 3) changes in consumer attitudes toward obesity

and heart disease; and 4) the image of pork (12).

The development of new products to satisfy growing

consumer demands is a reflection of material progress.

Thousands of separately coded sizes, brands, flavors and

types of items are available. The relative decline in pork

consumption may be due partially to this proliferation of

food items but not entirely since the per capita consump

tion of beef and sugar has doubled and that of poultry and

cheese has tripled (12).

The USDA report of 1966 showed that 79% more beef

was consumed per person than pork. Other animal protein

sources which showed an increased consumption in the last

decade were poultry 85%, breaded shrimp 120%, and fish

sticks 53%, However, pork showed a 3% loss, even though

population had increased 19% (12).

The threat to pork consumption also may be attrib

uted to the development of spun soy protein products which

already are playing an increasingly important role in the

consumer's diet. Soy protein is roughly half the cost of

animal protein and has the ability to provide a wide range

of texture, flavor and appearance (13) , Thus it is reason

able to conclude that vegetable proteins will make further

intrusions into the market for pork products.

Recorded history has viewed obesity as a prestigious

sign of affluence since only the prosperous could afford

enough food to provide the calorie surplus that results in

obesity. However, consumer attitudes toward obesity have

changed radically because of increased medical knowledge

and a substantial change in education level (14, 15, 16, 17,

18, 19). Diet is now considered to be one of the factors

which can be manipulated to aid in the prevention and con

trol of heart disease (20). The publicity about the role

of saturated animal fat in arteriosclerosis has condemned

pork unnecessarily, when actually pork fat is less satu

rated than that of beef and lamb (21). With proper selec

tion and trimming, pork can be among the leanest of meats,

but the average consumer does not perceive pork to be lean.

It is difficult to understand why the producer, the packer

and the retailer do not produce what people want to buy

rather than sell them what happens to be produced (12).

The last reason why people are eating relatively

less pork is due to the image that pork presents as a food.

The so-called uncleanness of the pig and the vague fear of

certain diseases long have been associated with pork (12).

There are also numerous biblical references forbidding the

consumption of pork (22) . Such ideas have pervaded and

have conditioned every consumer since childhood.

Factors Which Affect Pork Quality

It has been stated that pork carcass quality is

dependent upon genetics, nutrition and management. It is

relatively simple to turn a good pig into a poor carcass

and a relatively poor pig into a reasonably good carcass

by the appropriate management systems (8).

Gentic factors

Considerable research has been conducted on the

inheritance of the more standard pork carcass evaluation

measurements (length, backfat thickness, loin eye area,

and lean cut yield). These heritable traits are rather

well established, but research regarding the inheritance

of quality aspects of pork muscle are more limited (23,

24, 25). However, based on the data available at present,

it appears that most measures of quality are moderately to

highly heritable. The heritability estimates tend to be

8

lower than most estimates for carcass length, backfat thick

ness, and loin eye area, but apparently are sufficiently

high to justify selection in a breeding program. The data

available indicate that superior meat type hogs with ac

ceptable quality can be produced. However, lean meat syn

thesis by pigs is genetically controlled and genetic poten

tial cannot be exceeded by feeding excessive nutrients (8).

Ration and management

Rapidity of gain in pigs and carcass characteristics

are genetically controlled, but each may be greatly influ

enced by the balance of nutrients and the rationing of the

diet. Any essential nutrient may directly or indirectly

affect carcass measurements through its influence on rate

or pattern of growth. Nutritional deficiencies, which re

sult in an extended and marked reduction in growth rate

followed by ad libitum intake of an adequate diet, may re

sult in excessive fat deposition and results in an animal

with a high ratio of fat to lean in the carcass. The most

common and readily demonstrated effect of nutrition on car

cass characteristics relate to energy intake, kinds and

amounts of amino acids, and protein to energy ratio in the

diet (8).

Braude et_ al . (26) established that feed restriction

resulted in a reduction in rate of gain and backfat thick

nesses and in size of loin eye. Restricting the feed intake

during the finishing stage resulted in a higher ratio of

lean to fat in the carcass, depending upon degree of re

striction and length of time restriction was imposed. Die

tary protein levels and energy levels have a much greater

influence on intramuscular fat deposition than on backfat

thickness, percent of lean cuts or performance character

istics. Wagner e_t aj . (27) found that fat in the longis-

simus dorsi of pigs finished on a 12% protein ration aver

aged 16.3% fat, whereas that of pigs finished on 16% pro

tein averaged only 9.3%,

Even greater differences in intramuscular fat may

be demonstrated by varying the protein and energy levels.

Pigs fed high energy-low protein diets had twice the amount

of fat in the longissimus dorsi as did animals fed a low

energy, high protein diet (8).

The chemical composition of dietary fat greatly

affects the composition of pork carcass fat. The pig con

verts excess carbohydrate to saturated or monounsaturated

fatty acids of 16 or 18 carbon chains. Thus the poly

unsaturated fatty acids in the carcass are primarily of

dietary origin (8).

Dahl (28) found that the fat present in barley or

in oats had a measurable effect on the linoleic acid con

tent of carcass fat. Research with corn and barley diets

also indicated retention of a high proportion of the die

tary linoleic acid.

10

Though barley is low in fat and contains less than

0.3% linoleic, if the pig is fed barley to market weight,

the fat in the carcass contains much higher levels of

linoleic acid, Oats are both higher in linoleic acid and

lower in digestible carbohydrates and yield a carcass

markedly higher in linoleic acid, a combined result of the

deposition of dietary fatty acids and the reduced synthesis

of saturated fatty acids from carbohydrates. These results

illustrate how readily the composition of pork fat may be

influenced by dietary variations (29).

Swine, because their digestive system can make only

limited use of forage, must be fed chiefly concentrates.

The cereal grains, rich in total digestible nutrients and

net energy are therefore desirable for feeding stock.

Among the various grains, corn, wheat and the grain sor

ghums are leading in nutritive value. Though grains are

easily digested, they are relatively low in protein and

poor in protein quality. In feeding swine, protein sup

plements of good quality are fed in addition to grain to

obtain efficient results (4).

Corn ranks far ahead of any other cereals in im

portance for livestock feeding in the United States. About

90% of the huge corn crop is fed to farm animals. Corn is

highest among the grains in total digestible nutrients and

net energy, and is probably the most palatable of the

cereals for most farm stock (4).

11

Grain sorghum is used principally for livestock

feeding in the United States. It is most widely grown in

areas where corn is not successful, because it is well

tolerant of heat and drought. In the southern Great Plains

states of Texas, Kansas, Oklahoma and New Mexico the sor

ghums are of great value (4, 32). In 1972, Texas grain

sorghum production was 74,197,000 bushels, which was about

half of the nation's production (5),

Wheat is grown mostly for the manufacture of flour

and other human foods. However, wheat is satisfactory for

all classes of stock when properly used, and is equal or

nearly equal to corn in feeding value (4). Some experi

ments have shown that pigs fed wheat gained slightly faster

than those fed corn (30).

Sex

Barrows gain somewhat faster and finish markedly

fatter at a given weight than gilts. Gilts gain more ef

ficiently and produce longer, leaner, and more heavily

muscled carcasses (31). Pigs that were grown during the

fall and winter were more highly marbled than those grown

in spring and summer. Sex differences in marbling ap

proached significance (P<.05) with barrows exhibiting

more intramuscular fat (32).

Wallace (33) showed that chops from barrows were

more tender than chops from gilts, and chops from pigs fed

12

the low-protein diet were far more tender than those from

pigs fed adequate protein. Heretofore, tenderness in pork

has not been a very important consideration since animals

are usually quite young when slaughtered and differences

in tenderness do not approach those seen in beef. However,

it is well to understand that factors such as sex, feed

restriction, and level of dietary protein intake can influ

ence tenderness markedly.

Consumer's Criteria for High Quality Pork

Knowledge of the factors that are related to the

quality of pork is important. Even though the quality of

fresh meat has a substantial influence upon its acceptance,

the final judgement is based upon the palatability of the

cooked meat (34).

According to Kramer (35) the overall quality of

food can be divided into three main categories: quanti

tative, hidden, and sensory. The quantitative aspect, i.e.

yield of the product as a result of raw material, is mainly

the concern of the producer and the processor. The hidden

aspect, i.e. nutritive value, and the sensory attributes

are both related to quality and are the primary concern of

the consumer. Sensory attributes of food include: 1) ap

pearance, which includes color, size, shape and absence of

defects; 2) kinesthetics, which may include texture, con

sistency or viscosity; and 3) flavor, which involves taste

and odor (36).

13

Pork quality as measured by consumer acceptability

includes tenderness, flavor, juiciness (10, 37, 38, 39,

40), color (10, 37), and marbling (37, 40, 41).

Hinnergardt (42) indicated that marbling score,

grade, and loin weight have been advanced as the means by

which the tenderness of the cooked meat could be predicted

from the raw state. Marbling level was significantly af

fected by sex (41), and was significantly correlated with

meat firmness (38). Wellington (43) also indicated that

the higher the level of marbling in beef, the more tender

it would be, A moderate amount of marbling in pork pro

vides an acceptable product (32). The sensory juiciness

and tenderness of lean pork also are correlated to marbling

levels (44).

Tenderness is probably the most important factor

affecting consumer evaluation of meat quality and accepta

bility. In testing the tenderness of meat using a sensory

panel, several components of tenderness have been separated

to use as a guideline. These include: 1) the ease with

which teeth sink into the meat, or softness; 2) the crumb-

liness of the muscle fibers; 3) the amount of connective

tissue or the amount of residue remaining after the meat

is chewed for a certain time; and 4) the time and effort

required to masticate a given portion in the mouth as de

termined by the number of chews required (9).

14

Mechanical measurements of tenderness

According to the mode of action, the mechanical

methods of measuring tenderness involve four different

types: 1) shear; 2) penetration; 3) biting; and 4) minc

ing (36), The Warner-Bratzler Shear Apparatus represents

one of the most commonly used and accepted mechanical de

vices to evaluate consumer acceptance of meat (45, 46) ,

Warner-Bratzler shear values have been found to be highly

significantly correlated with panel tenderness scores

(37, 40, 45),

Most methods mechanically determining tenderness

on a raw sample destroy its integrity so that the same

sample cannot be meaningfully tested again. One of the

most successful methods to relate mechanical measures of

raw meat tenderness to cooked meat tenderness is the pene

trometer. The penetrometer, which is a modified Allo-

Kramer Shear press, contains five needles to give resist

ance to make a time-force curve in penetrating. It was

developed by Hinnergardt (42) to use in comparing sensory

scores when cooked pork chops were evaluated. The results

of his study showed that the correlation between raw and

cooked pentration was 0.6982, the correlation between raw

penetration and the sensory panel was 0.5032, and between

cooked penetration and the sensory panel was 0.6283. The

correlations were statistically significant and its advan

tage was due to the fact that it was nondestructive compared

15

to other devices.

Kulwich et. al . (47) developed and evaluated a slice-

tenderness evaluator (STE). The STE consists of a sample

holder in which the slice of cooked meat is mounted, and a

penetrator first punctures, and then shears off a circular

portion of the slice. This STE was used in conjunction

with a commercial materials-testing instrument that pro

vided for continuous recording of the force-penetration

curve. The results showed that STE shear force was a more

effective predictor of taste panel tenderness score than

STE puncture force. The simple correlation coefficient

between STE shear force and taste panel tenderness score

was -0.72, and the correlation between STE puncture force

and taste panel tenderness score was -0.65. The advantage

of the STE technique is that the measurement is made on a

0.2 inch-thick slice, which is typical of a roast meat

serving. It can also measure at many locations in a slice.

Sperring et. al . (46) devised a tenderness press for

measuring meat tenderness by pressure. In this technique,

a meat sample was compressed by a motor driven hydraulic

press between a plunger and a cylinder base. The reading

on the pressure gauge, when the first protrusion of sample

muscle appeared in the hole of the disk was taken as the

toughness of that sample. When the tenderness press was

used to measure tenderness of beef samples it showed a

significant correlation with Warner-Bratzler shear values

16

and a highly significant correlation with the sensory panel.

Alsmeyer eit al . (48) developed a modified tenderness press

and v^en compared with the Warner-Bratzler shear values,

the STE method and sensory scores, results indicated that

all the methods were equally effective as measures of beef

tenderness. When correlated with the panel scores from pork

samples with high marbling the scores were -0.88, -0.90 and

-0.89 respectively.

A more recent device for measurement of tenderness

in raw meat is known as the Armour Tenderometer (49) . This

apparatus consists of a probe assembly and a strain gauge.

The probe assembly includes 10 stainless steel needles,

each 3 inches long, mounted on a manifold attached to a

strain gauge, which is connected by cable to a peak force

indicator. The depth of the needle penetration is deter

mined by a guard bar that regulates the penetration to

exactly 2 inches. The instrument was designed to be used

on the raw longissimus dorsi at the area of the 12th and

13th thoracic vertebrae while the carcass hangs from a

cooler rail. Readings should be taken on muscle chilled

to a minimum of (4°C) but not more than (0 C).

Henrickson et. al.. compared tenderometer values with

Warner-Bratzler shear scores and found them unrelated (11).

The authors felt that the units most likely measured a dif

ferent element of tenderness. The tenderometer measures

the force necessary to separate the individual raw muscle

17

fibers, while the Warner-Bratzler shear measures the force

required to cut the cooked fibers at right angles to their

long axis. However, Luckett et_ al . (50) compared the same

two devices using rib steaks from 104 steer carcasses. A

highly significant correlation coefficient was obtained

between tenderometer and Warner-Bratzler shear values

(r = 0.48). Tenderometer values were also significantly

(P<.01) associated with carcass weight (r = -.32), yield

grade (r = -.18) and marbling score (r = 0.00). Based on

this data, the tenderometer when compared with the Warner-

Bratzler shear, was of value in measuring carcass tender

ness.

CHAPTER III

METHODOLOGY

Animals

Eighty-eight crossbred pigs consisting of 43 gilts

and 45 barrows were purchased from a commercial producer.

All the animals had been reared in complete confinement.

In order to determine sex differences as well as the

effect of ration, corn, milo and wheat were compared by feed

ing each treatment to 15 barrows, corn and milo to 14 gilts

and wheat to 15 gilts. The pigs were started on a grain-

soybean meal ration containing approximately 17% protein and

changed to a 14% protein ration when they weighed about 135

pounds. The animals were removed from the experiment when

they exceeded 215 pounds on the weekly weighing day, and

slaughtered at a.local packing plant the following morning.

Ration

Corn and grain sorghum used in the rations were pur

chased from local sources. The grain sorghum was locally

produced, elevator-run type. The corn was trucked into the

area and the exact origin was not known. Wheat was produced

under irrigation on the Texas Tech University Farm. It was

a hard, red winter wheat, Wichita variety. A quantity of

each grain and soybean meal adequate to complete the study

was stored and analyzed for lysine content prior to formu

lating the rations.

18

19

Marbling

Degree of marbling of the pork carcasses was deter

mined by using a 10-point USDA Scale ranging from devoid-1

to abundant-10. Three categories were used for classifying

the pork: 1) traces or slight degree of marbling with a

score of 3 to 4; 2) small, modest or moderate amounts of

marbling, 5, 6, or 7; 3) slightly to moderately abundant

with a score ranging from 8 to 9.

The Sample

The sample consisted of 88 roasts taken from the

loin of the right side of each animal. Each roast was re

moved beginning 11 centimeters posterior to the fifth rib.

The roasts were wrapped, labeled, blast frozen, and main

tained at -23.3 C until ready for cooking.

Cooking Procedure

Six roasts from one ration, with three marbling

levels from each sex, were prepared at each test period.

The cooking periods were every Tuesday and Thursday for

seven weeks until 88 roasts were tested.

Thirty-six hours before cooking, the six roasts for

one test period were removed from the freezer and allowed

to thaw in a refrigerator at 6°C. Each roast was then un

wrapped, coded, and weighed. Three readings for tenderness

were made on each roast with the Armour Tenderometer by the

same person each time. Each roast was placed with ribs down

20

and anterior end to the front in a Teflon-coated pan. A com

mercial double deck Toastmaster electric oven was preheated

to 177 C before placing the roasts inside to begin the cook

ing period. The internal temperature of each roast was re

corded by means of a stainless steel potentiometer lead at

tached to a Honeywell Electronik 15 Multipoint Recorder. As

soon as the internal temperature reached 77°C the roasts were

removed from the oven and allowed to cool for 15 minutes.

They were then weighed and tenderness readings were again

made with the Armour Tenderometer.

The weight difference of raw and cooked roasts was

calculated to be the evaporative loss. Aqueous and fat

drippings were weighed and poured into a graduated cylinder

and allowed to cool to determine the volume of each portion

(Appendix A).

After the cooked roasts were weighed, the bones, the

outer fat and the browned portion were removed with an elec

tric slicing knife. The trimmed longissimus muscle was then

placed on a Hobart electric slicer with anterior end down and

10 one-fourth inch thick slices were removed. A one inch

circle was taken from each slice for sensory evaluation

(Figure 1).

Sensory Evaluation

A sensory panel of 9 members was chosen to evaluate

the pork samples for appearance, odor, flavor, juiciness.

21

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22

tenderness and over-all acceptability. The sensory panel

consisted of 5 men and 4 women, all Texas Tech students.

All the members had previous experience in sensory evalu

ation.

A sheet of instructions which indicated the method

for scoring was given prior to evaluation (Appendix B). The

9 point hedonic scale ranging from 9, like extremely, to 1,

dislike extremely, was used for evaluation (Appendix C). An

additional space on the scoring sheet was designed to write

comments.

All samples were color coded and served on white

plates. Caution was exercised so that each judge would re

ceive the same numbered slice from each roast each time.

The plate of samples and a glass of slightly acidulated

water for rinsing the mouth between samples were placed in

individual booths.

Warner-Bratzler Shear

For use with the Warner-Bratzler Shear Apparatus

three, one-half inch in diameter cores were removed by the

hand method (52) from the posterior portion which remained.

Three shear readings were taken on each core and the values

were averaged.

Total Fat Content

The lean muscles which were left after core samples

were removed for the Warner-Bratzler shear values were then

23

placed in an Oster electric blender to obtain a homogenous

mass. A 10 gram sample was weighed from each homogenized

mass for the fat analysis.

A simplified Folch et. aj^. method (52) developed by

Bligh and Dyer (53) was used to determine fat content. The

method has been compared with the official AOAC method,

ether extraction, alkaline saponification method, and the

Mojonnier method and was found to give more desirable result

than others (54).

CHAPTER IV

FINDINGS AND INTERPRETATION

Data were analyzed to determine variations caused by

treatment, marbling levels, and sex. Differences in tender

ness as evaluated by Armour Tenderometer, Warner-Bratzler

shear and sensory panel were determined by analysis of vari

ance. When the difference was significant, the Duncan's

Multiple rank order was applied to determine the order of

difference.

For analysis of data obtained from sensory panel

evaluation the standard deviation, standard errors, and the

significance of difference between means were calculated

and analyzed by analysis of variance (55).

Variation Caused by Treatment

Variation in Cooking Losses

There were no significant differences (P>.05) noted

in cooking losses of roasts from animals fed three different

types of grain rations. The roasts from animals fed the

corn rations appeared to have lower cooking losses than those

from other treatments, but the difference was statistically

non-significant (P> .05). Moreland observed that pork from

the wheau treatment had the least weight loss as a result of

cooking (6), however, the result was also statistically non

significant. No interaction was observed between grains and

24

25

marbling, or grains and sex. It appears that the variations

in cooking losses were probably caused by individual animal

differences rather than by treatment (32).

Sensory Panel Evaluation

Samples of roasts from different treatments were

rated from 9 (like extremely) to 1 (dislike extremely) by

sensory panel members.

Sensory evaluations for appearance, odor, flavor,

juiciness, tenderness and overall acceptability were ana

lyzed, and showed no statistically significant differences

attributable to the three rations, or from interactions

between grain and sex, or grain and marbling. However, a

slight tendency indicated that roasts from animals fed the

grain sorghum ration were less tender (lower tenderness

score, higher chew count number) than the roasts from ani

mals fed the wheat or corn rations. When Moreland (6) con

ducted her investigation on effects of four rations, corn,

wheat and sorghum on pork quality, she found that pork from

the grain sorghum treatment was less tender than that from

the other treatments (P<.05) when evaluated by the sensory

panel. However, for appearance, odor, flavor and juiciness

evaluation no significant differences were found which were

attributable to treatment (P>.05).

Objective Measures of Tenderness

When tenderness was evaluated by the Armour Ten

derometer in either raw or cooked pork no significant

26

differences were noted which were attributable to ration

(P>.05). Neither was a difference found as a result of

interactions between grains and marbling or grains and sex

(P>.05). The Warner-Bratzler shear values of cooked meat

also showed no significant difference in tenderness due to

treatment (P>.05). However, a slight trend was apparent

indicating that cooked roasts from the grain sorghum treat

ment were slightly less tender than roasts from the other

treatments (Table 1). These findings were similar to those

noted by Moreland (6).

Intramuscular Fat

Least-square analysis of variance showed intramus

cular fat was significantly affected by different grain

treatments (P<^.01). Duncan's multiple rank order test

showed no significant differences in intramuscular fat

content of roasts from corn and grain sorghum treatments

(P>.01). However, the roasts from pigs receiving the wheat

ration had a significantly higher fat content than the corn

and grain sorghum fed pigs (P <.01).

Variation Caused by Marbling

Least-square means for selected variables for the

three marbling levels are shown in Table 2. Analysis of

variance was used to determine the differences. When the

differences were significant, a Duncan's multiple rank

order test was applied.

TABLE 1

LEAST SQUARE MEANS FOR VARIABLES DUE TO TREATMENT

27

Corn Grain Sorghum Wheat

Raw weight (gms)

Cooked weight (gms)

Evaporative loss (% of raw wt) 19.15

Total drip loss (% of raw wt)

Fat loss (% of total drip)

Water loss {% of total drip)

Intramuscular fat {%)

1190 .82

9 6 2 . 8 4

1 9 . 1 5

4 . 5 3

6 3 . 3 7

3 7 . 2 7

1 1 8 4 . 9 1

941-40

2 0 . 5 3

5-40

6 5 . 7 8

3 4 . 2 1

1149 .20

9 1 0 . 1 0

20 .77

4 . 7 1

7 3 . 2 5

2 6 . 7 5

5.88 5.60' 7.38'

Tenderometer (raw) (lbs)

Tenderometer (cooked) (lbs)

Shear values (lbs)

Appearance

Odor

Flavor

Juiciness

Tenderness

Number of chew counts

Overall acceptability

6 .96

1 6 . 4 8

6 . 7 2

6 . 7 9

6 . 8 7

6 . 7 1

6 . 6 2

7 .10

2 3 . 1 3

6 . 8 2

7 . 0 5

17 .09

7 .68

6 . 6 3

6 . 6 4

6 . 7 0

6 . 4 5

6 . 7 5

2 4 . 3 8

6 . 5 8

7 .52

16 .00

7 .36

6 . 5 9

6 . 7 5

6 . 7 5

6 .40

7 .22

22 .97

6 . 7 4

'•• Means for a factor bearing different superscripts are significantly different P<.01.

*Sensory evaluations based on Fledonic Scale (1-9) .

TABLE 2

LEAST SQUARE MEANS FOR VARIABLES DUE TO MARBLING

28

Low Moderate High

Raw weight (gms)

Cooked weight (gms)

Evaporative loss (% of raw wt) 21.17



Water loss (% of total drip)

Intramuscular fat (%

173.13

925.37

21.17

4.88^

66.18

33.82

1177.67

944.23

19.82

5.36^

65.61

35.59

1174.13

944.74

19.51

4.39

70.90

29.12



Shear value (lbs)

* Appearance

Odor

Flavor

Juiciness

Tenderness



5.64"-

7.92

17.48^

7.98*

6.63

6.64

6.45^

6.20-

6.68''

25.34^

6.40

6.39"

6.93

16.86^

7.13^

6.71

6.71

6.80'

6.53

7.03

23.68

6.83'

6.83

6.68

15.24^

6,64^

6.67

6.67

6.91^

6.74^

7.35^

21.46^

6.91^

a^^Means for a factor bearing different superscripts are significantly different P<.01.

^'^Means for a factor bearing different superscripts are significantly different P<.05. Means without a superscript are not significantly different from each other. *Sensory evaluations based on Hedonic Scale (1-9).

29


No significant difference was found in evaporative

loss due to marbling levels, interaction between marbling

and sex or marbling and grain (P> .05) . However, the total

drip loss from the moderate marbling level was significantly

higher (P<.01) than from either low or high marbling level.

The composition of the drip was not affected by marbling

(P> .05).


The subjective evaluation of pork indicated that the

abundantly marbled pork received higher scores in flavor,

juiciness, tenderness, and overall acceptability than the

poorly marbled roasts. The difference was statistically

significant (P<.01). When comparing the moderately marbled

roasts with the poorly marbled ones, only flavor and overall

acceptability scores were affected (P<.01). Statistically,

there were no significant differences between moderate and

high marbling in flavor, juiciness, tenderness and overall

acceptability (P> .05). However, a definite trend was

noticeable in the scores from the poorly marbled to the

abundantly marbled roasts (Table 2) . Judge ejt al . (38) also

attempted to find the relations between marbling and sensory

tenderness, juiciness and flavor. Their results showed that

only juiciness was correlated with marbling (P <.01) .

When the number of chew counts was compared, the

poorly marbled meat required more chewing than the highly

30

marbled (P<.01). Statistically, there were no significant

differences between low and moderate, and moderate and high

marbling in chew count numbers (P>.05).

Work conducted by Field et al. (37) with beef also

indicated that bull roasts with more abundant marbling re

ceived significantly higher sensory ratings when age was

held constant. Sensory ratings in the study included ten

derness, juiciness and flavor.


The tenderometer readings on the raw pork were not

significantly affected by either marbling level or inter

action between grains and marbling, or marbling and sex

(P> .05) .

Meat tenderness measured in the cooked state by both

the Armour Tenderometer and the Warner-Bratzler shear appa

ratus showed significant differences (P<^.01) with levels

of marbling. It appeared that the higher the marbling level

the more tender the cooked meat (lower tenderometer and shear

values). These results coincide with those of Wellington's

study on beef tenderness (43). The poorly marbled pork

was significantly less tender than the highly marbled pork

(P<.01). The moderately marbled pork was more tender than

that with low marbling according to the shear values but

less tender than that with high levels of marbling when

evaluated by the tenderometer. The difference was sig

nificant (P<^.05). Field £t al_. (37) when testing beef

31

tenderness indicated that Warner-Bratzler shear scores were

not affected significantly by marbling when age was held

constant.

Intramuscular Fat

The intramuscular fat content of roasts was related

significantly to marbling (P<.01). The lower the level of

marbling, the less the intramuscular fat content of the lean

roast. Though statistically, the fat content in the high

level of marbling was not significantly higher than that in

the moderate level but the difference exists. However, the

pork with the moderate level of marbling was significantly

higher in fat content when analyzed (P<.01) than that with

the low level of marbling.

Judge et_ al . (38) found the relationship between the

degree of marbling in the muscle and the chemical fat con

tent was 0.76. They indicated that the degree of marbling

in pork as judged subjectively, is a measure of the actual

fat content of the muscle.

Variation Caused by Sex

Least-square analysis of variance showed that sex

affected significantly the total roast weight (P<.01).

Roasts from gilts were much heavier than those from barrows.


There was no significant difference in evaporative

loss due to sex difference (P>.05). However, the roasts

32

from the barrows had more drip loss than those from gilts

as a result of cooking (P<.01).


Analysis of appearance, odor, flavor, juiciness and

tenderness scores of pork when rated by the sensory panel

showed no significant differences (P>.05) attributable to

sex or interaction between sex and grain or sex and marbling

The results are presented in Table 3. Similar results were

indicated by Skelley and Handlin (34) and Field (37).

Analysis of overall acceptability scores showed

roasts from barrows rated higher than those from gilts

(P <.05) .


Tenderness as measured by the Armour Tenderometer

in either raw or cooked muscle and by the Warner-Bratzler

shear apparatus showed no significant differences between

gilts and barrows (P>.05). This is in agreement with the

results of Skelley (34) and Field et_ aJ . (37) who concluded

that shear value is not affected by sex difference. How

ever, Wallace (33) found that chops from barrows were more

tender than those from gilts.

Intramus":ular Fat

The intramuscular fat content of roasts was not sig

nificantly influenced by sex differences (P>.05). This

result is different from the results of Hiner et aj . (44)

33

TABLE 3

LEAST SQUARE MEANS FOR VARIABLES DUE TO SEX

Barrow Gilt

Raw weight (gms)

Cooked weight (gms)

Evaporative loss (% of raw wt)



Water loss (% of total drip)

Intramuscular fat (%)



Shear value (lbs)

Appearance

Odor

Flavor

Juiciness

Tenderness



1145.84=*

914.76^

20.11

5.38^

72.00^

28.00^

6.50

6.75

16.42

7.25

6.63

6.75

6.78

6.60

7.09

22.85

6.85*

1204.ir

961.47

20.19

4.37'

63.12

3 7 .

6 .

7 .

1 6 .

7.

6.

6.

6,

6

6

24

69"

07

,60

,63

.25

. 71

.76

. 6 5

. 3 8

. 9 6

-14

d

6.58

^'^Means for a factor bearing different superscripts are significantly different p<.01.

^'^Means for a factor bearing different superscripts are significantly different P<.05.

*Sensory evaluations based on Hedonic Scale (1-9).

34

and Kauffman (41) which indicated that barrows had signifi

cantly more intramuscular fat in the longissimus muscle than

gilts.

Correlation Among Tenderometer, Warner-Bratzler Shear, Sensory Tenderness Scores and Number of Chew-Counts

Correlations among measurements of tenderness by

different methods are presented in Table 4. Tenderness of

cooked pork measured by the Armour Tenderometer was signifi

cantly correlated (P<^.01) with the Warner-Bratzler Shear

Apparatus (r = .59), the sensory tenderness score (r = -0.47),

and the number of chew counts (r = .47) . However, the ten

derometer values of the raw pork were not related to shear

values nor to sensory tenderness values. The tenderometer

values from the raw and the cooked pork were significantly

related, however, (P<.05) (r = .26). The Warner-Bratzler

shear values were found to be related to every tenderness

measurement except the tenderometer value for the raw pork

(P>.05). The sensory panel evaluations of pork tenderness

for both tenderness scores and chew count numbers were sig

nificantly related to tenderometer measurements on the cooked

pork and to Warner-Bratzler shear values (P<.01). Similar

results were found by Field ejt aj . (37) .

In sensory evaluations for tenderness the higher the

score the more tender the meat, which is in contrast with

other measurements since the higher the reading the tougher

the meat. Therefore, the sensory tenderness scores were

35

negatively correlated with the other measurements.

TABLE 4

CORRELATION COEFFICIENTS BETWEEN TENDEROMETER, WARNER-BRATZLER SHEAR, SENSORY TENDERNESS

AND CHEW-COUNT SCORES

1. Raw tenderometer 1.00

2. Cooked " 0.26* 1.00

3. W-B shear 0.03 0.59** 1.00

4. Sensory tender 0.04 -0.47** -0.70** 1.00

5. No. chew count 0.02 0.47** 0.73** -0.88** 1.00 •

*P <.05 r = .232

**P< .01 r = .302

Selected Variables

r I'l i M

Correlation Coefficients Between * n

Simple correlation coefficients were analyzed to j

determine the relations among the following selected vari

ables: intramuscular fat, raw pork tenderometer readings,

cooked pork tenderometer readings, Warner-Bratzler shear

values, sensory scores of appearance, odor, flavor, juici

ness, tenderness, number of chew counts, and overall ac

ceptability. The results are presented in Table 5.

It appears that flavor, juiciness, and overall ac

ceptability were highly correlated with every selected

variable except intramuscular fat and tenderometer readings

measured in raw pork (P<.01).

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37

The intramuscular fat content was related to raw

pork tenderometer measurements at 1% level (r = .31), but

was nonrelated to any other variables.

The results of correlations between juiciness,

flavor and overall acceptability supports the findings of

Pengilly and Thornton (40) who concluded that flavor and

juiciness were correlated with overall acceptability.

Results also are compatible with the study conducted by

Judge e;t a^. (38) , and Field et_ al_, (37) that tenderness,

juiciness, and flavor were all correlated.

CHAPTER V

SUMMARY AND CONCLUSIONS

Texas is the leading grain sorghum producing area in

the United States since it produced in 1972 about half of the

nation's total. Due to climatic conditions, corn is not

grown in as great a quantity as grain sorghum in Texas.

Therefore, the substitution of grain sorghum for corn in

swine ration would be not only convenient but also economi

cal and agriculturally sound.

This study was undertaken to determine the differ

ences in pork quality which could be attributed to three

rations, wheat, corn and grain sorghum, and the interaction

effects of sex differences and of three levels of marbling.

In order to make the comparison, 88 loin roasts from

43 gilts and 45 barrows were used. Roasts were selected

from 15 barrows fed each ration and from 14 gilts fed corn

and sorghum and 15 gilts fed wheat ration. Three marbling

levels within each treatment were determined according to

the USDA Scale.

In determining the pork tenderness, the Warner-

Bratzler Shear Machine and the Armour Tenderometer were the

objective methods used. For subjective methods, a 9 member

sensory panel evaluated the pork for tenderness by determin

ing the ease of chewing and the number of chew counts re

quired to comminute the pork sample to a mushy consistency.

38

39

Other sensory qualities such as juiciness, flavor, and over

all acceptability were evaluated to determine their relation

to each other and to tenderness.

Results of the study indicated that variation of

grains in the ration did not have a significant effect on

cooking losses, meat tenderness, flavor, juiciness, odor

and appearance. However, slight trend indicated that roasts

from grain sorghum fed animals were less tender than those

roasts from the wheat or corn fed animals. The trend was

observed through lower tenderness scores, higher chew count

number, higher shear values, and higher tenderometer read

ings measured on cooked roasts. The intramuscular fat con

tent was significantly affected by the various grain treat

ments. The roasts from animals fed the wheat ration had a

higher fat content than the roasts from animals fed the corn

or grain sorghum rations.

Marbling level significantly affected the intra

muscular fat content, tenderness of cooked pork, and the

flavor, juiciness, and overall acceptability. The more

abundantly marbled pork received the better rating in qual

ity. Even though the consumer is sensitive to fat in meat,

it must be concluded that the higher levels of marbling

resulted in roasts which were not only more tender by all

methods of evaluation but also were scored higher for flavor,

juiciness and overall acceptability.

40

Sex difference affected the total roast weight as

roasts from gilts were heavier than those from barrows.

Other quality factors such as intramuscular fat content,

tenderness scores and scores for appearance, odor, flavor

and juiciness were not significantly affected by sex dif

ference. However, roasts from barrows received signifi

cantly higher overall acceptability scores than those from

gilts.

When comparing different methods for evaluating pork

tenderness, both the Warner-Bratzler Shear and the Armour

Tenderometer values for the cooked pork were as precise in

determining tenderness as sensory evaluations. When the

Armour Tenderometer was used to measure tenderness of raw

pork it correlated only with those values from cooked pork

at 5% level of significance, but the raw pork values were

not significantly correlated with values from other methods.

Among selected variables, flavor, juiciness, and

overall acceptability were highly correlated with every

selected variable except intramuscular fat and tenderometer

readings measured in raw pork.

LIST OF REFERENCES

1. Trotter, C. and G. Engleman. Consumer Responses to Graded Pork. Pennsylvania Agricultural Experiment Bulletin 650: 1, 1959.

2. Birmingham, E. , D. E. Brady, S. M. Hunter, J. C. Grady, and E. R. Kiehl. Fatness of Pork in Relation to Consumer Preference. Missouri Agricultural Experimental Research Bulletin 549: 1, 1954.

3. Texas Livestock Reporting Service. Texas Livestock Slaughter. Texas Department of Agriculture and United States Department of Agriculture Statistical Reporting Service. April 2, 1973.

4. Morrison, F. B. Feed and Feeding, Abridged. Clinton, Iowa: The Morrison Publishing Company, 1961.

5. Texas Crop and Livestock Reporting Service. Texas Stock of Grain, Texas Department of Agriculture and United States Department of Agriculture Statistical Reporting Service, October 26, 1972.

6. Moreland, M. R. Effect of Feeding Various Grains Upon Quality of Pork. Master's Thesis. Department of Food and Nutrition, Texas Tech University, May, 1971, Lubbock, Texas.

7. Elsley, F. W. H. Prenatal and postnatal effects on subsequent performance and carcass quality. The Pork Industry: Problems and Progress, ed. D. G. Topel. Ames, Iowa: Iowa State University Press, 1968.

8. Hays, V. W. Nutritional and management effects on performance and carcass measurements. The Pork Industry: Problems and Progress, ed. D. G. Topel. Ames, Iowa: Iowa State University Press, 1968.

9. Harrington, G. and A. M. Pearson. Chew count as a measure of tenderness of pork loins with various degrees of marbling. J. Food Sci. 27: 106, 1962.

10. Carpenter, Z. L., R. G. Kaufmann, R. W. Bray, and K. F. Weckel. Objective and subjective measures of pork quality. Food Tech. 19: 1424, 1965.

41

42

11. Henrickson, R. L., J. L. Marsden and R. D. Morrison. An evaluation of the Armour Tenderometer for an estimation of beef tenderness. j. Food Sci. 37: 857, 1972. -

12. Twedt, D. General acceptance of pork. The pork Industry: Problems and Progress, ed. D. G. Topel. Ames, Iowa: Iowa State University Press, 1968.

13. Caster, W. V. The Promises and Problems of the New Foods. The Inter-Institutional Committee on Nutrition Report, No. 3, 1971, University of Georgia, Athens, Georgia.

14. Wilson, R. H. L. , and N. L. Wilson. Obesity and respiratory stress. J. Am. Diet. Assoc. 55: 465, 1969.

15. Mayer, J. Obesity, causes and treatment. Am. J. Nurs. 59: 1732, 1959.

16. Food and Nutrition Board: Dietary Fat and Human Health. Pub. 1147. National Academy of Sciences-National Research Council, Washington, D. C , 1966.

17. Hundley, J. M. Heart Disease: Recent trends in morbidity and mortality. J. Am. Diet. Assoc. 52: 195, 1968.

18. Hodges, R. E. Dietary and other factors which influence serum lipids. J. Am_. Diet. Assoc. 52: 198, 1968.

19. Dayton, S., and M. L. Pearce. Prevention of coronary heart disease and other complications of atherosclerosis by modified diet. Am. J. Med. 46: 751, 1969.

20. A Council Statement: Diet and coronary heart disease J. Am. Med. Assoc. 222: 13, 1972.

21. Coons, C. M. Fatty acids in foods. J. Am. Diet. Assoc. 34: 242, 1958.

22. The Bible: King James Version. Lev. 11: 7, Deut. 14: 8, Prov. 11: 22, Matt. 7: 6, Luke 15: 15.

43

23. Duniec, H. , J. Kielanowski, and Z. Osmska: Heritability of chemical fat content in the loin eye muscles of baconers. Animal Prod. 3: 195, 1961.

24. Jensen, P., H. B. Craig, and O. W. Robinson: Genetic variation and co-variation among carcass traits of swine. J. Animal Sci. 26: 204, 1967.

25. Smith, C. and G. J. S. Ross. Genetic parameters of British Landrace bacon pigs. Animal Prod. 7: 291, 1965.

26. Braude, R. , M. J. Townsend, G. Harrington, and J. G. Rowell. A large-scale test of the effects of food restriction on the performance of fattening pigs. J. Agr. Sci. 51: 208, 1958.

27. Wagner, G. R. , A. J. Clark, V. W. Hays, and V, C. Speer. Effect of protein-energy relationships on the performance and carcass quality of growing swine. J. Animal Sci. 22: 202, 1963.

28. Dahl, O. Influence of the basal diet on the quality of pig fat. Acta Agr. Scand. 10: 33, 1960.

29. Greer, S. A., V. W. Hays, V. C. Speer, J. T. McCall, and E. G. Hammond. Effects of level of corn and barley-base diets on performance and body composition of swine. J. Animal Sci. 24: 1008, 1965.

30. Tribble, L. F., A. F. Lennon, C. T. Gaskins, C. B. Ramsey, and K. D. Lind. Formulation of Growing-Finishing Swine Rations from Different Energy Sources. Unpublished Data. Texas Tech University, 1971.

31. Wallace, H. D., A. Z. Palmer, J. W. Carpenter, G. Taki and G. E. Combs. The influence of protein level on feedlot performance and carcass characteristics of barrows and gilts. Fla. Anim. Sci. Mimeo. Series An6416, 1964.

32. Bray, R. W- Variation of quality and quantity factors within and between breeds: The Pork Industry: Problems and Progress, ed. D- G. Topel. Ames, Iowa, Iowa State University Press, 1968.

33. Wallace, H. D. Nutritional and management effects on muscle characteristics and quality. The Pork Industry: Problems and Progress, ed. D. G- Topel Ames, Iowa, Iowa State University Press, 1968.

44

34. Skelley, G. C , and D. L. Handlin. Pork acceptability as influenced by breed, sex, carcass measurements and cutability. j. Animal Sci. 32: 239, 1971.

35. Kramer, A. Parameters of quality. Food Tech. 20: 1147, 1966.

36. Pomeranz, Y. , and C. E. Meloan. Food Analysis: Theory and Practice. The Avi Publishing Company, Inc. Westport, Connecticut, 1971.

37. Field, R. A., G. E. Nelms, and C. O. Schoonover. Effect of age, marbling, and sex on palatability of beef. J. Animal Sci. 25: 360, 1966.

38. Judge, M. D., V. R. Cahill, L. E. Kunkle, and F. E. Deatherage, Pork quality. II. Physical, chemical and organoleptic relationships in fresh pork. J. Animal Sci. 19: 145, 1960.

39. Searcy, D. J., D. L. Harrison, and L. L. Anderson. Palatability and selected related characteristics of three types of roasted porcine muscle. J. Food Sci. 34: 486, 1969.

40. Pengilly, C. I., and D- L. Harrison. Effect of heat treatment on the acceptability of pork. Food Tech. 20: 330, 1966.

41. Kauffman, R. G. What is pork quality? Proc. 7th Nat. Pork Industry Conf. 1964, Kansas City, Missouri.

42. Hinnergardt, L. C , and J. M. Tuomy. A penetrometer test to measure meat tenderness. J. Food Sci. 35: 312, 1970.

43. Wellington, G. H. and J. R. Stouffer. Beef marbling— its estimation and influence on tenderness and juiciness. Cornell Agr. Exp. Station Bulletin 941, 1959.

44. Hiner, R. L. , J. W. Thornton, and R. H. Alsmeyer. Palatability and quality of pork as influenced by breed and fatness. J. Food Sci. 30: 550, 1965.

45. Burrill, L. M., D. Deethardt, and R. L. Baffle. Two mechanical devices compared with taste-panel evaluation for measuring tenderness. Food Tech. 16: 145, 1962.

45

46. Sperring, D.D., W. T. Piatt, and R. L. Hiner. Tenderness m beef muscle as measured by pressure. Food Tech. 13: 155, 1959.

47. Kulwich, R., R. w. Decker, and R, H, Alsmeyer, Use of a slice-tenderness evaluation device with pork. Food Tech. 17: 201, 1963,

48. Alsmeyer, R, H. , J, W. Thornton, R. L. Hiner, and N. C. Bollinger. Beef and pork tenderness measured by the press, Warner-Bratzler, and STE method. Food Tech. 20: 683, 1966.

49. Hansen, L. J. Measuring the tenderness of meat. U. S. Patent3, 602, 038. Armour and Company, Chicago, Illinois, 1971.

50. Luckett, R. L., T. D. Bidner, B. E. Humes, E. A. Icaza. Comparison of tenderometer and Warner-Bratzler Shear. Food Science and Technology Section Abstracts. 70th meeting Association of Southern Agricultural Workers, Atlanta, Georgia, February 4-7, 1973.

51. Kastner, C. L., and R. L. Henrickson. Providing uniform meat cores for mechanical shear force measurement. J. Food Sci. 34: 603, 1969.

52. Folch, J., M, Lees, and G. H. S. Stanley. A simple method for the isolation and purification of total lipids from animal tissue. J. Biol. Chem. 266: 497, 1957.

53. Bligh, E. G., and W. J. Dyer. A rapid method of total lipid extraction and purification. Can. J. Biochem, Physiol. 37: 911, 1959.

54. Lee, C. F., M. E. Ambrose, and P. Jr. Smith, Determination lipids in fish meal. J. Assoc. Offie. Agr. Chemists. 49: 946, 1966.

55. Amerine, M. A., R. M. Pangborn, and E. B. Roessler. Principles of Sensory Evaluation of Food. New York Academic Press, 1965.

APPENDIX

A. Pork Roast Marbling Study Data Sheet

B. Instructions to Sensory Panel Members

C. Sensory Panel Score Sheet

46

47

APPENDIX A

PORK ROAST MARBLING STUDY DATA SHEET

RATION SEX

MARBLING GRADE

ANIMAL NUMBER

SYMBOLS

1. Weight of pan and raw roast

2.

3.

4.

5.

Cooking time

Weight of pan (gms)

Difference (wt of roast)

Weight of pan & cooked roast

6. Weight of pan & drippings

7. Weight of cooked roast

8. Weight of drippings (3-6)

9. Evaporative loss (4-7)

10. Total volume (ml) drippings

11. Volume of fat portion

12. Volume of aqueous portion

13. Tenderometer readings: raw

cooked

average

14. Shear values: core 1

core 2

core 3

average of all cores

48

APPENDIX B

INSTRUCTIONS TO SENSORY PANEL MEMBERS

HOW TO SCORE

•nnnMn^of ^ ^T""^ for appearance, odor, flavor of lean, juiciness, and overall acceptability within a range of 9

^ L ;^^^^^ T^^^^S'"''^ ^^^^^ ^ ° ^ descriptive terms. Record the score which best describes your impression of the sample. /

SCORING FOR APPEARANCE

Large portions of the meat will be available for scoring appearance. ^

SCORING FOR ODOR

A small snifter containing warm chopped meat and covered by a watch glass will be available for scoring odor.

SCORING FOR FLAVOR AND JUICINESS

Bite the 1 inch circle of meat in half and record the score describing your impression of flavor and juiciness at the beginning of the chewing period.

SCORING FOR TENDERNESS

Count the number of times you chew the half circle of meat before swallowing it. Record the number of chews required to thoroughly masticate the sample to a mushy consistency. Record a score from 9 to 1 that describes your impression of the tenderness of the half circle.

Set up for yourself a range of the number of chews for each score from 9 to 1. For example: if you chew from 5 to 15 times, you might record a score of 9; if you chew 15-25, a score of 8; 25-35 times, a score of 7; continue to reduce the score by a given number of increased chews. Each judge should set his own range of chews for a given score.

COMMENTS

Comments about a sample and/or explaining your reason for giving a particular score are helpful and you are strongly urged to comment on each sample.

Take your time to score each sample. Water is provided for rinsing your mouth between samples.

49

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