Optimisation of enzymatic directed interesterification of palm oil for high yield of triunsaturated triacylglycerol using response surface methodology

Abstract

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.