溶剂和水分活度对OPO结构脂合成中酰基迁移的影响

Effect of solvent and water activity on acyl migration in the synthesis of OPO structural lipids

以三棕榈酸甘油酯(PPP)和油茶籽油游离脂肪酸(FFA)为底物制备1,3-二油酸-2-棕榈酸甘油酯(OPO)结构脂为反应模型,以专一性脂酶Lipozyme RM IM为催化剂,研究不同有机溶剂(正己烷、丙酮、叔丁醇)、不同反应时间(0、2、4、6、8 h)、不同水分活度(aw)(0.11、0.53、0.97)对酰基迁移的影响。结果表明:在3种溶剂中,丙酮的反应环境下酰基迁移发生率最低且油酸的键入率最高;在不同溶剂、不同水分活度的条件下,均在aw为0.53时sn-2位棕榈酸和sn-1,3位油酸的含量较高,说明aw影响脂肪酶的1,3位置选择性强弱决定于aw的高低。鉴于结构脂制备过程中的绿色环保安全角度,可以采用无溶剂体系但是应较好地控制反应体系的aw以抑制酰基迁移。

The reaction model of producing 1,3-dioleic-2-palmitate(OPO) from substrates of tripalmitate(PPP) and oil-tea camellia seed oil free fatty acid(FFA) catalyzed by Lipozyme RM IM was used to investigate the influence of solvent(acetone, tert-butanol, n-hexane), reaction time(0, 2, 4, 6, 8 h) and water activity(aw)(0.11, 0.53, 0.97) on acyl migration. The results showed that among the three solvents, acetone promoted the incorporation of oleic acid and limited acyl migration. While the highest contents of oleic acid in sn-1,3 position and palmitic acid in sn-2 position were observed when water activity was 0.53 no matter in different solvents, meaning that the water activity was the dominant factor influencing the selectivity of Lipozyme RM IM. From the view of the green, environment and safety, the non-solvent system could be used but the water activity should be carefully controlled to inhibit acyl migration.