Kinetic study of staling in breads with high-amylose resistant starch

High-amylose resistant starch breads were long-stored (11 days) at 20 degrees C for kinetic analysis of different aspects of the staling process. Bread products were formulated on a French-bread recipe basis and replacing wheat flour by type II resistant starch at different levels: 0% (control), 10% (HM10), 20% (HM20) and 30% (HM30). Experiments included measurements of water activity, moisture loss, amylopectin retrogradation by DSC, crystallinity changes by X-ray diffraction, and firmness by texture analysis. In the presence of resistant starch water loss was slower, allowing amylopectin retrogradation to be more extensive. However, HM10 and HM20 had similar firming behavior to the control, likely due to the similar and adequate quality that these breads showed initially (at day 0). In contrast, samples with high resistant starch content such as HM30 presented a poor-quality and highly filled crumb that led to the highest firmness during storage.