Changes in the Amino Acid Composition of Gelatin After Treatment of Bovine Collagen with Enzyme Preparations

Recently, increased attention has been paid to the study of the amino acid (AA) composition of gelatins, which is associated with the quality of the corresponding gels as intermediates for human and animal nutrition. In a brief review, a modification of the general method of acid extraction of collagens for the preparation of gelatins using enzymes (such as papain, actinidin, and others) is considered and the corresponding changes in the amino acid composition of gelatins are discussed. It is clear that there are changes in the content of glycine in gelatins from any collagens, but in all cases the content of glycine is about a third of the content of all amino acids (as in the original collagens). It is important that the content of imino acids (the sum of proline and hydroxyproline, which largely determines the properties of gels) in gelatins from any collagens with the use of all the studied enzymes is much higher than without them. In addition, the content of imino acids in gelatin from the bovine skin of cows with the use of any enzymes is significantly higher than in gelatins from the skin of pigs and fish. This also holds true for other key proteinogenic AAs. The reverse trend is observed only for a few AAs: serine, threonine, tyrosine, and phenylalanine, whose content is low in gelatins from any collagens.