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This study reports the optimization of geranyl butanoate production by esterification of geraniol and butanoic acid in a solventfree system using two immobilized lipases as catalyst. The operating conditions that optimized geranyl butanoate production were determined to be 40 °C, a geraniol to butanoic acid molar ratio of 3:1, 150 rpm, 5 wt% of enzyme, and 1 h of reaction, which resulted in a reaction conversion of about 97% for Novozyme 435. When homemade Novozyme NZL-102-LYO-HQ (Cal-B) immobilized in polyurethane foam was used as catalyst, the experimental conditions of an alcohol to acid molar ratio of 5:1, 70 °C, 150 rpm, 5 wt% of enzyme, and 1 h of reaction gave a conversion of 95%. New experimental data on enzymatic esterification of geraniol and butanoic acid for geranyl butanoate production are reported in this work, showing that the technique is promising for overcoming the well-known drawbacks of the chemical-catalyzed route.

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The confinement of lipase from P. crustosum in a membrane reactor was possible, resulting in the satisfactory conversion of butyric acid to ethyl butyrate with the possibility of reuse of the immobilized enzyme.

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BACKGROUND The 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. RESULTS Before 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. CONCLUSION Activation 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. © 2017 Society of Chemical Industry

Synthesis of isoamyl acetate by mechanical and ultrasonic solvent‐free agitations using Candida antarctica lipase B (CALB) as biocatalyst immobilized in polyurethane was studied. Temperature (24.8–75.2 °C), ultrasonic power (35–123 W; only in ultrasonic system) and molar ratio of substrates (1:3.64–1:10.36) were the parameters evaluated. The responses taken into account were the acetic acid conversion in the esterification reaction (21–95%) and the residual conversion of substrates after successive reuse cycles of CALB. Ultrasonic system was advantageous because the substrate conversions into isoamyl acetate were reached six times earlier than in mechanical system. An increase in the temperature and ultrasonic power and a reduction in acetic acid : isoamyl alcohol ratio favored an increase in conversion yields. CALB used in ultrasonic reactions maintained more than 60% of its residual activity after 27 reuse cycles, which was more than thrice (eight reuse cycles) when using CALB in mechanical reactions. Practical applications The practical uses of isoamyl acetate are mainly as a food additive and as a solvent in the aircraft industry. In food‐related areas, this ester is used to confer characteristics such as banana (or pear) smell and flavor in foods and beverages. It has a pleasant odor and low toxicity, which encourages its widespread use in different receipts, including in the formulation of beers.

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