That clump of industrial buildings along the river in the left foreground are mostly flour mills; Minneapolis was one of the world's leaders in developing automated flour mills based on steel rollers and not the old-style millstones
Roller mills were developed in the 19th century and the earliest examples were in wheat-growing regions that specialized in hard red wheats. The first was in Budapest, serving the Hungarian plain, and the second in Minneapolis, serving the upper Midwest
For thousands of years, millers had relied on millstones, which typically smashed and ground the wheat all at once, in a process called "low grinding" or "sudden death." This was well-suited to softer, whiter wheat varieties, but was less effective with dry, hard, red wheats
By the middle of the 19th century, engineers in Budapest had begun using iron, steel, and even in at least one case porcelain rollers. These allowed a much more precise grinding process called "gradual reduction" or "high grinding."
The advantage of high grinding on rollers was that millers could slowly strip away the hard layers of bran around the starchy endosperm, producing uniform, much whiter flour than was possible with millstones. Hungarian millers pioneered this but didn't really automate the process
Hungarian mills relied on hand labor for much of this. American milling engineers in Minneapolis then took the innovation of rollers and integrated them into sophisticated suites of machinery that cleaned and sorted the grain and middling products, making it much, much cheaper.
The third region to develop a lot roller milling was Britain, not because it grew much hard red wheat--indeed, British millers were accustomed to soft, white, British wheat, and found that hard red wheat from Canada, Russia, or California often caught fire in their mills
Rather, Britain began to import tremendous quantities of wheat, particularly from North America, but also Eastern Europe, Russia, India, Argentina, and Australia. In 1846, Britain imported about a quarter of its wheat; by 1870 about half, and by 1914 more than four-fifths
By the 1880s, British millers were struggling to grind hard, dry, red wheat on their millstones and feared--rightly--cheap imports of ultra white, American roller-milled flour. So they adopted steel rollers with astonishing speed, especially in Liverpool and London
Liverpool and London (and the Bristol Channel ports, Glasgow, and Hull) were not in hard wheat growing regions the way Budapest and Minneapolis were; but, they became nodes in a much wider global wheat ecology, and that ecology grew a hell of a lot of hard wheat
If you mill hard, high-gluten wheats on steel rollers, producing lots of extremely white high-gluten flour, you get significantly whiter bread for everyone. It was at this moment, in the 1880s, that Britain really got "proper white bread" for basically anyone
I could go on, but I have papers to grade. Anyway, bread is an environmental, technical, and biopolitical object!
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