Wax esters are long-chain esters that have been widely applied in premium lubricants, parting agents, antifoaming agents and cosmetics. In this study, the biocatalytic preparation of a specific wax ester, cetyl octanoate, is performed in n-hexane using two commercial immobilized lipases, i.e., Lipozyme® RMIM (Rhizomucor miehei) and Novozym® 435 (Candida antarctica). Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) are employed to evaluate the effects of reaction time (1–5 h), reaction temperature (45–65 °C), substrate molar ratio (1–3:1), and enzyme amount (10%–50%) on the yield of cetyl octanoate. Using RSM to optimize the reaction, the maximum yields reached 94% and 98% using Lipozyme® RMIM and Novozym® 435, respectively. The optimum conditions for synthesis of cetyl octanoate by both lipases are established and compared. Novozym® 435 proves to be a more efficient biocatalyst than Lipozyme® RMIM.

Waxes are esters obtained from long-chain fatty acids and long-chain alcohols which are biodegradable, biocompatible and nontoxic. Seafowl feather oil is a natural wax ester that exists on seafowl feathers. Cetyl 2-ethylhexanoate is the major ingredient of seafowl feather oil. Cetyl 2-ethylhexanoate is widely used in cosmetics as a base oil because of its lubricity, moisture retention and non-toxic properties. An optimal production of cetyl 2-ethylhexanoate by direct esterification of cetyl alcohol with 2-ethylhexanoic acid was developed using an immobilized lipase (Novozym Ò 435) as a catalyst in n-hexane. Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) were employed to evaluate the effects of reaction time, reaction temperature, substrate molar ratio, and enzyme amount on the yield of cetyl 2-ethylhexanoate. The results show that reaction time, reaction temperature, substrate molar ratio, and enzyme amount have significant effects on the yield of the esterification reaction. On the basis of ridge-max analysis, the optimum conditions were as follows: a reaction time of 2.65 days, a reaction temperature of 56.18°C, a substrate molar ratio of 2.55:1, and an enzyme amount of 251.39%.The predicted and experimental values of molar conversion were 91.95 and 89.75 ± 1.06%, respectively.