Strain hardening properties and extensibility of flour and gluten doughs in relation to breadmaking performance

The mechanical properties of flour-water doughs and hydrated gluten of different wheat cultivars were determined. Measurements were performed at small deformations (dynamic measurements) as well as at large deformations (biaxial extension measurements). Results of dynamic measurements of hour doughs related poorly to breadmaking quality. For hydrated gluten doughs, all having the same water content, it was found that glutens from wheat cultivars with good baking quality had higher values for the storage modulus, G', and lower values for the loss tangent. The relevant type of deformation around an expanding gas bubble is biaxial extension. Wheats with a good baking performance exhibited greater strain hardening and greater extensibility. The differences in strain hardening observed at 20 degrees C were also present at 55 degrees C. No clear effects of NaCl or emulsifiers on the biaxial extension properties of flour dough were found. Extensograms as well as Alveograms from the flour doughs showed that, in general, good baking flours exhibited stronger resistance to extension and a greater extensibility, but differences found were not directly related to the results of the baking tests. The results indicate that the baking performance of dough is related to a combination of at least three different theological characteristics. (C) 1996 Academic Press Limited