DSC heating profiles of starch with low water content are complex, featuring a number of endothermic transitions. The LT endotherm is due to enthalpy relaxation that occurs on ageing below Tg. TheM and HT endotherms represent the melting of starch granules and the transition into a molecular melt, respectively. In potato starch with 16% water, the individuality of the granules is preserved until the end of the M2 transition, i.e., at least up to 178 C. Heating through the M transition is accompanied by a strong reduction in swelling capacity, analogous to a heat-moisture treatment. This reduction parallels the overall decrease in crystallinity and the partial recrystallization on cooling without restoration of the lamellar order, which were reported by other workers (Zobel et al., 1988; Vermeylen et al., 2006a). This suggests that randomly
dispersed crystallites are much more effective as physical cross-links than crystallites in ordered arrays that exist in the intact granules. The transition into a molecular melt is accompanied by significant molecular degradation. It is likely that the HT endotherm, which persists at water contents up to at least 35%, does not represent a true thermodynamic transition, but is an artefact due to a volume change in the sample