Infrared dehydration is more advantageous than the convective system under similar conditions, and studying this process
is important to further develop equipment and procedures. Thus, the aim of this work was to study the dehydration process
of tomato (
Solanum lycopersicum
L.) slices obtained by infrared drying at three different maturity stages throughout two
different procedures: Firstly, the drying model was determined by applying the mass and energy balances under wet bulb
temperature for the constant drying rate period and secondly, the mass effective diffusion coefficient was determined
throughout the experimental data and the theory of diffusion of the liquid phase for the decreasing drying rate period.
Tomato fruits cv. Santa Cruz were used. Three maturity stages were selected: green (stage 1), orange (stage 2), and red
(stage 3). Mathematical models frequently used to represent drying of agricultural products were fitted to the experimental
data of tomato drying. The effective diffusion coefficient was obtained by adjusting the liquid diffusion mathematical model
to the experimental data of the descending period of dehydration. The two-term model was the best one to represent the
tomato dehydration process. The critical moisture content for tomato dehydration was 2.97 kg
w kg
dm-1. There is an initial
dehydration period in which the drying rate reaches its maximum (approximately 1.05 kg
w kg
dm-1, about 3 min). Three
different methods were used to obtain values of the effective diffusion coefficient, including the finite element method,
which had the lowest values for the least square sum of deviation 1.00 × 10
-7 m
2 s
-1. The global coefficient of heat transfer
was 12.45 W m
-2K
-1, and the global coefficient of mass transfer was 0.0105 m s
-1.
