A number of common food preservation processes lower water activity (aw) to eliminate deterioration from microorganisms, enzyme activity, and potentially adverse chemical reactions that occur between food components. Reducing the amount of "free" or "unbound" water minimizes the undesirable chemical and structural changes that can take place in foods during storage. The processes used to reduce the amount of "free" water in foods include dehydration techniques such as concentrating and drying. Dehydration is defined as the removal of water due to simultaneous heat and mass transfer during heating under controlled conditions of temperature, humidity, and air flow (Okos et al. 1992, Barbosa- Canovas and Vega-Mercado 1996).