Molecular Mobility in Glassy Bread: A Multispectroscopy Approach

The molecular mobility in low-moisture (<9%, web) white bread was studied as a function of temperature using pulsed-proton nuclear magnetic resonance (NMR), and dielectric and dynamic mechanical spectroscopies. The water was mobile, even in glassy samples. Different processes below glass transition temperature (sub-T_g) were observed, and a relaxation map of the studied system was drawn. These results have been interpreted and extrapolated to suggest that the T_g is not a universal predictive parameter for the physical stability of glassy food.