The history and processes of milling

January 25, 2011

I believe in eating local, nutritious foods. It is relatively easy to do this with vegetables, eggs and dairy products but buying bread that I feel good about is much more challenging.  This past summer, during the Our Daily Bread Course, I learned more about why buying local healthy bread is very difficult because bread is a highly processed product by its very nature. Beyond this, there are a variety of issues including where different varieties of grain are grown, how grains are milled into flour, how and whether the flour is processed, whether bakeries purchase local grains and how much time, effort, and money individuals spend on ensuring they have access to good quality flour. I learned about our current mode of flour production, and the smaller scale alternatives of home milling and stone grinding and the systems associated with these alternatives.  In this essay, I will explore the history of milling, the processes involved, the impact on our nutrition and the directions that we can choose to go in, if we want to consume healthier, more localized bread.

To begin with, a field of wheat is converted into a loaf of bread by breaking the grain open and grinding it in a process called milling, which is one of the common processes for making grains digestible and making their nutrients available to us. However, mainstream flour production, for the most part, takes the nutritious grain and turns it into nutritionally poor flour. To understand why this happens, we have to think about the structure of wheat, which is made up of the bran, the germ and the endosperm. The husk of the wheat grain, called the bran, contains some protein as well as many vitamins, minerals and other nutrients, including potassium, phosphorus, magnesium, calcium, niacin, phytic acid and dietary fiber. The germ is the embryo of the grain, containing proteins, fats, lipids, sugar and B vitamins. The endosperm contains a lot of the protein and carbohydrates to make flour. The aleurone layer between the germ and the endosperm contains essential amino acids. Since the endosperm contains most of the dry matter it is technically the only part of the grain needed to make flour. However, the majority of the nutrition is contained in the bran and the germ.

Stone milling was the only way to make grain into flour for millennia. Farmers would sell their grain to the mill in their area and the mill would process that grain and sell it to bakers. Stone mills were powered by water or wind to grind the grain between two large stones. Stone mills were common throughout Europe and they were excellent for grinding soft wheat varieties. The grain is poured into a hole in the upper stone, called the runner, and is distributed across the bottom stone, called the sleeper. The movement of the stones crushes the entire grain, which gives the flour a nutty flavor and retains all the vitamins, enzymes, amino acids and fiber contained in the grain (Marriage). The friction between the stones heats the flour up gradually preventing the loss of the enzymes and the vitamins in the flour without compromising the baking quality. The grain is ground once and then sifted to remove large parts of leftover grain.  These pieces can be milled once again to even out the size of the flour. Screens are also used to remove the bran, because it is unappealingly dark, and the germ, because it contains lipids that could cause the flour to go rancid. Flours with different proportions of bran and germ are graded differently.

Despite this spectrum of flour grades, there were two main types in Europe during the nineteenth century. “Low grinding” was the unsifted flour from a single pass through the millstones. This flour had a 100% extraction, meaning it contained all parts of the original grain.  This flour made dark hearty bread that retained all of the original nutrients of the grain. However, the whiter grades of flour were always more desirable to the higher classes and they were therefore more expensive. “High grinding” was flour that had been reground multiple times and sifted extensively to remove the bran. Ironically, the flour consumed by the upper classes, who could have eaten the very best, was the less nutritious flour that had the bran and germ taken out.

The Northeastern area of the United States also produced soft wheat varieties, so stone milling was also used there. In the late 18th century, Oliver Evans invented the first automated flour mill in the United States that did the work of seven men (Basey 7). It used millstones, had an enormous amount of levers and pulleys, and was very noisy. Evans’ mills were water powered, so they were situated along rivers. This invention dramatically increased flour production, but produced only one grade of wholemeal flour.

Meanwhile, in Hungary, stone grinding was not adequate to grind the hard wheat varieties that grew well there. New ways of milling were explored and the steam roller mill was invented in 1865. During the next two decades, over 300 of these new mills were built in Hungary to support the growing flour milling industry, which became the country’s largest sector (Perren 430).  The new mode of milling was much faster and therefore more economical than stone milling had been.  In the roller milling process, the grain is ground into middlings, which are then sifted by hand and reground. The extensive amounts of sifting to remove the bran and the germ required a large labor force.  

The US ignored the new “high grinding” system for a while because of its labor-intensity.  However, a conglomeration of factors quickly shifted the perception of roller milling. First of all, the United States was shifting from growing wheat in the harsh weather and rocky soils of the northeast to the optimal Midwest conditions where hard wheat varieties were grown instead of soft wheat varieties because they have a higher gluten content and a more easily removed bran. This transition required a new type of milling because stone mills were not sufficient to grind hard wheat. Secondly, flour was needed that would not go rancid on the long migrations that some people were beginning to make westwards across the continent. The last and, perhaps most important factor, was the invention of the purifier machine which uses air streams to blow the bran off of the wheat middlings. This removed the unappealing labor-intensive aspect of hand sifting the bran out.

In 1875, the Americans combined the European roller mill, Oliver Evan’s automated mill, and the recent invention of the purifier to create an outstanding new version of the roller mill.  The process of the roller mill system is to clean the grain of straw, dust, stones, and any other debris. Afterwards, the grain is fed between two corrugated steel break rollers, where it is broken in half along its midline, becoming break stock. The pieces, consisting of layers of bran and germ with an endosperm covering, are put through the roller system again and then they are mechanically sifted according to size. The purifier then removes most of the bran and the germ and the endosperm goes through the system several more times.  The following step in the process is reduction, in which the grain pieces are crushed into flour with flat textured rollers. Any remaining germ and bran is completely removed in this stage. These roller mills are able to process a large quantity of grain, so rather than bringing grain to local stone mills, significant quantities of grain were transported to centralized roller mills. This meant that along with the loss of nutrition when the new system was introduced, there was also a loss of small-scale milling on the community level.

Although the United States seized this opportunity to improve the efficiency of their flour production system, Great Britain was slow to adopt the newly improved technology. They grew soft wheat varieties, so it was not until 1900, when the United States began exporting surplus wheat to England and Wales, that they needed to use roller mills (Perren 431). When this occurred, there was a lot of backlash from the British medical society due to the fact that the roller mills produce less nutritious flour. For example, in 1924 medical doctor Charles Edward Shell wrote to the British Medical Journal,

When the steel “roller flour mill” were introduced into this country from America a vital injury was inflicted on our national well-being….[the flour] lacks the proteins, fat, vitamins, and mineral constituents present in the original grain, providing only an emasculated substitute which is not merely inefficient, but also directly harmful. For a dietary overloaded with starchy material produces fermentation and flatulence : it favours the development of an abundant intestinal flora embarrassing to the digestive economy, burdensome to the gastro-intestinal organs, and favourable to the free development and increased virulence of such pathogenic microbes as may obtain access to the intestinal tract. (Shell 789).

There was also resistance to the roller mills in the United States. In the early 1900’s, some people protested the new flour systems because of these nutritional concerns. In 1920, the first head of the Food and Drug Administration (FDA), Dr. Harvey Wiley who advocated for pure foods and drugs in the United States tried to outlaw refined, bleached white flour because of the processes involved with making it, and the loss of nutrition (Basey 23).   

Despite the backlash in the beginning of the introduction of roller mills, the nutritional loss of flour due to the usage of roller mills has fallen out of the public’s sight. Efficiency took priority over nutrition when it comes to milling, as seen from the fact that ninety-nine percent of the world’s grain is ground in roller mills (Marriage).

Although the current automated way of milling may seem better in the economical sense, it caused us to lose the many nutritional benefits of the bran and the germ.  Medical professionals protested the introduction of roller mills because of the severe loss of nutrition. As can be seen from the following chart, the vitamins A and B1 are almost entirely lost in roller-milled, bleached flour.

                          Stone-Ground White Flour    Roller-mill Bleached White Flour

Extraction                                                  81%                                                     72%

Protein                                                   11.20%                                               10.70%

Fat                                                            1.20%                                                 0.70%

Carbohydrate                                            67%                                                    80%

Calcium mg. per 100 g                               50                                                        22

Iron mg. per 100 g                                         4                                                          1

Vitamin A (units per 100 g)                    200                                                          0

Vitamin B1 (units per 100g)                    150                                                         22

Calories per 100 g                                      370                                                       370

                                                                                                        (adapted from Drummond 942)

Bread could be, and used to be, one of our main sources of Vitamin B1, yet as we can see from the chart, this is one of the most notable losses in roller-milled, bleached flour. The removed bran and germ are currently sold either as animal feed or as health supplements and pharmaceuticals. This means that rather than receiving our nutrition directly from the milled grain, we buy it from a bottle.

As Hannah Jones from the Organic Research Centre in England points out, when we transitioned to roller milling, we lost the essential amino acids contained in the aleurone cell layer in the endosperm of the wheat. Our bodies are unable to make these essential amino acids so we need to have a dietary source of these amino acids to be healthy individuals.  Another problem with removing all the bran and germ is that all the fiber is removed from the finished product.  Fiber is important in our diets because it helps with digestion and smooth bowel movements.

More processes occur after the grain is milled that further undermine its nutrition. It is conditioned or heated to adjust the moisture content of the flour. According to Doug Brown, a Canadian baker at the Kneading Conference, it is easier to add moisture to the flour than it is to remove it.  Two types of conditioning are used — warm and hot. In warm conditioning, the flour is heated up to 115 degrees Fahrenheit. With hot conditioning, the flour is heated to 140 degrees Fahrenheit, which makes the gluten less elastic, thereby lowering the baking quality. Another issue with hot conditioning is that almost all the naturally occurring enzymes in the grain are denatured.

The next step is to add chemicals that make the flour act as though it had been stored for a month’s time because aged flour provides better baking results due to its lower pH. It is cheaper to add either potassium bromate or ascorbic acid to achieve this than to actually store the flour.  After this, bleaching agents such as chlorine dioxide, nitrogen peroxide, chlorine, benzoyl peroxide or acetone peroxide are added to the flour to whiten the naturally yellow endosperm.  

In the United States, a wartime health measure in 1941 required that mills add synthetic vitamins to the flour to replace all of the lost nutrition (Basey 14). Thiamin, riboflavin, niacin and iron all must be added to flour. This is intended to replace what was removed when the bran and germ were taken out; however, the full amounts are not added back. Andrew Whitley of the Real Bread Campaign, among others, believes that our bodies cannot incorporate these supplemental vitamins as well as we could absorb the naturally occurring forms.

Often times people buy whole wheat rather than white flour to avoid these processing problems. A little known fact is that most whole wheat flour has undergone all of the same processes as white flour. The millers add back some of the bran and germ after the flour has gone through the system (Basey 20).

At this point in time, it is worthwhile to search for wholemeal grain on the market. This is flour in which nothing has been added and nothing has been taken away. That means that all of the bran, germ and endosperm, and all the associated vitamins, enzymes, and amino acids are contained within the flour. This flour also goes by the names of unbolted wheat meal, entire wheat flour, and graham flour.  Along with the benefit of retaining the nutrition and fiber in the grain, wholemeal flour is less processed, less energy intensive, and it bakes delicious bread.

Due to the fats contained in the germ of the wheat, it is important to use the wholemeal flour soon after it is ground. Some bakeries deal with this restriction by grinding their own grain. This way they can ensure that the flour is used before it has a chance to go rancid. We visited Backhuas in Germany where the bakery contains a small stone mill. They purchase grain from local farmers which supports the local community as well as reduces the distance that the grain has to travel to reach the mill. The flour is used within a couple of days of being ground, so the nutrition of the bran and germ is retained without giving the lipids the chance to go rancid. We were offered a variety of breads that they had baked and all were delicious!

The issues of rancidity and nutrition are dealt with through the positive solution of returning to localized grain systems. This has positive implications on many levels. There are many ways to bring the grain system to the local level. One is through a model like Backhaus in Germany. In Western Massachusetts, Wheatberry Bakery is following a similar model where the bakery buys local grain and mills it in the bakery.  Another important possibility is establishing connections between millers and bakers, such as the connection between Aurora Mills and Borealis Bread in Maine. The overall goal is to set up local food systems that include local grains.

For people who would rather bake their own bread rather than buy it, a home mill provides a way to bake with fresh, wholemeal flour. Home bakers can choose whether to get their grain from local sources. Wheatberry has pulled in the concept of community supported agriculture – they have set up a grain CSA. The members can use the mill in Wheatberry Bakery to grind their own flour.

We lost a lot of important things when we switched to roller milling, most notably, the nutrition that our daily bread ought to provide and the connections between farmers, millers and bakers.  New England used to grow soft wheat, so we could begin doing this again and be able to mill our own grain. We can restore local connections between farmers and bakers by re-establishing stone mills. We can support local grain farmers by buying their grain and milling it at home to bake into bread. There are many solutions to this, depending on whether you are interested in buying bread made from local grain or grinding your own grain to home bake with. No matter which path you choose to take, it will help bread become more nutritious, and it will help to implement the whole grain system into our local communities.


Basey, Marleeta F. Flour Power: a Guide to Modern Home Grain Milling. Albany, Or.: Jermar, 2004. Print.

Brown, Doug, and Kate Conway. “Baking Pastries with Whole Wheat and Alternative Grains.” 2010 Our Daily Bread: Following Grains Through The Food System. Kneading Conference, Skowhegan, Maine. 29 July 2010. Lecture.

Drummond, J.C. “The Nations Larder in Wartime — Food in Relation to Health in Great Britian – The Historical Background.” The British Medical Journal (1940): 941-43. Print.

“Harvey Washington Wiley.” Wikipedia, the Free Encyclopedia. Web. 12 Oct. 2010. <>.

Jones, Hannah. “Cereal Grain Quality.” 2010 Our Daily Bread: Following Grains Through The Food System. Organic Research Centre, Hamstead Marshall, England. 12 Aug. 2010. Lecture.

Marriage, Michael. “Introduction to Dove’s Farm.” 2010 Our Daily Bread: Following Grains Through The Food System. Dove’s Farm, North Wessex Downs, England. 10 Aug. 2010. Lecture.

Perren, Richard. “Structural Change and Market Growth in the Food Industry: Flour Milling in Britain, Europe, and America, 1850-1914.” The Economic History Review 43.3 (1990): 420-37. Print.

Shelly, Charles Edward. “Millstone Flour and National Nutrition.” The British Medical Journal. Correspondence. (1924) Print.

Whitely, Andrew. “Bread Nutrition.” 2010 Our Daily Bread: Following Grains Through The Food System. Organic Research Centre, Hamstead Marshall, England. 11 Aug. 2010. Lecture.