Optimizing Drying Conditions for the Microwave Vacuum Drying of Enzymes

Abstract

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.

Keywords:

• Drying kinetics
• Enzyme
• Experimental design
• Microwave vacuum drying
• Moisture sorption isotherms

ACKNOWLEDGMENTS

The authors acknowledge financial support received from the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, proc. 99/12379-5 and 01/00571-0).

Notes

% Variation explained by the model (r²) = QSR/QST = 93.4% (EA) and 86.1% (a_w) and % Explainable maximum variation = (QST − Q_Spe)/QST = 98.6% (EA) and 97.5% (a_w), where Residues = lack of adjustment + pure error.