The effects of hydrolysis condition on the antioxidant activity of protein hydrolysate from Cyprinus carpio skin gelatin

The aim of the study was the selection of food grade, an inexpensive and commercially available enzyme that would allow to obtain a hydrolysate from carp (Cyprinus carpio) skin gelatin with the highest antioxidant activity. Moreover, the objective of the study was to investigate the effects of pH temperature and incubation duration of the hydrolysis on protein degradation, free amino acids and antioxidant properties of the obtained hydrolysates. Protein hydrolysates obtained from carp skin gelatin using Protamex show potent antioxidant properties, which differed depending on the hydrolysis parameters. The hydrolysis parameters significantly influenced the free amino acid profiles as well as protein depolymerization and antioxidant properties of the hydrolysates. The acquired hydrolysates showed very potent antioxidant properties (FRAP value of 5.12 mu M Trolox/mg) and a high degree of the depolymerized protein (27.73%). Furthermore, there was a clear positive correlation between the pH of the hydrolysis and the metal chelating activity of the hydrolysate, with all the hydrolysates produced at pH 6 exhibiting no metal chelating activity, while hydrolysates produced at pH 8 showed metal chelating activity. The carp skin gelatin hydrolysates with the highest antioxidant properties were obtained using Protamex at pH 7 and a temperature of 50 degrees C for 3 h.