Dough and baked products can be described as polymer systems according to the Food Polymer Science approach. The structure evolution of a bakery product can be tentatively depicted as the result of the cure of a gluten network, which mainly occurs at high baking temperatures, and that of starch amorphous matrix, which is still in progress during the shelf-life at room temperature. In particular, the final structure can be referred to as the result of a water dependent process, related to the number and kind of cross-links formed between the nearest neighbouring chains of biopolymers present in the starting dough. These links:can be either direct like hydrogen bonds across functional grups belonging to dose chains, or mediated by interstitial water molecules bridging across interchain gaps: water molecules would be displaced along polymer chains acting as sliders of an interchain ''zipper''. The glass transition temperature, Tg, of the crumb formed is rather close to room temperature, although it: increases with aging, as the firmness of the staled product clearly reveals. It is moreover well known that Tg is strictly influenced by water which acts as polymer's placticizer. The addition to dough of highly water-binders macromolecules as pentosans is therefore expected to significantly modify the mechanism of water mobility in bread crumb. Useful experimental data to support the ''zipper'' model and to assess the effects of water soluble pentosans on staling of bread crumb have been obtained by means of differential scanning calorimetry investigations and thermogravimetry analysis and are presented in this paper.