It seems that the few US flour mills that still use traditional techniques, using quartz millstones, advertise their milling process and flour as superior. Is that really true and how is non-stone ground flour different? And how is it actually done if you don’t use stones for milling?
Stone Milling
Traditionally, flour was produced using milling stones, those ancient quartz 6-foot 2-ton mill stones (they come in smaller versions today too). Powered by wind or water and more recently steam power, they rotate, one on top of the other, grinding grain into flour. By adjusting the distance between the two stones you can mill finer or coarser flour. Flour may be milled multiple times and sifted to create types of white flour or left unsifted for whole wheat flour. This process was slow and labor intensive. People typically ate whole wheat bread while white bread was considered a luxury item, even a status symbol, and usually only eaten by the wealthy.
All of this changed rapidly with the introduction of roller mills and additional innovation and automation during the 1860-70s.
Roller Milling
Roller mills use a complex system of steel rollers that break the grain into its components such as bran, germ, and endosperm and then use sifters to separate them. Multiple steps of grinding, sifting and conditioning are typically used until all particles are separated and the flour finely ground. The grain components can be blended again depending on the desired grades of flour (there are different types of flour that the professional baker maybe using such as straight grade aka all-purpose flour, clear, patent, and whole wheat).
Below is a simplified diagram (from flour.com) of the steps used for roller milling. It is definitely a complex process. The result is that millers can produce very fine flour very fast, which is great for airy white bread and baked goods. Not surprisingly, roller mills dominate the industry within a decade of introduction and still do today. They produce the vast majority of flour which is 90% or more white flour.
So, with all this efficiency, time savings and finer, more consistent flours, white flour became cheap quickly and widely available. Not only was it cheaper than traditionally milled whole wheat flour, but everyone could suddenly afford the luxury of white bread, which before was only available to the rich. White bread became a symbol of modernity and progress.
Then, who would want to buy stone ground flour today? Is it all nostalgia?
There are some differences and benefits to stone milling, not just wanting to do things simply and the traditional way. Stone mills run slower than roller mills which can mean lower temperatures during the milling process thus retaining more of the nutrients in the final flour. High temperatures during milling destroy vitamins and enzymes.
But maybe the most important reason to choose stone ground over roller milled flour is the intended use. Whole grains or less refined flours are typically used in sourdough and artisan style breads which aim to maximize nutrition and flavor.
Roller mills are efficient at separating the nutritious parts of the grain (bran and germ) from the starchy endosperm. The resulting very fine white flour is preferred in large scale commercial baking operations as it is easy to use within the large automated production facilities creating more consistent results with minimal labor input.
With our growing awareness and focus on the health benefits of whole wheat flour, stone milling is receiving more interest among home and artisan bakers again. So, there is still a place for stone milled flour.
One last comment: did you know …
… what happens to all the bran and germ removed from wheat to make white flour?
Most flours produced today are white flours (more than 90%), so there are a lot of by-products in the milling process.
About 83% of a wheat kernel is the endosperm, the starchy part that makes white flour.During milling the components of grains cannot be separated perfectly. When milling wheat to achieve white flour, the extraction rate (what is left in weight) is only 72–76% of the original kernel, at best.
So what happens to the 25% or so of grain not used in white flour?
They can be bought in the health food section as nutritious additions to your baking or cooking. But most of these wheat by-products, aka wheat middlings, are used for animal feed, for example to raise or “finish” cattle.