A fundamental rheological method to characterize yeasted dough was developed.
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Saccharomyces cerevisiae causes a plasticization of the wheat dough structure.
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Monitoring the density during rheological tests improves the validity of results.
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The gas retention capacity does not depend on the kinetics of CO2-production.
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The pH-value of yeasted dough is suitable to evaluate the state of expansion.
Abstract
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.
