Translational Diffusion in Sucrose Solutions in the Vicinity of Their Glass Transition Temperature

@article{citeulike:2735310, abstract = {Abstract: The prediction of the stability of low-moisture products is complex, particularly close to the glass transition temperature. This study demonstrates that the relations used to evaluate the influence of temperature on the viscosity of carbohydrate media cannot be applied to the diffusivity. The translational diffusion coefficient of a fluorescent molecule (fluorescein) is measured in sucrose-water mixtures as a function of temperature. The main result is that the mobility of the fluorescein is not simply coupled to the viscosity of the diffusion medium at temperatures close to the glass transition temperature. Indeed the WLF equation, which gives a good prediction of the viscosity, does not allow the determination of the diffusivity in a temperature range close to Tg because the translational diffusion follows a weaker temperature dependence. Different possible explanations for this apparent decoupling between translational diffusion and viscosity are suggested: a small change in the hydrodynamic radius of the diffusing molecule due to low water content and/or a connection with the relaxation process.}, address = {Laboratoire de Biochimie, Physico-chimie et Propri\'{e}t\'{e}s Sensorielles des Aliments, Ensbana, 1, Esplanade Erasme 21000 Dijon, France, and Lab. de Physique de la Mati\`{e}re Condens\'{e}e, Coll\`{e}ge de France, 11 place M. Berthelot, 75000 Paris, France}, author = {Champion, D. and Hervet, H. and Blond, G. and Le Meste, M. and Simatos, D. }, citeulike-article-id = {2735310}, doi = {10.1021/jp971899i}, journal = {J. Phys. Chem. B}, keywords = {decoupling, diffusion, glass}, month = {December}, number = {50}, pages = {10674--10679}, posted-at = {2008-04-29 20:55:19}, priority = {2}, title = {Translational Diffusion in Sucrose Solutions in the Vicinity of Their Glass Transition Temperature}, url = {http://dx.doi.org/10.1021/jp971899i}, volume = {101}, year = {1997} }

TY - JOUR ID - citeulike:2735310 L3 - citeulike-article-id:2735310 TI - Translational Diffusion in Sucrose Solutions in the Vicinity of Their Glass Transition Temperature JF - J. Phys. Chem. B VL - 101 IS - 50 SP - 10674 EP - 10679 AD - Laboratoire de Biochimie, Physico-chimie et Propriétés Sensorielles des Aliments, Ensbana, 1, Esplanade Erasme 21000 Dijon, France, and Lab. de Physique de la Matière Condensée, Collège de France, 11 place M. Berthelot, 75000 Paris, France N2 - Abstract: The prediction of the stability of low-moisture products is complex, particularly close to the glass transition temperature. This study demonstrates that the relations used to evaluate the influence of temperature on the viscosity of carbohydrate media cannot be applied to the diffusivity. The translational diffusion coefficient of a fluorescent molecule (fluorescein) is measured in sucrose-water mixtures as a function of temperature. The main result is that the mobility of the fluorescein is not simply coupled to the viscosity of the diffusion medium at temperatures close to the glass transition temperature. Indeed the WLF equation, which gives a good prediction of the viscosity, does not allow the determination of the diffusivity in a temperature range close to Tg because the translational diffusion follows a weaker temperature dependence. Different possible explanations for this apparent decoupling between translational diffusion and viscosity are suggested: a small change in the hydrodynamic radius of the diffusing molecule due to low water content and/or a connection with the relaxation process. KW - decoupling KW - diffusion KW - glass AU - Champion, D AU - Hervet, H AU - Blond, G AU - Le Meste, M AU - Simatos, D PY - 1997/12/11/ UR - http://dx.doi.org/10.1021/jp971899i ER -