Fully hydrogenated expanded press soybean oil (FHEPSO) rich in naturally bioactive components was prepared using Palladium on Carbon (Pd/C) catalyst. Interesterified fat was prepared from binary blends of FHEPSO and cold press corn oil (CPCO) with FHEPSO/CPCO mass ratios of 50:50, 40:60 and 30:70. Lipozyme RM IM (6 wt% of total substrate) was used in a supercritical CO2 system to catalyze the transesterification. The fatty acid compositions had no significant changes in the fats before and after interesterification, and trans-fatty acid (TFA) was not detected. The fatty acid compositions within triacylglycerol (TAG) were rearranged, and the amounts of trisaturated and triunsaturated TAG decreased, whereas that of mixed TAG increased as a result of interesterification. The enzymatic interesterified fats (EIEF) had a lower solid fat content (SFC), broader melting and plasticity ranges compared to the noninteresterified blend (NIB). According to X-ray diffraction (XRD), the predominant crystal form had changed from β to β'. EIEF contained 0.33-0.51 g/100 g phospholipids, 88.6-105.6 mg/100 g total tocopherols, and 916-1053 mg/100 g total phytosterols, which could confer health benefits. The results indicated that EIEF may have a potential use in trans-free margarine stock preparation.
Keywords: interesterification; margarine stock; naturally bioactive components; press oils; zero trans fatty acid.