Rye Flours for Bread
Germany is one of the few countries which uses rye flour extensively. Rye was brought from Asia in prehistoric times and was grown extensively during the Middle Ages as a bread grain and for alcohol distillation. It grows in poor, sandy soil and under mixed weather conditions, while wheat grows best in a warm dry climate, so despite poorer yields than wheat, it was grain of choice in colder areas.
There is some speculation that rye fell out of favor in France and Italy as wheat flour became more available due to the prevalence of ergot (Claviceps purpurea, a fungus) in rye grain. While ergot can infect wheat and other cereal grains, it prefers rye as a host. It also grows well under cool and moist conditions, where wheat does not. When grain is highly infected with ergot and not cleaned before grinding into flour, humans and livestock can be poisoned and even die (more on the history of ergot here).
Germany, Poland and other East European countries relied on the rye crop to grow in unfavorable conditions and measures have been taken to reduce or even eliminate the fungus from the grain. Measures include cleaning the seed and applying various fungicides.
Rye flour breads are still made and consumed because of tradition, taste and because rye has many health benefits. In 2010, researchers in Lund, Sweden published research that shows that even light rye flour (without the bran) is good for your blood sugar levels. The bran also contains important minerals and vitamins.
Rye Flour Chemistry
Rye flour can be tricky to work with because sugars (carbohydrates) called pentoses (xylose, arabinose) reduce the ability of the gluten proteins to form stretchy, hollow areas which help trap the gas in bread, but are themselves responsible for trapping water and building the crumb "scaffold". Starches in the flour help this scaffolding hold together and create a bread that does not crumble.
However, since these starches can be cut into many smaller pieces by alpha amylases (a type of enzyme) which would reduce their ability to interact with the pentoses, a low pH is used (sourdough) to inhibit the amylase. (See also this entry on "Sauerteig".)
All these interactions make the crumb of rye bread denser than that of wheat bread. Often, rye is used together with wheat flour to make what the Germans call "Mischbrot".
Definition of "Mischbrot"
"Mischbrot" (lit. mixed bread) is also called "Graubrot" (gray bread) in southern Germany or "Schwarzbrot" in Austria and Switzerland. It is defined as bread made with sourdough or yeast and a mixture of wheat and rye flours. Many, if not most, breads in Germany are technically "Mischbrote".
- "Roggenmischbrot", or rye mixed bread, contains 51 - 89% rye flour.
- "Weizenmischbrot", or wheat mixed bread, contains 51 - 89% wheat flour.
- "Mischbrot", or mixed bread, is a 50 - 50% mixture of wheat and rye flours.
As the amount of rye flour in a bread increases, the longer the bread stays fresh and the stronger it tastes of rye. The more wheat flour, the higher the bread rises and the "milder" it tastes.
There is also a popular rye bread called pumpernickel, which was a West Phalian specialty (Osnabruck and surrounding area). It consists of cracked and whole rye berries which are soaked overnight in hot water, then packed into a closed mold and steamed for 16 - 24 hours. Modern production has reduced this time to 12 hours by adding yeast or sourdough to the mixture to help the heat penetrate through the dense dough through rising. Beet syrup is often also added, but the taste and aroma comes from caramelization and the Maillard reaction during baking. It can be stored for several month to several years and was used in the Middle Ages as emergency rations.
- The Fresh Loaf
- Practically Edible
- King Arthur Flour
- The Artisan
- Bread Bakers Guild of America
- See how a modern flour mill is run, Flechtorfer Mühle
- Flour and Meal Products from Historic Mills
- Flour Bolting and Sifting
- Pictures of Industrial Milling Machines
- The North American Millers' Association
- Bob's Red Mill