Enzymatic Protein Hydrolysates of Common Carp Fish: II. Antioxidant Activity

Common carp fish were hydrolysed using papain, bacterial protease, and bovine protease. The antioxidant activity of the three hydrolysates were determined. Partial hydrolysates with different degrees of hydrolysis and peptide fractions were also examined for their antioxidant activity. Then, the hydrolysate prepared using papain enzyme was chosen for further investigation. It was added to a meat model system capable to inhibit lipid oxidation, and its Hunter Lab. colour was tested. Moreover, the effects of three drying methods on the antioxidant activity and some functional properties of the papain hydrolysate were examined. Data revealed that the three fish hydrolysates possessed antioxidant activities which were boosted to about 98% by addition of 0.5% BHT. Partial hydrolysates exhibited antioxidant activities which increased with the increase in degree of hydrolysis. The highest antioxidant activity (73.2 %) was achieved with 35.2 % degree of hydrolysis for papain hydrolysate. Results also showed that the smaller the molecular weight of the peptide fraction, the higher its antioxidant activity. Addition of papain hydrolysate to meat model system delayed oxidation. Freeze drying of papain hydrolystate maintained their antioxidant activity and functional properties.