Reesterification of free fatty acids and glycerol for edible oil production

Abstract

Studies on the reesterification of rice bran oil was performed to find out optimum condition of the reaction. Reesterification of crude rice bran oil (A.V. 119.7) was attempted with addition of theoretical equivalent of glycerol. Tin chloride ($SnCl_2.2H_2O$) was used as a catalyst at 0.2\% concentration. In the preliminary analysis of the reactant, the crude rice bran oil contained 92.9\% of neutral lipid. Triglyceride content of the reactant was 10.4 \%. Oleic acid (42.5\%), linoleic acid (29.0\%), and palmitic acid (20.3\%) were the major components of fatty acids from HPLC analysis of fatty acid composition. According to the analysis of product, catalyzed reaction at 250$^\circ$C decreased the acid value to 2.7 in six hours, while uncatalyzed reaction decreased the acid value only to 12.1 under the same condition. The rate of reaction was increased as the temperature was elevated. In case of catalyzed reaction, A.V. of each reesterified oil was decreased to 16.1, 5.4, and 2.7 in six hours, when the reaction temperature were 170$^\circ$C, 210$^\circ$C, and 250$^\circ$C respectively. Iodine value (I.V.) was decreased considerably when the reesterification temperature was elevated regardless of the presence of catalyst. The decrease in I.V. of reesterified oil at 250$^\circ$C for 6 hours was about 2.0, but the decrease was less than 0.5 when reesterified at 170$^\circ$C respectively. Reesterified oil of A.V. 12.1, and A.V. 2.7 contained 61.1\%, and 72.9\% of triglyceride respectively.