New insights into crumb formation in model systems: Effects of yeast metabolites and hydration level by means of multiwave rheology

The solidification of wheat dough is induced by a complex sequence of polymer transition processes. The extend of the polymer transitions is thereby strongly dependent on the hydration level of each constituent. Further, yeast metabolites, resulting from the fermentation of dough, are hypothesized to impact the functionality of dough’s polymers in their thermal transitional behavior. Hence, the aim of this work was to elucidate the occurrence of polymer transitions in dependency of (i) the amount of water available for hydration and (ii) the presence of yeast metabolites. An approach of reduced complexity was chosen to reveal the interactions during the hydrothermal treatment by Multiwave SAOS rheology together with basic physicochemical characterization methods (DSC, 1H NMR). By excluding single dough polymers from the solidification cascade, their functionality in the polymeric system was elucidated. In combination with a non-invasive yeast inactivation method, sophisticated information on the dependence of the matrix solidification on the matrix hydration level and presence of yeast metabolites were established. Water shortage was shown to limit the extend of starch gelatinization, resulting in a reduced overall matrix solidification, whereas the extend of gluten polymerization was not affected by water shortage. In contrast, a water surplus favored the progression of starch gelatinization, which was also shown to be induced indirectly by yeast metabolites. Therefore, the water availability and accessibility of starch were shown to be decisive for the solidification of the dough matrix. The knowledge obtained contributes to the elucidation of the impact of baker’s yeast on the dough matrix.