Moisture Diffusivity Analysis in a Microwave Drying Process under Different Operating Conditions

Abstract

This article deals with the kinetic analysis of the drying of sliced mushrooms (Agaricus bisporous) and apples (Golden Delicious), as representatives of vegetables and fruits, by the application of microwave. The drying experiments were carried out in monomode or multimode cavities, depending on the purpose of the study. In the former, the location of the temperature control is analyzed, and in the latter, the effect of pressure, air humidity, and temperature control. In the experiments, the mass loss was monitored over time and the drying kinetics described by means of a model, assuming effective diffusivity to be constant. The changes in the diffusion coefficient could be explained in terms of possible texture modifications of the product derived from the different conditions experienced during drying.

Keywords:

• Apple
• Diffusivity
• Drying kinetic
• Microwave drying
• Mushroom

ACKNOWLEDGEMENTS

The authors are grateful to Universidad del País Vasco (UPV/EHU) for a research grant and to the Basque Government for financial support for the study through the INTEK programme from 2002 to 2005.

Notes

^a Experimental set (including the following two) for analyzing temperature control location: left (L), center (C), and right (R).

^b Experiment (including the following one) for analyzing convective heating effect induced by pressure.

^c Experimental set (including the following nine) for analyzing pressure and temperature effects. Temperature was positioned on the surface (C.S) and inside the product (C.In).

^d Experimental set (including the following four) for analyzing the effect of dry air at several control temperatures.

^a Standard deviation between modeled (from diffusivity and β) and experimental values of M vs. t drying kinetics.

^a Standard deviation between modeled (from diffusivity and β) and experimental values of M vs. t drying kinetics.

^a Standard deviation between modeled (from diffusivity and β) and experimental values of M vs. t drying kinetics.

^a Standard deviation between modeled (from diffusivity and β) and experimental values of M vs. t drying kinetics.

Additional information

Notes on contributors

R. Rodríguez

Present address for R. Rodríguez: Department of Food Research, AZTI-TECNALIA, Technological Institute for Fisheries and Food, 48395 Sukarrieta (Spain).