The way the wheat is milled into flour can make or break all of the hard work put into it thus far. There is a huge difference between stone milling and roller milling wheat.
Roller milling wheat into flour is the modern conventional method in which most commodity wheat is milled. With this method, the three components of the grain are separated. Steel rollers cut away the oily germ and peel off the bran leaving a flour made of only the endosperm. This endosperm-only flour has a much longer shelf life, especially without the oils from the germ and will be a far brighter white than if it contained the entire grain.
In contrast, stone milling crushes the complete grain between two stones. While some of the larger bran particles may be filtered out, the germ remains with the endosperm creating an off white flour that is rich in flavor and nutrients.
What are the benefits of stone milling?
To put the answer as simply as possible, stone milling grains retains all of the nutritional value and the complexity of flavor that has been labored over to get to this point. Just to look a the nutritional benefits of a grain of wheat is to begin to understand the benefits of stone milling.
Endosperm is mostly carbohydrates (in the form of starch) along with protein and iron.
Bran is the outer shell of the grain that protects it from the elements and contains vitamin B, folic acid, fiber and minerals.
There is a thin layer between the bran and endosperm known as the aleurone layer. This is rich in fats, proteins and enzymes.
The wheat germs is the grains powerhouse. Contained in this little fraction of the grain are unsaturated fats, B vitamins, folate, phosphorus, thaimin, zinc, magnesium and vitamin E.
It is not hard to see that if you remove everything but the endosperm, you have taken out most of what is beneficial in the grain. How much worse this becomes if you are starting with a commodity wheat that is already lacking in nutrients! There is really nothing but the carbs left!
There is something else that lives in the whole grain. This is the first thing people notice when first trying bread made with stone milled flour:
Flavor.
When the grain is milled whole, there are wide varieties of flavors that distinguish one type of wheat from another. White Sonora has a light sweetness to it. Hard winter red is very nutty, rye is earthy. In fact, each local region's wheat varieties has it own distinct set of flavors! Bread should not all taste the same. A loaf of bread made with California or Arizona wheat should taste different from a loaf of bread made with Carolina wheat.
Why does anyone use a roller mill?
If stone milling is so great, why does anyone use a roller mill? In the 19th century there was growing demand for whiter, softer breads. It's just not possible to have an absolutely, bright white flour with a stone mill. Once the roller mill was developed, the demands of the public could be met and bright white flour became common.
Contemporary concerns are completely driven by cost. Roller mills are faster, require less skill and less labor and they create a commodity with a longer shelf life. Plain and simple.
What is enriched flour?
In the 1920's these nutrient deficiencies caused by roller milling were first discovered. During World War II flour being used for American and British troops began to be "enriched" to introduce nutrients back into bread. After that time, this became common practice. Now, according to FDA guidelines, enriched flour must contain thiamine, niacin, folic acid, riboflavin and iron.
While it's good to attempt putting these nutrients back into the flour, the body does not process additives the same way it does the naturally occurring nutrients that already exist in the grain of wheat.
For a flour that is full of both nutritional value and flavor, there is really nothing better than stone milled.
