EFFECT OF ADDITION OF NATIVE AND FERMENTED RICE BRAN ON THE PHYSICOCHEMICAL, FUNCTIONAL AND NUTRITIONAL PROPERTIES OF RICE FLOUR AND BREAD

Abstract

The study investigated the effect of addition of native and fermented rice bran on the physicochemical, functional and nutritional properties of rice flour and bread. Response surface methodology was used for the experimental design which generated a total of thirteen runs. Four best runs were selected based on the optimization of the crude protein and fibre content, viz: runs (1, 4, 8 and 10) which had rice, fermented rice bran and wheat flours in the ratios 60.00:24.20:15.80, 86.92:13.80:0.00, 60.00:10.00:30.00 and 69.29:21.89:10.23 respectively. The proximate composition of the selected runs gave protein content (7.33-9.47%) and crude fibre content (0.79-4.99%). The functional properties of the flours from the optimum runs were water absorption capacity (77.72-84.95%), oil absorption capacity (110.73-127.81%), foaming capacity (5.00-5.90%), swelling capacity (201.00-271.00 g/ml). The anti-nutritional factors of the flour blends gave low value of anti-nutrients such as oxalate (0.270-1.305 mg/g), tannin (1.060-1.941 mg/g), alkaloid (6.813 -10.413 mg/g) and phytate (9.476-19.364 mg/g). Further analyses on the mineral components of the flour blends, showed significant quantities of potassium (1183-4906 mg/kg), phosphorus (108.60-475.00 mg/kg), sodium (113.50-19.90mg/kg) and iron (19.00-32.00 mg/kg). More so, the antioxidant properties of the flours were Fe2+ chelation (0.270- 1.305%), FRAP (3.261- 8.689 mg AAE/g), DPPH (69- 76%), ABTS (0.011 -0.023%), total phenol (2.310 -4.544%) for flour samples and the bread samples have higher values in both DPPH (47-81%) and FRAP respectively (9.30- 13.93 mg AAE/g). The flours also showed soluble and insoluble fibre in the range of (17.750 -36.630%) and (61.870- 82.150%) respectively. Bread was produced from the composite flour and subjected to sensory evaluation on a nine point hedonic scale with overall acceptability in the range of (5.80 -6.03), crumbiness (6.17 – 6.57) and crustiness (6.30 -6.63). The study concluded that composite flour made from rice, fermented rice bran and wheat flours could significantly increase the valorization potential of rice and rice bran.