天然低共熔溶剂中酶法甘油解制备富含石榴酸的甘油二酯

    Enzymatic glycerolysis in natural deep eutectic solvents for the preparation of punicic acid-enriched diacylglycerols

    • 摘要: 为解决无溶剂体系中石榴籽油与甘油互溶性差导致的传质限制,提高甘油二酯(DAG)制备效率,引入天然低共熔溶剂(NADESs)作为绿色反应介质,以石榴籽油为原料,系统筛选NADESs体系与脂肪酶种类,优化反应温度、底物物质的量比、酶添加量及反应时间等参数,通过高效液相色谱分析产物组成,并基于阿伦尼乌斯方程进行热力学分析,评估甘油解过程中产物的积累规律及生成选择性。结果表明:在氯化胆碱-甘油(ChCl∶2Gly)体系中,Lipozyme 435催化性能最优;优化所得最佳反应条件为70 ℃、底物物质的量比1∶2、加酶量6%、反应时间8 h,此时甘油三酯(TAG)转化率为47.11%,DAG产率达43.09%,其中石榴酸含量超过84%;与无溶剂体系相比,DAG产率由38.02%提升至43.09%,副产物甘油单酯(MAG)产率由8.69%降至3.90%;热力学分析表明,DAG生成活化能(52.96 kJ/mol)低于MAG(56.70 kJ/mol),体系对DAG具有较高选择性。综上,本研究建立了基于NADESs的绿色高效制备富含石榴酸DAG的工艺,为石榴籽油基功能性脂质的开发提供了理论与技术支撑。

       

      Abstract: To enhance the efficiency of producing diacylglycerols (DAG) from pomegranate seed oil and overcome the mass-transfer limitations caused by poor miscibility between oil and glycerol in conventional solvent-free enzymatic glycerolysis, this study introduced natural deep eutectic solvents (NADESs) as a green reaction medium to establish an efficient and environmentally friendly DAG production process. Using pomegranate seed oil as the substrate, various NADES systems and lipases were systematically screened, and key reaction parameters-including temperature, substrate molar ratio, enzyme loading, and reaction time-were optimized. The compositions of the reaction products were analyzed by high-performance liquid chromatography, and thermodynamic properties were evaluated using the Arrhenius equation to elucidate the accumulation pattern and formation selectivity of glycerolysis products. The results showed that Lipozyme 435 exhibited the best catalytic performance in the choline chloride-glycerol (ChCl∶2Gly) system. Under the optimal conditions (70 ℃, substrate molar ratio 1∶2, enzyme loading 6%, and reaction time 8 h), the triglyceride conversion reached 47.11%, with a DAG yield of 43.09%. The obtained DAGs contained more than 84% punicic acid. Compared with the solvent-free system under the same conditions, the ChCl∶2Gly system significantly increased DAG yield (43.09% vs 38.02%) and markedly reduced the formation of the by-product monoacylglycerol (MAG) (3.90% vs 8.69%). Thermodynamic analysis further revealed that the activation energy for DAG formation (52.96 kJ/mol) was lower than that for MAG formation (56.70 kJ/mol), indicating a clear selectivity toward DAG generation in the NADES-based system. In conclusion, this study successfully established a green and efficient NADES-mediated process for producing punicic-acid-rich DAGs, providing theoretical support and technical guidance for the development of functional lipids derived from pomegranate seed oil.

       

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