The stones that give stone milling it's name are located just below the hopper (shown here.) Millstones grind at a slower rate than roller mills and this lower-heat processing keeps the germ fat from oxidizing and becoming rancid, which can destroy some of the nutrients inherent in the grain.
Our mill has several sifting chambers and each pass through a sifter results in a finer grind. But because stone milling does not strip the bran before processing, even a very finely ground and sifted flour will retain more color than it's roller-milled counterpart.
Down the Chute
The flour comes out of the mill via chutes. The whole grain flour comes out directly below the hopper (pictured above). The sifted flours come out of the chambers in the above right photo, with the screen determining the fineness of the flour.
Stone grinding grain dates back to the third century B.C., and was the norm in milling until the 19th Century when roller milling became widely used. Roller milling allows for a longer shelf life and greater shipping capacity, but similar to a grocery store tomato much can be lost in terms of flavor and nutrition. Stone milling leaves the wheat kernel intact for milling, keeping the bran on the kernel and resulting in a more nutrient rich product. Typically, roller milling involves removing the bran immediately before processing - stripping the wheat of it's nutrients and often adding nutrients in at the end of the process - what we know as "enriched" flour.