W. Nierle et al., Changes of physical properties of wheat gluten and starch as a function ofremoving some attending substances, STARCH, 50(11-12), 1998, pp. 493-499
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.