THIN LAYER DRYING OF GARLIC SLICES USING INFRARED

Abstract

Infrared drying of thin layer garlic slices have been studied at four levels of radiation intensity 0.075, 0.15, 0.225 and 0.3 W/cm 2 , three levels of air velocity 0.25, 0.75, and 1.25 m/s and constant air temperature of (40 0 C). Three mathematical models (Page, Modified Page, and Henderson and Pabis) were examined for describing the drying behaviour of garlic slices at the above mentioned experimental treatments. The results were compared to their goodness of fit in terms of coefficient of determination (R 2), Standard deviation (SD), the average percentage of error (%E), Chi-square (χ 2) and the modeling efficiency (EF). The results showed an increase in drying rate, thermal efficiency, rehydration ratio and colour difference and a decrease in drying time, specific energy consumption, hue angle and the flavour strength with the increase of infrared intensity and decrease of air velocity. Page model showed better prediction of drying process in comparison with the modified Page and the Henderson and Pabis models and it was satisfactorily described the drying behavior of garlic slices under the studied ranges of the experimental treatments. Meanwhile, drying constant of page model (k) increased and the constant (n) decreased with the increase of radiation intensity and the decrease of air velocity.