Zero trans shortening using rice bran oil, palm oil and palm stearin through interesterification at pilot scale

Abstract

Fat blends, formulated by mixing refined, bleached and deodorised (RBD) palm oil (PO) or RBD palm stearin (PS) with RBD rice bran oil (RBO) in various ratios were subjected to chemical interesterification (CIE) at pilot scale using sodium methoxide (NaOMe) as catalyst. The resultant interesterified fat was processed through a margarine crystalliser under optimised conditions. The blends before and after CIE were investigated for triacylglycerol (TAG) composition, solid fat content (SFC) and melting characteristics, polymorphic form, fatty acid composition (FAC), bioactive (tocols, sterols, oryzanol) constituents and trans fatty acids (TFA). CIE was found to be very effective in terms of rearrangement of fatty acids (FAs) among TAGs and consequent changes in the physical characteristics. The SFC of the interesterified PS/RBO blends decreased significantly (P <= 0.05) when compared with those of PO/RBO blends. The interesterified binary blends with 50-60% PS and 40-50% RBO, and 70-80% PO and 20-30% RBO had SFC curves in the range of all-purpose type shortenings. CIE facilitated the formation of beta' polymorphic forms. FAC of shortenings prepared using the optimised blends contained 15-20% C(18:2) polyunsaturated fatty acid (PUFA) and no TFA. Total tocol, sterol and oryzanol content of zero trans shortenings were 650-1145, 408-17 583 and 1309-14 430 ppm. CIE using NaOMe did not affect the bioactive constituents significantly (P <= 0.05)