Optimization of enzymatic interesterification of coconut (<i>Cocos nucifera</i>) and Sesame (<i>Sesamum indicum</i>) oils using <i>Thermomyces lanuginosus</i> lipase by response surface methodology

Blends ofcoconut ( Cocosnucifera ) oil (CO) and sesame ( Sesamumindicum ) oil (SO) were enzymatically interesrerified using aqueous lipase derived from Thermomyceslanuginosus and the reaction conditions were optimized using Response Surface Methodology (RSM). A three-factor, three-level central composite design (facecentred cube design) was employed to optimize the reaction parameters, namely temperature (45-65°C), time (16-48 h) and mass ratio of oils (CO:SO; 70:30 - 50:50). Lipase, diluted in phosphate buffer (pH 8) was used at 0.2% (v/w) of the substrate. Degree of interesterification (DI), and the ratio of monounsaturated and polyunsaturated fatty acids (MUFA:PUFA) of triacylglycerols (TAGs)were used as response variables. Triacylglycerol (TAG) fractions of the samples were separated using Thin Layer Chromatography (TLC) and the fatty acid composition of TAGs was determined using Gas-Liquid Chromatography (GLC). Thelinear and squared effects of temperature and time were significant (p<0.05) for DI whilethe reaction conditions did not exhibit a significant (p<0.05) effect on MUFA: PUFA ratio. The optimum conditions for enzymatic interesterificationwere45°C (temperature), 40.24 h (time) and 70:30 (weight ratio of CO:SO).Under these optimized conditions, the DI was 28.98% and MUFA:PUFA was 1.50±0.06. According to the response surface regression analysis, the R2 value for DI versus reaction parameters was 91.85% and MUFA:PUFA ratio versus reaction parameters was 61.82%. Therefore it can be concluded that enzymatic interesterification can effectively be applied to develop nutritionally and functionally superior modified oilknown as structured lipids using coconut and sesame oils.