Functional and antioxidant activity of Ziziphus jujube seed protein hydrolysates

Ziziphus jujuba is a medicinal plant with well demonstrated biological functions for which various bioactive compounds except antioxidants peptides from seeds have been reported. Therefore, the aim of this study was to determine antioxidant activity, metal ion chelation and reducing power of Z. jujuba seeds-derived protein hydrolysate. The concentration of protein was 5.72 mg/g in 50 mM Tris-HCl buffer pH 7.5. The solubility of protein was above 90 % at pH 2 and 3, decreased at pH 4 and subsequently increased further with an increase in pH. The seed derived protein showed an excellent solubility and possessed interfacial properties, which were governed by their concentrations. The antioxidant activities of protein hydrolysate were evaluated using various in vitro antioxidant assays. Alcalase, papain and protease hydrolysate shows (8.09, 9.14 and 8.92 mu M of TE/g) antioxidant capacity by ABTS and radical scavenging activity (7.21, 17.54 and 8.36) by DPPH. From this study, it was observed that the papain hydrolysate of Ziziphus jujube is a good source of natural antioxidants and peptides with interesting functionalities.