酶催化合成维生素C脂肪酸酯的反应条件优化

Optimization of the enzymatic synthesis of L-ascorbyl fatty acid esters

以维生素C(Vc)和若干种脂肪酸为底物,采用自制假丝酵母Candidasp.99-125固定化脂肪酶,催化合成维生素C脂肪酸酯。结果表明,在该酯化反应中,油酸为最佳脂肪酸底物,丙酮为最佳反应介质。同时研究了各反应因素对Vc转化率的影响,优化后的反应条件为:当Vc浓度为0.06 mol/L时,温度40℃,固定化酶量1.5 g,油酸与Vc物质的量比为5∶1,反应时间48 h,分子筛添加量0.5 g,底物Vc分4次流加,Vc转化率可达91%,批次实验表明该固定化酶在重复使用10次后仍具较高活力。

The enzymatic synthesis of L-ascorbyl fatty acid esters （AFAE） has been studied using a self-made immobilized lipase generated by Candida sp. 99 - 125 as the biocatalyst. Oleic acid was found to be the best source of a fatty acid acyl group in the synthesis of AFAEs. Through screening of different reaction media, acetone was found to be the most suitable solvent for the esterification. The effects of various other factors on the synthesis of AFAEs were also investigated. Under the following optimized reaction conditions： initial ascorbic acid （vitamin C） concentration （Vc） of 0.06 mol/L at 40℃, 1.5 g of immobilized enzyme, substrate molar ratio of 5：1, reaction time of 48 h, content of molecular sieve of 0.5 g and four times fed-batch addition of the substrate, an esterification ratio of 91% was obtained. Furthermore, repeated batch reactions revealed the durability of the immobilized lipase, which retained high activity after sequential reaction for 10 rounds.