Gluten

Gluten is a special type of protein contained in the grains like wheat, rye, and barley. Being insoluble in water, they can be purified by washing away the associated starch. Not all foods from the grain family, however, contain gluten. Examples of grains that do not have gluten include wild rice, corn, buckwheat, millet, soybeans, and sunflower seeds. Worldwide, gluten is an important source of nutritional protein, both in foods prepared directly from sources containing it, and as an additive to foods otherwise low in protein.

Gluten helps make bread elastic, providing it with that chewy texture it has when eaten. For this reason, flour that has had most of its gluten removed, produces a sticky dough that feels much like chewing gum. When cooked in broth, gluten absorbs some of the surrounding liquid (including the taste) and becomes firm to the bite, so is widely used in vegetarian, vegan and Buddhist cuisines as a meat substitute.

Some people suffer from a disease called celiac disease, a condition which results from an inappropriate immune system response to gluten. Individuals with celiac disease must eat foods that do not contain gluten in order to prevent illness.