Antimicrobial Capacity and Antioxidant Activity of Enzymatic Hydrolysates of Protein from Rushan Bay Oyster (Crassostrea gigas)

The active oyster peptides (AOPs) in enzymatic hydrolyzed oyster protein product have been determinated by gel column chromatogrphy. They were investigated to determine their antimicrobial and antioxidant properties. Three commercial food-grade proteases were used to hydrolyze the oyster. Among the three hydrolysates, alcalase hydrolysate exerted the highest scavenging activity against a,a-diphenyl-b-picrylhydrazyl (DPPH) for use in oyster hydrolysis. The optimum parameters for hydrolysis using alcalase were established by the single-factor and orthogonal tests. Under these conditions, the highest degree of hydrolysis (DH) was 39.89%. Antioxidants of protein hydrolysates at 30.12, 32.69, 38.47 and 39.89% of DH were further investigated by the evaluation of DPPH and hydroxyl radical-scavenging activity. The resulting AOPs' antibacterial activities against some pathogenic microorganisms, including human pathogenic bacteria and marine Vibrio species, were investigated using the agar diffusion method. The results showed interesting antimicrobial potentials against the tested microorganisms, except Vibrio anguillarum. The highest DH of AOPs exhibited a higher antimicrobial potential than lower DH. Practical Applications: Rushan oyster (Crassostrea gigas), with high production in China, is still underutilized despite the fact that it is rich in high quality protein. Oyster protein hydrolysates have been shown to have potential for nutritional or pharmaceutical applications. The aims of this study were to prepare peptides from Rushan oyster by enzymatic hydrolysis and to evaluate the antimicrobial capacity and antioxidant activity of the resulting hydrolysate. The hydrolysis of protein with proteolytic enzymes can provide more marketable and value-added food ingredients or industrial products.