ABSTRACT
Drying is a physical separation process that has the objective of removing a liquid from a solid phase by means of thermal energy. The liquid is generally water and is liberated by vaporization rather than by breaking chemical bonds between the liquid and the solid; i.e., the liquid is not chemically bound to the solid. In most industrial drying applications, it is neither necessary nor economically feasible to remove every vestige of water from the solid; thus, commercially dry solids will usually contain a certain amount of residual moisture, the amount of which is determined by a compromise between product quality and economic factors. In food and biological materials, low moisture levels are necessary to stop or slow the growth of spoilage microorganisms, as well as the occurrence of undesirable biochemical and enzymatic reactions.
