ENZYMATIC SYNTHESIS OPTIMIZATION OF CETYL STEARATE

Rice husk silica (RHS) has been extracted by a hydrothermal process and functionalized with triethoxy(octyl)silane (OCTES) to produce a hydrophobic support (Octyl–SiO2) to be used in the immobilization of lipase from Thermomyces lanuginosus (TLL) via interfacial activation. Maximum immobilized protein loading of 21.9 ± 0.1 mg/g of support using na initial protein loading of 35 mg/g was observed. The prepared biocatalyst was used in cetyl estearate synthesis via direct esterification reaction in a hexane system. The effect of certain factors on the ester synthesis has been evaluated. Under optimal conditions (64 °C, biocatalyst concentration of 21% m/v, 170 rpm and acid:alcohol equimolar ratio – 1:1), maximum conversion percentage of around 90% after 60 min of reaction was attained. After nine successive cycles of reaction in a batch system, the biocatalyst retained 90% of its original activity. These results show the potential application of the support obtained in lipase immobilization and its use as biocatalyst in ester synthesis.