Probing the Staling Process in Chickpea Composite Bread Through Dynamic Mechanical Analysis

The inclusion of chickpea flour in bread formulation could be a great opportunity for enhancing nutritional quality. However, significant effort is required to study the technological effects, both on fresh bread and throughout storage. Dynamic Mechanical Analysis (DMA) is a relatively underexplored technique for this purpose, but it could offer great potential as an analytical tool. In our study, composite bread loaves were produced by the inclusion of chickpea flour at 0, 10, 20 and 30% (flour based) in bread formulation. Bread staling was assessed over 7 days of storage, following moisture content, texture, and mechanical properties by DMA with frequency sweep and temperature scan tests. PCA (Principal Component Analysis) and OPLS (Orthogonal – Partial Least Squares) techniques were used to assess the overall effect of formulation and storage time. The presence of chickpea flour resulted in significantly harder crumbs and reduced springiness due to the dilution of the gluten proteins, while no differences in terms of cohesiveness were found. Hardness, and viscoelastic parameters evaluated by DMA frequency sweep test, were grouped together in the OPLS biplot. The temperature scan test (-50 to 120°C) with DMA revealed the drop of moduli around 0°C associated to the frozen water melting transition. Both chickpea flour and storage time significantly decreased the moduli drop temperature. Furthermore, during storage, the frozen water melting transition was characterized by a significant decrease of the ranges of moduli in which the transition occurred. In conclusion, DMA has proven to be a valuable tool for the analysis of staling of chickpea composite bread highlighting different thermal parameters changes due to the effect of formulation and storage time and able to describe water-solids interactions at mesoscopic level.