Preservation of flour was a major issue during the industrial revolution. Natural shelf life collided with transportation distances and a relatively slow distribution system. The germ’s fatty acids, which react as soon as they are exposed to oxygen, are to blame for the short shelf life.
When grain is milled, this happens; The fatty acids begin to oxidize, and the flour begins to go rancid. Contingent upon environment and grain quality, this cycle requires six to nine months. This process was too short for an industrial production and distribution cycle at the end of the 19th century. In the late 19th century, vitamins, micronutrients, and amino acids weren’t known at all, so getting rid of the germ worked well.
Flour cannot turn rancid without the germ. Degermed flour became standard. Degermation began in areas with a lot of people and took about a generation to spread to the countryside. Heat-processed flour is flour in which the germ is separated from the endosperm and bran before being processed again with steam, dry heat, or the microwave.
Grain is ground between stones or steel wheels during flour milling. Nowadays, the term “stone-ground” typically refers to a mill in which a revolving stone wheel and a stationary stone wheel, with the grain in between, grind the grain.