It has just become clear to me that extraction rates of flour are not always comparable.
When someone says that straight flour (white flour, AP flour, whatever) is about 72% extraction, that means 72% of the whole grain was kept as flour. 28% was tossed out as animal feed, including the bran, germ, and some wasted endosperm.
On the other hand, when talking about patent flour and clear flour, the percentages are not of the whole grain, but of the straight flour. So patent flour of 85% extraction is 85% of the straight flour (which was 72% of the grain). So that's actually only 61% of the whole grain.
This link describes it in more detail: http://www.theartisan.net/flour_descriptions_and_definitions.htm
Here is another page about it: https://bakerpedia.com/ingredients/straight-grade-flour/
Here it is visually:
Here are several links that use %-of-whole-grain when talking about extraction:
- mikedilger's Blog
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Bran and germ are not necessarily "tossed out", both are widely available separate from the AP flour. I buy both and add them to various breads and other recipes.
These parts are widely available as health foods.
However, I suspect that there is not enough demand to get it all sold, and so most of it goes into feed. Click on the first link above at theartisan.net and search for the term "feed". That's where I got my information.
... the "Whole Wheat Flour" line isn't drawn all the way to the top is that some countries don't require all of the bran to be present to use the term "whole wheat." The argument is that "whole wheat" can't possibly be taken literally -- nobody includes the chaff, stalk and roots! So if its not literally the entire plant, the definition is up for grabs, and industries in various jurisdictions have defined it differently.
In the USA, I believe 100% of the berry must be present, and they use pin mills to grind the bran/germ finely before the mix it back into straight flour. In Canada they only need to provide 95% of the original berry.