Sérgio S. de Jesus

Optimizing Drying Conditions for the Microwave Vacuum Drying of Enzymes

The aim of this study was the methodological use of experimental planning for the optimization of microwave vacuum drying of enzymes using α-amylase as a model. A factorial in star designwas used to optimize the microwave vacuum–drying process, and the variables were power output and vacuum pressure. The material dehydrated by this technique was analyzed with regard to its enzymatic activity, water activity, and moisture content. Response surface methodology was used to estimate the main effects of vacuum pressure and power on the enzymatic and water activities. The experimental in star design revealed that microwave vacuum drying is influenced mainly by power. The dehydrated product showed high enzymatic activity and low water activity.

Enzyme conformational predictions by molecular modeling

Abstract The main objective of this paper is to verify the influence of temperature on α-amylase conformation during the drying process by atomization and freeze drying as well as to realize predictions by molecular modeling. These allows to verify structural changes due to partial or total activity loss during either drying processes as well as to investigate, by simulation what are the better conditions of pressure and temperature. Studies at bench scale used a α-amylase from Bacillus . Atomization experiments used a vertical spray dryer and freeze drying of enzymes. Computational simulations were carried out using a ECEPP/3 program for IBM-AIX. Tertiary structure of the α-amylase was obtained using a SWISS PROT data bank, in which was modeled the structure concerned with the 512 aminoacids that exists in this protein. The minimized structured characteristics were quantified using calculations from RMSD (root mean squared desviation). The characteristics were compared with the original structure using a PDB (protein data bank). The whole optimization was carried out to the 483 residues that exists in the chain. Through the obtained results it was possible to verify that the conformational structure is strongly influenced by the temperature even for relatively low values. The molecular modeling showed to be very efficient to predict the temperature which allows to carry out freeze drying experiments in such conditions to preserve the desired properties of the enzyme. The modelling predictions have shown a very good agreement with the experimental data which allow to conclude that it may be used to the search of operating conditions as well as for process optimization.