Effect of enzymatic trans- and interesterification on the thermal properties of groundnut and linseed oils and their blends

Abstract

The present study was undertaken to compare the alterations observed in the triacylglycerol (TAG) molecular species of blended and interesterified oils containing groundnut oil (GNO) and linseed oil (LIN). The blended oil (BLE) was subjected to a lipase catalyzed reaction to prepare transesterified oil (TRA). A structured lipid (STR) was also prepared by a lipase catalyzed acidolysis reaction of GNO and free fatty acids concentrate from LIN. The changes in the molecular species of modified lipids were determined by high performance liquid chromatography. The thermal profiles were determined by differential scanning calorimetry. In comparison with GNO, the triunsaturated triacylglycerols were increased and the disaturated triacylglycerol molecular species were decreased in TRA and STR. Both BLE and TRA showed a decrease in the onset temperature for crystallization as compared to that observed with GNO. The total transitional enthalpy for crystallization was higher for BLE, TRA and STR as compared to GNO. The melting temperature of TRA and STR showed a decrease in comparison to GNO, reflecting on the changes in the TAG molecules species present in the oil. Thus, interesterification of oils introduced changes in the physical properties of oils, even though the overall fatty acid composition of blended and interesterified oils remained similar. © AOCS 2012.