Esterification of (−)‐menthol with fatty acids in isooctane was successfully catalyzed using a commercial lipase, Lipase AY “Amano” 30 from Candida rugosa in original powder form. The esterification reactions were performed to elucidate the effects of temperature, enzyme load, molar ratio of (−)‐menthol/fatty acid, and fatty acid type, keeping the (−)‐menthol concentration at 200 mM. At the optimal conditions for (−)‐menthol esterification, determined at a (−)‐menthol/lauric acid molar ratio of 1∶1 and 35°C [1.5 g enzyme/g (−)‐menthol, 0.1 g molecular sieves], the molar conversion of (−)‐menthol after 48 h reached 93%. After 24h, the lowest and the highest molar conversions of fatty acids at 2∶1 molar ratio were obtained with myristic acid (71%) and margaric acid (98%), respectively. After 48 h, the molar conversions of lauric acid at molar ratios 2∶1, 1∶1, and 1∶2 were 98, 93, and 49%, respectively.

Esterification of (−)‐menthol and (±)‐menthol with lauric acid in isooctane was successfully catalyzed by a commercial nonioic surfactant (sorbitan monosterate)‐coated lipase from Candida rugosa (Lipase AY “Amano” 30) at the molar ratio of 1∶1 and at 35°C using 1.5 g enzyme/g (−)‐menthol and 0.1‐g molecular sieves. After 1 h, molar conversion of (−)‐menthol reached 81%. Equilibrium was reached after ca. 4 h, giving a (−)‐menthol molar conversion of 94%. Under the same conditions, native lipase catalyzed the esterification of (−)‐menthol and lauric acid to yield a molar conversion of 93% after 72 h. Coating the lipase with sorbitan monosterate increased the esterification rates of both (−)‐menthol and (±)‐menthol with lauric acid. After 6 h, the molar conversions of (−)‐menthol and (±)‐menthol were 94, and 62%, respectively.

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