Antioxidant Activities of Hydrolysates from Abalone Viscera Using Subcritical Water-Assisted Enzymatic Hydrolysis

Antioxidant hydrolysates were prepared from abalone viscera using subcritical water (AVS)-assisted by enzymatic hydrolysis with papain (AVSE-P), bromelain (AVSE-B), neutral protease (AVSE-N), and flavourzyme (AVSE-F). The protein and carbohydrate contents reached 38.33% and 24.36%, respectively. When AVS was digested by any of the proteases, the protein content increased, but carbohydrate content decreased. The main amino acids of AVSEs included alanine, glycine, and aspartic acid. The IC50 values of ferric reducing antioxidant power, and 2,2-diphenyl-1-picrylhydrazyl (DPPH)•, 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)•+, N,N-Dimethyl-p-phenylenediamine dihydrochloride (DMPD)•+, and hydroxyl radical (•OH) scavenging abilities of AVS were 2.93, 1.48, 1.61, 3.72, and 5.51 mg/mL, respectively, which decreased after enzymatic hydrolysis by any of the proteases. The DMPD•+ and •OH scavenging abilities of AVSE-P and AVSE-B were higher than those of others, whereas the opposite was observed in lipid peroxidation inhibition efficiency, DPPH•, and ABTS•+ scavenging abilities. Hence, antioxidant activities of AVS could be enhanced by enzymatic hydrolysis, but the influence depends on the type of protease. At the same time, results also suggest that the proposed approach can be used for treating abalone viscera, and the obtained antioxidant hydrolysates could be used in nutraceutical and pharmaceutical industries.