In his book In Defense of Food: An Eater’s Manifesto, Michael Pollan writes that that stone ground flour is more nutritious than flour made in a mill equipped with metal or porcelain rollers. The thing that really surprised me is that he wasn’t just saying that whole wheat flour is healthier (which it is), but that white flour ground with stones is healthier than white flour ground with rollers.
I decided it was time for me to learn a little about the history of flour. After all, it’s a ubiquitous ingredient, seen in cuisines the world over and humans have been making it for thousands of years. For the purposes of this article I’ll be discussing wheat flour, but of course there are many other flours used in different cultures. First, a little wheat nutrition lesson, and then we’ll explore the different ways there are to make flour. A kernel of wheat has three parts, the bran, the endosperm, and the germ. Here’s an illustration:
Most of wheat’s important nutrients are located in the bran and the germ. The bran contains insoluble fiber (important for digestive health), incomplete protein, some trace amounts of B vitamins, and Iron. The germ is the most nutritious part of the wheat kernel containing protein; vitamin E; almost all of the B vitamins, including folic acid; carotenes and other antioxidants; and omega-3 fatty acids. The endosperm (which is the largest part of the wheat kernel) consists of carbohydrates, incomplete protein and trace amounts of vitamins and minerals.
One of the oldest technologies for making flour is the combination of a stone mortar and pestle to initially break the grain, and the saddle quern for grinding it. The saddle quern is an elongated stone with a depression in it where the grain is placed, and then a woman (it was usually a woman) kneels in front of the short end and pushes a smaller stone back and forth over the grain in a rocking motion. It takes a long time to make any useful amount of flour in this manner. In fact, archaeologists examining women’s bones from a Neolithic site in what is now Northern Syria, found many of the women had deformities to their toes, legs, back, and pelvis which can be attributed to spending many hours kneeling in front of a saddle quern. Boy am I glad we don’t have to make flour that way anymore!
The next development is the rotary quern which consists of two round stones placed on top of each other. The lower stone is slightly convex, and the upper, concave. The top stone has a vertical handle coming from it’s top and a hole in the middle where the grain is fed. The operator (also most likely a woman) uses the handle to turn the top stone, grinding the grain between the stones. The finished flour flows out from between the edges of the stones. Some versions included a spout which would feed the finished flour out into a container. Here’s a great video of someone operating a rotary quern. That still looks like an awful lot of work to get enough flour to make a loaf of bread.
As one might expect, the ancient Greeks and Romans made some important contributions to grain milling technology. The Romans built larger versions of the rotary quern and used animal or slave power to drive them and the ancient Greeks invented the first water mill. A wooden spindle ran from the top stone through the bottom stone. This spindle extended down into a stream and a horizontal water wheel was placed on it. The flow of the water causes the top stone to turn, thus grinding the grain. Eventually the Romans turned the water wheel in the other direction and used gears to transfer the power of the water to the grinding stones. This configuration: a vertical wheel, gears, and two grinding stones working in a rotary manner, remained the predominant method of milling flour until roller mills were introduced in Europe in the 19th Century. There were some changes as to how the stone mills were configured and powered, but essentially the technology was the same for almost 2000 years.
The latest development in flour milling I’ll discuss here is the replacement of grind stones with metal or porcelain rollers which happened around 1870. A mill equipped with rollers uses multiple sets of them turning at different speeds to break the grain and then to grind it. Rollers were faster than grind stones, they produced more flour from a pound of grain and they produced a product with a longer shelf life (more on that later). So it makes sense that the millers of 19th Century Europe and America would jump at the chance to convert their mills to this new technology that would help them make more money and increase their customer base. In fact, in only took about 10 years for most stone mills to be replaced by rollers.
So, how do these different milling technologies affect the nutrition of the flour? At some point people discovered they could separate the bran and the crushed pieces of germ from ground wheat fairly easily by sifting it through cloths of an appropriate weave. In Medieval England this was called “boulting” and by using multiple cloths of differing weaves quite fine flour could be made which contained little bran and germ. However this “white” flour still contained the oil from the germ which was released when the germ was crushed during milling. Wheat germ oil, being rich in beta carotene, gave a yellowish gray cast to the flour. The oil also began to oxidize as soon as it came into contact with air, which meant that this “white” flour would only stay fresh for about six months, after which time the wheat germ oil would turn rancid, affecting the taste.
This all changed when rollers were introduced. When grain passes through two rollers moving at different speeds the slower one holds it and the faster one strips it. This meant that not only could the outer bran of the grain be removed as could be done with stone milling, but the germ could be scraped off before grinding. And so was created the first truly white flour, ground solely from the endosperm of the wheat. It was a snowy white and due to the lack of wheat germ and wheat germ oil, it had double the shelf life of the old style “white” flour. Before roller milling was introduced, “white” flour was very expensive and only affordable to the wealthy. The poor used what we would call whole wheat flour today and the truly poor could only afford rye or barley flour. Once roller mills made it more affordable, white flour’s popularity exploded and everyone felt wealthy to have it.
Unfortunately, the lack of nutritional knowledge at the time, meant that millers didn’t understand that in removing the germ from their flour they were taking away a major source of vitamin B, especially from the poor for whom bread was the main source of nourishment. Once roller mills became ubiquitous we see a higher incidence of diseases caused by lack of B vitamins such as pellagra and beriberi.
Once the requisite vitamins were discovered and better understood (during the 1930s) we began enriching some of our flour with Iron, Niacin, Thiamine and Riboflavin. Folic Acid was added to the list in the 1990s. These are of course the nutrients contained in the wheat germ which was removed during the roller milling process. In stone ground “white” flour there is no need for enrichment.
Having learned some of the history of flour milling and how it affects our nutrition, I would now like to bake some bread with stone ground “white” flour and compare it to bread made with good quality all purpose, unbleached, roller milled flour. I’m curious to see if the flavor, color or texture is different. After a cursory bit of looking around, there seems to be plenty of stone ground whole wheat flour available in the US, but hardly any stone ground “white” flour. So far I’ve only found it at Wade’s Mill in Virginia and Central Milling in Ogden, Utah. I might consider mail ordering some from them, but since freshness is so important, I’d really rather get it locally. Please contact me if you have any sources in the New York tri-state area and stay tuned to read the results of my bread baking experiments.
Campbell, Judy, et. al. “Nutritional Characteristics of Organic, Freshly Stone-Ground, Sourdough and Conventional Breads” in Ecological Agricultural Projects (McGill University, Quebec, Canada, 1991)
Elton, John “Evolution of the Flour Mill, From Prehistoric Ages to Modern Times” in Souvenir of the First International Miller’s Congress and Annual Convention of the National Association of British and Irish Millers (Paris, 1905)
Hazen, Theodore, R. “How the Roller Mills Changed the Milling Industry” in Pond Lily Mill Restorations
Pollan, Michael. In Defense of Food: An Eater’s Manifesto (New York: The Penguin Press, 2008)