|ZHANG, HUIJUAN - Jiangnan University|
|Yokoyama, Wallace - Wally|
|ZHANG, HUI - Jiangnan University|
Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2011
Publication Date: 5/14/2012
Citation: Zhang, H., Yokoyama, W.H., Zhang, H. 2012. Concentration-dependent displacement of cholesterol in micelles by hydrophobic rice bran protein hydrolysates. Journal of the Science of Food and Agriculture. 92(7):1395-1401. DOI: 10.1002/jsfa.4713.
Interpretive Summary: Peptides derived from proteins have been shown to have bioactive properties such as blood pressure lowering, bile acid binding, antimicrobial, cholesterol lowering and others. Rice bran is an abundant byproduct due to recent production of rice bran oil. In this study we evaluated the possibility of a cholesterol lowering peptide from the hydrolysis of rice bran. Four different enzymes were evaluated and the enzyme, alcalase, was the most efficient and had the highest activity in an in vitro assay of cholesterol lowering. The hydrolysate was further fractioned using a resin to produce a more hydrophobic fraction with the highest inhibitory index.
Technical Abstract: The recent production of rice bran oil in Asia and the U.S. has resulted in large quantities of defatted rice bran as a low-value byproduct. Peptides from soy, milk, and other foods have been shown to have the potential hypocholesterolemic property and rice bran protein (RBP) may also contain bioactive peptides. The potential hypocholesterolemic property of rice bran protein hydrolysates (RBPH) by determining their ability to displace cholesterol from bile acid-phosphatidylcholine micelles was evaluated. RBP was digested using four different proteases (alcalase 2.4L®, neutrase 0.8L®, papaya latex papain and porcine pancreas trypsin). The degree of hydrolysis of RBP by alcalase was highest and the alcalase hydrolysates displaced the most cholesterol from micelles. The adsorption dynamics of alcalase hydrolysates onto four different macroporous resins (MARs), DA201-C, Sepabeads SP207, SP825, and Diaion HP20, were determined. The resins were mixed with varying concentrations of the alcalase hydrolysates until equilibrium adsorption was reached and the adsorption data were fitted to the Langmuir isotherm. The resin with the highest adsorption capacity was DA201-C with an equilibrium concentration of 220 mg/g. The hydrolysates were eluted from DA201-C stepwise with 25, 50, 75, and 95% ethanol and evaluated by cholesterol displacement from micelles. Relative to cholestyramine, the hydrolysates eluted by 25, 50, 75, and 95% ethanol displaced 11.88, 14.76, 19.37, and 7.56% of the micellar cholesterol, respectively. DA201-C was the best resin to desalt and enrich RBPH with higher content of hydrophobic amino acids.