title: Enzymatic synthesis of phytosterol esters catalyzed by Candida rugosa lipase in water-in-[Bmim]PF6 microemulsion.
abstract: A water-in-ionic liquid microemulsion ([Bmim]PF6/Tween20/H2O) was applied as reusable reaction medium to esterify phytosterols with fatty acid by Candida rugosa lipase (CRL) successfully. Two kinds of commercial CRLs, AY30 and AYS which cannot effectively catalyze esterification in conventional reaction system were found effective in the microemulsion system. Effects of reaction parameters on esterification were investigated; results showed that the conversion rate of 87.9 and 95.1 % was obtained in 24 and 48 h of reaction, respectively, under the optimized condition: the molar ratio of water to Tween 20 (w 0 value) at 5.4, Tween 20 at a concentration of 305 mM, 50 °C,pH 7.4, 10 % of enzyme loading (w/w, with respect to total reactants), and phytosterols/lauric acid molar ratio of 1:2. Moreover, by using n-hexane as the extraction agent, the lipase-encapsulated microemulsion could be reused at least seven times (>168 h) without significant changes in the conversion rate, while achieving a purpose of simple separation and purification.
authors.affiliation: College of Light Industry and Food Sciences, South China University of Technology, No.381 Wushan Road, Guangzhou, 510640, China.
authors.forename: Chaoxi
authors.initials: C
authors.lastname: Zeng
authors.forename: Suijian
authors.initials: S
authors.lastname: Qi
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Li
authors.forename: Riming
authors.initials: R
authors.lastname: Luo
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Wang
mesh_terms: D055162:Biocatalysis; D002175:Candida / Q000201:enzymology*; D002384:Catalysis; D004655:Emulsions; D004800:Enzymes, Immobilized / Q000378:metabolism; D004952:Esters / Q000737:chemistry*; D006586:Hexanes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007218:Industrial Microbiology; D007477:Ions; D007850:Lauric Acids / Q000737:chemistry; D008049:Lipase / Q000378:metabolism*; D010840:Phytosterols / Q000096:biosynthesis*; D011136:Polysorbates / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D004800:Enzymes, Immobilized; D004952:Esters; D006586:Hexanes; D007477:Ions; D007850:Lauric Acids; D010840:Phytosterols; D011136:Polysorbates; D014867:Water; C030358:lauric acid; D008049:Lipase