Influence of pre-treatment and drying methods on process of rehydration of dried apple

Abstract

Fruit and vegetable processing is a difficult problem in the food industry. The raw materials are characterized by limited durability, and at the same time may belong to highly different varieties and species, which is why their suitability for processing varies. The most important task of the agricultural and food industry is to secure harvests so that they can be consumed throughout the year. The factors that determine the quality of fresh and processed food are primarily the type and quality of the raw material, the type of pre-treatment and further processing, as well as the conditions under which the raw material and the finished product were stored. The scope of the paper includes: - preparation of raw material samples (slices), - pre-treatment (blanching in steam, soaking in a starch solution), - drying the raw material (dryer with air circulation, no air circulation), - rehydration of the dried material (cold and warm water, time: 150 minutes). On the basis of the conducted tests, it was found that in the case of patches, the largest mass after the rehydration process was shown by samples dried in an air dryer, blanched in steam and rehydrated in hot water. In comparison with the mass of the fresh raw material, the patch after rehydration returned in 85.5 % to its initial state. The weakest effect on the mass gain of the dried slices results from pre-treatment in the starch solution, drying without air circulation, and then rehydration in cold water. None of the samples after 150 minutes of hydration reached the mass of the fresh raw material.