State Diagram of Foods and Its Importance to Food Stability During Storage and Processing

Foods undergo different phase and state changes during their processing and storage; and these changes play a significant role in determining their stability during processing, storage and even during consumption. Examples of the phase changes are freezing, melting, crystallization, gelatinization and boiling. A state diagram is a stability map of different states and phases of a food as a function of solids or water content and temperature. Glass transition is a second-order time-temperature and moisture dependent transition, which is generally characterized by a discontinuity in physical, mechanical, electrical, thermal, mass transfer and other properties of a material. The freezing point is the temperature at which the ice crystals are formed during cooling, appeared at a critical mass where both phases, liquid and solid, and coexisted in equilibrium. A successful combination of water activity and glass transition could open more precise and unified determination of stability criteria.