Green technologies in food dehydration

Abstract

The massive scale of drying operations in many food processing industries makes this unit operation an important one to focus on in the development of “greener” food production and processing practices. Drying techniques and equipment used by many industries today are characterized by high energy consumption and relatively low thermal efficiency. In this chapter, each step of a typical food dehydration process, that is (1) wet feed pretreatment, (2) preparing (mostly heating) of the drying agent, (3) drying process, (4) maximal retrieval of the dry product, and (5) heat recovery from the exhaust gases, is discussed in detail. Because drying is associated with high investment costs and high energy consumption, elimination of the drying operation from the production process, or its replacement with lower-energy consuming operations, are primary recommendations. If this is not possible, reduction of the initial moisture content of the wet feed (thickening, preconcentration, preforming, etc.), use of environmentally friendly energy sources and energy-efficient drying installations and maximal recovery of energy from exhaust gases are recommended. Reduction or elimination of environmental pollution by complete recovery of finished dry product from exhaust gases is another important issue that needs to be considered.