A simple and efficient method for synthesis and extraction of ethyl ferulate from γ-oryzanol

Ethyl ferulate (EF) is a ferulic acid (FA) derivative with high commercial value. It is not found
naturally and is mostly synthesized from FA via esterification with ethanol. The present work aimed to
synthesize the EF from γ-oryzanol, a natural antioxidant from rice bran oil via acid-catalyzed
transethylation at refluxing temperature of ethanol. The reaction was optimized by central composite design
(CCD) under response surface methodology. Based on the CCD, the optimum condition for the synthesis of
EF from 0.50 g of γ-oryzanol was as follows: γ-oryzanol to ethanol ratio of 0.50:2 (g/mL), 12.30% (v/v)
H2SO4, and a reaction time of 9.37 h; these conditions correspond to a maximum EF yield of 87.11%.
Moreover, the optimized transethylation condition was further validated using 12.50 g of γ-oryzanol. At the
end of the reaction time, distilled water was added as antisolvent to selectively crystallize the co-products,
phytosterol and unreacted γ-oryzanol, by adjusting the ethanol concentration to 49.95% (v/v). The recovery
yield of 83.60% with a purity of 98% of EF was achieved. In addition, the DPPH and ABTS assays showed
similar antioxidant activities between the prepared and commercial EF.