RHEOLOGICAL PROPERTIES OF WHEAT-FLOUR DOUGHS IN STEADY AND DYNAMIC SHEAR - EFFECT OF WATER-CONTENT AND SOME ADDITIVES

Dynamic tests and steady flow measurements were made with a controlled stress rheometer to study rheological properties of wheat flour doughs and to examine how theological properties are related to dough composition (water content, oxidizing and reducing agents, emulsifiers, etc.). Water added to doughs has mainly strong plasticizing effects, but it probably does not change dough structure. The phase angle tgs, the shift parameter a, related to the extended Cox-Merz rule, and the power law exponent n are practically independent of water content, and these parameters may reflect the structure level of the protein network. Ascorbic acid has strengthening effects, and lecithins have softening effects, but dough structure is little modified by the presence of these components. Beyond 50 ppm, glutathione has strong softening effects, but it simultaneously affects dough structure. In all cases, when dough composition varies, either tgo, a, or n remain constant, or they vary simultaneously. Results obtained with glutathione lead us to assume that these parameters are closely interrelated.