Antioxidant activity of peptide fractions derived from cottonseed protein hydrolysate

BACKGROUND: Cottonseed protein is widely regarded as a potential source of nutrients for humans and animals, but it is mainly used as forage in China. In the present study, Neutrase was employed to hydrolyse cottonseed protein to produce a hydrolysate with antioxidant activity suitable for conversion to high-value products. The antioxidant potential of the cottonseed protein hydrolysate (CPH) and its fractions was investigated using different in vitro methods. Furthermore, the amino acid composition of the CPH fractions was determined to evaluate the relationship between antioxidant activity and amino acid composition. RESULTS: The CPH prepared using Neutrase was separated into four fractions (I, II, III and IV) by gel filtration on Sephadex G-25. All fractions were effective antioxidants, with fraction III (0.8-1.2 kDa) showing the strongest activity. The amino acid analysis showed that fraction III also had the highest total amino acid content (616.8 g kg(-1) protein) and was rich in Phe, His, Pro, Met, IIe and Cys compared with the other fractions. CONCLUSION: The results showed that the hydrolysate derived from cottonseed protein, particularly fraction III, could be a natural antioxidant source suitable for use as a food additive. (C) 2010 Society of Chemical Industry