Effects of Saccharomyces cerevisiae on the structural kinetics of wheat dough during fermentation

As shown in previous studies the application of yeast presents a challenge for rheological measurements. The continuously produced metabolites of this living organism strongly influence the resulting data. In the study on hand, the method for fundamental oscillatory tests was modified to fit the needs of the flow behavior of yeasted dough. The analysis of the pH-value offered a method to indirectly determine the carbon dioxide production, as was proven by a linear correlation with the density (R²=0.88, p<0.001). As evidenced by Rheofermentometer measurements, the gas holding capacity of wheat dough was not affected by the kinetics of CO₂-production, whereas the total amount of gas was decisive. Moreover, the method associated density correlated significantly (p<0.001) with the resistance to extension, the extensibility and the complex shear modulus. Finally, different yeast concentrations provoked up to 57% higher loss factors immediately after kneading. In summary, it was proven that yeasted wheat dough was significantly more plastic and susceptible to pressure than the non-leavened models. In turn, this provides a practical and realistic insight into the structural changes of wheat dough as affected by the metabolism of Saccharomyces cerevisiae.