Prediction of the effect of water on the glass transition temperature of low molecular weight and polysaccharide mixtures

The right storage conditions for food powders containing amorphous carbohydrates are crucial to avoid structural changes. By combining the sorption isotherm and the glass transition temperature (Tg) data for these food powders enables the determination of appropriate moisture and temperature conditions for their storage. In this study, the modified Flory-Huggins free volume theory was utilized to predict the stability diagrams purely from the composition of the powders. The validation of the approach using the literature data of blends of grapefruit, mango and acai powders with various blends of maltodextrin (MD) and gum Arabic. The blends of fructose, glucose individual and in combination with citric acids as well as blackcurrant juice concentrate with MD DE 9–13 were also investigated. The alignment of experimental and predicted data of fruit powders demonstrates that it was possible to predict the relation of the Tg well as a function of the water activity for carbohydrate mixtures.