ANTIOXIDANT ACTIVITIES OF ROSELLE (HIBISCUS SABDARIFFA L.) SEED PROTEIN HYDROLYSATE AND ITS DERIVED PEPTIDE FRACTIONS

In this study, peptide fractions with strong antioxidant activity were obtained from Roselle seed protein hydrolysates. Pepsin followed by pancreatin were used to digest Roselle protein at different time in order to produce hydrolysate with antioxidant activity suitable for conversion to high-value products. The hydrolysates obtained after different hydrolysis times were analyzed for antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl radical scavenging method. The 3 h hydrolysate showed the highest antioxidant activity therefore, it was separated into four fractions (I, II, III, and IV) by gel filtration on Sephadex G-15. The antioxidant efficacies of the 3 h Roselle seed protein hydrolysates and its fractions were investigated using different in vitro methods. All fractions were effective antioxidants, with fraction III showing the strongest antioxidant activity. The fractions were then analyzed for amino acid composition. The analysis revealed that fraction III contained higher amounts of Serine, Glycine, Arginine, Alanine, Tyrosine, Valine, Phenylalanine, and Proline compared to the other fractions. Most of these amino acids have been reported to show antioxidant activity. The results showed that the hydrolysate derived from Roselle seed protein, particularly fraction III, could be a natural antioxidant source suitable for use as a food additive.