The determination of different stabilization conditions on the properties of rice brans

This study was planned to determine the effect of different stabilization conditions on lipase activity, phytic acid content, antioxidant properties, phenolic profile, molecular and thermal properties of rice bran (RB). For this purpose, stabilization process was applied to the RB obtained from the rice milling industry and the changes in the RB samples were determined. RB was stabilized by conventional oven and microwave (MW) oven. Three different oven temperature (120, 140 and 160 °C) and three different MW power (600, 700 and 800 W) were used for stabilization. Peroxide values of raw RB and stabilized RB samples showed a linear increase up to 30 days after storage but a decrease was observed in all samples on day 60. Stabilization procedures significantly affected the antioxidant activity, phenolic profile and protein fractions of RB. The antioxidant activities of the RB increased significantly with the stabilization. Microwave-based (MW) stabilization decreased the amount of albumin-globulins and prolamins (p<0.05) and it did not change the amount of glutelins (p>0.05). Conversely, the stabilization with conventional oven significantly increased the amount of albumin-globulins and prolamins and it significantly decreased the amount of glutelins. The results obtained from Fourier-transform infrared spectroscopy (FTIR) spectra, showed that stabilization changed the intensity and location of some bands. The best method to reduce the lipase activity and to improve the functional properties of RB was MW based treatment. Also, thermal decomposition was delayed by MW based stabilization. Consequently, it was revealed that MW based treatment was short-term and effective method to stabilize of RB.