Lipase from Candida rugosa was coated with surfactants and immobilized on silica to catalyze esterification reaction to produce ethyl butyrate, a flavour ester. Various surfactants were tested amongst which non-ionic surfactant performed better than cationic surfactant, whereas inhibitory effect was observed with an anionic surfactant. The optimal temperature of the esterification reaction was 37 degrees C. Triton X 100 and cetyltrimethyl ammonium bromide (CTAB) were further characterized in order to achieve the optimum catalytic activity of lipase. A low amount of surfactant proved to be most effective. (c) 2005 Elsevier Ltd. All rights reserved.