Study of Vitamin C ester synthesis by immobilized lipase from Candida sp.

Oleoyl ester Of L-ascorbic acid was synthesized by using immobilized lipases from Candida sp. A series of solvents, such as ethanol, tetrahydrofuran, pyridine, butanol, tertiary amyl alcohol (t-amyl alcohol), hexanol, octanol and hexane (log P from -0.24 to 3.5) were investigated for the reaction, and t-amyl alcohol was found to be the most suitable from the standpoint of the substrate concentration and the enzyme activity. And the equilibrium of the reaction was affected by the addition of the molecular sieves and the temperature. Reaction carried out at 55 degreesC and with 50 g/l of 4 Angstrom molecular sieves is good for the enzyme to keep its activity and for making the equilibrium go to the product. The kinetic model was studied and the result showed that the reaction can be described by Ping-Pong mechanism. Parameters value of V-m and K-m' were obtained. Last, In the pure products of the reaction were attained and determined by IR spectra, mass spectrometry and H-1 NMR spectra. (C) 2002 Elsevier Science B.V. All rights reserved.