Study of drying, thermal, shrinkage, and color kinetics using digital and thermographic imaging of potato slices under real-time convective drying

Abstract

Convective drying has been widely used for extending the shelf life of foodstuffs as well as for the study of mass and heat transfer phenomena. This contribution aims to conduct a comprehensive study involving mass and heat transfer kinetics, modeling, and evaluation of surface temperatures, shrinkage, and color during the real-time convective drying of potato slices. A tunnel dryer was specially designed to couple digital and thermal cameras to follow the real-time evolution of the surface temperatures, shrinkage, deformation, and color parameters. Drying and thermal kinetics were studied with Fick's second law, Fourier’s approach, and semi-empirical mathematical models to obtain effective moisture diffusivity and energy activation to select the best model for describing drying and thermal kinetics. Effective diffusivity coefficients ranged from 6.12 x 10-10 to 9.71 x 10-10 m2/s, the activation energy was 13.79 kJ/mol, while Page’s model and an exponential function of three parameters were shown to be suita le for modeling drying and thermal kinetics. In addition, morphometric and color parameters obtained in real-time help select the best drying conditions and final product quality. This contribution provides essential information for a fuller understanding of the drying, design, and operation of drying equipment for food materials.