Rice bran oil extraction by ethanol: optimization of γ-oryzanol and polyphenol

Abstract

Rice bran oil (RBO) contains γ-oryzanol and polyphenols which are very beneficial for health. The work investigated the effect of temperature (oC) (X1), time (hr) (X2), and volume of ethanol (mL) (X3) as a solvent on the oil yield (%) (Y1), γ-oryzanol (Y2), and total polyphenol content (TPC) of RBO (Y3) with apply reflux extraction method. The study was conducted using Response Surface Methodology (RSM) based on Central Composite Design (CCD) model with three levels and six centre points. The data were analyzed using Design-Expert 10 software to create and evaluate models and to plot the response curves of three-dimensional surfaces. The maximum of Y1 = 16.4%, Y2 = 195.49 mg.L-1, and Y3 = 1.02 mg gallic acid equivalent (GAE).g-1 were achieved under the optimum conditions process of X1, X2, and X3 were 78.7oC, 1.6 hrs, and 496.5 mL ethanol/100 g rice bran, respectively. The average of Y1, Y2, and Y3 on verified models were 16.1±0.66%, 189.12±1.18 mg.L-1, and 0.91±0.54 mg GAE.g-1, respectively. These indicated that this method is very promising to be applied in industry and as an effort to apply the concept of "green" solvents that is safe for humans and the environment.