Modelling the developmental rheology of wheat-flour dough using extension tests

Modern cereal science has progressed to the point where a more detailed and explicit understanding of the rheological properties of wheat-flour dough at the molecular level is required in order to improve plant breeding metho dologies, the manufacturing of wheat-flour dough products and the assessmen t of wheat and wheat-flour quality. The formulation of molecular models pro vides a basis for predictive tests that can be combined with other protocol s. The actual modelling must, in turn, be based on experiments which direct ly monitor the changing rheology of the dough which occurs during mixing, a s it is this evolving rheology which in effect monitors the dough at a mole cular level. There are various ways in which this can be done. The perspect ive adopted here is that, at least on a Mixograph(TM), the mixing of the do ugh can be viewed as a series of extension tests. It therefore follows that one way to monitor the evolving rheology of a wheat-flour dough during mix ing is to perform extension tests on the dough at various stages during the mixing. The results obtained from such experiments are reported in this pa per. They show how-the study of the evolving rheology of a wheat-flour doug h, during mixing with varying amounts of added water, in effect monitors th e molecular processes occurring during mixing in terms of the behaviour of the bonded and unbonded water within the dough. In addition, these results yield confirming evidence for the hypothesis, tentatively proposed by vario us authors, that the bandwidth of a Mixogram is a key (qualitative) charact eristic of a dough for assessing its strength. Together, both these conclus ions imply that, as well as a measure of the strength and quality of the do ugh being mixed, the variation in the bandwidth of a Mixogram is indicative of the role played by the added water during the mixing.