Phase separation of wheat flour dough studied by ultracentrifugation and stress relaxation .2. Influence of mixing time, ascorbic acid, and lipids

Separation by ultracentrifugation provides a simple tool for studies of the aqueous phases of wheat flour dough. A separation into liquid, gel, gluten and starch, phases was maintained. More or less unseparated dough was also found at the bottom of the test tube. In the present study, the separation behavior was studied for three wheat cultivars when influenced of factors known to affect the baking behavior. The separation properties differ among cultivars. Increased mixing time caused an approximately linear increase for incorporation of water into the gluten phase. For winter wheat, the amount of unseparated dough decreased with increased mixing time, while the separation of spring wheats was not influenced. The general effect of adding ascorbic acid to dough or using defatted flour was improved separation. Lecithin impaired separation. An advantage of this technique is that the phases could be studied without disturbing the composite system. This resulted in valuable information for the interpretation of rheological measurements on dough. It was possible to relate effects on the modulus to either gluten strength, the liquid phase, or interactions between starch and gluten.