Synthesis Of Raffinose Fatty Acid Ester Catalyzed By Candida SP.99-125 Lipase

Made from esterification of carbohydrate and fatty acid, carbohydrate fatty acid esters with amphiphilic structure is a kind of new nonionic surfactant. By controlling the sugar in sugar ester type and length of carbon chain fatty can achieve the purpose of regulating surface activity. Lipase catalyzed synthesis of sugar esters in organic medium avoid the disadvantage of complicated chemical synthetic process and poor selectivity, and has the advantage of mild reaction conditions and selectivity, which is becoming the main trend of systhcarbohydrate fatty acid ester synthesisIn this study, raffinose fatty acid esters were synthesized by different lipases, following the the establishment of the characterization methods, single-factor experiment, qualitative analysis and physical property analysis.1. Establishment of the characterization methods.Thin-layer chromatography (TLC) was performed on silica gel plates with a mixture of chloroform, ethyl acetate, methanol, and acetic acid (at a ratio of 50:50:5 0.1, v/v/v/v) as eluents. The HPLC was equipped with an Akasil column(4.6 mm×250 mm) packed with C18 and a ELSD detector and with methanol as the mobile phase with a flow rate of 1 mL/min, the drift tube temperature of 60℃.2.Optimization of the lipase catalyzed reaction.Comparing the difference of solubility of raffinose and activity of lipase of Candida sp.99-125 in different solvents, we made the tert-amyl alcohol as the better choice of the media of the reaction. In tert-amyl alcohol, the transesterification activity of Candida sp.99-125 and conversion of raffinose was 108.71U and 33.97%, respectively.In this study, raffinose fatty acid esters were synthesized by different lipase from raffinose and fatty acid, and lipase from Candida sp.99-125 was choosen for production of raffinose fatty acid esters which showed a conversion rate of 34.42%. The highest conversion rate of 45.6% at 6h was obtained in the lipase loading of 40 wt%. The conversion rate of raffinose monoesters and conversion of raffinose both decreased with increasing chain length of the acyl donor. The initial water content of 2% was better choice and the molecular sieve could control the water content effectively. In addition, the temperature of 40℃ and the initial concentration of raffinose and fatty acid ester were 1.65×10’2 mmol/ml and 8.27×10-2 mmol/ml respectively.3. The separation and identification of production.TLC, UPLC-MS and IR spectrum results confirmed the synthesis of raffinose fatty acid monoester.4. Properties analysis of the production. Having the HLB of 11.5, raffinose lauric acid monoester was proved to be the better choice of oil-in-water emulsion. The emulsifying property and emulsifying stability of product were 78.77% and 84.48%, respectively. In addition, the production showed antibacterial activity on E. coli and S. aureus.