Pear drying: experimental validation of a mathematical prediction model.

In the present work, drying experiments were carried out with pears of the variety D. Joaquina for a number of different operating conditions, with the purpose of validating a diffusion based model previously developed to represent the drying behaviour of pears in a continuous convective drier, which includes the timely variation of the fruit chemical, physical and thermal properties. The drying experiments were carried out at 30, 40 and 50 ºC, with an air containing 60 % of relative humidity passing at a variable speed ranging between 0.5 and 1.5 m/s. The pears were dried uncut, after peeling, and the evolution of the moisture content along drying for the different temperatures was analysed and later compared with the resulting curve obtained from the program simulation. Apart from the drying curves, also the time and space evolutions of the moisture and sugar concentrations were analysed, either in terms of experimental essays or in terms of model prediction. The good accordance between the experimental points and the previsions given by the model enables to conclude that the model adequately describes the drying behaviour of the pears under study, in the range of operating conditions tested