DESIGN AND FABRICATION OF FREEZE DRYER

Thesis Abstract

Water is responsible for changes in the physical, chemical and/or biological characteristics of foods. It is an important component of all biological or living systems. In fresh foods, the percentage of water varies from 60% to more than 90% (Davide and Salvatore, 2012). Water content in foodstuffs during processing, storage and distribution may lead to deterioration of aroma and degradation of nutritional substances because it supports the existence and development of micro-organisms and chemical reactions within the foodstuffs. Drying or dehydration of foods is the basic food-processing operation used to preserve foods for a long period of time. Although both terms are applied to the removal of water from food, using heat and mass transfer, drying usually refers to natural desiccation such as spreading fruit on racks in the sun; and dehydration designates drying by artificial means such as a blast of hot air.