Immobilization of Candida antarctica lipase onto cellulose acetate-coated Fe_2O_3 nanoparticles for glycerolysis of olive oil

摘要

Candida antarctica lipase was covalently immobilized onto the surface of cellulose acetate-coated Fe_2O_3 nanoparticles. The characterizations of immobilized lipase were examined by Fourier transform infrared spectropho-tometer (FTIR) and field emission gun-scanning electron microscopy (FEG-SEM). The immobilized lipase was assayed for production of monoglycerides (MG) and diglycerides (DG) by glycerolysis of olive oil in a solvent medium. The effect of various reaction conditions on the MG and DG production such as reaction time, temperature, the molar ratio of glycerol to oil and amount of immobilized lipase was investigated. The optimum condition for MG and DG production was found at 50 ℃ temperature and 0.025 g of lipase with the molar ratio of glycerol to oil 1.5: 1 in 5 h of reaction time. The effect of substrate concentration on enzymatic activity of the free and immobilized lipase showed the best fits to the Lineweaver-Burk plots. The K_m and V_(max) values of immobilized lipase were found to be 25 mM and 0.58 mM/ min, whereas that for free lipase was 52.63 mM and 1.75 mM/min, respectively. The activation and deactivation energy was found to decrease for immobilization of lipase on cellulose acetate-coated Fe_2O_3 nanoparticles.