Convective drying rates of thermally blanched slices of potato (Solamum tuberosum): Parameters for the estimation of drying rates

Thermal blanching is a pre-drying treatment applied to some food products in order to inactivate enzymes for preservation of flavours and colour. This process leads to modified surface layers in the products. Drying of such products involve moisture transfer across such layers leading to build-up of moisture concentration gradients within the material being dried. In this study microscopic investigation of surface layers of blanched potato confirms that the presence of such surface layers. Rates of drying of thermally blanched slices of potato (Solamum tuberosum) of different thicknesses are obtained experimentally in a laboratory convective tray dryer at 85 °C and 95 °C. A model (Fernando et al., 2008) for estimation of dehydration rates of materials with surface layers which describe three parameters (l/D), r and Kp·H·Co related to the drying material and the process is employed in order to evaluate the respective parameters based on the experimental data with the aid of a Matlab optimization program. Consistent values of the parameters were obtained for different thicknesses indicating applicability of the parameters in the model for characterization of species for drying of the blanched materials. Drying rates regenerated using the averaged parameters showed compatibility with experimental data with a correlation coefficient of 0.992.

Research highlights▶ Drying rates of blanched potato slices parameterized with three parameters. ▶ Existence of layers observed at the surfaces of blanched potato slices. ▶ Respective drying rates regenerated with satisfactory co-relation coefficients. ▶ Estimation of drying rates in drying systems of sliced and blanched potato.