Enhanced production and extraction of phenolic compounds from wheat by solid-state fermentation with Rhizopus oryzae RCK2012

Antioxidant phenolic compounds (PCs) are gaining popularity day by day for their health promoting properties. Wheat is a very good source of natural antioxidant PCs. In the present study, extraction of PCs was improved by solid-state fermentation (SSF) of wheat by Rhizopus oryzae RCK2012 which helped to release the bound compounds from matrix. Different extraction conditions such as solvent composition (water, methanol, 70% methanol, ethanol, 70% ethanol, acetone and 70% acetone), extraction temperature (30-60 °C), extraction time (15-90 min) and solid-to-solvent ratio (1:2.5 to 1:20, w/v) have been optimized for the extraction of PCs from R. oryzae fermented wheat. Maximum PCs were extracted by water at 40 °C within 45 min with solid-to-solvent ratio of 1:15 (w/v). Compositional analysis of PCs was carried out by UPLC and TLC. Improved ABTS•+ [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl), hydroxyl radical and hydrogen peroxide scavenging capacities, ferric reducing property and in vivo antioxidant capacity using Saccharomyces cerevisiae were observed in case of freeze-dried water extract of fermented wheat as compared to unfermented sample. Hence, SSF could be a promising technology to enhance the production and extraction of phenolic compounds for the design of different functional foods and for the specific use as nutraceuticals.