Modelling of electrohydrodynamic drying kinetics for carrot at varying electrode distance.

Abstract

This study was conducted to analyze the drying kinetics of carrot slices in electrohydrodynamic (EHD) dryer at different electrode distances. Higher drying rate was observed up to about 70% (w.b.) moisture content, which has been noted as first falling rate period. The time taken to dry the carrot slices to the safe moisture content of 2.5% (wb) was about 9, 8.5 and 6.8h at a distance of 7, 5 and 3cm respectively. Five empirical models, Page Model, Newton model, Henderson and Pabis model, logarithmic model and two term model, were tested for the best fit. The drying rate constant (k) increased in all the empirical models as the distance between the electrode decreased. For 7cm electrode distance, the Page model fitted best whereas the Logarithmic model was found to be the best fit for 5 and 3cm electrode distance. There is no significant difference found in shrinkage of dried carrot slices at different electrode distance. Rehydration ratio increased as the distance between electrodes decreased. Moisture diffusivity increased as the distance between the electrode decreased. No significant difference in colour, β-carotene and sensory attributes were found between fresh and EHD dried carrot slices at 3cm electrode distance. Specific energy consumption was significantly influenced by the electrode distance.