Strain-dependent assessment of dough's polymer structure and functionality during the baking process

During the baking process, the functionality of the heterogeneous dough matrix changes as the composing polymers experience conformational transition processes. The thermally induced structural changes affect the involvement and functionality of the polymers in the dough matrix. With the main hypothesis being that different types and magnitudes of strain exerted during the measurement would provide information on different structural levels and interactions, SAOS rheology in multiwave mode and large deformation extensional rheometry were applied to two microstructurally different systems. The functionality of the two systems, a highly connected standard wheat dough (phi approximate to 1.1) and an aerated, yeasted wheat dough (phi approximate to 2.3), depicting limited connectivity and strength of interactions, was accessed under different deformations and types of strains. Applying SAOS rheology, starch functionality prevailed on the behavior of the dough matrix. In contrast, gluten functionality prevailed the large deformation behavior. Using an inline fermentation and baking LSF technique, the heat-induced gluten polymerization was shown to increase strain hardening behavior above 70 degrees C. In the aerated system, the strain hardening effect became already evident under small deformation testing, as the expansion of gas cells caused a pre-expansion of the gluten strands. The expanded dough matrix of yeasted dough was further shown to be substantially subjected to degradation once the network reached beyond its maximal gas holding capacity. Using this approach, the combined impact of yeast fermentation and thermal treatment on the strain hardening behavior of wheat dough was revealed for the first time by LSF. Furthermore, the rheological properties were successfully linked to oven rise behavior: a decreasing connectivity combined with the initiation of strain hardening by fast extension processes occurring in the yeasted dough matrix during the final baking phase was linked to limited oven rise functionality prematurely around 60 degrees C.

Automated summary

During the baking process, the functionality of the dough matrix changes as the polymers undergo structural transitions. SAOS rheology and large deformation extensional rheometry were used to assess the functionality of two microstructurally different systems. Starch functionality dominated the behavior of the dough matrix in SAOS rheology, while gluten functionality prevailed in large deformation behavior. The heat-induced gluten polymerization and gas cell expansion in the aerated system were shown to affect the strain hardening behavior. The rheological properties were also linked to oven rise functionality, with limited functionality observed prematurely at around 60°C.