Handbook of Food Science and Technology 3

2.1. The biochemistry of muscle (land animals and fish)
 
The muscle tissue of land animals and flesh of fish have similar 
biochemical compositions, especially with regard to protein, carbohydrates, 
Chapter written by Catherine G
UÉRIN
. 
Handbook of Food Science and Technology 3
:
 Food Biochemistry and Technology
, 
First Edition. Edited by Romain Jeantet, Thomas Croguennec, Pierre Schuck and Gérard Brulé.
© ISTE Ltd 2016. Published by ISTE Ltd and John Wiley & Sons, Inc.

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66 Handbook of Food Science and Technology 3 
minerals and vitamins. However, their lipid and water contents are quite
different. 
The distribution of fat varies significantly in fish and meat. Lipids in oily 
fish are primarily located in the muscle tissue, whereas they are mostly 
contained in the liver of white fish. Lipids in meat can be intramuscular 
(marbled), but are mainly extramuscular: this includes subcutaneous or 
external fat and visceral or internal fat. The overall biochemical 
composition, in particular the lipid content of the muscle, refers here to the 
composition of the skeletal muscle. Only intramuscular fat will be taken into 
account, as subcutaneous (often removed during slaughter) and visceral fat 
are generally not consumed.
2.1.1.
 The structure and composition of meat and fish muscle 
2.1.1.1.
 Tissue structure
Meat 
Meat and meat products vary significantly. This is demonstrated by the 
fact that there are almost 900 terms to define these products. Even if meat 
were restricted to only muscle, there would still be a wide diversity; more 
than 100 muscles with different structures and compositions are found on a 
carcass and each muscle is itself heterogeneous.
The carcass of terrestrial animals consists of several types of tissue: 
muscle, connective tissue, fat, blood, nerves and bones. Each contributes to 
the sensory quality of the meat: muscle and connective tissue to tenderness, 
blood tissue to color, fatty tissue to flavor and so forth. Bone tissue is 
generally not consumed, except in minced meat where a small proportion of 
bone is permitted by law.
Animals have two main types of muscles: striated and smooth muscle. 
They differ not only in their fibrous or non-fibrous appearance, clearly 
visible under an optical microscope, but also in their color: smooth muscle is 
white whereas striated muscle tends to be red. However, white striated 
muscle exists such as the pectoral muscle of chickens for example. Smooth 
muscle is mainly found in the organs (stomach, intestines, etc.) and is 
generally not consumed as meat. As a result, we will focus mainly on 
striated muscle.

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From Muscle to Meat and Meat Products 67 
Muscle tissue 
Muscle tissue is highly differentiated and specialized to perform different 
tasks. It is composed of fibers with metabolic or contractile properties, which 
are held together by connective tissue. The main chemical component of 
connective tissue is collagen. The typical characteristics of fibers are based 
on the relative proportion of the constituent elements: myoglobin, inter-
fibrous lipids, enzymes and so on. Thus, the chemical composition of a 
muscle depends on the relative proportion of each type of constituent fiber, 
but also the relative structure of the connective tissue (endomysium, 
perimysium, epimysium and tendon; Figure 2.1).