Water and the glass transition temperature of organic (caramel) glasses

Abstract The glass transition temperature ( T g ) of sugar-related glasses is close to room temperature and here we report the affect of water concentration on the T g of caramel–water mixtures. Based on viscosity measurements, thermal analysis and X-ray diffraction (XRD) experiments we have investigated the occurrence of the T g during differential scanning calorimetry (DSC) runs on cooling (down to ∼170 K) and heating cycles of the caramel glasses and caramel–water mixtures. The caramel–water mixtures are viscous melts with Newtonian rheology. Their melts bear a resemblance to a silicate melt which do not deviate from Vogel–Fulcher–Tammann (VFT) equation fit as the glass approaches T g . The DSC measurements did detect low temperature transitions in caramel–water mixtures and the T g of the dried caramel glass sample. If crystallization is avoided on cooling to ∼170 K then a glass transition and devitrification of the mixture will occur on heating the sample from ∼170 K up to the ambient room temperature. The detectability of the glass transition depends on the cooling rate and water concentration.