The enhancement of rice bran oil quality through a novel moderate biorefining process

Abstract

Edible grade rice bran oil (RBO) rich in γ-oryzanol and phytosterol but without glycidyl esters (GEs) and monochloropropanediol esters (MCPDEs) was obtained from rice bran by moderate biorefining. High-acid RBO (acid value of 51.22 mg KOH/g) was firstly extracted from rice bran and was then moderately biorefined by combining improved enzymatic degumming, dewaxing, enzymatic deacidification, bleaching, and low-temperature purification (120 °C). Through monitoring the refining process, results showed that the improved enzymatic degumming by combining partial glyceride lipase SMG1-F278N and phospholipase A1 enabled the phosphorus content to quickly decrease to 4.56 mg/kg after optimization by response surface methodology. After biorefining, the final RBO with the acid and peroxide value of 0.10 mg KOH/g and 2.05 mmol/kg reached the grade-one standard of edible oil. Additionally, the final RBO contained 20.66 mg/kg γ-oryzanol and 20.63 mg/kg phytosterol with the retention rate of 71.67% and 59.2% but with undetectable GEs and MCPDEs. The environmental friendliness of the novel moderate biorefining process and superior product quality of the final product point toward a promising viable process for RBO refining in the further.