Determination of γ-Oryzanol in Rice Bran Oil Refinery Soap Stock

Abstract

The method of Seemanathan et al (J. Food Sci. Tech. 23: 270-273(1989)) for determination ofγ-oryzanol, in soap stock of rice bran oil, is very tedious and time consuming. This would hinder theevaluation of the method of extraction and purification of γ-oryzanol. Thus, a simple and rapid methodof determination of γ-oryzanol in rice bran soap stock is proposed. The method depends on theaccurate determination of the partition coefficient (K) either by two consecutive or two parallelextractions. K and concentration of γ-oryzanol in the soap stock are then solved mathematically.

By using ethyl acetate as solvent for extraction, it is found that soap stock contained 7.6% ofγ-oryzanol on the dry weight basis and 2.9% on the wet weight basis. The K of γ-oryzanol distributedbetween ethyl acetate and soap stock (pH 9.5) is 4.11. Thus it is estimated that about 80% of theγ-oryzanol is extracted into ethyl acetate of equal volume.

Keywords : Oryzanol / Partition Coefficient / Rice Bran Oil / Soap Stock