Effect of particle size of rice bran on gamma-oryzanol content and compounds

The reduction of particle size can facilitate the extraction of phytochemical compounds. In this study was evaluated the effect of rice bran particles size in the yield and characteristics of γ-oryzanol compound. The γ-oryzanol extraction was realized with hexane and isopropanol solvents and quantification by spectrophotometric method. The γ-oryzanol extracts were characterized in relation of theirs majority components in HPLC-UV and the antioxidant capacity verified by the free radical DPPH● consumption. The γ-oryzanol yield varied of 0.10-1.54 mg/g of bran, and the highest yield was obtained in particles smaller than 0.39 mm. The γ-oryzanol majority components presence (cycloartenyl ferulate, 2,4-methylenecycloartanyl ferulate, campesteryl ferulate e β-sitosteryl ferulate) in the extracts was confirmed and verified differences in the profile of this components in function of different particles sizes. The γ-oryzanol extract obtained from particle sizes between 0.73 and 1.67 mm demonstrated most specific inhibition of DPPH radical (6.7%) and IC50 6.63 μg/mL. When the particle size is reduced, the access surface to the extraction solvent is increased resulting in more γ-oryzanol extraction, however the extract from larger particles was more efficient as antioxidant.