title: Stability and activity of lipase in subcritical 1,1,1,2-tetrafluoroethane (R134a).
abstract: The stability and activity of commercial immobilized lipase from Candida antarctica (Novozym 435) in subcritical 1,1,1,2-tetrafluoroethane (R134a) was investigated. The esterification of oleic acid with glycerol was studied as a model reaction in subcritical R134a and in solvent-free conditions. The results indicated that subcritical R134a treatment led to significant increase of activity of Novozym 435, and a maximum residual activity of 300% was measured at 4 MPa, 30 degrees C after 7 h incubation. No deactivation of Novozym 435 treated with subcritical R134a under different operation factors (pressure 2-8 MPa, temperature 30-60 degrees C, incubation time 1-12 h, water content 1:1, 1:2, 1:5 enzyme/water, depressurization rate 4 MPa/1 min, 4 MPa/30 min, 4 MPa/90 min) was observed. While the initial reaction rate was high in subcritical R134a, higher conversion was obtained in solvent-free conditions. Though the apparent conversion of the reaction is lower in subcritical R134a, it is more practicable, especially at low enzyme concentrations desired at commercial scales.
authors.affiliation: College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China. gyu0928116@yahoo.com.cn
authors.forename: Gang
authors.initials: G
authors.lastname: Yu
authors.forename: Yong
authors.initials: Y
authors.lastname: Xue
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Chang Hu
authors.initials: CH
authors.lastname: Xue
mesh_terms: D002175:Candida / Q000201:enzymology*; D004795:Enzyme Stability; D006845:Hydrocarbons, Fluorinated / Q000378:metabolism*; D007218:Industrial Microbiology / Q000592:standards; D008049:Lipase / Q000378:metabolism*; D011312:Pressure; D013696:Temperature; D013997:Time Factors; D014867:Water; D004980:Ethane / Q000031:analogs & derivatives; D005466:Fluorocarbons
chemical_list: D006845:Hydrocarbons, Fluorinated; D008049:Lipase; D014867:Water; C063006:norflurane; D004980:Ethane; D005466:Fluorocarbons