Structure and properties of bread dough and crumb : calorimetric, rheological and mechanical investigations on the effects produced by hydrocolloids, pentosans and soluble proteins

The effects of hydrocolloids (guar and locust bean gums), soluble pentosans, and whey proteins on staling of bread crumb were investigated by means of DSC, rheometry, and image analysis. One current hypothesis, that these ingredients would behave as ''water binders'' and, at least the former two, as anti-staling agents, was indeed confirmed, although this action might be indirect. All the samples considered showed an exothermic DSC peak preceding the endotherm of the amylopectin fusion. According to a previous work, this signal was attributed to a water-de pendent cross-linking process that would involve next-neighbouring polymer chains. To check the effect produced by molecular modifications that were expected to increase the water uptake of these ingredients, doughs containing added succinylated pentosans and whey proteins, and a polycarboxylate polymer, PEMULEN TR-1, were examined. These modifications enhanced starch retrogradation and yielded a firmer crumb. It was tentatively concluded that some direct interaction between these modified molecules and the crumb polymers might have taken place. In line with the food polymer science approach, the use of Time-Temperature-Transformation (TTT) diagrams is also discussed.