Abstract:

Through double-enzyme hydrolysis, tilapia scraps were separated into two fractions, namely a compound amino acid solution and an insoluble residue left after the hydrolysis. The residue was processed into power and further hydrolyzed acidically to offer a calcium-containing solution for the reaction with the above prepared compound amino acid solution, producing amino acid chelated calcium. The optimal chelation reaction conditions for achieving maximum chelation rate were investigated, and the reaction product was tested for its for its antioxidant activity by reducing power and free radical scavenging assays. pH of 7.0, reaction time of 90 min, reaction temperature of 60 ℃ and amino nitrogen content of 1.6 g/L were found optimal, and the resultant chelation rate was 57.22 %. The antioxidant evaluation indicated that the condensed amino acid chelated calcium solution obtained had reducing power in a positive volume-dependent fashion in a proper range. The maximum scavenging rates against hydroxyl and superoxide anion free radicals were 6.60% and 51.67%, respectively.

Key words: tilapia bone powder, compound amino acid solution, amino acid chelated calcium