Changes of physical properties of wheat gluten and starch as a function ofremoving some attending substances

Gluten and starch, the main components of a dough were extracted with diffe rent solvents and conditions, without heat or mechanical denaturation. By removing substances especially lipids and lipoproteins physical properti es of gluten and starch are altered. Solubility, water absorption capacity and rheological properties of ethanol extracted gluten were changed as a fu nction of different conditions of extraction. Extracting the lipids of starch alterations of the kernel starch surface pr operties can be observed by TEM. Most changes of physical properties become evident above all when starches are gelatinized by heating. But this behav iour is not important for binding starch and gluten during dough kneading. Intensive extraction of lipid substances from gluten leads to an enhanced w aterbinding capacity, but at the same time the ability to form a homogenous wet gluten structure is diminished. Rheological studies in ethanol-water s lurries point to variations in viscosity behaviour. For physical and microscopical studies doughs of gluten-starch mixtures wer e prepared from gluten, differently extracted starches and water soluble su bstances. Freshly prepared flour extract was added to dry mixtures (82% sta rch, 18% gluten) and the dough system was characterized in a mixograph and in a rotation viscosimeter. Doughs prepared with same amounts of extract sh owed differences in kneading and viscosity properties. In general the extra ction of lipids from gluten influenced dough properties in a higher degree than extraction of starch. More intensive extraction of gluten causes distu rbance of dough structure. A certain restoration of viscoelastic properties of dough is attainable by adding more water soluble substances.