Effect of flavorzyme digestion on the antioxidant capacities of ultra‐filtrated rice bran protein hydrolyzates
Ahmed A. Zaky, Yangliu Liu, Panpan Han, Aijin Ma, Yingmin Jia
Abstract
The antioxidant capacities of rice bran protein hydrolyzates (RBPH) using the flavorzyme digestion system were studied. The hydrolyzates were fractioned by ultrafiltration membranes into three fractions (FI: molecular weight (MW) >10 kDa, FII: MW 3–10 kDa, and FIII: MW < 3 kDa). Furthermore, free amino acids, amino acid composition, and SDS-PAGE of obtained hydrolyzates and its active peptide fractions were evaluated. The results showed that fraction FIII with MW < 3 kDa possessed the greatest antioxidant activity: DPPH of 31.65% ± 0.18%, ABTS of 52.03% ± 0.32%, and metal chelating activity of 71.06% ± 0.38%, and was further purified by RP-HPLC. Five sub-peptide fractions (F1, F2, F3, F4, and F5) were collected and their antioxidant abilities were evaluated. The data exhibited that the F2 sub-peptide fraction possessed a higher metal chelating activity (82.13% ± 0.51%) than other fractions. The RBPH using flavorzyme could be utilized as an antioxidant source in functional foods. Practical applications The high activity of <3 kDa fraction and its sub-peptide fractions in these antioxidant assays might be associated with the high proportion of hydrophobic and aromatic amino acids. The results from this work confirm that rice bran proteins are rich in bioactive peptides, which could be employed as a prospective source for natural antioxidant components, therefore, can be useful for future food applications.