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Keywords:

  • Blending;
  • Coconut oil;
  • Differential scanning calorimetry;
  • Interesterification;
  • Palm oil;
  • Rice bran oil;
  • Sesame oil;
  • Solid fat content;
  • Thermal properties;
  • Triacylglycerol molecular species

Abstract

Blended oils were prepared by mixing appropriate amounts of coconut oil (CNO) or palm oil (PO) with rice bran oil (RBO) or sesame oil (SESO) to get approximately equal proportions of saturated/monounsaturated/polyunsaturated fatty acids in the oil. These blended oils were subjected to interesterification reactions using lipase to randomize the fatty acid distribution on the glycerol molecule. The fatty acid compositions of the modified oils were evaluated by gas chromatography while changes in triacylglycerol molecular species were followed by HPLC. The triacylglycerol molecular species of the blended oils reflected those present in the parent oil. Interesterification of the blended oils resulted in the exchange of fatty acids within and between the triacylglycerol molecules, resulting in alterations in the existing triacylglycerol molecules. Emergence of new triacylglycerol molecular species following interesterification was also observed. The thermal profiles of the native, blended and interesterified oils were determined by differential scanning calorimetry. Thermal behaviour, melting and crystallization properties of the modified oils showed significant changes reflecting the changes in the triacylglycerol molecules present in the oil. Therefore, interesterification of oils introduces significant changes in the physical properties of oils, even though the overall fatty acid composition of blended and interesterified oils remains the same.