January 17, 2022 - 5:42am
70% extraction but all the bran/germ is gone?
I'm just trying to figure out a nuance in the difference between all purpose flour and high extraction wheat flour. It seems like some flour that fall into either category might have a proximate extraction rate between 70-80%. Yet narrative around high extraction wheat is all about retaining the nutritional profile of the still included bran and germ, while improving performance because there is less of it. And narrative around AP or white flour often says that virtually all of the bran and germ are removed. Anyone know what I'm missing here? Something to do with stone v. roller? Thank you!!
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http://www.theartisan.net/Flours_One.htm
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and yes, there is a difference between roller and stone milling. Roller mills are more able to "peel off" the outer bran layers and keep the bran separate.
Whereas a stone mill crushes or shatters the kernal into various size chunks.
So if you sift stone-ground flour, you "mostly" get white endosperm passing through the seive. But it's not so clean-cut. Small bran chunks pass through the seive along with small chunks of endosperm, and large endosperm chunks are retained in the seive along with large bran chunks.
There are intermediate layers too, called the "aleurone", which are generally/mostly not in AP/bread flour. But, depending on the extraction rate of a roller mill, the miller can include or exclude them to varying degrees. It's not until, roughly, the extraction rate gets near 80%, that the bran starts to get included.
Since a stone mill can't be as precise and "discriminating" as a multi-million dollar roller mill that "tempers" the bran with water in order to keep it together... two flours with the same extraction rate, one from a roller mill, and one from a stone mill, will actually have different compositions.
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To complicate matters, stone-millers sometimes use a machine called a "peeler" to remove some of the outer bran before the grain goes into the stone mill. Search on "wheat peeler" or "grain peeler."
Super helpful. Thank you!!