Thermal inactivation kinetics of Aspergillus oryzae β-galactosidase in concentrated lactose solution
Department of Chemical and Biochemical Engineering, Institute of Chemical and Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia
Abstract: Thermal inactivation of a commercial β-galactosidase from Aspergillus oryzae in a 300 g/L lactose solution was studied in the temperature range of 65—75 °C. Lactose exhibited a stabilisation effect when similar inactivation rates as those in lactose solution were observed in a lactose-free solution at temperatures lower by 5 °C. Inactivation process in the lactose solution was biphasic. A kinetic model based on the Lumry-Eyring mechanism was proposed and successfully verified. Estimated activation energy values were very different. Rather high activation energy values of the forward reactions were responsible for both the significant change of rate constants and the rate-controlling reaction with temperature. For these two reasons, an increase of the operational lifetime of the enzyme from 7 days at 55 °C to 580 days at 60 °C was predicted.
Keywords: β-galactosidase, thermal inactivation, kinetics, Lumry-Eyring mechanism, multitemperature modelling
Full paper in Portable Document Format: acs_0315.pdf
Acta Chimica Slovaca, Vol. 11, No. 2, 2018, pp. 170—174, DOI: 10.2478/acs-2018-0024