title: Effects of temperature on the hydrolysis of lactose by immobilized beta-galactosidase in a capillary bed reactor.
abstract: The effects of temperature on the hydrolysis of lactose by immobilized beta-galactosidase were studied in a continuous flow capillary bed reactor. Temperature affects the rates of enzymatic reactions in two ways. Higher temperatures increase the rate of the hydrolysis reaction, but also increase the rate of thermal deactivation of the enzyme. The effect of temperature on the kinetic parameters was studied by performing lactose hydrolysis experiments at 15, 20, 25, 30, and 40 degrees C. The kinetic parameters were observed to follow an Arrhenius-type temperature dependence. Galactose mutarotation has a significant impact on the overall rate of lactose hydrolysis. The temperature dependence of the mutarotation of galactose was effectively modelled by first-order reversible kinetics. The thermal deactivation characteristics of the immobilized enzyme reactor were investigated by performing lactose hydrolysis experiments at 52, 56, 60, and 64 degrees C. The thermal deactivation was modelled effectively as a first order decay process. Based on the estimated thermal deactivation rate constants, at an operating temperature of 40 degrees C, 10% of the enzyme activity would be lost in one year.
authors.affiliation: Department of Chemical Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Peterson
authors.forename: C G
authors.initials: CG
authors.lastname: Hill
authors.forename: C H
authors.initials: CH
authors.lastname: Amundson