Gluten

Gluten [ glute ː n] ( from Latin gluten " glue " ), glue or adhesive protein, is a collective term for a mixture of proteins that occurs in the seeds of some species of grain.

If water is added to corn flour, then the gluten from the flour during dough preparation is a rubbery and elastic material, that the dough. The adhesive has a central importance for the baking properties of flour.

Construction

The adhesive is made up of the two Osborne fractions prolamins ( soluble in 70 percent ethanol solution) and glutelins ( in the alkaline soluble) together, which is (as opposed to enzymes and other cytoplasmic proteins ) to reserve proteins ( storage proteins in the seed, root and tubers of ) is. In wheat they are called " gliadin " ( prolamin fraction ) and " glutenin " ( Glutelinfraktion ) and are in the subgroups " high molecular weight " gliadins and " low molecular weight " gliadins and "medium molecular" glutenins ( ω1 ,2- gliadins ) and " low molecular weight glutenins " ( α - and β - gliadins ) divided. Prolamins and glutelins come in wheat present in a ratio of about 1:1 and provide around 80 %, the most abundant protein fraction dar.

Food Technological Significance

In conjunction with water gluten forms a so-called gluten. This makes the Teiggerüst on bread and pastries. Only from flours with gluten bread can be in the form of a loaf (as opposed to flat bread) baked. The amount of gluten for baking quality ( " gas holding capacity " ) of wheat flours decisive. Gluten is extensible and provides the wheat dough on the Gare sure that the fermentation gas (carbon dioxide ) is maintained and thus merge the pastry. In the finished pastry clotted gluten framework ensures that the pastry holds its shape.

The task of the miller is wheat batches to mix so that the adhesive quality for the production of bread and biscuits is optimal. In commercial wheat flour gluten content in the dry matter at about 13%. Since dry adhesive can accommodate two to three times its own weight in water, the water-containing gluten content is then in doughs at about 30-35%.

Laboratory adhesive is washed by using a dough with a saline solution is flushed until the iodine sample indicates that the washing water no more strength is present. What remains is the gum -like adhesive. The properties of the adhesive ( elastic - elastic or stubborn - short) are mainly determined by the properties of varieties of wheat. The gluten quality can be determined by various studies ( elongation test with the Extensograph or gluten index with the Glutomatic device) in the laboratory.

When washing the glue changes the protein composition, in particular because the essential amino acid lysine is partially removed together with the starch. The biological value is reduced by 69% (with whole wheat flour ) to 38% ( wheat gluten).

Cereals with a high gluten content are wheat, spelled, rye, kamut, emmer, einkorn and durum wheat. Oats and barley have a low percentage of gluten. Grains such as teff, millet, corn, rice and pseudo cereals such as quinoa, amaranth and buckwheat are gluten-free. Gluten is a component of foods that were prepared from the corresponding grain, and it is the main ingredient for seitan, a wheat meat offered as a meat substitute.

Gluten -free flour is commercially available; However, it behaves differently than gluten-containing flour. The quantitative data for individual ingredients may differ from classic recipe information. Baked goods without gluten succeed often not as airy and juicy as with conventional flour, because gluten makes when baking for good pore formation and a firm crumb.

Also offered in the commercial gluten-free beer.

Health aspects

Components of gluten in people with a predisposition can lead to gluten sensitivity or celiac disease, an inflammatory disease of the intestinal mucosa with far-reaching health consequences. However, a gluten intolerance occurs in less than one percent of the population.