Near-fluidizing microwave drying to stabilize encapsulated material: Analysis of kinetic, energy and quality elements

Abstract

Dehydration of the encapsulated material containing nutritional ingredients was determined to be necessary for functional foods and probiotics production. The application of a suitable drying process was required. This study proposes the development of a new dehydration process, called near fluidizing microwave drying (NFMD), to minimize the problems observed in other drying processes, such as spray drying or lyophilization. Several heating strategies, which are employed in microwave applications under fluidizing conditions, were adequately modeled to analyze the effect of the operational variables. The fitting of experimental data has enabled the determination of the mass and heat transfer coefficients: diffusivity and heat convection. The drying phases were analyzed based on the obtained values of these parameters as basis for the selection of the most favorable operational conditions. Under these conditions, the NFMD process has been employed for the dehydration of the encapsulated probiotic Bifidobacterium animalis subsp. Lactis (BB12). The best results of the cell viability were around 90%, demonstrating the suitability of this novel technology for these thermo-sensitive materials.

Keywords:

• Encapsulation
• fluidization
• drying
• microwave
• modeling
• cell viability
• energy consumption

Acknowledgements

The authors are thankful to Chr. Hansen S.L. (Madrid, Spain) for the aid through the provision of all used probiotic materials.

Additional information

Funding

The authors are grateful to the Basque Government for providing financial support for the study through the aid PPG17/53 within the program to Consolidated Groups (Basque University System) and to the University of the Basque Country (UFI 11/39 UPV/EHU).