Drying characteristics and sorption isotherm of tomato slices

The drying behaviour of tomato slices was investigated at 45, 60 and 75 degrees C. Three falling rate periods were observed with diffusion coefficients in the range 3.72-12.27 x 10(-9) m(2)s(-1). The water vapour sorption isotherm of dehydrated tomato slices in the water activity (a(w)) range of 0.08-0.85 was also determined at three temperature levels, i.e., 25, 30 and 40 degrees C. Five sorption models were fitted with the adsorption data generated from the gravimetric method. GAB and Oswin models describe the adsorption characteristics of dehydrated tomato at 25 degrees C better than other models with GAB model being the best applicable model. The isosteric heat of adsorption decreases with increasing moisture. (c) 2005 Elsevier Ltd. All rights reserved.