title: Esterification activity and stability of Candida rugosa lipase immobilized into chitosan.
abstract: Microbial lipase from Candida rugosa immobilized into porous chitosan beads was tested for esterification selectivity with butanol and different organic acids (C2-C12), and butyric acid and different aliphatic alcohols (C2-C10). After 24 h, the acids tested achieved conversions of about 40-45%. Acetic acid was the only exception, and in this case butanol was not consumed. Different alcohols led to butyric acid conversions >40%, except for ethanol, in which case butyric acid was converted only 26%. The system's butanol and butyric acid were selected for a detailed study by employing an experimental design. The influence of temperature, initial catalyst concentration, and acid:alcohol molar ratio on the formation of butyl butyrate was simultaneously investigated, employing a 2(3) full factorial design. The range studied was 37-50 degrees C for temperature (X1), 1.25-2.5% (w/v) for the catalyst concentration (X2), and 1 and 2 for the acid:alcohol molar ratio (X3). Catalyst concentration (X2) was found to be the most significant factor and its influence was positive. Maximum ester yield (83%) could be obtained when working at the lowest level for temperature (37 degrees C), highest level for lipase concentration (2.5% [w/v]), and center level of acid:alcohol molar ratio (1.5). The immobilized lipase was also used repeatedly in batch esterification reactions of butanol with butyric acid, revealing a half-life of 86 h.
authors.affiliation: Chemical Engineering Department, State University of Maringá, PR, Brazil.
authors.forename: Ernandes B
authors.initials: EB
authors.lastname: Pereira
authors.forename: Heizir F
authors.initials: HF
authors.lastname: de Castro
authors.forename: Flávio F
authors.initials: FF
authors.lastname: De Moraes
authors.forename: Gisella M
authors.initials: GM
authors.lastname: Zanin
mesh_terms: D000438:Alcohols / Q000737:chemistry / Q000378:metabolism; D002175:Candida / Q000201:enzymology*; D002686:Chitin / Q000031:analogs & derivatives*; D048271:Chitosan; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D004952:Esters / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000438:Alcohols; D004800:Enzymes, Immobilized; D004952:Esters; D002686:Chitin; D048271:Chitosan; D008049:Lipase