Optimization of Enzymolysis Technology and Physical and Chemical Properties of Collagen Peptides from Skin of Red Stingray(Dasyatis akajei)

The optimum hydrolytic enzymes were screened out from different enzymes using gelatin extracted from the skin of red stingray as raw material. The effects of pH,temperature,hydrolysis time and amount of enzyme on the hydrolysis degree of gelatin were investigated by single factor experiment. The gelatin was hydrolyzed with proteases to prepare collagen peptides using response surface methodology,and then their physicochemical properties were analyzed. The results showed that the best enzyme was bromelain.The optimal hydrolysis parameters were determined as follows:pH5.00,hydrolysis temperature 44.5 ℃,hydrolysis time 3.7 h,enzyme concentration 6.00 g/L. The experimental degree of hydrolysis under optimal conditions was 20.47%±0.11%,which agreed with the predicated value of 21.18%. 180 peptides were identified from the sample by liquid chromatography-tandem mass spectrometry,and their molecular weights ranged from 707.40 to 2021.04 Da. Of these peptides,66.11% were hydrophilic peptides,and 33.89%were hydrophobic. Physicochemical property analysis showed that the water-holding capacity of the collagen peptides was(3.25±0.05) g/g protein,the fat binding capacity of collagen peptides was(8.98 g±0.01) mL/g protein,the solubility of collagen peptides was over 90%,the highest foaming capacity and foaming stability values obtained at pH6 were 15.38%±0.15% and 14.36%±0.14%,respectively. The highest emulsification value of 78.82%±0.22% was obtained at pH3.This study provided technical guidance and a theoretical basis for the high-value utilization of red stingray skin processing byproducts.