Bio-enrichment of phenolics and free radicals scavenging activity of wheat (WH-711) fractions by solid state fermentation with Aspergillus oryzae

Abstract

This study was conducted to determine the total phenol content (TPC) and free radicals scavenging activity of methanolic and ethanolic extracts of wheat (WH-711) fractions (grain, bran and flour) fermented with Aspergillus oryzae (MTCC 3107). Maximum TPC (1469.35 ± 4.5, 1426.44 ± 5.5 and 1268.91 ± 5.3) was obtained in methanolic extracts as compared to ethanolic extracts (1368.65 ± 3.5, 1155.46 ± 4.7 and 1314.17 ± 5.6 respectively) of wheat bran, grain and flour on the 5th day of fermentation. The free radical-scavenging activity of ethanolic extracts of fermented wheat grain, flour and bran was found to be maximum (62.68 ± 0.49, 32.87 ± 0.71 and 43.89 ± 0.88 %, respectively) whereas methanolic extracts of wheat grain and flour was 59.67 ± 0.78 and 28.52 ± 0.56 %, respectively on 5th day of incubation using DPPH assay. Free radical-scavenging activity (71.30 ± 0.36%) of wheat bran was significantly higher than that of fermented grain and flour on the 2nd day of incubation. Likewise in ABTS assay, wheat bran extracted with ethanol and methanol showed higher inhibition (28.48 ± 0.62 and 43.55 ± 0.72%) on 5th day of incubation than to the fermented  grain and flour. Among all the three fractions, methanolic extract of fermented wheat bran has the highest TPC and hence has highest free radical scavenging activity. Total phenolic contents, DPPH and ABTS+ radicals scavenging activity of wheat fractions were significantly correlated (P<0.01) which provide the strong evidence that the antioxidant activity in wheat fractions was derived from phenolic compounds. Key words: Antioxidant activity, wheat, solid state fermentation, Aspergillus oryzae.