Effects of molecular weight fraction on antioxidation capacity of rice protein hydrolysates

Rice protein was used as a starting material to provide rice protein hydrolysates (RPH) through enzyme-assisted extraction. RPH was further fractionated using ultrafiltration membrane (UF) and classified by molecular weight (MW; MW < 1 kDa, MW 1-10 kDa, and MW > 10 kDa). Peptides with MW < 1 kDa possessed superior antioxidant properties (p < 0.05). Therefore, UF demonstrated great efficacy in selectively separating antioxidant peptides. A Pearson correlation analysis revealed that the total phenolic concentration was correlated with oxygen radical absorbance capacity (ORAC; r = 0.999, p < 0.05). Amino acid contents had negative correlations with the scavenging activity (specifically, IC50) of 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radicals (r = - 0.986 to - 1.000). Reducing power was related to aromatic amino acid contents (r = 0.997, p < 0.05). In this study, enzymatic hydrolysis was discovered to be an effective method of extracting and isolating natural antioxidant proteins from broken rice, thus preserving the nutritional quality of rice and making those proteins more accessible in future applications.

Automated summary

Rice protein was enzymatically hydrolyzed to produce rice protein hydrolysates (RPH), which were further fractionated using ultrafiltration membrane (UF) based on molecular weight. Peptides with molecular weight less than 1 kDa exhibited superior antioxidant properties. UF was effective in selectively separating antioxidant peptides. Pearson correlation analysis showed a strong positive correlation between total phenolic concentration and oxygen radical absorbance capacity (ORAC). Amino acid contents were negatively correlated with the scavenging activity of certain radicals. Reducing power was associated with aromatic amino acid contents. Enzymatic hydrolysis proved to be an effective method for extracting and isolating natural antioxidant proteins from broken rice, preserving their nutritional quality and facilitating future applications.