Effect of air temperature, slice thickness and pretreatment on drying and rehydration of tomato

Abstract

The effect of air temperature, pretreatment with alkaline emulsion of ethyl oleate (AEEO) and slice thickness on drying and rehydration characteristics of tomato slices was studied. Drying time decreased with pretreatment, but it increased considerably with the increase in air temperature and slice thickness of tomato. Besides, pretreatment was found to improve the rehydration ratio of tomato slices. The experimental drying curves obtained show only falling rate period. To estimate and select the suitable form of drying curves, five different mathematical models were applied to the experimental data. Among the mathematical models investigated, the Midilli etal. and logarithmic models satisfactorily described the drying characteristics of tomato slices with highest R-2 and lowest (2) and root mean square error. The effective moisture diffusivity varied from 3.123 to 10.03x10(-11)m(2)s(-1) over the temperature range studied, and the activation energy values varied from 59.6 to 70.2kJmol(-1).