Fundamental and empirical rheological behaviour of wheat flour doughs and comparison with bread making performance

The rheological characteristics of wheat flour doughs from the cultivars Obelisk and Katepwa and of biscuit flour doughs, and also of biscuit flour doughs containing glutens isolated from cv. Obelisk and cv. Katepwa flour, were compared and discussed in relation to bread making performance. Four different rheological methods were employed: two fundamental methods, i.e. dynamic (oscillatory) and uniaxial compression tests, and two empirical methods, i.e. tests using a Brabender Extensograph and a Chopin Alveograph. The fundamental methods showed that a dough of cv. Katepwa flour had a higher resistance to deformation and was more elastic than a dough of cv. Obelisk flour. Doughs of biscuit flour exhibited an intermediate behaviour, except that loss tangent values were close to those of a cv. Obelisk flour dough. Addition of cv. Obelisk gluten to biscuit flour hardly affected the rheological behaviour, whereas addition of cv. Katepwa gluten resulted in a higher resolution resistance to deformation and a higher elasticity. Uniaxial compression tests clearly showed the strain hardening and strain rate thinning characteristics of the flour doughs, which were most pronounced for a dough of cv. Katepwa flour. The rheological characteristics of cv. Obelisk and cv. Katepwa flour doughs and of biscuit flour doughs containing the glutens corresponded with those of the isolated hydrated glutens. The information about the rheological behaviour of the flour doughs obtained by the four methods was complementary and in good agreement, despite differences in applied strains, deformation rates and modes of deformation. The empirical tests showed that the extensibility of the biscuit flour dough was less compared to that of the other doughs. This study suggests that in order to obtain a high loaf volume and a fine crumb structure, wheat flour dough has to exhibit biaxial strain hardening and extensibility exceeding a minimum level; it is likely that the resistance to deformation may vary within a certain range. (C) 1996 Academic Press Limite