Introduction to phase transitions

Phase transitions are changes in the physical state of materials. Thermodynamic properties of materials are required for the analysis of phase and state transitions. Gibbs energy is a useful parameter for the understanding of equilibrium and nonequilibrium states in foods. Classification of phase transitions may follow that of Ehrenfest. First-order transitions show discontinuity in heat capacity while second-order transitions have a step-change in heat capacity at the transition temperature. Raoult’s law provides an important relationship for composition dependence of equilibrium properties of food materials.