Composition of Meats

Meats are composed of a combination of water, muscle, connective tissue, adipose (fatty) tissue, and often bone. The proportions of these elements vary according to the animal and the part of its anatomy represented by the cut of meat.

Muscle Tissue of Meat

Most of the protein in animals is found in their muscles, which serve as the main sources of dietary meat. The characteristics of muscles are an important consideration in deciding how the resulting meat should be prepared. Muscles are made up of a collection of individual muscles cells, called muscle fibers, that are each surrounded by an outer membrane called the sarcolemma. Each muscle fiber is further filled with cell fluid (sarcoplasm) in which are about 2,000 smaller muscle fibrils serving as the contractile components of the muscle fiber. If the muscle fibrils are small, the result is finer muscle bundles, which give the meat a very delicate, velvety consistency.

These muscle fibrils play an important role in muscle contraction and relaxation. The muscle fibril is separated into segments called sarcomeres, which are bordered by dark bands called Z lines. The sarcomeres contain two proteins, actin (thin) and myosin (thick), that are alternately aligned. It is thought that muscle contraction occurs when the sarcomeres shorten as the thick and thin filaments “slide” past each other, forming another protein called antinomyosin. The energy for muscle contraction is provided by adenosine triphosphate.