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Principles of
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WESTRECO, INC.
201 HOUSATONIC AVENUE
Principles of
NEW MILFORD, CT 06776
Meat
Science
ThirdEdition
HaroldB. Hedrick
University ofMissouri
Elton D.Aberle
University ofNebraska
John C. Forrest
Purdue University
MaxD.Judge
Purdue University
RobertA. Merkel
Michigan State University
»
KENDALL/HUNT PUBLISHING COMPANY
4050 Westmark Drive PO. Box 1840 Dubuque, Iowa 52004-1840
Cover photograph by Bob Coyle, Dubuque, Iowa
Copyright© 1975 by W. H. Freeman and Company
Copyright© 1989, 1994 by Kendall/Hunt PublishingCompany
ISBN 0-8403-8470-X
LibraryofCongress Catalog Card Number: 93-61227
All rights reserved. No partofthis publication may be reproduced,
stored in a retrieval system, or transmitted, in any form or byany
means, electronic, mechanical, photocopying, recording, orotherwise,
withoutthe prior written permission ofthecopyright owner.
Print9ed i8n th7e U6nit5ed4Stat3es2ofA1merica
10
Contents
Preface v
1. Meat as a Food 1
Part I Muscle and Associated Tissues 9
2. Structure and Composition of Muscle and Associated Tissues 11
3. Growth and Development of Carcass Tissues 55
4. The Mechanism of Muscle Contraction 79
Part II Meat Science 93
Conversion of Muscle to Meat and Development of Meat Quality 95
Properties of Fresh Meat 123
Principles of Meat Processing 133
Microbiology, Deterioration and Contamination of Meat 173
9 Storage and Preservation of Meat 201
10 Retail Meat Merchandising 223
11 Meat for Food Service 261
12 Palatability and Cookery of Meat 269
13 Nutritive Value of Meat 289
14 Meat Inspection 299
15 Meat Grading and Evaluation 311
16 By-products of the Meat Industry 333
III
Preface
Meat science courses at many universities serve students having a broad range of interests and
bacicgrounds. Our goal in preparing this book was to provide a text for sophomore-level college
students enrolled in theirfirst meatsciencecourse. Although manyexcellent referenceworkswere
available for use in our own introductory meat science courses, no single up-to-date text covered
the bulk ofthe information included in our courses. Principles ofMeal Science was generated to
fill this void.
In our quest for completeness we have attempted to provide information on meat produced by
cattle, swine, sheep, poultry, seafood, and other species. Because many of the basic principles of
meat science apply to all meat-producing species, specific references to species were considered
unnecessary. Properties ofmeat that are unique toan individual species have been included where
appropriate. This text also is oriented toward the meat industry as it exists in the United States;
there is wide variation in much of the specific information presented here when consideration is
given to the industry in other areas of the world. This is particularly true with regard to meat
inspection regulations, standards, and grades, and the nomenclature of meat cuts.
Special thanks are extended to those individualswhocontributed materials and suggestions for
this, the third edition of Principles ofMeat Science.
September, 1993 Harold B. Hedrick
Elton D. Aberle
John C. Forrest
Max D. Judge
Robert A. Merkel
Chapter
1
Meat as a Food
Eating is a process essential to the maintenance of life itself, and few foods can quiet the pangs
ofhunger and satisfy the appetite so quickly and completely as meat. In Western society, so great
is the pleasure derived from consumption ofsizzling steaks, succulent roasts, spicy sausages, crisp
fried chicken,juicy lobster tail, or any ofthe hundreds ofother meat dishes available as the main
attraction for a meal, that other nutritious foods are hard pressed tocompete. A complex industry
has developed to provide the nutritious, high-quality meat supply sought after by much of the
world's human population. You are beginning a study of that industry and the unique food prod-
ucts it prepares for the hungry masses.
What Meat?
Is
Were you surprised to see lobster tail and fried chicken listed along with steaks and roasts? If so,
itistime to broaden yourconcept ofmeat. Meat isdefined as thoseanimal tissues that are suitable
for use as food. All processed or manufactured products that might be prepared from these tissues
are included in this definition. While nearly every species of animal can be used as meat, most
meat consumed by humans comes from domestic animals and aquatic organisms.
Meat as an entity can be subdivided into several general categories. The largest category, in
terms of volume of consumption, is "red" meat. Beef, pork, lamb or mutton, and veal are com-
monly identified as "red" meats. (However, some muscles of pork and those ofveal are pale and
do not fit easily into the category of"red" meats.) Horse, goat, eland, llama, camel, water buffalo,
and rabbit meats also are used for human consumption in many countries. Poultry meat is the
flesh ofdomestic birds, and includes that ofchickens, turkeys, ducks, geese, and guinea fowl. Sea
foods are the flesh of aquatic organisms, of which the bulk are fish. The flesh of clams, lobsters,
oysters, crabs, and many other species also is included in this category. A fourth category is game
meat, which consists of the flesh of any nondomesticated animal.
2 Meat as a Food
Muscle as Meat
It should be emphasized that any discussion of meat must be directed primarily toward muscle.
Although meat is composed ofnumerous tissues, such as those in nerves, adipose tissue, and blood
vessels, the major component of meat is muscle. Yet, muscle tissue did not evolve to serve the
needs of meat consumers, but rather, to perform the functions oflocomotion and heat production
in living animals.
Because muscles are organs whose unique structure primarily serves biological functions, they
possess several characteristics that influence their value as food. For example, certain muscles
contain relatively large quantities of connective tissue, which is associated with meat toughness.
However, these muscles can be as palatable as any other, provided a cooking method is used that
degrades the connective tissues.
Had muscle been engineered and designed to function primarily as a food product, it undoubt-
edly would have differed in several characteristics. With advances in technology, many foods are
being engineered tospecifications, and attempts arebeing made tosubstituteother protein sources
for the muscle in meat. Surprisingly, it is extremely difficult to imitate the texture and flavor
imparted to meat by muscle and other animal tissues. Attempts to prepare meathke products
without using animal tissue have met with only limited success. However, the partial replacement
of muscle with other protein sources in various meat products has great potential for extending
the meat supply to more of the world's people.
Meat is consumed largely for the muscle it contains. Consumers usually leave the adhering or
separable fat of meat servings on the plate. The important characteristics of manufactured meat
products such as moisture-binding ability, fat-emulsifying capacity, and color are provided by the
proteinsofmuscle fibers. Consequently, the focus ofPart I ofthis book ison muscle and associated
tissues, and its principal objective is to bridge the gap between muscle biology and meat science.
What Is Meat Science?
Part II of this book addresses the broad field ofstudy known as meat science. An important part
ofthis field is the basic study ofunique characteristics of muscle and other animal tissues as they
A
aretransformed intomeat. complete understandingofthe basic propertiesofthetissues present
in meat may lead to improved utilization and better meat products.
Meat science is not limited to the study of tissues. It is a component of all facets of the meat
industry, beginning with animal production and ending with final preparation of meat for con-
sumption. Animal breeding, feeding, and management are extremely important parts of the food
chain because meat quality control actually starts on the farm or ranch or in the feedlot.
The market system through which livestock move from production units to packing plants en-
compasses economic and other dimensions ofmeat science. Market signals represent the only line
ofcommunication betweenconsumersand producers.The languageis money, and producersadjust
their production to meet market demands, which ideally reflect desires ofconsumers. Whether or
not the market system accurately communicates consumer wishes to producers, it is a major de-
terminant of the type of livestock and poultry being produced.
Meat as a Food 3
Meat science encompasses the activities ofpackers, processors, and purveyors, or that segment
of industry which converts live animals into food products and then distributes such products to
merchandisers. Meat technology is applied to maintain product quality and wholesomeness and
to develop new and different products.
Retailmeat markets, hotels, restaurants, and institutions are importantcomponentsofthemar-
keting system. Retailers and food service operators are the meat industry's representatives tocon-
sumers. Meat retailers prepare many fresh meat cuts, display all meat products in an attractive
manner, and maintain product qualityand wholesomeness. The hotel, restaurant, and institutional
management groupcarries meat processing to its ultimate end, and placescooked meat before the
consumer. Thefinal cookingand servingofmeat isjustas importantasanysegmentofthecomplex
industry that brings meat from grazing lands, feedlots, and housing units to consumers.
One reason for the increasing complexity of the livestock and meat business is that new com-
petitive food products are being developed continually. These new competitors seek to entice con-
sumerswith modificationsinconvenience, price,quality, uniformity, nutritionalvalue,orevenwith
novelty. Ifthemeat industryistomaintain itspresent positionofimportancein thefood production
chain and maintain a dynamic and growing market, it must produce the highest quality products
with the greatest possible efficiency, develop innovative new products, and employ sophisticated
advertising and promotion programs. Such developments require the input of students trained in
meat science.
Students who plan to be associated with the meat industry during their working careers must
not be satisfied with learning only the status of the industry today, for this knowledge will soon
be out ofdate. Instead they must learn basic concepts and be prepared to apply these to changing
situations. Indeed, they should prepare to initiate change.
It is not the purpose of Part II of this book to describe the intricacies of all phases of meat
science as it affects the complex meat industry. This would provide only a historical background
and would not prepare students for involvement in a dynamic industry. Rather, emphasis is placed
on basic principles that govern meat industry operations. Characteristics ofanimals that produce
tissues used for meat are considered, with emphasis on growth mechanisms responsible for dif-
ferences in body composition. Structure, composition, and function of muscle tissue components
are examined in detail, and contributions that each makes to characteristics of final products are
stressed. Meat processing and preservation are described, as are principles from which processes
have been developed to prepare and preserve hundreds of different meat products. (Recipes and
detailed instructions for manufacture ofspecific products are available from other sources, ifthey
are needed for reference.) Manyother topics, such as inspection, grading and standardization, and
by-products are included, providing an in-depth coverage of many aspects of the total meat
industry.
Meat Consumption and the Economy of a Nation
Throughout recorded history,consumption ofmeat has indicated a position ofsocial and economic
prestige among people and nations. As nations industrialize and improve their economic position,
their meat consumption increases. Moreover, as persons raise their social or economic status, they
tend to demand a greater quantity and higher quality of meat products.
