Antioxidant and antibacterial activity and in vitro digestion stability of cottonseed protein hydrolysates

In this study, five fractions (F–I to F–V) were successfully isolated from cottonseed protein hydrolysates (CPH) by using ion exchange resin system, and proved to be mainly composed of peptides with molecular weights less than 1 kDa by size exclusion high performance liquid chromatography (SEC-HPLC). All fractions possessed the DPPH radical and ABTS radical cation scavenging abilities. However, the antibacterial experiment revealed F–I and CPH had no inhibition against E. coli. By analyzing the composition of amino acids, the antioxidant and antibacterial activities were found to be positively correlated with basic amino acid contents (Arg and Lys), but negatively correlated with acidic residual (Glu and Asp). Furthermore, the in vitro digestion had slightly effects on antibacterial activity of the fractions (CPH, Fraction I-Ⅴ), while it showed great impacts on the antioxidant capacity. The work here provided basic theory and a new strategy for preparing bifunctional peptides from cottonseed protein, which could be used as an alternative in the functional food formulations.