title: Organic phase synthesis of ethyl oleate using lipases produced by solid-state fermentation.
abstract: This paper reports a study of the enzymatic esterification of oleic acid and ethanol. The reaction was catalyzed by lipases produced by solid-state fermentation with Rhizopus sp. Olive oil and perlite were used as an inducer and inert support, respectively. Synthesis of ethyl oleate was carried out in a 10-mL batch reactor with magnetic stirring. The effects of substrate ratios, biocatalyst concentration, and temperature on the reaction rate and conversion efficiency were evaluated. The highest reaction rate (1.64 mmol/L min) was reached with an oleic acid/ethanol mol ratio of 1:5 (oleic acid 50 mM:ethanol 250 mM) and 1 g of biocatalyst. Conversions approaching 100% were obtained after 60 min of reaction at 45 degrees C with n-hexane as a solvent. The initial reaction rate increased proportionally with respect to biocatalyst concentration, which suggests that the reaction rate was not controlled by mass transfer. The biocatalyst retained more than 80% of its catalytic activity after 7 months of storage at 4 degrees C. The results demonstrate that the biocatalyst produced by Rhizopus sp. in solid-state fermentation can be successfully used for ethyl oleate synthesis over short reaction periods under conditions when ethanol is in excess.
authors.affiliation: Departamento de Biotecnología, Universidad Autónoma Metropolitana-Iztapalapa, Col Vicentina, Mexico City, Mexico.
authors.forename: Antonio
authors.initials: A
authors.lastname: Martínez-Ruiz
authors.forename: Hugo Sergio
authors.initials: HS
authors.lastname: García
authors.forename: Gerardo
authors.initials: G
authors.lastname: Saucedo-Castañeda
authors.forename: Ernesto
authors.initials: E
authors.lastname: Favela-Torres
mesh_terms: D004795:Enzyme Stability; D004952:Esters / Q000138:chemical synthesis; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D008049:Lipase / Q000378:metabolism*; D019301:Oleic Acid / Q000378:metabolism; D009829:Oleic Acids / Q000096:biosynthesis*; D012233:Rhizopus / Q000201:enzymology; D013696:Temperature
chemical_list: D004952:Esters; D009829:Oleic Acids; D019301:Oleic Acid; D000431:Ethanol; D008049:Lipase; C033180:ethyl oleate