“Gluten is the spongy complex of proteins found in wheat, barley, and rye that allows dough to rise. As yeast ferments sugar and releases carbon dioxide, gluten inflates like a hot air balloon, giving breads and cakes their delectable texture.”

Read More: http://www.slate.com/articles/health_and_science/medical_examiner/2013/02/gluten_free_diet_distinguishing_celiac_disease_wheat_allergy_and_gluten.html