Optimization of Vitamin E Extraction from Rice Bran Oil Deodorizer Distillate using Response Surface Methodology

Rice bran oil deodorizer distillate (RBODD) is the low valuable secondary product of refinery rice bran oil. However, RBODD contains bioactive compounds such as vitamin E, gamma-oryzanols, and phytosterols. To increase value of vitamin E obtained from underutilized product, tocopherols and tocotrienols were extracted from RBODD using ethanol followed by a freezing step. The response surface method (RSM) is known as a potential tool for optimizing processing parameters in order to save time, energy, and chemical material. In current study, vitamin E extract (VEE) was extracted using ethanol and response surface method (RSM) was employed to investigate the optimum condition. The ratio of RBODD: ethanol (1:5, 1:10, and 1:15) and the incubation temperature (0, -20, and -40℃) of vitamin E extraction were used to design the experiment using a central composite design (CCD). Once the optimization process was completed, the RSM was executed using the following 5 responses simultaneously: VEET3, VEEToc, VEETot, RecoveryVEE, and YieldVEE. Results showed that values of each parameter were VEET3 (10.69-89.60 mg/g), VEEToc (2.85-23.37 mg/g), VEETot (13.53-112.97mg/g), RecoveryVEE (16.15-134.76%), and YieldVEE (12.64-44.48%). All model predictions were significant (p-value < 0.05), with non-significant lack of fit (> 0.05). In addition, the values of R2 and R2(Adj) of model were in the range of 0.922-0.988 and 0.893-0.982, respectively. According to these findings, response values were associated with RBODD:ethanol ratio and the incubation temperature. The ratio 1:9.5 (RBODD: Ethanol) and incubation temperature at -26.5 ℃ provided the optimal condition for vitamin E extraction from RBODD. At this optimum condition, it was determined that the predicted responses for VEET3, VEEToc, VEETot, RecoveryVEE, and YieldVEE were 81.87 mg/g, 23.70 mg/g, 103.64 mg/g, 123.63 %, and 20.05%, respectively. The obtained product with high content of tocopherol and tocotrienol can be used as ingredient in food as well as pharmaceutical applications.