Kinetics of lactulose, galactose and epilactose formation during heat-treatment of milk

The kinetics of formation of lactulose, galactose and epilactose during heating of milk were examined over a wide temperature/time range (). Formation of the studied carbohydrates was best described with apparent first order reactions. The Arrhenius plot of the logarithm of the rate constant as a function of the reciprocal of the temperature (°K) enabled calculation of the activation energies (125 kJ/mol for lactulose, 131 kJ/mol for epilactose and 139 kJ/mol for galactose). By using the kinetics parameters for calculating lines of equal degrees of formation in a plot of log-time versus reciprocal of absolute temperature it was possible to predict the effect of different heat-treatments on the formation of individual carbohydrates.
The authors wish to acknowledge financial support for the research project No. 158/88 provided by the Comisi6n Interministerial de Ciencia y Tecnologia.