DSC AND PROTEIN-BASED TIME-TEMPERATURE INTEGRATORS - CASE-STUDY OF ALPHA-AMYLASE STABILIZED BY POLYOLS AND OR SUGAR/

Differential scanning calorimetry (DSC) was used as a tool for rapid a ssay of the thermostability of two Bacillus sp. alpha-amylases and hor seradish peroxidase as a function of the concentration of glycerol, so rbitol, and sucrose. In this screening study, the DSC peak temperature proved to be a good measure of protein thermostability. By means of i sothermal heating experiments, the kinetics of heat decay of B. amylol iquefaciens alpha-amylase were studied by following the course of the DSC peak area (heat exchange (Delta H/wt)) as a function of time. The high stability of this enzyme in the presence of polyolic alcohols or carbohydrates allowed working at temperatures as high as 127 degrees C . The results of this study can have particular relevance with regard to research on and development of protein-based time-temperature integ rators (TTIs) for evaluating heat pasteurization or sterilization trea tments of foods or pharmaceutical products. The use of the DSC peak ar ea (Delta H/wt) as TTI-response was validated in experiments with a ti me-variable temperature profile. Finally, it was shown how the results of such non-isothermal experiments can even be used for (re-)estimati on of the protein decay kinetic parameters (k, E(A)). (C) 1994 John Wi ley & Sons, Inc.