Molecular Weight and Antioxidant Activity of Enzymatic Hydrolysates of Silver Carp

The molecular weight( M w) and antioxidant properties of enzymatic hydrolysates of silver carp with different degree of hydrolysis(DH) were studied. The antioxidant properties evaluated included total antioxidant capacity(T-AOC), radical scavenging activity against hydroxyl and superoxide anion free radicals and lipid oxidation inhibitory effect. The hydrolysates were prepared by respective use of protamex and alcalase. The results showed that the M w of the hydrolysates produced by alcalase were generally lower than those of the hydrolysates obtained with Protamex, and at DH 10%, over 95% of peptides fractions had M w lower than 1500 u. The hydrolysates prepared by each enzyme preparation had excellent antioxidant activities. The hydrolysates with DH 10% prepared by alcalase possessed the highest T-AOC and hydroxyl radical scavenging capacity, which were 1.025 U/mg pro and 21.31 U/mg pro, respectively. The hydrolysates with DH 10% prepared by protamex displayed the strongest superoxide anion radical scavenging ability and lipid oxidation inhibitory effect, which reached 24.92 U/mg pro and 27.88% at a concentration of 5.0 mg/mL, respectively. The antioxidant activities of these hydrolysates might be related to their molecular weights despite being not significant.