Unsaturated fatty acids (USAFA), especially monounsaturated fatty acids (MUFA), has been shown to provide substantial health benefits. This study attempted to increase the triunsaturated (U3 ) triacylglycerols (TAG) content in palm oil (PO) via lipase-catalysed directed interesterification (EDIE), to enable the production of a liquid fraction that is high in USAFA, especially MUFA. A response surface methodology with three factors and five levels in a central composite design was employed for optimisation of the EDIE conditions for the U3 TAG production. The effects of reaction temperature (20°C-50°C), reaction time (12-28 hr) and enzyme load (2%-18%) on the U3 TAG and by-products yields were investigated. Well-fitted quadratic and linear models were successfully established for both responses. All processing conditions affected significantly (p<0.05) U3 TAG yield. By-products yield was affected by reaction time and temperature. Although increasing reaction temperature and enzyme load, and extending the reaction time resulted in a higher U3 TAG yield, a higher amount of by-products were formed as well. The optimised processing conditions were a reaction temperature of 30°C and reaction time of 18 hr, when immobilised lipase enzyme load was set at 10% (w/w), and resulted in yields of about 27% of U3 TAG and 23% of by-products.

Keywords: enzymatic directed interesterification, palm oil, response surface methodology, triunsaturated triacylglycerol, unsaturated fatty acid