I am sure that this will be an interesting read both for those who are unclear about what is meant by the “strength” of a flour and for those who want to explore the topic further.
I think it is unnecessary to reiterate that all flours are not the same. A wheat flour suitable for a panettone certainly cannot have the same characteristics as one designed to make Neapolitan pizza.
It is self-evident that they should be used to do different jobs.
And indeed, that is what work is all about. The so-called strength index, expressed in “W,” is nothing more than an indicator of how much work a dough can withstand before it breaks or tears.
Ah! small footnote. In today’s article you will not find any strange charts relating strength to the amount of protein or water to be used in the dough.
And the reason is simple. They have no use, they are wrong and baseless, and if you read to the end you will find out why.
By now you must have realized that for me, making it easy to use our products means explaining them to you for what they are, not giving you misguided directions because “at least then you can manage on your own.”
But back to us.
Briefly
The strength index is measured in the laboratory using Chopin’s alveograph.
A special tool that inflates 3 discs of 50% hydrated dough (1 part water to 2 parts flour) with 2.5% salt added, until they break apart.
The result of these measurements determines the rheological properties of a wheat flour.
The pressure applied to the dough until it reaches the breaking point and the diameter of the bubble obtained by swelling are measured.
- The pressure applied indicates the toughness“P” of the dough balloon
- Its increase in volume determines its extensibility“L“
The values of toughness “P” and extensibility “L” are plotted on a graph, and the area “occupied” by the curve represents the strength index “W.”
Simply put, i
gluten is able to absorb water one and a half times its weight, so
the higher the W of the flour and
the greater the ability of the dough to:
- expand under the action of carbon dioxide produced during rising;
- Retain fluids or fats;
- Support fillings or suspensions (solid parts such as candied fruit for panettone).
In a good wheat flour for pizza or leavened foods in general, both the strength index“W” and the ratio of toughness to extensibility“P/L” are always given.
Please note: Each flour in our store comes with complete data sheets as you can see in the example below.
Force “W”
Let us try to understand practically how to interpret the value of W we find on our beloved flour packages.
Soft wheat varieties according to their strength can be divided into 4 categories by assigning them a synthetic quality index (ISQ):
W 80 to 140 (FB) Baking Wheats– These grains yield flours unsuitable for baking that develop little gluten and absorb very little water.
W 140 to 220 (FP) bread wheat – Used to produce weak flours, suitable for making some pastry products, pizzas such as Roman scrocchiarella, crackers and breadsticks. All baked goods that do not require development in leavening. They create little gluten and can absorb a limited amount of water.
W 220 to 270 – (FPS) Superior breadmaking wheat– Used for medium-strength flours suitable for making bread, pizzas such as Neapolitan, focaccia or baked goods with medium or short rising times. They develop good gluten and can absorb a fair amount of water.
W 270 to 340 – (FF) strength wheats– Used for so-called strength flours, suitable for Roman pan pizza doughs, for preferments such as biga and poolish, and for bread. They develop a resistant gluten, can absorb large percentages of water and withstand long leavening.
W over 340 – These are special strength flours commercially called “Manitoba type,” used for prebaking, for special doughs with high liquid or fat percentages such as for recurrence products (large leavened goods) or for doughs that require very violent or prolonged rising. They develop an extremely tough gluten that can hold liquids, fats and solids in significant amounts.
“P/L” Ratio
The indication of how extensible and tough the dough you are about to prepare will be is given to you by the value of the P/L ratio.
If the P/L is less than 0.40 – We have flours that will form excessively stretchy and sticky doughs even at low hydrations.
With P/L higher than 0.70 – Dough formed with these flours will be excessively tough and difficult to work with.
P/L between 0.4 and 0.7 – These are perfectly balanced flours suitable for baking.
Application
Now the sour notes begin. The values we have just discussed give us only a rough indication of the flour we are about to use.
The first thing that jumps out is that all measurements are taken on a standardized, yeast-free dough with 50 percent hydration and a 20-minute rest.
It is a scenario in which you will never find yourself working, or at any rate very rarely.
There is a tendency, especially in recent years, to obsessively fossilize on these values when they should be taken for what they are, a broad indicator.
We can say with absolute certainty that the rheological characteristics of a flour are conditioned by:
- Amount of water absorbed:
increased hydration increases the extensibility of the dough “L” and decreases both its toughness “P” and strength index “W”. The resulting curve (P / L ratio) will be completely different from the “standard” curve.
In contrast, a poorly hydrated dough would show increases in P, W and a decrease in L.
What does it mean? Simple, by adding more or less water we can change the behavior of the dough we are “designing.” - Kneading technique:
The type of mechanical action applied to a dough can also affect its rheological properties.
An “intense” action (planetary or spiral kneading machine) will return a stronger gluten while kneading by hand will give us less toughness.
The targeted mechanical action of professional machines such as spiral mixers give the dough both greater toughness and extensibility, greatly improving the end result, which is difficult to achieve either by hand or with planetary mixers. - Rest times:
Another factor often overlooked, perhaps because it is quite complex to explain at the molecular level, is rest times.
I will not go into this tortuous topic. Be aware, however, that a mixture of water and flour left to rest for an appropriate amount of time (hydrolysis or self-silting) is capable of returning a more extensible dough, among other things.
This practice is very useful if you need to work with tough flours (high P/L ratio) to get softer, more workable doughs.
Strength and protein
You often see tables around that relate protein content to the strength of a flour.
I regret to inform you that they are not entirely accurate. They can give you reliable values only and exclusively on “0” and “00” type flours. They may be unreliable with type “1”, type “2” and Whole wheat flours. They are completely useless on flours made from grains other than soft wheat.
This is because the cruscal part contains a good amount of protein but does not contribute to the formation of gluten.
Not too bad anyway,
all of our flours
have complete data sheets with all the data you need.
To recap
Use the data you find in the flour data sheets by giving them their proper importance.
Translated in print, don’t be too taxing. If you need to make a Roman-style pan pizza and only have a medium-strength flour with a W of 270 available, you can use it. You will slightly decrease hydration and resting time without giving up your favorite pizza.
The watchword in these cases is to test how a flour behaves in your dough; figures written on paper will never be able to tell you everything.
I know you would have preferred to have a table with directions for figuring out what hydration to use depending on the strength or P/L of a flour, but that would be totally unnecessary.
While it is true that the greater the force, the greater the amount of usable water, it is not possible to directly relate the two parameters. It makes much more sense to take the minimum absorption figure given on the sheets of each flour and increase it by 15-20%. Absorption is measured by means of another instrument, the BRABENDER farinograph, which we will discuss soon.
The ability of a flour to absorb water depends, yes, on the gluten, but also on the grain size, the amount of cruscal parts present, and its inherent characteristics. Strength is only one of many elements that contribute to its maximum hydration.
So experiment, experiment, and experiment-you may be amazed at the results you can achieve using quality products even under seemingly suboptimal conditions.
Strong flours: are they bad?
Honestly, I have always struggled to understand how such hogwash could be spread, but I can try to fantasize about what the confusing message that has been circulating for a few years might be.
First fantasy:
In the past, Italian flours were purely weak flours. The temperate climate of our peninsula seemed not to allow the cultivation of wheat suitable for the production of strength flour, which “forced” us to import wheat or finished product from abroad.
Today the situation is a tad different. New cultivation techniques and specially selected cultivars allow us to grow and process in Italy, wheat for the production of flour of strengths even higher than 340 W.
Second fantasy:
The best known strength flour is Manitoba. The name comes from the Canadian province where the wheat to produce it came from.
Unfortunately, we have had the bad idea of calling any flour with a W above 350/370 “Manitoba” even if it is grown and produced in Italy, confusing the minds of the uninitiated.
In the common imagination, an American flour (and we’ll throw in Canada too since it’s close by) is grown with the use of pesticides and additivated with various improvers.
Assuming this is true, the limits for it to be imported are exactly the same as those imposed on local production and weaker grains, so it is certainly not the strength that determines its genuineness.
Third fantasy:
Gluten is bad for you, and a strength flour produces a lot of it.
Of course if you have celiac disease, gluten is your worst enemy, but whether the flour is strong or weak matters little. For an intolerant person it is always poison.
In “healthy” subjects the difference in gluten produced by strong and weak flour is minimal, we are in the range of 7-8%.
Concluding
Whenever you approach a new flour, think about what can be useful to you without dwelling too much on the hearsay of those who often inaccurate fragments of information “grabbed” here and there. There are wonderful texts on which to delve into the subject such as Piergiorgio Giorilli’s “The Big Book of Bread,” for example.
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See you soon
Rudy
