A DSC Study of Hydrated Sugar Alcohols. Isomalt

A DSC study has been carried out on isomalt, a commercial sugar alcohol derived from sucrose and widely used as a sweetener in the food industry. Isomalt is a mixture of two isomers:α-D-glucopyranosyl–1-6-mannitol (GPM) and α-D-glucopyranosyl–1-6-sorbitol (GPS). Release of the water of crystallisation (around 100°C)and melting (around 150°C) have been phenomenologically characterised using different scanning rates and heat treatments. The effect of dehydration/re-hydration on the melting has been investigated. The isomalt glass transition, at about 60°C, was studied on samples cooled after melting. The dynamic aspect of structural relaxation of isomalt has been quantified by its fragility parameter. Glassy state stability has been evaluated by performing ageing experiments at sub-T _g temperatures. During ageing, apart from the expected enthalpy relaxation effects, isomalt showed a peculiar behaviour, due to its isomeric composition. These preliminary and phenomenological results have been interpreted in terms of isomer structure and of carbohydrate-water interactions in the mixture. This revised version was published online in July 2006 with corrections to the Cover Date.