title: Effect of pH on the production of lipolyzed butter oil by a calf pregastric esterase immobilized in a hollow-fiber reactor: I. uniresponse kinetics.
abstract: A calf pregastric esterase immobilized in a hollow-fiber reactor was employed to hydrolyze milkfat, thereby producing a lipolyzed butteroil. The reaction kinetics can be modeled by a two-parameter model of the general Michaelis-Menten form based on a ping-pong bi-bi mechanism; the rate of enzyme deactivation can be modeled as a first-order reaction. The initial concentration of accessible glyceride bonds, [G](O), was estimated by complete saponification of the substrate butteroil as 2400 mM. An extra sum of squares test indicated that not only the parameters of the kinetic generalized Michaelis-Menten model, but also the deactivation-rate constant varied significantly with pH. The optimum pH, for lypolysis is near 6.0 at a temperature of 40 degrees C because at this pH the rate of deactivation of the esterase is minimized.
authors.affiliation: Department of Chemical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, Wisconsin 53706, USA.
authors.forename: L P
authors.initials: LP
authors.lastname: Lessard
authors.forename: C G
authors.initials: CG
authors.lastname: Hill
mesh_terms: D000818:Animals; D019149:Bioreactors; D002079:Butter; D002417:Cattle; D004042:Dietary Fats, Unsaturated / Q000302:isolation & purification*; D004800:Enzymes, Immobilized; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008049:Lipase / Q000378:metabolism*; D008066:Lipolysis; D008954:Models, Biological
chemical_list: D004042:Dietary Fats, Unsaturated; D004800:Enzymes, Immobilized; D002079:Butter; D008049:Lipase; C043101:gastric triacylglycerol lipase