植物甾醇酯制备方法的研究

Study on Preparation of Phytosterol Esters

目的以脂肪酶为催化剂,在有机溶剂中催化月桂酸和植物甾醇合成月桂酸植物甾醇酯。方法筛选出的最佳溶剂为正己烷,最佳的脂肪酶是固定于大孔树脂NKA的假丝酵母脂肪酶(CRL)——固定化酶NKA-CRL。分别以薄层色谱法和气相色谱法为产物定性和定量,以酯化率为考察指标,优选反应温度、酶添加量、底物摩尔比、反应时间等参数。结果在反应温度40℃,酸醇摩尔比2:1,反应时间16 h及酶添加量5%(占底物总质量)的条件下,酯化率达96%,固定化酶NKA-CRL在相同条件下重复催化6次,酯化率仍可维持在80%以上。结论本工艺利用自制的固定化酶,在保证最高转化率的前提下,降低了反应温度,缩短了反应时间,增强了酶的重复利用率。

Objective To synthesize lauric acid phytosterol esters by lipase in organic solvent. Methods It was found that n-hexane was the best organic solvent and the best lipase was immobilized enzyme NKA-CRL （Candida rugosa lipase immobilized on macroporous resin NKA） through screening test. The qualitative and quantitative detections for the product were performed by Thin-Layer Chromatography（TLC） and Gas Chromatography（GC）. With esterification rate as an index, the optimization of reaction conditions was studied in detail. Results The optimal conditions were as follows：reaction temperature of 40℃, molar ratio of lauric acid to phytosterol of 2：1, addition of the lipase of 5%and reaction time of 16 h. Under these conditions, the esterification rate reached 96.56%. A yield of more than 80%for phytosterol ester could be obtained with NKA-CRL even after it was used continuously six times. Conclusion With NKA-CRL self-made, this technology can has a better transform rate under the conditions of low reaction temperature, short reaction time and high reuse of lipase.