Comparative study on antioxidant activity of hydrolysates from splendid squid (Loligo formosana) gelatin and protein isolate prepared using protease from hepatopancreas of Pacific white shrimp (Litopenaeus vannamei)

Antioxidative activities of splendid squid gelatin hydrolysate (SGH) and squid mantle protein isolate hydrolysate (SMPIH) with different DHs (10-50 %) prepared using crude protease from hepatopancreas of Pacific white shrimp were comparatively studied. At the same DH, SGH had higher FRAP and metal chelating activity and SMPIH showed higher ABTS radical scavenging activities. However, SMPIH had higher ABTS radical scavenging activity than SGH at all DHs tested. SMPIH showed higher DPPH radical scavenging activities than SGH when DHs were up to 30 % DH. However, the former had the lower activity as DHs were 40 and 50 %. ABTS radical scavenging activity of SGH and SMPIH with 50 % DH in gastrointestinal model system increased in the duodenal condition, while SGH showed higher activity in stomach condition than SMPIH. SGH and SMPIH (500, 1000 and 2000 mg/L) could retard lipid oxidation in a lecithin liposome system in a dose dependent manner. Based on Sephadex G-25 column chromatography, the fraction with ABTS radical scavenging activity had MW of 283 and 1381 Da, respectively. Therefore, both hydrolysates from squid gelatin and mantle protein isolate could be used as the alternative natural antioxidants.