What is an “Extraction Rate”?

“Extraction rate” sounds like a technical term. Which it is. Though that’s not to say that home bakers like you and I can’t understand it and use it. Particularly if you like to bake bread, an extraction rate can give you a good deal of information about a flour, as well as several clues about how it will behave.

So, to business. When someone uses an extraction rate in a sentence, say, “this is a 65% extraction flour”, at least two important types of information are being conveyed. The first is the region of the wheat berry where the flour has been taken from. The second is the composition of the flour, i.e., how much of the softer inner endosperm, harder outer endosperm, and even bran and germ the flour contains. And when you know all that, you also have a sense for how much gluten (protein) the flour contains, even the grind of it. It’s one pretty darn info-packed number.

To make sense sense of an extraction rate, it helps to think of a wheat berry as an onion. On the very outside is the skin: the bran. Beneath the bran is the starchy endosperm. Most people think of wheat endosperm as a uniform piece of starch, but that isn’t true. The endosperm is actually comprised of layers, each of which differs somewhat in composition and texture. The very outer layers, for instance, are the hardest, least uniform part of the endosperm. These layers are brownish-white, having a fair bit of bran still in them, as well as a good deal of the wheat berry’s nutrients, and a high proportion of the berry’s protein (gluten). Progressing inward toward the center of the wheat berry, the endosperm layers get more uniformly starchy and softer, until you get to the very center of the berry where they’re almost completely pure, white-to-yellow starch.

Knowing that, we can get back to what this post is about: extraction rate. In the most literal sense, an extraction rate can be taken to mean: “this is how much flour I got when I took my sack of wheat berries to the mill for grinding”. If 100% of what was in your sack was handed back to you as flour from the mill, then you have a 100% extraction flour. It contains every bit of the endosperm, hard and soft layers, as well as all the wheat bran and the wheat germ (the wheat embryo that’s attached the end of the berry). That 100% extraction flour is — you guessed it — whole wheat flour.

But what if the mill started taking away pieces of the wheat berry? Like the germ, the bran, and some of the outer endosperm layers? In that case you’d be getting back less than 100% of what you gave them. Your flour would therefore be a lower extraction rate flour. Its composition (and by extension its performance) would also be different.

So let’s say they started by removing the bran and the germ from the berry, as is typical when wheat first comes into a mill, then ground what was left into flour. The bran covering makes up about 12% of the wheat berry, and the germ another 3% or so. Add that together and you have 15%. Take that away from your 100% extraction flour and you have 85% of the total berry. Grind it and the result is an 85% extraction flour, which is still a pretty stout item, since it has all the outer protein-rich endosperm in it and some residual bran as well.

But let’s say we took that harder outer endosperm away. Those layers make up about another 15% of the wheat berry. Remove them, grind what’s left and you have 70% extraction flour. This is a down-the-middle sort of flour, not too hard, but not too soft either, good for lots of things. Which is why most all-purpose (AP) flour is about a 70% extraction flour.

As we keep stripping layers away, heading toward the center of the wheat berry, we get purer and purer starch, until we get to the very middle third of the berry. This is the softest inner endosperm, lightest in color, and containing the least amount of the protein and nutrients. Ground, this ultra-low, 33% extraction flour is great for cakes and pastries.

So you see how all this extraction-rate stuff works, yes? And why it isn’t just a term for in-the-know bread heads. Much can be gleaned from just this one humble little number. You can even infer the fineness of the flour’s grind by the extraction rate, since lower extraction flours tend to be a finer grind and higher extractions coarser. This isn’t a hard-and-fast rule, mind you, as there are a lot of very find whole wheat flours on the market these days, but it works as a rule of thumb.

Of course an extraction rate won’t tell you everything. It won’t tell you what type of wheat the flour was made from, for instance, and that can be important when you’re trying to decide what kind of flour to use for what application. Flour made from hard north American wheat, for example, isn’t ideal for Southern biscuits no matter how low the extraction. Still, I hope this helps clear up a topic that, for many, has become highly confusing.

20 thoughts on “What is an “Extraction Rate”?”

  1. Thank you! I’ve heard the term before but been too lazy to do my own research. That was crystal clear and will be easy to remember from now on.

  2. Thanks for this explanation, Joe!

    I recently received a flour mill as a gift from my husband, so I’ve been experimenting with baking bread and other things with home stone ground flour. Mine’s all 100% extraction of hard wheat right now, but I’m thinking I should look into some proper sieves to see what else I can do with it. I’ve also got some soft wheat, but I haven’t tried doing anything with it yet.

      1. I’ll try and start documenting my experiments on my blog (see the link on my username). I’m making cookies tonight, so I should be able to write something up within the next few days. 🙂

  3. How does this relate (if it relates at all) to a flour’s protein content? Is it another way of saying the same thing, or is it apples and oranges?

  4. Thanks, Joe. One part is just a little hazy for me- in order for pastry flour to be mostly composed of the “inner third” of the wheat berry, does that mean the mechanical process of grinding the wheat berry involves it being processed in stages from the outside in, somehat like polishing rice (and peeling an onion), or is the purity made easier to achieve by (relatively) coarser particles of the first milling of the berry?

    1. That’s a good question, Dani. One thing I should have mentioned in the post is that as the starch in the wheat berry gets purer and purer, which is to say as you get closer and closer to the very center of the berry, the starch breaks into finer and finer pieces when it’s crushed. So the endosperm pieces that fall to the bottom levels of the sieves — i.e. the smallest ones — are by definition the pieces from inner endosperm. Or most of the are. Does that makes sense?

      – Joe

  5. So the same amount of grinding force simply yields particles with a varying sizes because of the difference in the composition of the wheat berry parts, and the inner parts naturally fall through the finer sieves more easily.

  6. If I’m looking at a recipe that calls for “85% extraction flour”, what’s a reasonable equivalent?

    1. Hey Jane!

      85% extraction is what we in the US would call all-purpose flour. Easy to find!

      – Joe

  7. Hi joe…! I saw ye mentioned in ur article that AP is 70% extraction.. So, I m wondering if 85% extraction of AP in ur answer to Jane is different from the above 🙁

    1. Hey FP!

      Good question. The thing about extraction rates is that they’re not always the last word when it comes to flour type. If you’re milling a softer wheat a higher extraction rate would not necessarily translate to a stronger flour. Similarly, a lower extraction rate of a hard wheat wouldn’t necessarily make it softer. That’s why extraction rates are best thought of in terms of ranges. For me 70-85% extraction is in the range of an all purpose.

      Thanks for a good question!

      – Joe

  8. this was very helpful
    but, do you know the extraction rates for the different types of flours?
    please i really need it

    1. Hi Raneil,

      I wish I could say! Milling is a highly secretive business and extraction rates vary from mill to mill and product to product. I’m sorry I can’t be more specific. A Google search might be helpful here!

      Best of luck,

      – Joe

  9. Why is it important to know the extraction rate of flour and why is wheat commonly used as abaking flour for bread rolls

    1. Hi Regina!

      Personally I don’t think it’s important to know the extraction rate of flour. It’s just a another way of talking about flour. In North America we use terms like “whole wheat flour” “all purpose flour” and “pastry flour”. Europeans will use extraction rates to mean the same thing. The degree of extraction tells you how white (and fine) the flour is. Granted extraction rates are a more precise system, but unless you’re a professional bread baker there’s really no need to speak in those terms about flour.

      Regarding the second question, I’m not totally sure what you’re asking. Do you want to know why wheat is more common than other flours like amaranth or spelt? Let me know!

      – Joe

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