Enzyme Inactivation During Drying of a Single Droplet

Abstract

The effects of various drying conditions on the enzyme inactivation during drying of a single droplet were investigated. Moisture, temperature and enzyme activity of the drop during drying were measured as a function of drying time. The enzyme inactivation rate constants and the diffusion coefficients were measured as functions of moisture content and temperature. By use of these values, the drying histories including the enzyme retention in the drop were computed and compared with the experimental results. Good agreements were observed between the experimental and calculated results. A simple correlation between the enzyme retention and the initial drop radius was derived theoretically and verified experimentally. Furthermore, the effects of oxidation and pH change during drying on the enzyme inactivation were examined experimentally by the addition of a reducing agent and also by using nitrogen as a drying medium. It was found that these additional effects as well as the thermal inactivation must be considered in order to predict the enzyme retention during drying.