The Studies On Optimization Of Preparation And Properties Of Monoglyceride Laurate And Sucrose Esters

Monoglyceride laurate and sucrose fatty acid esters have especial amphipathicstructure. They are a kind of safe, non-toxic, unstimulating and biodegradable foodemulsion agents, featuring the properties of emulsifying, antisepsis, dispersing,antitumoral and antimicrobial, which are widely used in foods, cosmetics, detergents,and pharmaceutics. Enzymes as a kind of biocatalysts, have the properties ofcatalysing reactions under mild conditions, high specificity, and high regioselectivityet al. Enzymatic synthesis have been widely used in organic synthesis andbio-synthesis. Duo to the mechanical effects produced by the untrasound, it has beensuccessfully used in organic synthesis to accelerate the reaction rate and reducingreaction time. In this thesis, following research have been conducted focusing on theoptimization of the preparation of monoglyceride laurate and sucrose fatty acid esters:Iniatially, we performed the synthesis of monoglyceride laurate catalyzed bylipase LS-10. The parameters, such as molar ratio of lauric acid to glycerol, reactiontime, temperature, lipase loading, initial water content, and molecular sieve loading onthe reaction were investigated. Using the orthogonal experiment, the optimalcondition for the synthesis were obtained as following: reaction temperature45℃,molar ratio of lauric acid to glycerol1:1.5, lipase loading13%, reaction time10h,initial water content0.41%, molecular sieve loading2.0%. Under the optimizedconditions, the content of monoglyceride laurate reached20.1%, the conversion oflauric acid is49.8%.The synthesis of sucrose palmitate was performed in2-methyl-2-butanol/dimethylsulfoxide mixtures by lipase LS-10catalyzed esterification of palmitic acid withsucrose. Monosucrose esters was obtained by column chromotography andcharacterized by1H-NMR、ESI-MS、FT-IR. By the orthogonal experiment, theoptimal condition for the synthesis were obtained as following: molar ratio of sucroseto palmitic acid1.5:1, reaction time6d, lipase loading15.0%, molecular sieveloading10.0%, reaction temperature55℃, initial water content0.9%. Under theoptimized conditions, the content of sucrose palmitate reaches50.0%.Synthesis of sucrose stearate by transesterification of ethyl stearate with sucrose was performed in propylene glycol by using potassium carbonate as catalyst. TheHLB values of the products were around3. By the orthogonal experiment, the optimalcondition for the synthesis were obtained as following: reaction temperature70℃,reaction time9h, molar ratio of sucrose to ethyl stearate1.4:1, molar ratio of sucroseto propylene glycol1:17, catalyst loading1.5%. Under the optimized conditions, thecontent of sucrose stearate can be improved to94.0%.The synthesis of sucrose stearate by transesterification of sucrose with ethylstearate was investigated under ultrasound irradiation in N, N-dimethylfomamide. Theeffects of molar ratio of N, N-dimethylfomamide to ethyl stearate, molar ratio ofsucrose to ethyl stearate, ultrasonic temperature, ultrasonic time, catalyst loading, andultrasonic power on the reaction were investigated. By the orthogonal experiment, theoptimal condition were obtained as following: molar ratio of sucrose to ethyl stearate1.5:1, N, N-dimethylfomamide to ethyl stearate13:1, ultrasonic temperature70℃,ultrasonic time4h, catalyst loading1.0%, ultrasonic frequency45kHz, andultrasonic power200W. Under the optimized conditions, the content of sucrosestearate is92.2%.