Rheological Properties of Dough Made with Starch and Gluten from Several Cereal Sources'

Cereal Chem. 72(l):53-58 The range in moduli for isolated starch and vital gluten doughs showed action of the starch with the gluten. The source of gluten also had a the existence of starch-gluten or starch-gluten-water interactions in dough. significant effect on dough rheology, as indicated by the range of elastic Starches isolated from different wheat cultivars and mixed into dough (G') and loss (G) moduli for isolated wheat gluten and commercial starch with a constant gluten, both amount and source, gave large Theological doughs. Hard wheat gluten doughs had low G' and G" values, indicating differences. This shows that starch had an active role in determining a greater extensibility and possibly less starch-gluten interaction. Soft dough rheological characteristics. Soft wheat and nonwheat starch doughs wheat gluten doughs had higher G' and G" values, possibly because of had higher moduli compared to the hard wheat starch and the control increased starch-gluten interaction. (commercial gluten and starch) doughs, possibly because of greater interBread dough exhibits the viscoelastic behavior combining the properties of both purely viscous fluids and purely elastic solids (Hibberd and Parker 1975, Billington and Tate 1981). For example, because of its viscous component, a freshly mixed dough will flow under the force of gravity. The same dough when rapidly stretched and then released will spring back (elastically recover). That elastic component helps to determine the dough's resistance to deformation. On a moisture-free basis, wheat flour contains -80% starch, 14% proteins, 4-5% lipids, and 2% pentosans (Chung 1986). The gluten proteins constitute the predominant fraction controlling the viscoelastic properties of wheat flour doughs (Faubion and Hoseney 1990). The most critical component in bread dough, the flour, is responsible for much of the viscoelastic character and is also the focus of much dynamic rheological research. A dough formula simplified to flour and water still encompasses a complex series of flour component interactions. Gluten and prime starch mixtures often are used in Theological testing, not only to control the protein content in the dough, but also to avoid complex interactions of other flour constituents. These include damaged starch, watersoluble and insoluble pentosans, cellulose, lipids, and soluble proteins including enzymes. Dynamic rheological testing has provided information about the effect on dough properties of protein content (Hibberd 1970b, Smith et al 1970, Navickis et al 1982, Mita and Matsumoto 1984); addition of starch granules (Hibberd 1970b); effect of moisture variation (Hibberd 1970a, Smith et al 1970); dependence on testing frequency (Hibberd and Wallace 1966, Hibberd 1970b, Smith et al 1970, Szczesniak et al 1983); and changes in strain amplitude (Smith et al 1970, Szczesniak et al 1983) on dough properties. The rheological response of any material is expressed physically by stresses, which, in turn, are mathematically expressed as functions of either strain and strain rate, or strain and time (Menjivar 1990). Dynamic oscillatory rheometers simultaneously measure the elastic as well as the viscous components of a material's complex viscosity and can assess the frequency-dependent properties of materials being tested (Weipert 1990). Dynamic deformation patterns commonly utilize parallel-plate sample geometry and sinusoidal oscillation for measurement of simple shear stress 'Contribution 94-521-J, from the Kansas Agricultural Experiment Station, Manhattan. 2 Graduate research assistant and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan.