脂肪酶二步法催化鱼油下脚料富集DHA

采用Pseudomonas sp．脂肪酶水解，Geotrichum sp．脂肪酶选择性酯化的两步法显著提高游离脂肪酸（FFA）中二十二碳六烯酸（DHA）的含量。通过筛选合适的底物醇，优化水解和选择性酯化反应条件达到富集DHA的目的。结果表明月桂醇为选择性酯化的最适底物醇。确定的最佳水解条件：4g反应底物，m（水）／m（粗鱼油）=1，1000 U Pseudomonas sp．脂肪酶，40℃，搅拌速度200r／min，反应24h；最佳酯化条件：3g反应底物，n（FFA）／n（醇）=1／2，1000 U固定化Geotrichum sp．脂肪酶，1g正己烷，30℃，200r／min搅拌，反应20h。经过水解和一次选择性酯化反应后，DHA含量从原料粗鱼油中的18．9％提纯到72．8％；经二次选择性酯化后，DHA含量上升到92％。脂肪酶水解-选择性酯化的两步法是富集DHA的有效方法。

Two-step lipase catalysis process for enrichment of DHA using waste fish oil as raw material

Hydrolysis and selective esterification were investigated for the enrichment of Docose Hexaenoie Acid（DHA） by Pseudomonas sp. lipase and Geotrichum sp. lipase. The result showed that the lauryl alcohol was the most suitable fatty alcohol for the enrichment of DHA by the selective esterification. And the optimal hydrolysis conditions were obtained： 4 g substrate, m（H2O）/m（fish oil） = 1, 1000 U Preudomoras sp. lipase, 40 ℃ agitation rate 200 r/min and reaction time 24 h. The optimal esterifying conditions were as follows： 3 g reaution substrate, n（FFA）/n（alcohol） = 1/2, 1 000 U Geotrichum sp. lipase, n-hexane 1 g , 30 ℃, agitation rate 200 r/min and reaction time 24 h. The DHA content in free fatty adid mixture was increased from 18. 9% in raw fish oil to 72. 8% after hydrolysis-selective esterification enzymaic reaction, and further increased to 92% by one more selective esterification under the same condition.