Bread and its main ingredient: THE FLOUR
Erre4m's friends, good morning and welcome to this new post to continue talking about bread and in particular about the main ingredient to prepare it; a very magic powder that you absolutely need to know in depth in order to obtain the best results, that is the flour: THE FLOUR.
After having dealt in the previous posts with the various procedures for the preparation of bread we are going to analyze and know the ingredients that make up bread. Making a good bread implies the perfect knowledge of the substances used to make it. It is therefore easy to understand how this preparation is very variable according to the ingredients and production processes we use.
Flour is the basic ingredient of bread making and its knowledge is of fundamental importance. Technically, the term FLOUR refers to the powder obtained by grinding cereals or other products in general.
Cereals are plants that belong to the grass family. The most commonly used are wheat, maize, rice, barley, oats, rye, millet, spelt and the recently introduced Khorasan, quinoa and amaranth (the latter two come from Latin America and are not really cereals but are used in small quantities in the preparation of bread for their excellent protein content).
In common use, however, the term flour is used to indicate wheat flour, as the bread we buy at the bakery or that we prepare at home is normally made with this cereal; although in recent years, due to the increasing intolerance, it is being replaced with alternative cereal flours such as spelt, kamut and ancient grains that are normally organic or that have undergone few changes and crossbreeds.
To continue the discourse on the knowledge of the flour that is used to make bread, it is important to know its composition because from its constituents we know their influence in the finished product. Wheat flour is composed of:
Water: from 8% to 18%;
Carbohydrates: 72% of which 60-68% Starch, 1.5% SUGARS, 2-2.5% CELLULOSE, 6.5% PENTOSANES;
Proteins: 7% to 18% ;
Fats: (lipids) 2% ;
Mineral salts:present mainly in the cortical part of the cereal 1.5-2% ;
Vitamins:which are also located in the outer layers and therefore are largely discarded in very refined flours;
Enzymes:which we have already mentioned in previous posts and will analyze in depth in the next ones. Enzymes are protein substances called biological catalysts namely alpha and beta amylases and proteases.
photo credits @Sonia Nadales
From the milling of the wheat grain we obtain a flour yield that varies between 70 and 80% while the remaining 18 20% is made up of non-digestible flour used in animal feed.
As we all know, flour is divided into categories. The categories of flour depend on two factors:
- the method of milling (by mechanical cylinders or stone grinding);
- the milling yield.
The milling yield, also known as the degree of sifting (which is the part of the categories that interests us most), is the quantity of flour that is obtained by milling 100 kg of wheat; it is easy to see, therefore, that the higher the extraction rate, the less refined the flour is, i.e. a wholemeal flour will have a higher milling yield than a 0 flour.
The categories of wheat flour are distinguished according to the rate of sifting in:
- Category 00 flour
- Category 0 flour
- Category 1 flour
- Category 2 flour
- Wholemeal flour
The characteristics of a flour determine its behaviour in the various bread-making processes, and the quality of the dough and, consequently, the quality of the finished product depend on them.
These characteristics in the milling field are:
- The characteristics of the gluten in the flour
- The fermentation characteristics of the flour
Gluten is a porous, compact and elastic mass, very similar to a sponge, which represents the main structure of a dough. The characteristics of the dough itself depend on the quantity and quality of the gluten. The characteristics of gluten are determined by certain proteins in the flour, the gliadins and the glutenins. Gliadins and glutenins are proteins that are insoluble in water and salt. When they come into contact with liquids and are subjected to energy movement, they bind together to form gluten. The gliadin in contact with water forms a sticky and fluid mass, while the glutenin absorbing water produces a compact, elastic and extensible mass. The amount and ratio of gliadins and glutenins generates the quality of gluten.
Gluten is the variable that generates the STRENGTH OF THE FLOUR. The strength of flour is defined as its ability to absorb water during kneading and to retain the carbon dioxide generated by the yeast during rising.
A flour is strong (i.e. with a high quantity of gluten) when it requires a high quantity of water to produce a soft dough. This dough will also be dry, elastic and non-sticky and, having a resistant gluten, will have a high capacity to retain carbon dioxide. Generally, doughs made with strong flours can be fermented for a long time (e.g. doughs with biga or large leavened items) and produce voluminous products because they can withstand the pressure of water vapour during baking and have a developed alveolation.
A weak flour (i.e. with a low quantity of gluten), on the other hand, absorbs little water, is not very resistant to prolonged kneading due to a modest quantity of gluten, retains less carbon dioxide for a shorter period of time, preferring short fermentations (e.g. valance), and has a low development during baking.
A flour of normal or medium strength is the one that has intermediate characteristics between the two mentioned above.
A flour of normal or medium strength is the one that has intermediate characteristics between the two mentioned above.
To summarize, the importance of gluten and consequently the strength of the flour defines:
- The amount of water needed and the time of a dough
- The characteristics of the dough itself
- The variations of the dough during the various stages of preparation (fermentation, shaping, leavening and baking)
- The development of bread shapes during leavening in relation also to time and temperature
- The final volume of the bread, its shape and the characteristics of the crumb
But how do you determine the strength of a flour in relation to its gluten and protein content? This is the crucial point to which the work of the miller is dedicated. As mentioned above, the mill analyzes the characteristics of the grains it receives in order to determine the quantity and quality of gluten. This will generate mixtures of grains to obtain flours more or less strong, so the flours that are distributed in bakeries or retail stores are nothing more than a mixture of various grains. But let us return to the determination of the strength of the flour. The mills to analyze the capacity of the gluten present in a batch of wheat have at their disposal various devices, in this case we will see the work of one of them: the Chopin Alveograph. CHOPIN'S ALVEOGRAPH provides information on the extensibility, resistance and strength of a flour. Thanks to this instrument the mill technician will have at his disposal a curve graph that indicates:
1) the resistance of the dough with the letter P and it is the maximum height of the curve;
2) the extensibility of the dough with the letter L and it is the length of the curve; the strength of the flour with the letter W and it is the area of the analysed graph. In this case it is important to know that the W, i.e. the strength of the flour, is indexed in a table with progressive values, i.e.: W 180 = very weak flour, W 200-220 = weak flour, W 250-280 = normal flour, W 300 = strong flour, W 360< = very strong flour.
It follows that knowing the W value of a flour means knowing its strength. Mills provide bakers with detailed tables so that they always know the characteristics of the flour they are using. For some time now, however, some brands of flour on the market, even in retail stores, have begun to report the W value of their product on the package, as more and more even the amateur is aware of these issues and wants to know what product he is working with.
In the next post we will continue to learn about the flour talking about its fermentation characteristics.
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Blog by Enrico Gumirato pastry chef and trainer
