A Spectrum of Flour: Extraction, Ash & Type

A Spectrum of Flour: Extraction, Ash & Type

A call {plea} for a uniform standard of nomenclature

By Thom Leonard Guild Member and owner, Independent Bakery, Athens GA

Not so very long ago, we bakers had only a choice between white flour and whole wheat; there was nothing between the two extremes. Today, thanks mostly to a new wave of craft millers and miller-bakers, we have available a variety of flours, ranging from creamy-white roller-milled bread flours through light tan fine-bolted flour and nearly-whole high extraction flours to a whole wheat. The white-whole extremes remain the same, but now we have a spectrum of beige between. Our bread is better for it. While it is difficult to produce a true white flour with a stone mill/bolter combination the rest of this spectrum of variously refined flour can be produced with either roller or stone mill operation.

Not surprisingly, there is considerable confusion about what to call flours that are neither white nor whole wheat. Fortunately, we’re not the first bakers to encounter this range, and a relatively simple solution is at hand: European countries have established ash-based flour classifications that grade flours into “Type”. Unfortunately, some bakers and millers are conflating two concepts, that of “extraction” and “Type". Both of these terms are already in use and have distinct meanings. I’m not advocating for one or the other, just that we not conflate the meanings.

Please bear in mind that neither extraction rate nor ash-based “Type” classification says anything about wheat quality and whether the flour is actually suited for your intended purpose. You need access to typical rheological data or to bake test information (perhaps your own) to know if the flour will do what you want it to do. Extraction rate is simply how much flour the miller got from the wheat, and “Type 80” only means that the ash is about 0.80%. Neither says anything about strength, extensibility, nor tolerance.


A prominent western US flour mill has offered a Type 00 flour, a designation used in Italy for a low-ash flour. Flour with this ash designation (Tipo 00) is required for the dough for Vera Pizza Napoletana, Tipo 00 from Italian mills has become popular among contemporary Neapolitan pizzerias in the US, and Italian Tipo 00 flour has an ash content between 0.40 and 0.44%. I asked a representative for the US mill offering Type 00 flour what the ash of the flour was, and was told that it was about 0.55%. I’ve eaten pizza with dough made with this flour, and it was among the best pizza I’ve eaten. The flour may certainly be used to make great pizza, but it’s not Type 00.

In Italy, flour is classified into four major ash-based categories starting with 00 with the lowest ash, with Tipo 0 next, then Tipo 1, and Tipo 2. The higher the “Tipo” the higher the ash. This “type” refers only to the ash content of the flour. While in Genoa in 1989, my favourite bread was a large, round loaf from Panificio Pugliese with complex fermentation flavours, dark crust, and an open creamy crumb. The paper label pasted in the centre of the baked loaf listel ingredients. The flour? Tipo 0.

By chance one evening I shared a table with a flour mill director. I turned the conversation to that delicious bread from Panificio Pugliese.

“This is the best bread in the city,” I said. “How do I make it? Where can I get this Tipo 0 flour?”

“Any mill can sell you Tipo 0 flour. That is not enough,” he explained. “This tell you only the ash in the flour. You need to know more than this.”

I have used excellent stone-milled, bolted flour from a regional mill, but I was unclear about what was actually in the bag marked “Type 75". A visit to the mill’s website cleared things up a little, but still left me a little baffled. We use the term, “Type” to refer to the degree of extraction of our SIFTED flours. So, whereas our whole wheat bread flour is 100% - no sifting, everything’s there – our type 85 flour, for example has around 10 – 15 parts sifted out. The mill is confusing extraction with type. Type is determined by ash level, not by flour yield.

French baguettes are typically made with Type 55 flour. Within the last few years, a formula circulated in American craft baking circles for a traditional French miche that called for “Type 80” flour. What do these numbers mean? The number refers to the approximate ash of the flour. French Type 55 flour has 0.50 – 0.60%.Type 80? You guessed it, about 0.80%, though the range is from 0.75 to 0.90%.

These Italian and French ash values are expressed on a 0% moisture basis, meaning that the percentage is based on the weight if the dry matter in the flour, excluding any moisture that may be present. The American industry expresses ash on a 14% moisture basis – a French ash content of 0.55% is equivalent to an American ash content of 0.46%. Originally published on The Artisan website, the table below shows a wide range of flour ash levels.

Type 100 French flour would have, under the American system, an ash content of 0.85%.

The second table, also from The Artisan, shows the relationship between ash and extraction rate. Please note that these extraction rates are for a well-engineered and well-tuned gradual reduction roller mill, not a single-pass stone mill with a bolter. As a rule the ash for the same flour yield/extraction will be higher on a stone mill/bolter operation.


USA (14% moisture) France (0% moisture) USA (14% moisture) France (0% moisture) USA (14% moisture) France (0% moisture)
0.40 0.48 0.55 0.67 0.70 0.85
0.41 0.49 0.56 0.67 0.71 0.85
0.42 0.50 0.57 0.68 0.72 0.86
0.43 0.51 0.58 0.69 0.73 0.87
0.44 0.52 0.59 0.70 0.74 0.88
0.45 0.54 0.60 0.71 0.75 0.89
0.46 0.55 0.61 0.73 0.76 0.90
0.47 0.56 0.62 0.74 0.77 0.92
0.48 0.54 0.63 0.75 0.78 0.93
0.49 0.58 0.64 0.76 0.79 0.94
0.50 0.60 0.65 0.77 0.80 0.95
0.51 0.61 0.66 0.79 0.81 0.96
0.52 0.62 0.67 0.80 0.82 0.98
0.53 0.63 0.68 0.81 0.84 1.00
0.54 0.61 0.69 0.82 0.85 1.01

Originally published on “The Artisan” website www.theartisan.net/MainCommFrm.htm



French Classification Extraction Rate Ash Content
Type 45 60 – 70% <0.5%
Type 55 75% 0.5 – 0.60%
Type 65 78-80% 0.62 – 0.65%
Type 80 85% 0.75 – 0.90%
Type 110 88 – 90% 1 – 1.20%
Type 150 95% 1.40%

Originally published on “The Artisan” website www.theartisan.net/MainCommFrm.htm


Extraction rate is basically the yield of flour expressed as a percentage of the whole grain entering the mill. 75% extraction means that if the miller started with 100 pounds of clean wheat berries, he or she ended up with 75 pounds of flour.

What is “high extraction” flour? Good question. Anything above 0.60% ash? Above 0.80%? Something above 80% extraction?

Flour “Type,” as illustrated in the above examples, is based on ash content of the flour. Flour ash is measured by burning a given weight of flour in a controlled environment and weighing the residual ash. The higher the ash content, the more germ and bran (especially bran) remains in the flour. The unbleached, roll-milled all-purpose and bread flours that most bakers use have an ash percentage between 0.48 and 0.54. A well-designed and well-managed long flow roller mill should be able to produce 72 – 75 pounds of such flour from 100 pounds of good wheat. Such flour would represent a 72% - 75% extraction.

Extraction rate, while essential for the miller, is not meaningful for the baker when comparing flours from different mills. As mentioned above, a well-adjusted gradual-reduction flour might yield 75 pounds of 0.54% ash flour from 100 pounds of wheat. The same mill, less well-tuned, might yield 75 pounds of a higher ash flour or less flour of the same ash.

The same wheat milled in the above example could be stone-milled and run through a bolter to remove a portion of the bran. In stone mill/bolter setups, it is difficult, at best, to separate as much of the bran from the endosperm as with a long-flow roller mill.

A slow-turning, flat-running stone mill, followed in the process by a rotary bolter, might yield 75 pounds of beige flour with ash closer to 0.85%, from the same wheat. That same mill, with the same screens but different wheat, may yield 85 pounds of flour with a somewhat higher ash content. When some samples of hard, dry wheat are stone-milled, more bran tends to shatter into fine particles that may not sift out. Differently dressed (or worn) stones may result in more or less bran being milled more or less finely, resulting in more or less bran passing through the screen into the flour.

Its fine (even welcome) to publish extraction rates of flours. However, as mentioned earlier, this is an imperfect measure for bakers, as the ash content for the same extraction flour from different mills varies, as it does for different wheat selections, even from the same mill. If a mill wants to name flours by their extraction rates, that’s perfectly acceptable, however, it would be less confusing if the word “Type” were not used in this context, only because there is an already established usage for that term in the flour world. It seems it would be easy enough to call a flour “75% Extraction", “No. 75 Flour”, or just about anything other than “Type” – unless the flour is classified by ash content.



My first, and simpler, proposal is that we agree to use the term “extraction” and not “Type” when we are making reference to a percentage of flour obtained from the grain. Related to this, that when we use the word “Type” or “Tipo” combined with a number in a flour name or description we adhere to established criteria.

The second proposal is, admittedly, a bit more ambitious, that we adopt an ash-based flour classification system, at least for these new flours that fall between the two extremes of white and whole. Type 80 flour, from any mill, would, under such a system have 0.80% ash, type 110, 1.10%.

It would not be necessary for a mill to run an ash test on every mill run. Once a screen array is established for a particular flour, the ash content from day to day, and week to week should vary only within an acceptable range. Occasional ash tests performed by an established lab, and run at regular intervals should be sufficient and affordable.

Those who choose to classify their flours by extraction rate, may, of course, do so. However, it would be helpful to everyone, including their customers, if we would all limit our use of the term “type” to reference to flour ash level.

There does remain at least one question in the use of ash-based “type” flour classifications. Do we use the French system as is, or do we make a minor adjustment to agree with the US practice of expressing the percentage of flour components on a 14% moisture basis? I suggest we remain consistent with the US convention of expressing values on a 14% moisture basis.

I’ll again emphasize what that Italian Miller told me in Genoa years ago, obtaining the right “Tipo” (or “type” or “extraction rate”) of flour is not enough. As a baker, you need to know a lot more than a flour’s ash level or its extraction rate to make wise flour choices for the various products produced in your bakery. Protein quantity and quality are essential properties and have significant influence on the suitability of any flour for any purpose. Look at Alveograph and/or farinograph values, if available. You should know the falling number. Flour should look, smell and taste good – and allow you to make good bread of the styles you favour.