Effects of chemical interesterification on the physicochemical properties of palm stearin and rice bran oil blends / Tunku Saidatul Sa’adiah Tunku Saffuan

The aims of this study were to determine the effects of chemical interesterification on the physicochemical properties of palm stearin, rice bran oil and their blends, and to identify the most suitable blend that could be used for certain food applications. Palm stearin and rice bran oil (PSRBO) were blended according to mass ratios of 100:0, 30:70, 50:50, 70:30 and 0:100 (PS:RBO) followed by chemical interesterification using sodium methoxide as catalyst. The effects of chemical interesterification on the triacylglycerol (TAG) composition, slip melting point (SMP), solid fat content (SFC), microstructure, polymorphism and hardness index (HI) of the blends were determined. Results show that after chemical interesterification there were decrease and increase in the amount of several TAG. Changes in TAG composition caused changes in the physical properties of the blends. Both SMP and SFC of all blends decreased significantly (p<0.05) after interesterification except for 100% RBO. However, only the HI of blends of 100% and 50% PS were decreased significantly (p<0.05) after interesterification. The crystals of the blends became smaller and reduced in number after interesterification. Interesterification promoted the formation of more β' crystals than β in all blends. The 30:70 PSRBO blend was the most suitable for margarine production as it melted close to body temperature.