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Keywords:

  • Drying;
  • kinetics;
  • kinetics model;
  • magnetic resonance imaging;
  • mathematical models;
  • thermal effects;
  • vegetables

Summary

The paper investigated the effect of hot-air drying (50, 60 °C) on the physical properties of cylindrical eggplant samples. Drying kinetics, water profiles along longitudinal and transversal sample sections through nuclear magnetic resonance imaging (MRI) and volumetric shrinkage were determined. During the drying process at 50 °C, the volume of removed water was found lower than the reduction in sample volume, while at 60 °C it was higher. MRI showed that the water migration mainly occurs transversally than longitudinally. The curves of mass water loss obtained by both the standard weighting method and MRI showed conformity. Experimental data of moisture ratio and of shrinkage volume were fitted using empirical models available in the literature. This preliminary study showed that the nondestructive MRI technique offers the possibility to study water distribution in food during drying processes. The quantitative moisture distribution maps allow future development and verification of models for prediction of mass transport phenomena in foods during drying.