The Characteristics Of Palmitoylsucrose Monoester Synthesized By Selective Enzymatic

Sugar esters are recommended food additives by WHO and FAO.As non-ionic surfactants with both hydrophilic and hydrophobic groups,they are widely used in the pharmaceutical,cosmetic,food and other industry due to a wide range of HLB values,non-toxicity,biodegradability and favorable surfactant property.Plamitoylsucrose was obtained using the lipase-catalyzed synthesis in microfluid chips.The resulting monoester was purified,and the factors of batch synthesis were optimized.We also evaluated its physicochemical properties in this paper.The palmitoylsucrose monoester was synthesized in tert-butyl alcohol/DMSO solvent with lipase TLIM catalyst.The solvent system condition in thin layer chromatography(TLC)was tested and optimized,and the mixture of chloroform/methanol(4:1,v/v)was finally conducted for elution.Reaction product was isolated by silica gel column chromatography with chloroform/methanol(10:1,v/v)as its mobile phase.The purified palmitoylsucrose monoesters were analyzed by 1H-NMR and HPLC-ELSD.The product was obtained with a high degree of purity(94%).In order to synthesize palmitoylsucrose monoester selectively,the optimal condition for biphasic system was conducted as follows:the mixture of tert-butyl alcohol/DMSO(4:1,v/v)used as reaction solvent;25 mg/ml Lipozyme TLIM as catalyst;the molar ratio of vinyl palmitate to sucrose was 8:1;20 mg/ml 3 A molecular sieve;40℃ as reaction temperature with a shaking speed of 170 r/min for 8 hours.The conversion ratio of the palmitoylsucrose monoester reached 94%in this optimized condition.Synthesis of palmitoylsucrose monoester in microchannel reactor was more efficient than that in a round-bottom.The influence of flow rate and reaction time on yield was investigated.86.2%and 80.6%palmitoylsucrose monoester conversion were obtained after 100 min reaction in microchannels in width of 1.6 mm and 2.5 mm,respectively.In comparison,only 28%conversion was obtained in a bulk reaction.The properties of palmitoylsucrose monoester were also determined.The result showed that the palmitoylsucrose monoester exhibited good water-solubility with the hydrophilic-lipophilic balance(HLB)value of 16.11.The parameters of surface tension were determined by Du Nouy,and then CMC(24.86 mg/L),yCMc(35.78 mN/m)were calculated.The foam and emulsion show a certain regularity in the rang of experimental concentration.The antimicrobial activities of 6-O-palmitoylsucrose were tested on Escherichia coli,Staphylococcus aureus and Bacillus subtilis.,and the result showed that the monoester had no antibacterial activity apparently.