Effect of saponification on composition of unsaponifiable matter in rice bran oil

Abstract

Rice Bran Oil contains a variety of Unsaponifiable Constituents (USC) that are presumed to contribute to the high value of Unsaponifable Matter (USM). The objectives of the present study were to identify and quantify the constituents in USM. The changes that the unsaponifiables undergo during saponification were also quantitatively investigated. While analyzing the percentage of all constituents, the percentage of sterol get increased from 22.46 to 23.77 in USM of crude rice bran oil (CRBO) and 33.42 to 36.79 in USM of refined rice bran oil (RRBO). Oryzanol that comprised 34% of the unsaponifiable in the crude oil by direct estimation was almost eliminated in USM and same in refined oil. The results also revealed the presence of four additional classes of compounds that were quantified in USM (policosanol, fatty aldehydes, triterpene alcohols and potassium salt of oryzanols). Among the four classes of compounds, policosanol contributed high percentage in USM, (43.39% in CRBO and 28.46% in RRBO). Fatty aldehydes, triterpene alcohols and potassium salt of oryzanols together contributed 27.68% and 25.13% of USM from CRBO and RRBO respectively. The HPTLC method employed here thus, accounted for 96.75% by wt of the USM of CRBO and 92.00% by wt of the USM of RRBO