Ohmic heating assisted extraction improves the concentrations of phytochemicals in rice bran oil and unsaponifiable matter

Abstract

The impact of ohmic heating-assisted solvent extraction (OHM-AE) of oil and unsaponifiable matter (USM) from rice bran was investigated for different concentrations of tocols and γ-oryzanol. Rice bran samples with moisture contents (MC) of 30% and 40% were ohmically-treated with three levels of electric field strength (E) at 100, 150 and 200 V/cm prior to extraction of rice bran oil and USM. Oil and USM prepared by conventional methods (CM) were included as controls. OHM-AE increased the concentration of phytochemicals and antioxidant activity of both rice bran oil and USM. The highest concentrations of γ-tocopherol, γ-tocotrienol, γ-oryzanol and total phenolic content in the oil and USM were observed in the bran with 30% MC (extracted by OHM-AE at 150 and 200 V/cm), and the bran with 40% MC (extracted at 100, 150, and 200 V/cm). Similarly, OHM-AE under these conditions yielded higher oil recovery with stronger antioxidant activity than the CM method. This suggested that OHM-AE could be an effective method to extract rice bran, offering both increased oil yield and high concentration of phytochemicals.