Influence of enzyme concentrations in enzymatic bioprocessing of red rice bran: A detailed study on nutraceutical compositions, antioxidant and human LDL oxidation inhibition properties

Abstract

Enzymes and their concentrations are crucial factors in improving the release of nutraceuticals bounded to rice bran's cell wall matrix. This study aims to investigate the optimal concentrations of Viscozyme and Fiberzyme at 3–30 beta-glucanase units/2 g in improving the release of phenolics, tocopherols, tocotrienols, and γ-oryzanol fractions and enhancing the bioactivities of red rice bran. At specific concentrations, Fiberzyme increased ferulic (301%) and caffeic acid (691%) in soluble phenolics, p-coumaric acid (98%), and catechin (161%) in bound phenolics as well as γ-oryzanol fractions(32%-134%) and increased ferric reducing power (90%), DPPH (41%), and hydroxyl (25%) radical scavenging activities. Viscozyme enhanced δ,γ,α-tocopherols (11%-164%) and tocotrienols (39%–271%) and scavenging activities against nitric oxide (144%), superoxide anion (120%), and inhibition of human LDL oxidation (40%). Cycloartenyl ferulate, ferulic acid, soluble phenolics, campesteryl ferulate, 24-methylenecycloartanyl ferulate, and α-tocotrienol showed a significant positive correlation with bioactivities. Thus, optimization of enzymatic processing will help process the red rice bran into a nutraceutical rich ingredient having higher biological activity.