Abstract:

Aspergillus oryzae AS3.951 was inoculated into Acanthogobius hasta muscle homogenate (pH 5.0) and incubated in order to produce proteases to hydrolyze fish proteins. Investigations on protease production kinetics during fermentation and the hydrolysis kinetics of Acanthogobius hasta muscle proteins were made. The fermentation broth was ultrafiltrated through membranes with molecular weight cut-off (MWCO) and its fractions were measured for their free radical scavenging and antioxidant activities. The results revealed that as fermentation time was prolonged, the degree of hydrolysis of Acanthogobius hasta muscle proteins and peptide yield gradually increased and the average chain length of ploypeptides decreased. After 48- hour fermentation, the average chain length of polypeptides, degree of hydrolysis, polypeptide yield obtained were 14, 26.6% and 8.98% and the resultant product exhibited a notable antioxidant effect. Among its ultrafiltration fractions, the polypeptides with an average chain length of 14 amino acid residues had the strongest antioxidant effect.

Key words: Acanthogobius hasta, Aspergillus oryzae, polypeptide, antioxidant activity, fermentation