(582dv) Production of Flavor Esters By Candida Antarctica Lipase Type B Immobilized On Magnetic Nanoparticles

The esters of short-chain fatty acids are an important group of flavor and fragrance compounds widely used in food, beverage, cosmetic and pharmaceutical industries. These aromas are typically extracted from natural sources, but some problems arise with respect to availability due to environmental problems. Thus natural catalysts are required  and products obtained from the enzyme mediated reactions are considered natural. Lipases produced by Candida sp. are well-established enzymes for biocatalysis purposes, especially Candida antarctica lipase type B (CALB). Therefore, in this work, Candida antarctica lipase B (CALB) immobilized onto iron magnetic nanoparticles was evaluated as biocatalyst for the synthesis of flavor esters. Methyl and ethyl butyrate were synthesized by esterification of butyric acid with methanol and ethanol in different solvents. The nanoparticles were produced by the co-precipitation method. Modifications were carried out on the nanoparticles' surfaces with aminopropyltriethoxysilane and glutaraldehyde. The immobilization was performed in the presence of 100mM bicarbonate buffer, pH 10, at 25 °C.  The process parameters (solvents, temperature, substrate concentrations, molar ratio, stirring speed and reaction time) were studied. The optimum conditions for both esters were heptano as solvent, 25 °C, 0,5 mol/L and  0,4 mol/L of substrates, molar ratio of 1:1, amount of biocatalyst: 10 mg, 150 rpm and 8 h of reaction. Maximum conversion of methyl butyrate (93,9 \%) and ethyl butyrate (96,8 \%) were achieved after 8 h of reaction at 25 °C for CALB immobilized onto magnetic nanoparticles. The synthesis of flavor esters was also evaluated by using novozyme 435, a commercial biocatalyst, for comparison. Operational stability (consecutive cycles of synthesis of esters) were performed and CALB immobilized onto magnetic nanoparticles retained 74 % of its initial activity after 12 cycles, while novozym 435 retained 81 %.