Separation of gamma oryzanol from soapstock by product from rice bran oil industry

This study aims to produce value added product, γ-oryzanol, by extraction of the compound from rice bran oil soapstock, the by product from rice bran oil industry. The suitable conditions for the separation of γ-oryzanol were determined. First, soapstock was saponified with 2.4 % wt of sodium hydroxide. The saponified product was then dehydrated and quantified for the content of γ-oryzanol. The γ-oryzanol content in the dried saponified soapstock was found to be 5.83 % by weight. Since the dried saponified soapstock was used as a starting material for extraction, the amount of γ-oryzanol in the dried saponified soapstock was taken as a basis for the calculation of the γ-oryzanol yield. Extraction was carried out using ethyl acetate as a solvent in a soxhlet apparatus. The ratio of raw material to solvent was varied in the range of 3-15 g raw material to 200 ml solvent. The results showed that the suitable ratio was 15 g/200 ml solvent. The extract was then evaporated and the solution was crystallized twice. For the first step crystallization, two suitable solvent mixture systems (15-35 % v/v of acetone in methanol and 10-30 % v/v of ethyl acetate in methanol), the temperature (25 and 30 °C), and time (1 and 2 hr) for crystallization were studied. The result showed that 20 % v/v of ethyl acetate in methanol was suitable and the yields are comparable to original solvent mixture at 25 % v/v of acetone. The suitable temperature and crystallization time was 30 °C and 1 hr., respectively. The supernatant from first step crystallization was then allowed to crystallize at lower temperature in second step. The suitable temperatures (2, 5 and 10 °C) and extraction times (8, 16 and 24 hr.) were studied. The suitable temperature and time were found to be 5 °C and 24 hr., respectively. After the second crystallization step, the purity and yield of γ-oryzanol as analyzed by HPLC were found to be 55.17 % wt and 74.6 % wt, respectively. Moreover, quantification of γ-oryzanol by using UV-visible spectrophotometric analysis was consistent and gave the same conclusion with HPLC.