Enzymatic hydrolysis of camel milk casein and its antioxidant properties

Abstract

The aim of this work was to investigate the enzymatic hydrolysis of whole casein from camel milk with proteolytic enzymes, viz. alcalase, α-chymotrypsin and papain, and to assess the antioxidant activity of hydrolysates. Casein powder was reconstituted (5% TS) and the selected enzymes were added at 1:100 (enzyme/substrate). Hydrolysis was carried out for 6 h at 55 °C for alcalase and papain and 37 °C for α-chymotrypsin, and samples were drawn at 2-h interval. The hydrolysates were analysed for pH, degree of hydrolysis (DH) and antioxidant activities, viz. 2, 2′-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), 2, 2′-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assay. The decrease in pH of the hydrolysates was observed with the progress of hydrolysis time, and as compared to alcalase, the rate of pH decrease was higher for α-chymotrypsin and papain. The DH increased significantly (P < 0.05) up to 6 h on hydrolysis with alcalase and papain, whereas with chymotrypsinolysis, DH increased significantly (P < 0.05) up to 4 h; thereafter, a non-significant increase was observed. The antioxidant activity assessed by ABTS, DPPH and FRAP assay increased significantly (P < 0.05) with the increase in hydrolysis time as well as the degree of hydrolysis. The chymotrypsinolysis exhibited higher antioxidant activity as compared to alcalase and papain. The results obtained in this study suggested that camel milk casein could be used as an ingredient in nutraceuticals or health-oriented foods.