Do you know how a kernel of wheat becomes the flour you use to make your favorite baked goods? Learn the difference between roller milling and stone grinding!
To understand more about flour production, it’s important to understand that there are two main methods for milling grain used today. The first is stone milling, about which we will go into further detail in a moment. The second is roller milling, the type of milling that is most commonly used to mill flour on a mass scale. Almost all of the flour you buy today is produced on a roller mill. And almost all of the bakery you buy was made from flour processed on a roller mill.
Roller milling uses metal, cylindrical rollers that crush materials into smaller and smaller particles. We’re focusing on grain, but roller milling can be used for gravel, plastic and ore, among other materials. In general, roller milling is a fast and efficient way to turn grains into flour - or large particles into smaller and smaller ones.
In roller milling, it’s common practice to separate out different parts of the wheat kernel during the milling process. To further comprehend this idea, it can be helpful to first take a look at the distinct parts of the wheat kernel.
The wheat kernel consist of three basic parts:
The endosperm: The endosperm makes up the largest part of the kernel. You can think of it as the stuff in the middle - it’s the flour.
The bran: The bran is the outside of the kernel. Wheat bran is sometimes sold as a separate product, and is very high in fiber. Added back to the endosperm gets you whole wheat flour.
The germ: This is the “sprouting” part of the kernel. Since a wheat kernel is a seed that could sprout if not ground into flour, it must contain the nutrients to feed a growing seed. These nutrients are contained in the germ.
How is white flour made on a roller mill? In roller milling, the kernels go through a highly refined mechanical process which first cracks the kernels in half, then removes the bran and the germ, leaving only the endosperm to be ground into white flour. Put another way, most of the white flour available for purchase at the grocery store is made up of only the endosperm, with no bran and no germ as part of the end product.
How is whole wheat flour made with a roller mill? Commonly, whole wheat flour is a mix of the endosperm (white flour) and some of the bran mixed back together, after they are separately milled.
Why do we remove the wheat germ altogether? Although the germ contains the highest concentration of nutrients in the kernel, it is often removed in roller milling because the high concentration healthy fats contained in the germ make the resulting flour product much less shelf stable. For reasons having to do with efficiency, storage and our centralized food system, it’s very convenient if flour can be kept on a shelf, rather than a refrigerator or a freezer.
What happens to the remaining bran and the unused wheat germ? Sometimes these products are made into animal feed, and it is more and more common to find both wheat bran and wheat germ being sold as high-quality health food supplements.
What is meant by enriched flour? Much of the flour we buy today is labeled “enriched” which means that nutrients have been added into the end flour product, to make up for the fact that nutrients were removed during the milling process.
So to recap, in roller milling the parts of the wheat kernel are separated during milling, milled into three distinct products and then sometimes combined later, depending on whether the flour is white or whole wheat. White flour contains no bran and no germ, though both are higher in nutrients than the endosperm. Whole wheat flour contains some bran, but no germ. In order to compensate for the removed germ and bran, nutrients are added back into the flour. This is known as Enriched Flour.
How does stone milling differ? By contrast, in traditional stone milling all parts of the wheat kernel are ground up together - endosperm, bran and germ. The kernels are not broken into separate parts before or during milling. After milling, the kernels are sifted to achieve different types of flour. Because the germ is always ground with the bran and the endosperm, the most nutrient dense part of the kernel (the germ) is always present in the flour. Likewise, though it changes depending on the sifting level, there is usually some bran present in stone milled flour. This has a few implications:
Stone-ground flour has more naturally-occurring nutrients than traditionally roller-milled flour.
These nutrients, along with the presence of all parts of the kernel, result in a more flavorful product, categorized by many as a “nuttiness.”
The “extraction” of the flour - which basically refers to how much bran is in the flour - is determined through a series of screens which range from very coarse to very fine. The finer the screen, the less bran there is in the flour, and the lower the extraction number.
A very finely sifted stone-ground flour will contain very little bran, but will still look visibly different than a roller-milled white flour because there will be small amounts of bran present.
Stone ground flour should be refrigerated to prolong its shelf life.
Just as it’s much easier for our body to assimilate nutrients when they come part and parcel with the foods we eat, it’s also much easier for our bodies to use the nutrition in a wheat kernel when it comes the way nature intended - as an original part of the grain. Today, physicians, nutritionists and other healthcare professionals acknowledge the importance of a diet rich in whole foods - vegetables, fish, meats, dairy and whole grains, which contain a variety of naturally occurring vitamins and minerals. This approach is understood to be superior to taking supplements in order to attempt to obtain these same levels of vitamins and minerals. It is the same with enriched flour. While enriched flour provides some nutrition, it can never provide the same amount of nutrition as flour that contains all parts of the grain, particularly the endosperm.
At Grafton Stone Mill, we use a mill designed and built in Austria, called an Osttiroler 700 MSM Mill. Our mill allows for grinding with stones, and then sifting through a process of sieves and screens, which allows us to produce flours with varying degrees of bran and “fineness.”
Check out our products to see for yourself! And stay tuned for a rundown of our flour lineup.