有机介质中脂肪酶催化合成棉籽糖脂肪酸酯Synthesis of raffinose fatty acid esters by lipase catalysis in organic media

为促进棉籽糖酯的规模化生产和高值化利用，以棉籽糖和脂肪酸为原料，通过脂肪酶催化合成棉籽糖脂肪酸酯，对酰基供体进行了选择，考察了脂肪酶种类、溶剂种类、加酶量、溶剂初始含水量、反应温度、溶剂用量对脂肪酶催化效率的影响，通过薄层色谱、超高效液相色谱-串联质谱和傅里叶红外光谱对产物进行分析鉴定，并对制备的棉籽糖月桂酸酯的亲水亲油平衡（HLB）值、乳化能力、乳化稳定性和抑菌活性进行测定。结果表明：选择月桂酸为酰基供体；脂肪酶催化合成棉籽糖月桂酸酯的最优工艺条件为棉籽糖与月桂酸物质的量比1∶ 5、叔戊醇为反应溶剂、溶剂初始含水量2%，溶剂用量60 mL(基于0.5 g棉籽糖）、脂肪酶LS-20添加量40%（以底物总质量计）、反应温度40 ℃，在此条件下反应6 h，棉籽糖转化率可达45.12%;酶促合成的产物为3种不同取代位置的棉籽糖月桂酸单酯，乳化能力和乳化稳定性分别为78.77%和84.48%，HLB值为11.5，具有制备水包油型乳液的潜力；棉籽糖月桂酸酯较商用糖酯具有更好的抑菌效果。综上，所制备的棉籽糖月桂酸酯具有优异的乳化性能、乳化稳定性和抑菌活性，有规模化制备的潜力。 To enhance the large-scale production and high-value application of raffinose fatty acid esters, raffinose fatty acid esters were synthesized by lipase catalysis from raffinose and fatty acids. Acyl donors were selected, and the effects of lipase types, solvent types, lipase dosage, initial water content of solvent, reaction temperature, and solvent dosage on lipase catalytic efficiency were studied. Thin layer chromatography, ultra-performance liquid chromatography-tandem mass spectrometry, and Fourier-transform infrared spectroscopy were used to analyze and identify the products. In addition, the HLB value, emulsifying capacity, emulsion stability and antibacterial activity of the prepared raffinose laurate were determined. The results showed that lauric acid was selected as the acyl donor. The optimal process conditions for the lipase-catalyzed synthesis of raffinose laurate were obtained as follows: molar ratio of raffinose to lauric acid 1∶ 5, tert-amyl alcohol as the reaction solvent, initial water content of solvent 2%, solvent dosage 60 mL(based on 0.5 g raffinose), LS-20 lipase dosage 40% and reaction temperature 40 ℃. Under these conditions, the reaction lasted for 6 h and the raffinose conversion rate reached 45.12%. The enzymatic synthesis products were three different positional isomers of raffinose monolaurate with emulsifying capacity and emulsion stability of 78.77% and 84.48%, respectively, and an HLB value of 11.5, indicating the possibility of preparing oil-in-water emulsions. Raffinose laurate had superior antibacterial properties to commercial sugar esters. In conclusion, the produced raffinose laurate exhibits good emulsifying capacity, emulsion stability, and antibacterial activity, and it has the potential for large-scale production.