Selecting the proper flour is crucial in baking. Flours are not all the same and we must choose them according to the type of product we want to bake. For example, have you ever tried to make panettone with a weak flour? Well, I wouldn’t recommend it, it could turn out into a big fiasco.
What is the strength of a flour? How can we select the right one? Let’s try to shed some light on the variety of products surrounding us.
The strength of flour
The strength of a flour is proportional to the percentage of proteins. Most of you might have read that strong flours are high in gluten content. It would be, actually, more appropriate to talk about gliadin and glutenin, two proteins contained in the seed wheat endosperm and involved in gluten formation.
As discussed in this post, it is the association between gliadin and glutenin during kneading that forms the gluten net:
Gliadin brings extensibility and elasticity, while glutenin gives tenacity. All together, they determine the viscoelastic properties of the gluten net, and, consequently, of the dough.
The gluten net acts as the dough’s scaffold and traps the CO2 molecules that develop during rising. Heavy dough as that of panettone requires flours with extremely high strength (about 15% proteins) or they collapse. On the other hand, cookies or shortcrust pastry must be crunchy and poorly elastic, so they need weak flours. Do you understand, now, why shortbread or shortcrust recipes reports tips as: work the dough as less as possible and with cold hands. We have to limit the development of the gluten net!
The W parameter
The strength of flour is usually measured with the Chopin’s alveograph. They are several parameters that characterize a flour, but the one I find the most useful for baking purposes is the so-called “W” that indicates the strength. I could speak about tenacity or extensibility, but those parameters are not reported on labels. On the other hand, the W parameters can be indicated (at least, on professional flours’ labels) and indicates, with a certain accuracy, the strength of a flour: the higher W, the stronger the flour.
Below, a graph to summarize different types of flours and their strength:
Unfortunately, W is not always reported, unless you go for professional flours.
Furthermore, the classification of flour might differ from country to country, just to make our life more complicated. Here, in Canada, they report the % of proteins, while in Italy we have the classification 00, 0, 1, 2, and in France and Germany another system is in use, what a chaos!
As I can’t find W on the flours I buy, I use the % of proteins as a reference. You understand this strategy is not the best as only gliadin and glutenin taken part in the formation of gluten net!
The degree of absorption of a flour
Gluten absorbs liquids for about 1.5 folds its weight. From that, we evince that the degree of liquid absorption is directly proportional to the strength of a flour. But...there’s a “but”, of course...the strength is not the only factor affecting the degree of absorption.
During milling, flours can get damaged, meaning that the grain dimensions are further reduced. This enhances the liquid absorption and exposes starches to amylase. Selecting a flour with the right degree of absorption could be crucial in the preparation of certain dough (in particular, when it is clearly requested in the recipe!). Believe me, I underestimated this factor a few times and I had to discard more than a dough!
Unfortunately, the degree of absorption is not reported on labels (and, honestly, I have no idea if that can be measured). Therefore, you have to try different flours until you find the right one. Another option is contacting the supplier and inquiring about that.
A little recap: how do we select the proper flour?
- Selection of the flour must be based on the product you want to bake, e.g. bread, cookies, pizza, shortcrust pastry...you can use the scheme I gave you as a reference, and there are even more complete ones available online (I wasn’t able to fit all the baking products in there, sorry :P).
- Look for the W parameters on labels. If not declared, it could be found on the supplier’s website.
- If you can’t get the W value, look for the protein %. It is not super accurate, but gives a good approximation.
- Try to find information on the degree of absorption of your flour (high, low...). Asking the suppliers could be a good option.
- Once you find the one, stay with it!
What if I do not find the flour with the right strength?!?!?!? :O
Well, this problem can be solved, but we will speak about that in another post ;)
C.W. Wrigley, F. Békés, and W. Bushuk, Chapter 1 Gluten: A Balance of Gliadin and Glutenin, 3-32, Gliadin and Glutenin: The Unique Balance of Wheat Quality, Editors: Colin Wrigley, Ferenc Békés, Walter Bushuk, 3340 Pilot Knob Road, St. Paul, Minnesota 55121, U.S.A. (AACC International, Inc.) 2006
Di Carlo, Tradizione in Evoluzione, 166-167, Chiriotti Editori
Ma et al., Soft wheat quality characteristics required for making baking powder biscuits, J. Cereal Sci., 2018, 79, 127-133