Thermal evaluation of sucrose-maltodextrin-sodium citrate bioglass: Glass transition temperature

•The Tg values were affected by all components of the bioglass system.•These changes in Tg suggest an interaction between sodium citrate and sucrose.•The width of glass transition zone narrowed as moisture content increased.•The interference of water on the intermolecular interactions increased ΔCp,GT.•The addition of NaCit can enhance the stability of low-moisture bioglass

Sucrose-maltodextrin-sodium citrate (SC-MD-NaCit) bioglass model systems were studied using modulated differential scanning calorimetry (DSC) to test the hypothesis that addition of salt to a complex amorphous carbohydrate system at low level of moisture content will significantly affect its glass transition properties. Samples were formulated with different SC/MD ratios (7:3, 5:5 and 3:7, by mass) and NaCit/SC ratios (0, 0.1 and 0.2, by mole) and two levels of residual moisture content, low (0.27–0.35%wb) and high (2.83–4.40%wb). The glass transition characteristics of these systems were strongly dependent on the moisture content and other constituents. On average, glass transition temperature (Tg) of the 7:3, 5:5 and 3:7 SC/MD systems were approximately 77, 84 and 101 °C, respectively. The Tg values tended to increase when NaCit was added, with a noticeable increase occurring in the 7:3 SC/MD system at low moisture content. The increase in moisture content from low to high level had a significant plasticization effect on the bioglass as elucidated based on the decrease in the Tg from approximately 106 to 67 °C. The DSC thermograms suggested that water molecules may interfere with intermolecular interactions between the glass-forming molecules causing changes in the molecular mobility of the bioglass matrix. The findings reveal that addition of NaCit can enhance the stability of low-moisture bioglass by primarily interacting with SC and forming large, less-mobile clusters, which helps to improve the Tg and restrict matrix mobility.

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