Optimization of extraction conditions for phytic acid from rice bran using response surface methodology and its antioxidant effects

Solid-liquid extraction of phytic acid (PA) from rice bran was optimized by the maximization of the yield using response surface methodology. A Box-Behnken design was used to monitor the effects of three processing parameters of extraction on the PA yield, including ratio of acid solution to raw material (mL/g), hydrochloric acid concentration (mol/L), and extraction time (h). The results showed that the optimal conditions were acid solution/raw material of 8.5:1 (mL/g), HCl concentration 0.62 mol/L and extraction time 5.5 h. Validation tests indicated that the actual yield of PA was (2.15 +/- 0.02)% with RSD = 1.92% (n = 5) under the optimized conditions, which was in good agreement with predicted yield. Antioxidant assays suggested that the extracted PA had weaker DPPH, hydroxyl and superoxide free-radical-scavenging capabilities than vitamin C at the same concentration of 0.5 mg/mL.