Subcritical liquified dimethyl ether and supercritical fluid carbon dioxide extraction of gamma oryzanol from rice bran acid oil

Abstract

Gamma oryzanol (γ-oryzanol) is a bioactive compound in rice bran acid oil, a by-product of the rice bran oil refining process that possesses various pharmacological properties. This study investigated the effect of green technology supercritical fluid carbon dioxide extraction (SF–CO2) and subcritical liquified dimethyl ether extraction (SUBLDME) of γ-oryzanol from rice bran acid oil. Results showed that subcritical liquified dimethyl ether extracted oryzanol at 4865.25 mg/100 g from rice bran acid oil without pretreatment by hexane and ethyl acetate compared with supercritical fluid carbon dioxide extraction (2569.04 mg/100 g), with high extraction efficiency (62.73 vs 18.86%). Further extraction of the filter cake remaining from supercritical fluid carbon dioxide extraction from rice bran acid oil without pretreatment using subcritical liquified dimethyl ether extraction gave the highest percentage yield and γ-oryzanol contents (8128.51 mg/100 g). Supercritical fluid carbon dioxide extraction together with subcritical liquified dimethyl ether extraction showed promise as a green technology to extract γ-oryzanol from rice bran acid oil. Further studies are required to optimize both SF-CO2 and SUBLDME extraction methods to increase the γ-oryzanol content.