Heat and moisture transfer and shrinkage simulation of beetroot (Beta vulgaris) drying

Drying is an important method of preservation of wet materials and is applicable to a wide range of industrial and agricultural products. Dried products have limited deterioration rates, due to the low water activity, are easily transported and stored because of the reduced volume, and have no need of refrigeration, representing energy economy. The purpose of the present study was to develop a model to describe the heat and mass transfer during the drying of beetroot. Temperature, moisture content, and shrinkage of a beetroot disc were simulated during drying at three different air temperatures (50, 60, and 70 °C). Simultaneous heat and moisture diffusion equations were solved along with convective boundary conditions, using a simulation language, MATLAB, based on finite difference technique. Shrinkage, variable thermal properties and moisture diffusivity were considered in the simulation. The simulated results matched satisfactorily with measured temperature and moisture content of the beetroot during drying.