Dryers Developed by AICRP on PHET

Abstract

Drying is mostly based on convection process in which moisture from a product is removed. Drying can be achieved by two processes viz. natural drying and mechanical dehydration or artificial drying based on source of energy. Natural drying takes place under the influence of sunlight and wind and is of three typesviz. sun, solar and shade drying. In case of natural drying, there is no control over temperature, air flow rate and humidity whereas in artificial drying, these conditions are well controlled. Preservation is the main reason but not the only reason for dehydrating foods. Food may be dehydrated for other reasons like decreasing etc. weight and bulk; to retain size and shape of original food; to produce convenience items. Dehydration/ drying are advantageous for being cheaper than the other methods of preservation with fewer requirements of equipments. Storage of dried food products does not require special facilities like refrigeration etc. Dried food products are simple to store and pack because of their low volume. Dehydrated foods however, suffer from some undesirable changes in colour, taste and flavour during storage and distribution. Dehydration techniques have been improved to overcome most of these defects. Various kinds of dryers have been developed by AICRP on PHET centres. It is expected that the present publication shall arouse the interest of readers in different type of dryers for effective post-harvest engineering interventions and help the interested persons in choosing the right kind of dryer for research or business endeavours. This publication also intends to provide a compiled literature on available dryers in the country and abroad for ready reference to students, researchers and entrepreneurs.