BACKGROUNDThe objective of this work was to evaluate the activation of Candida antarctica lipase B (CALB) in pressurized CO2 or liquefied petroleum gas (LPG) and, thereafter, to evaluate the synthesis of esters using activated CALB as a biocatalyst. Before activation, CALB was immobilized in polyurethane. For the esterification reactions, mechanical or ultrasonic agitations were studied. The stability of CALB after reuse cycles was also evaluated. RESULTSBefore activation, the enzymatic activity of immobilized CALB was 789 U g(-1). After activation in pressurized CO2 and LPG, the activities increased to 2486 U g(-1) and 1413 U g(-1), respectively. Consequently, the residual activities of CALB after activation in pressurized CO2 and LPG were 315% and 179%, respectively. For the best condition of reaction under ultrasonic agitation, oleic acid conversion was 51.2% when using non-activated CALB. Otherwise, oleic acid conversions were 66.5% and 77.1% when using CALB activated in LPG and CO2, respectively. This biocatalyst maintained more than 80% of its residual activity when reused for up to 13 cycles. CONCLUSIONActivation of CALB in pressurized CO2 provided enzymatic activities 1.76 times higher than activation in pressurized LPG did. Immobilized CALB had good performance as a stable biocatalyst for esterification reactions under ultrasonic agitation. (c) 2017 Society of Chemical Industry