Combination of mid dehydration and freeze-drying processes to obtain high quality dried vegetables and fruits

The use of a combination of thermal and freeze-drying processes was tested on different foodstuffs: apple, potato, carrot and courgette. The samples were predried by means of a thermal process and the complete dehydration was achieved via freeze-drying. The effect of the moisture content at which the first process stops and the second starts on the quality of the dry foodstuffs was experimentally determined. Physical and textural properties were determined for samples processed under different conditions and compared with those of freeze-dried products. The combination process was demonstrated to be a promising technique in the production of high quality dehydrated vegetables and fruits.