Lipase-catalysed synthesis of erythorbyl laurate in acetonitrile

Erythorbic acid, a stereoisomer of ascorbic acid, has been used as an antioxidant, but has poor lipophilicity. To overcome this problem, lipase-catalysed esterification between erythorbic acid and lauric acid was performed to synthesise the erythorbyl fatty acid ester in acetonitrile; subsequently, the time course of the enzymatic esterification was monitored, using HPLC equipped with RI- and UV-detectors. A steady state was achieved after 8 h, from initiation of the esterification, and the degree of esterification (molar conversion yield) reached 78.5%. After the purification procedure, the product synthesised by immobilised lipase (Novozym (R) 435) was identified as erythorbyl laurate (6-O-lauroyl-erythorbic acid) by LC-ESI-MS, H-1, and C-13 NMR analysis. The results suggest that erythorbyl laurate, produced in this study, could be used as an emulsifier with antioxidant activity to retard oxidation of lipid foods. (C) 2011 Elsevier Ltd. All rights reserved.