A cereal grain, closely related to wheat, widely used in baking and particularly popular in central and northern Europe. It contains gluten but cannot form a ‘gluten matrix’ in the way wheat flour can. Rye breads are denser but more flavoursome than wheat breads, and the two flours are often mixed. In 100% rye breads, it is possible to create a gluten-like effect via the hydration of starch and pentosans present in the grain.