Biochemistry

Ellastin protein is similar in composition to collagen. It is found in the ligaments and walls of blood vessels. It is rich in amino acids such as glycine, alanine, lysine, but is poor in proline. Meat rich in connective tissue remains stiff after heat treatment. The digestibility of collagen and ellastin is low. Within prolonged heat treatment of collagen, gelatin is formed. It is a defective protein (it does not have many amino acids). By-products proteins By-products arc called secondary products of slaughter of animals, internal organs, heads, tails, lower limbs, lips, ears, meat trimmings. By-products proteins differ from meat proteins in amino acid composition, in the content of connective tissue, in the ability to be digested by enzymes of the digestive tract. By composition, the By-products is divided into three groups. The first group includes parenchymal organs (liver, lungs, kidneys, brain, udder, spleen). The backbone of these organs consists of collagen. The second group of by-products is the heart, tongue, diaphragm, stomach. They include connective and muscle tissue. The third group includes heads, legs, lips, ears and tails. The structure of these parts of the carcass approaches the composition of muscle, connective and adipose tissue. In this regard, by-products are distinguished: meat and bone, muscle, pulpy wool (ears, lips), mucous membranes. By-products consist in a significant amount of protein, but their usefulness is different. In particular, the content of defective proteins in the liver is less than 10%, beef lungs - up to 60%, beeflips - 75%. Meat trim is slightly different from meat. The protein content in it is 18.9% (beef trimmings), the amount of collagen in trimmings proteins is up to 4%. According to the amino acid composition, trim proteins are close to meat (but they contain little tryptophan). Heart. There is a lot of hemoglobin in it, and in other indicators its protein composition does not differ from meat. Tongue. The composition is close to meat. The brain has low content of protein. These are mainly albumin, globulins, lipoproteins, nucleoproteins. Lungs are high in collagen. They have few high-grade proteins. Liver. The protein content is from 17 to 19%. It contains a lot of globulins and albumin, chromoproteins and ferritin (it is a supplier of iron in the body). In addition, the liver contains nucleoproteins, glycoproteins, collagen and ellastin. Liver proteins are well digested. 71