The developing countries suffer heavy losses of food in the post harvest period during which the harvested crop passes through a series of well defined steps - like threshing (or shelling), drying, storage and final plrocessing (Fig. 1). Drying is one of the most important steps of post harvest handling of the crop. The traditional methods of drying employed in developing countries are open air sun drying or natural drying in shade). Because of little control over the drying rate in these methods, the dried product is very often underdried or overdried. Underdrying results in deterioration of food due to fungi or bacteria whereas overdrying may result in case hardening followed by bursting and spoilage of the food. Under controlled conditions of temperature and humidity, the cropl dries reasonably rapidly to a safe moisture level. Such conditions also ensure superior quality (better nutritional and germination characteristics) in the dried product. Rationale for drying of various types of food products is summarised in Table 1.
KeywordsSolar Collector Chemical Pretreatment Absorber Plate Humidity Ratio Selective Coating
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