29C-3 |
Measuring extensional properties of dough during fermentation using a new technique in food rheology |
S. LEE, Dept. of Food Science, Purdue Univ., 1160 Food Science Bldg., West Lafayette, IN 47907 and O. H. Campanella, Dept. of Agricultural & Biological Engineering, Purdue Univ., 1146 Agricultural & Biological Engineering Bldg., West Lafayette, IN 47907-1146. Justification: Knowledge of the extensional properties of dough is necessary to be able to control the fermentation process for the best quality of baked products. However, the study of the rheology of fermenting dough is not easy because it is a complex and dynamic system. A new technique to be used in food rheology was developed to measure these properties. The technique, called impulse viscoelasticity, is based on the application of small extensional strains whose duration is short when compared to fermentation times. Objectives: The objectives of this study were to develop the necessary theory to apply the method for the measurement of the extensional properties of fermenting dough and to determine the changes in the extensional properties of dough during fermentation using the developed method. Methods: The extensional properties of dough during fermentation were investigated by using the impulse viscoelasticity technique, which was performed in a universal testing machine. It was applied to dough samples mixed for different times and fermented at 37oC. From the stress and strain responses, tensile moduli were obtained for doughs mixed for different times and over a range of fermentation times. Results: The tensile storage modulus (E') and loss modulus (E") were examined as a function of mixing and fermentation times. There were significant differences in the tensile moduli over mixing times and high extensional properties were observed for the optimally mixed dough. Also, fermentation had a great influence on the extensional properties of the dough. In general these properties decreased upon fermentation times. Finally, results were compared with those obtained from other methods such as ultrasonic and uniaxial extensional tests, showing similar trends. Significance: Our study has shown the great potential of the impulse viscoelasticity technique as a new method for the measurement of dough rheology during fermentation.
Session 29C, Food Engineering: Rheology and texture
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