Effect of water sorption on glass transition and microstructural variation of dextran & sugar mixtures

Dextran is widely used as a model polysaccharide to study the interactions between polysaccharides and small molecule sugars. This study examined water sorption isotherms and glass transition temperatures ( T g ) of mixtures of dextran with trehalose , lactose and sucrose for understanding how different disaccharides affect dextran's processing adaptation and storage performance relevant to water sorption. At the same chemical composition , monolayer water ( m 0 ) was dextran & sucrose (dex&suc) > dextran & trehalose (dex&tre) > dextran & lactose (dex&lac). The higher ratios of dextran, the higher was the Guggenheim constant ( C ) value of the mixtures. The compatibility of dextran and disaccharides was dex&tre > dex&lac > dex&suc. Gordon–Taylor model showed dex&tre (2:1) best inhibited water plasticization . Furthermore, trehalose and lactose were more effective in preventing morphological changes of hydrous matrices in the mixtures. The crystallinities of samples at 43% relative humidity (RH) were slightly lower than that at 11% RH.