Optimized synthesis of lipase-catalyzed l-ascorbyl laurate by Novozym® 435

l-Ascorbyl laurate is a fatty acid derivative of l-ascorbic acid which can be widely used as a natural antioxidant in both lipid containing food and cosmetic applications. To avoid any possible harmful effects from chemically synthesized product, the enzymatic synthesis appears to be the best way to satisfy the consumer demand for natural antioxidants. The ability of immobilized lipase from Candida antarctica (Novozym® 435) to catalyze the direct esterification between l-ascorbic acid and lauric acid was investigated. Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time (2–10 h), temperature (25–65 °C), enzyme amount (10–50% w/w of l-ascorbic acid), and substrate molar ratio of l-ascorbic acid to lauric acid (1:1–1:5) on percentage molar conversion to l-ascorbyl laurate. Based on the analysis result of ridge max, the optimal enzymatic synthesis conditions were predicted as follows: reaction time 6.7 h, temperature 30.6 °C, enzyme amount 34.5%, substrate molar ratio 1:4.3; and the optimal actual yield was 93.2%.