title: Microscopic analysis of ester hydrolysis reaction catalyzed by Candida rugosa lipase.
abstract: The relationship between the kinetics of the lipase-catalyzed oil hydrolysis and the surface area distribution of oil droplets was investigated using ethyl decanoate and gum Arabic (GA) as a model oil and an emulsifier, respectively. Along an ethyl decanoate concentration gradient between 2 and 8 mM, the initial hydrolysis rate increased at 0.25% (w/v) GA but did not change at 1.0% (w/v) GA. At 0.25% GA, the surface area of droplets was narrowly distributed regardless of the ethyl decanoate concentration. However, at 1.0% GA and with ethyl decanoate concentrations higher than 2 mM, the fraction of relatively large droplets with a surface area larger than approximately 200 microm2, suddenly increased. The microscopy of ethyl decanoate emulsion during the hydrolysis reaction indicates that the large oil droplets were not hydrolyzed. At 20 mM ethyl decanoate where the hydrolysis rate remained the same between 0.25% and 1.0% GA, the surface area of droplets was narrowly distributed at 0.25% and 1.0% GA. Therefore, the constant hydrolysis rate observed in the emulsion of ethyl decanoate between 2 and 8 mM containing GA at 1.0%, is believed to be caused by the relatively large oil droplets with the interface quality differing from that of the small oil droplets.
authors.affiliation: Department of Chemical Engineering, Yonsei University, Seoul 120-749, South Korea.
authors.forename: Sumin
authors.initials: S
authors.lastname: Lee
authors.forename: Sangpill
authors.initials: S
authors.lastname: Hwang
authors.forename: Kangtaek
authors.initials: K
authors.lastname: Lee
authors.forename: Ik-Sung
authors.initials: IS
authors.lastname: Ahn
mesh_terms: D002175:Candida / Q000201:enzymology*; D003651:Decanoates; D004655:Emulsions; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006170:Gum Arabic; D006868:Hydrolysis; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D008956:Models, Chemical; D010938:Plant Oils / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D003651:Decanoates; D004655:Emulsions; D004800:Enzymes, Immobilized; D010938:Plant Oils; D006170:Gum Arabic; D008049:Lipase; C091960:ethyl decanoate