Next to white and whole wheat, rye is the most popular flour for bread making. Although rye flour contains some proteins, these do not form gluten of good quality. This is because although it contains enough gliadin, rye flour does not contain enough glutenin. Therefore, breads made with 100% rye flour are heavy and dense. To make a lighter rye loaf, it is necessary to use a mixture of rye and hard wheat flours. Typical formulas call for 25 to 40% rye flour and 60 to 75% hard wheat flour.
Rye flour is also high in pentosan gumsāabout 4 times as much as wheat flour. The gums give some structure to rye breads, but they also interfere with gluten development and make rye doughs stickier than wheat doughs.