Phase transitions. DSC and DTA are routinely used in the food industry to characterize phase transitions ins foods, e.g. crystallization, melting, glass transitions and conformational changes. They can be used to provide information about the temperature at which transitions occur (T…), the enthalpy change associated with a transition (DH..), the type of transition involved (exothermic or endothermic), and the quantify of material that undergoes a transition. As an example’ we will consider the use of DSC to study the melting and crystallization of food components. When a material changes its physical state from solid-to-liquid (melting) or liquid-to-solid (crystallization) it absorbs or gives out heat’ respectively. A process that absorbs heat is an endothermic process, whereas a process that evolves heat is an exothermic process. Pure substances usually have very sharp melting or crystallization points and therefore all the heat is absorbed or evolved over a narrow range of temperatures, leading to a sharp DSC or DTA perk. Many food components are chemically complex materials and therefore the phase transitions occur over a wide range of temperatures, e.g. edible oils contain a wide variety of different triacylglycerols each with its own melting point. Peaks from food oils may also by complicated by the fact that triacylglycerols can crystallize in more than one different crystalline structure, i.e., they are polymorphic.