Gluten


 

Gluten is a formless protein composed of two smaller proteins called peptides or prolamines. Glutenin is one peptide and the other is a harmful peptide responsible for the development of symptoms in Celiac Disease.  The harmful peptide is called ‘gliadin’ in wheat, ‘hordein’ in barley, ‘secalin’ in rye, and ‘avenin’ in oats.  Gliadin is the most harmful while avenin is the least. The Celiac Sprue Association – USA coined the acronym “WBRO” to highlight the order of toxicity for these grains: Wheat, Barley, Rye, Oats.

Anatomy of Gluten-Containing Grains

Gluten is part of the seed or kernel of wheat, barley, rye, and oat grains where it is distinct from the living protoplasm. It is called a “storage protein” because it is stored in the endosperm component of the seed for the purpose of supplying the needs of the germ if it should germinate, or begin to grow. Gluten constitutes about 80% of the proteins contained in wheat.

Below is an illustration of a grain of wheat to show its structure.  Gluten is located in the endosperm.

Fig. 1.1. Wheat seed. Illustration Identifies the Bran, Endosperm and Germ.

The Grains That Contain Gluten

The chart below highlights the 4 gluten-containing grains, popular strains of wheat, and triticale.  Triticale does not naturally occur but is hybidized by crossing wheat with rye.

 
   Wheat and these wheat strains
                             Durum
                             Kamut 
                             Spelt
                             Einkorn
                             Emmer 
                             Farro
   Barley
   Rye
          Triticale (wheat / rye hybrid)
   Oat

                                     Figure 1.1 Gluten-containing grains. 

Function of Gluten in Foodmaking

When flour is mixed with water, the gluten in it becomes sticky. When the resulting dough is kneaded, the gluten in it makes the dough elastic. These are important qualities for bread making and for making other baked products. Gluten traps air produced by raising agents like yeast or baking soda, helping the dough to rise. When the dough is baked, the oven heat coagulates or sets the gluten, thereby ensuring that the final product keeps its shape.

Gluten in flour thickens cooking liquids, for example, gravy and soup.

Gluten flour is made by washing the starch out of wheat flour. A simple dough of flour and water is kneaded then rinsed with plain water until the rinsing water remains clear and free from starch and bran. The remaining lump of 100% gluten can then be milled into a flour.

When 100% gluten flour is formed into a dough and cooked, it becomes a product called seitan.  Seitan is firm to the bite and soaks up flavoring broth.  In this way, it is used to replace animal protein in vegetarian cuisine and vegan cuisine.