The effect of water on the esterification reaction. (A) The effect of adding water into the reaction mixture. Solid squares represent the esterification degree with various amounts of added water. Open circles indicate the esterification degree of the fresh esterification reaction catalyzed by the dried immobilized lipase membrane. (B) The effect of the addition of various amounts of molecular sieves. The reaction system comprised 2.82 g of fatty acid, 580 μl of ethanol added in various ways and 0.33 g of immobilized lipase at 30°C for 5 hours and spun at 190 rpm.