Types of Flour
Pastry and cake flours are characterized by low protein content (low gluten) which results in a crumbly texture preferred in cakes, pie crusts and biscuits. These are more or less equivalent to German 405 flour, French 40 flour and Italian 00 flour.
All-purpose flour can be made to make some white breads and is good in yeasted cakes. Its equivalent is German 550, French 55 and Italian 0 flours. This is an approximation since small differences exist between how finely ground the flour is and the "recipe" or composition of each flour from different mills. It is best to try various flours in the same recipe and then keep buying the one that gives you the best results.
High gluten or bread flour is a white flour with a high protein content, used to increase the stretch in white and mixed flour breads. Its equivalent is thought to be German 812 flour, French 80 flour and Italian 1 flour.
First clear flour is now on the market for home bakers, although it has been available to bakeries for some time. It contains some of the outer endosperm after the first sifting and is grey in color. It has a distinctively different taste from the patent flours and is used in the US in Jewish rye breads and in Germany with medium rye flours to make "Graubrot". Although it should be less expensive than patent flour, its rarity makes it more expensive at present. The equivalent to first clear flour is German 1050, French 110 and Type 2 flour in Italy.
Whole wheat flour is made from the entire wheat berry but there are many grades and variations. Normally, whole wheat flour is ground between iron rollers, which produces heat and destroys some nutrients. Stone ground flours are supposed to retain those nutrients for a time.
Both regular and stone ground, whole wheat flour can be fine or coarsely ground. If you use coarsely ground flour, your product will be dense, due to the bran, which are made up of flat, sharp pieces, which shear the gluten strands. One way around this is to create a sponge or mash which softens the bran over time.
The German equivalent to whole wheat flour is called Type 1700. However, much of the bread in German bakeries uses little if any whole wheat flour. This is changing as people look for healthier foods.
Graham flour is a type of whole wheat flour invented by Sylvester Graham an American. It is coarser than regular whole wheat flour and has no direct German equivalent.
Also worthy of mention are semolina and farina flours and cereals. Semolina is made from coarsely ground Durham wheat, a very hard wheat with high protein content. It is used to make pasta and couscous and is known as "Hartweizengrieß" in German, where it is made into pudding and dumplings and noodles like "Spätzle". Finely ground semolina is used in bread such as pizza.
Farina is a product made from the germ and endosperm of soft wheat, ground and sifted. It cooks up differently than semolina; it does not set up as much as Durham wheat products and gives you a silkier product. Some Germans use farina in pudding and cakes, although others use semolina for all recipes which call for "Grieß". You may know it as "Cream of Wheat" breakfast cereal. In German it is called "Weichweizengrieß".
The word "Grieß" refers to the size of the particles. The miller can set the grinder to produce middlings of different sizes. Below 150 micrometer diameter size is considered flour, above that they are often called grits or groats.
Ash Content and Extraction Rate
The numbers on German flour packages represent the milligrams of ash left per 100 grams flour burned in a muffle furnace at 900°C. The higher the ash content, the more bran is left in the flour and the closer it is to whole wheat flour. The ash content is correlated with, but does not completely represent the extraction rate. Many US companies decline to give out this number (Gold Medal Flour, email communication) but promise a consistent product over time.
The extraction rate describes the degree of separation of the bran from the endosperm and is measured in percent. A 100% extraction rate or straight run flour is not the same as whole grain flour. It is the first separation of the endosperm from most of the bran and germ. About 72 pounds of straight run flour is obtained from 100 pounds of wheat. The rest is middlings, which is fed to animals or reground for whole wheat products.
The lower the extraction rate percentage, the whiter the flour. Both extraction rate and ash content help a professional baker determine how much liquid, yeast, time and other ingredients to use with the flour to achieve the correct end product. As for home bakers, we must depend on trial and error and assume that the flour mill will make the product the same, from batch to batch.
Bleached and Enriched Flours
Flour contains carotenoids which are yellowish. Bleaching makes flour white. It also oxidizes the surface of the flour, which helps in gluten development. This results in a fluffier baked product. Maturing agents are also added to increase gluten development. This would happen on its own, but adding these agents speeds up the process.
Through artificial bleaching and maturing as well as removal of the bran and germ, many vitamins are lost. These are partially replaced by enriching the flour specifically with B vitamins and iron. Calcium is sometimes added as well (see FDA regulations here).
Go to page 3 for information on rye flour.