Investigation of Enzymatic Hydrolysis Conditions on the Properties of Protein Hydrolysate from Fish Muscle (<i>Collichthys niveatus</i>) and Evaluation of Its Functional Properties

This study was carried out to investigate the enzymatic hydrolysis conditions on the properties of protein hydrolysate from fish muscle of the marine fish species <i>Collichthys niveatus.</i> About 160 fish samples were tested, and the analyzed fish species was found to be a lean fish with low fat (1.77 ± 0.01%) and high protein (16.76 ± 1.21%). Fish muscle of <i>C. niveatus</i> was carefully collected and hydrolyzed with four commercial enzymes: Alcalase, Neutrase, Protamex, and Flavourzyme under the conditions recommended by the manufacturers. Among the tested proteases, Neutrase catalyzed the hydrolysis process most effectively since the hydrolysate generated by Neutrase has the highest content of sweet and umami taste amino acids (SUA). The effect of hydrolysis conditions was further optimized using response surface methodology (RSM), and the optimum values for temperature, pH, and enzyme/substrate ratio (E/S ratio) were found to be 40.7 °C, 7.68, and 0.84%, respectively. Finally, the amino acid composition of the hydrolysate was analyzed by AccQ·Tag derivatization and HPLC–PDA determination. Major amino acids of the muscle of <i>C. niveatus</i> were threonine, glutamic acid, phenyalanine, tryptophan, and lysine, accounting for respectively 10.92%, 10.85%, 10.79%, 9.86%, and 9.76% of total amino acid content. The total content of essential amino acids was 970.7 ng·mL^–1, while that of nonessential amino acids was 709.1 ng·mL^–1. The results suggest that the fish muscle and its protein hydrolysate from <i>C. niveatus</i> provide a versatile supply of the benefits and can be incorporated as supplements in health-care foods