Phase transitions are often categorized according to first-order,
second-order, or higher-order transitions (Roos 1995; LeBail and
others 2003). In a first-order transition, there is change in enthalpy,
H, of the material (heat is either released or accepted) as
the molecules go from one state to the other. In contrast, in a
second-order transition, there is no enthalpy change associated
with the transition, just a change in heat capacity, Cp. For example,
when studied in a calorimeter (such as a differential scanning
calorimeter [DSC]), a crystal melting (first order) is observed as
an endothermic heat flux associated with the enthalpy change as
heat is removed from the environment, whereas a glass undergoing
a transition to the liquid state (second order) in the calorimeter
exhibits only a small shift in the baseline at the glass transition
(Roos 1995). Crystallization and glass transition are the 2 main
phase/state transitions exhibited by sweeteners.