Solar drying kinetics of pears harvested at different ripening stages.

In Portugal, pears of the variety S. Bartolomeu have been used to produce a traditional product named “pêra passa de Viseu”. These pears are dried at direct open air sun exposure, following a multi-step procedure. In the last years some investigation around this product and the production method has been carried out to better understand them and establish alternative production techniques. In the present work pears of the variety S. Bartolomeu, harvested at three different moments, corresponding to three ripening stages, were dried in a solar stove and their drying kinetics were studied. From the results obtained it was possible to conclude that all the six equations used to model the drying kinetics fit with accuracy the experimental data, and that the differences found in the three essays result mainly from the climatic conditions that occurred in each drying period