Comparative analysis of solid-state bioprocessing and enzymatic treatment of finger millet for mobilization of bound phenolics

The present work investigates the probable bioprocessing technique to mobilize the bound phenolics naturally found in finger millet cell wall for enriching it with dietary antioxidants. Comparative study was performed between the exogenous enzymatic treatment and solid-state fermentation of grain (SSF) with a food grade organism Rhizopus oryzae . SSF results indicated that at the 6th day of incubation, total phenolic content (18.64 mg gallic acid equivalent/gds) and antioxidant property (DPPH radical scavenging activity of 39.03 %, metal chelating ability of 54 % and better reducing power) of finger millet were drastically enhanced when fermented with GRAS filamentous fungi. During the enzymatic bioprocessing, most of the phenolics released during the hydrolysis, leached out into the liquid portion rather than retaining them within the millet grain, resulting in overall loss of dietary antioxidant. The present study establishes the most effective strategy to enrich the finger millet with phenolic antioxidants.