Synthesis Of Monoacyl Fructose Catalyzed By Immobilized Lecitase^? Ultra

Sugar fatty acid esters are significant nonionic surfactant which produced fromrenewable and inexpensive substance. Because they are completely biodegradable underaerobic and anaerobic conditions, non-toxic, no-skin irritants, odourless and tasteless, sowidely used as emulsifler in food, cosmetic, pharmaceutical industries and so on. Sugar esterscan be produced by enzymatic or chemical methods. Enzyme-catalyzed reaction is superior tothe chemical synthesis because of the chemo-, regio-, and stereoselective catalysts. In addition,bio-catalytic processes are mild and lead to high product yield due to their specificity.In this study, a novel enzymatic-catalyzing process of monoacyl fructose was developed.Production of monolauroyl fructose catalyzed by immobilized Lecitase Ultra in anhydrousorganic solvent was investigated in a batch stirred tank reactor. We optimized the processparameters: such as organic solvent, enzyme load, lauric acid/fructose mole ratio, molecularsieves dosage, fructose concentration and time course. The optimal reaction conditions were:in4mL anhydrous2-methyl-2-butanol, biocatalyst25g/L, fructose250mM, lauric acid1000mM, molecular sieves load50g/L, temperature43°C. The maximum monolauroyl fructoseconversion could be70.45%after48h. Fructose concentration was the major factor affectingthe concentration of monolauroyl fructose. In the same condition, other monoacyl fructosewas synthetized and the conversion of monoacyl fructose decreased as the chain length.Also, silica gel column chromatography was usd to separate and purify the lauroylfructose. The qualitative analysis condition of TLC was confirmed and the purity wasidentified by RP-HPLC-ELSD. Structure was verified by HPLC-ESI-MS, FT-IR,13C NMR.As a result, a mixture of the C-1and C-6monoacylated frutose esters, four isomers ofmonolauroyl fructose were obtained: l-lauroyl-β-D-fructopyranose,1-lauroyl--D-fructopyranose,1-lauroyl-β-D-fructofuranose,6-lauroyl-β-D-fructofuranose, also l-lauroyl-β-D-fructopyranose was the highest proportion.Surface properties of monoacyl fructose with different long fatty acid chains (C10, C12,C14, C16and C18) were investigated at25°C. Each monoacyl fructose was dispersed indouble distilled water and surface tension of aqueous solution was measured using a staticdrop shape analysis. The critical micelle concentrations (CMC), surface tension at the CMC (γCMC), surface excess (Γmax) and residual area per molecule (Amin) of these amphiphiliccompounds was studied. Foaming activity and emulsion activity were also estimated. Theresults indicate that the value of CMC decreased as the chain length. There was no signifcantdependency of the γCMCvalue on the chain length. Cohesive energy change per methylenegroup passing from the bulk of the solution into the micelle of monoacyl fructose was0.56kJ/mol. Monomyristroyl fuctose with medium chain long has good surface activity andfoaming stability. Also we identified the optimal concentrations of different monoacylfructose in foamabilities and foam stabilities at25oC; the optimal concentrations of differentmonoacyl fructose in emulsifying activities and emulsion stabilities was verified, it indicatedthat monoacyl fructose with long acyl chain length has the better emulsifying activities in lowconcentration.