(2) The solubility of hydrolyzed collagen is good: the water solubility of protein depends on the number of ionizable groups and hydrophilic groups in its molecule. The hydrolysis of collagen causes the breakage of peptide bonds, leading to some polar hydrophilic groups. (Such as -C00H, -NH2, -OH) increase in the number, so that the hydrophobicity of the protein decreases, the charge density increases, the hydrophilicity increases, and the water solubility increases. By measuring the nitrogen solubility index (NSI) to compare the solubility of collagen and hydrolyzed collagen of different molecular weight collagen hydrolysates, the results indicate that the solubility of collagen is 93.81%. As the molecular weight of hydrolyzed collagen decreases from (2.7～4.5)×10 to (0.65～0.95)×10, its solubility increases significantly from 97.64% to 100.00%. [2]
(3) High water retention capacity of hydrolyzed collagen: The water retention capacity of protein is affected by protein concentration, molecular mass, ion species, environmental factors, etc., and is usually expressed by water retention rate. As the degree of collagen hydrolysis increases, the water retention rate also gradually increases. Since collagen contains a large number of polar amino acid residues, such as glycine, alanine, etc., collagen is hydrolyzed into hydrolyzed collagen, the exposure of hydrophilic groups increases, the release of polar bonds more, and the ability to bind water molecules It is also enhanced, thereby improving the water retention of the hydrolyzed collagen of the collagen proteolysis product. The water retention rate of collagen and hydrolyzed collagen of collagen hydrolysates of different molecular weight were compared by measuring the water retention rate. The result: in the same time interval, the hydrolyzed collagen decreased with the molecular weight from (2.7～4.5)×10 to (0.65). ~0.95) X10, its water retention rate gradually increases.