The term flour refers to the product obtained by grinding dried fruits or seeds of various plants. On the market it is possible to find different flours from cereals, fruit and legumes: corn, barley, spelled, rice, oats, rye, chestnuts, chickpeas, almonds, buckwheat. Commonly, however, it is indicated by the name of flour, without specifying its origin, that obtained from Wheat (Triticum aestivum) used a lot in the kitchen for baking and pastry. The flour of durum wheat, on the other hand, mainly used for the production of pasta, takes the name of semolina.
With the due exceptions the wheat flour it is the most suitable for baking, from pastry to pizza and bread.
According to Presidential Decree 187/2001, soft wheat flour is defined as “the product obtained from the grinding and consequent sifting (refining) of soft wheat freed from foreign substances and impurities”.
The grain of wheat is called caryopsis and in it three parts can be distinguished: the external part (bran) and the inner part (germ), rich sources of fiber, vitamins and minerals, and the central part (endosperm) source of starch and protein.
There are basically two characteristics to take into account when choosing soft wheat flour, the refining (defined in technical terms sifting) and the force. As for the sifting, we speak of sifting rate of flour, referring to the quantity of product in kilos (kg) obtained by grinding 100 kg of wheat. The higher this index, the coarser the flour. Conversely, a very refined flour has a low sifting rate.
The commercially available types of flour range from:
- 00, the most refined and defined also fine flour, which contains only the central part of the grain deprived of the external part
- 0, 1 to 2, with progressively higher percentages of bran
- wholemeal flour, which is obtained by grinding the grain entirely, except for separating a small amount of parts derived from the bran. The law, in fact, provides for a maximum level of ash, i.e. the components (mineral salts) that remain intact if subjected to a 'carbonization treatment' of the flour lasting at least six hours at a temperature of + 500/600 ° C. (table 1). The lower the ash content, the more the flour has been produced with only the endosperm and the whiter it is. The "wholemeal" flour, on the other hand, will have the maximum ash content because all the grain has been used and will therefore be darker
Table 1: Classification of flour (Table contained in Presidential Decree February 9, 2001, n. 187. Values calculated on 100 parts of dry matter)
|Type of soft wheat flour||Humidity max||Ash min.||Ash max||Protein min.||Sifting|
Note: the maximum humidity allowed at the time of placing on the market is 14.5% for all types of flours; it has in fact been seen that when the humidity exceeds 16%, the flour is not preserved; furthermore, since a wet substance weighs more, higher values border on food fraud.
The other parameter is the degree of strength of the flour, closely linked to the amount of gluten, a protein complex that develops when the two proteins, gliadin and glutenin, come into contact with water. In the dough phase, gluten forms a sort of lattice (gluten mesh) whose task is to keep starches and gases inside the mass: hence the leavening bubbles and the spongy structure of a well-leavened bread. The strength of the flour therefore indicates its ability to absorb liquids during mixing and to retain carbon dioxide during leavening. A tenacious gluten mesh ensures the doughs greater resistance to processing and leavening; on the contrary, a less tight gluten structure allows the starch to be released more easily.
The strength of the flour (indicated on the labels of the packs of flour for professional use with the letter W) is the quantity of gluten that it manages to develop and its consequent ability to absorb water. Its value is related to the protein richness of the wheat: the higher the protein in the grain, the more gluten will be developed in the dough. So, simplifying it, it could be said that the more protein there is in the flour, the greater its strength (W) (although not all proteins produce gluten). Flours of different strengths are therefore suitable for different types of processing (table 2).
Checking the quality of the flour and its properties in the kneading, leavening and baking phases is not a simple thing.For this purpose, various chemical and physical measurements are carried out in the mills to better classify the flours produced, evaluating a series of parameters such as:
- W, defined as the strength of the flour
- P., which represents the tenacity of the gluten, that is the force that opposes the processing of the dough (more precisely its ability to resist the stimulus given by a machine which, by injecting air into the dough, simulates a leavening. The value measures the capacity which has gluten not to deform the dough during this test)
- L, which represents extensibility, i.e. the ability of the dough to return to its initial shape if subjected to elongation (more precisely, the ability to expand without breaking during the test)
Table 2: Strength of flours and different types of uses
|W||Proteins||P / L||Usage|
|90/130||9/10,5||0,4/0,5||Direct dough biscuits|
|170/200||10,5/11,5||0,45||Common bread, Ciabatte, direct dough, bread rolls, pizzas, focaccias, rusks|
|220/240||12/12,5||0,45/0,5||Baguette, plain bread with direct dough, beetles, direct dough ciabatta and 5/6 hour chariot|
|300/310||13||0,55||Processed bread, leavened pastry with 15-hour chariot and direct dough|
|340/400||13,5/15||0,55/0,6||Puffed bread, pandoro, panettone, long fermentation leavened products, leavened pastry with biga over 15 hours, hamburger bread|
* P / L are usually evaluated as a single ratio: P / L (P divided by L, therefore the toughness divided by the extensibility) and have a reference value of 0.5. A P / L value that is too high indicates a flour that is too resistant and not very extendable, difficult to process. Conversely, a P / L that is too low indicates a flour that is not very resistant and too extensible. A flour for biscuits will have a low W and P / L value (for example W = 100 and P / L = 0.4) while a flour for leavened products will have high W and P / L (for example W = 350 and P / L = 0.6).
Note: for direct dough we mean a preparation in which all the ingredients are processed in a single phase respecting the correct order of insertion. For indirect dough, on the other hand, it means a preparation in several phases with a pre-dough containing part of the basic ingredients (flour, water and yeast) left to rest, to which the remaining ingredients are added at a later time.
For pizza, for example, the differentiation of the flour is aimed at obtaining a pizza with specific organoleptic and gustatory characteristics: the classic Neapolitan pizza must have an extensible dough and, at the end of cooking, be more or less thin and not too alveolar, for this uses flours of medium strength. In addition, it should only retain its characteristics for a few minutes after serving and cook at a slightly higher temperature. On the contrary, pizza by the slice requires greater elasticity and a tendency to retain water; at the end of cooking it is much thicker and should retain its characteristics for as long as it remains on the thermal display. The flours used for this last type of dough must be of the highest quality, and necessarily very strong, that is, capable of generating a strong gluten mesh capable of supporting the long maturation in cold rooms, typical of this semi-finished product.
There are also flours with W values higher than 400, called Manitoba because they originate from that region of Canada. They are called Manitoba even if the corresponding grain is now also cultivated in Europe. They have a high protein content and are often used in blends with weaker flours to increase their strength.
Semolina is a flour obtained by grinding durum wheat (botanical species Triticum durum). Although very similar, durum and soft wheat (T.aestivum) do not have the same botanical characteristics and do not produce seeds with identical nutritional properties.
There whole wheat flour (or semolina) is perfect for the production of dry pasta, while it is used in smaller percentages in bread dough, always mixed with that of soft wheat.
There semolina it can be classified according to the granulometry: coarse semolina (600-800 microns), medium semolina (400-600 microns), semolina (0-300 microns).
By further grinding the semolina, "re-milled semolina" is obtained, with a finer particle size than semolina and more similar to that of flour.
The semolina differs from the semolina for the size of the granules, it is slightly less sieved, therefore slightly more raw and corresponds to the definition of a semi-wholemeal semolina, therefore with a greater presence of fiber than refined semolina. There are also wholemeal granulates to which, also in this case, the portion of bran is kept (table 3).
Table 3: Classification of semolina (Table contained in Presidential Decree February 9, 2001, n. 187. Values calculated on 100 parts of dry matter)
|Product name||Humidity max||Ash min.||Ash max||Protein min.|
|Whole durum wheat semolina||14,50%||1,40%||1,80%||11,50%|
|whole wheat flour||14,50%||1,36%||1,70%||11,50%|
Note: Humidity allowed up to 15.50% if indicated on the label
Semolina is a food rich in starch; it also contains a good percentage of proteins, including gluten. It has been shown that the portions of proteins (peptides) specific to leavening are more abundant in soft wheat flour than in durum wheat flour, for this reason semolina is considered more suitable for the production of pasta. However, due to its protein composition, today semolina is also widely used in bread making and in the packaging of baked goods.Also in this case, due to the presence of gliadins and glutenins (proteins that form gluten), we can speak of the parameters P / L and W.
Edible flour can be produced starting from cereals other than wheat from which it takes the nutritional characteristics:
- spelled flour
- corn flour
- Rye flour
- rice flour
- millet flour
- oat flour
- barley flour
- teff flour, gluten-free cereal originating from the African continent, more precisely from Ethiopia and Eritrea
- Khorasan flour (and Kamut flour), a type of wheat first described in Iran, where it is still grown today. Today everyone can grow Khorasan wheat, but only the company that owns the brand can sell this wheat under the name of Kamut (read the buffalo)
- buckwheat, amaranth or quinoa flour, are the so-called pseudocereals, i.e. plants that do not belong to the same family of cereals (Graminaceae)
Flour can also be produced by grinding legumes:
- chickpea flour
- pea flour
- bean curd
- soy flour
- bean flour
- lentil flour
From the grinding of tubers and roots it is possible to obtain starch, starch of the extracted and dried product reduced to a very fine powder, similar to flour. The starch are usually used as thickeners:
- potato flour or potato starch, obtained by reducing the potatoes to a pulp and eliminating the fibers by washing in water
- cornstarch or corn starch, made from corn. The difference between starch and corn flour lies in the composition of the product. The flour is obtained by grinding the whole grain (endosperm + germ + bran) while the starch is contained only in the endosperm
- cassava flour (or tapioca flour), obtained from cassava root (or tapioca), a plant of the Euphorbiaceae family native to South America
Furthermore, flours can derive from fruit as in the case of:
- Chestnut flour
- almond flour
- hazelnut flour
- pistachio flour
- walnut flour
- dried fruit flour (coconut, bananas, etc.)
- seed meal (sunflower seeds, chia seeds, flax seeds ..)
From cereals that do not contain gluten it is possible to obtain flours particularly suitable for people suffering from celiac disease or gluten sensitivity (Gluten Sensitivity), Such as:
- amaranth flour
- buckwheat flour
- corn flour
- millet flour
- quinoa flour
- rice flour
- sorghum flour
- teff flour
- legume flours
- fruit flours, dried fruit, seeds
It should be emphasized that when it comes to semolina or flour, even if derived from naturally gluten-free cereals, the wording "gluten-free" on the label must be checked. These foods, in fact, are produced through a manufacturing process during which contamination with other processing of foods containing gluten can be determined, especially if dedicated production lines are not used. The complete guarantee of the absence of gluten is certified by the Spiga Barrata brand placed on products dedicated to celiac people.
On the contrary, people suffering from celiac disease must absolutely avoid:
- spelled flour
- wheat flour
- durum wheat flour
- Rye flour
- barley flour
- oat flour
In gluten-free doughs, the use of starches is usually required as thickeners or to help better bind the flours that cannot form the gluten mesh.
A defined organic flour comes from the grinding (milling) of grains grown with organic farming methods; it is later certified to be sold as such.
In particular, organic wheat, to be considered as such, must bear the certifications of the appropriate control bodies that verify the requirements of the producing farm. In Europe, as now in many other countries of the world such as the USA, Canada, Japan, organic farming is regulated by specific legislation. The organic farming method aims to obtain the products based on the use of pesticides (fungicides, insecticides, herbicides) present in nature, excluding the use of synthetic products (read the Bufala).
The yield of organic wheat crops is generally lower than those using conventional methods, which is why the price of organic wheat products is often higher.
From a nutritional point of view, to date, scientific research has not found significant differences in composition between organic and conventional products, nor on the safety of their consumption. Therefore, more than on the quality of the product, the reflection is often placed on the stability in the processing phases and on the possibility of the organic varieties, numerically smaller than the conventional ones, to always guarantee the same type of harvest, both in quantity and in quality.
On the other hand, the variables that affect the quality of the final product are many and include both factors related to the starting material, such as the genetic characteristics of the cereal or legume species; and external factors, such as environmental conditions (temperature, solar radiation, lighting duration). The type of cultivation is only one of these variables and processing plays a fundamental role. For this reason, when buying flours it is good practice to try to find as much information as possible about the product: its nutritional characteristics, the origin of the cereal and the place of processing.The real balance is often represented by the seriousness of the mills that produce them.
If you buy artisanal flours (without organic certification), or self-produce, it is important that the necessary hygienic conditions are ensured, both related to the cleaning of the grain and to the cleaning of the environment in which the grinding is carried out.
Today there is a lot of talk about ancient varieties in use up to 50 years ago. These are varieties that have a utility, especially environmental or economic, for the re-evaluation of biodiversity but do not have particular genetic characteristics with regard to health (read the Bufala).
The category "protein flours”Includes a wide range of low-carbohydrate, high-protein flours. The most common are legume flours.
From a technological point of view, these flours are excellent and have no particular contraindications, indeed it is often recommended that they be introduced into the daily diet to increase the variety of food choices. Due to their nutritional composition they are not always able to replace normal wheat, because kneading the dough is often difficult, but they are perfect for many recipes.
Today, they are also used for the preparation of ready-made doughs (for bread, pizza or baked goods), with a high protein content, mainly used among athletes and those who prefer to follow a high-protein diet. In these cases, in addition to flour, protein powders can be added to increase the protein quantity of the product.
The characteristic of this type of diet is the reduction, even very marked, in the intake of carbohydrates from all sources, which becomes much below the minimum reference level (45% of total calories) set by the reference intake levels. of nutrients (LARN) defined by the Italian Society of Human Nutrition. This pushes the person who follows this regime to an often excessive search for foods with a higher protein content than normal, as in the case of the doughs used for the preparation of sweet and savory foods.
However, it is good to remember that only in special cases (such as professional athletes) is a protein supplement required. In all other cases, the normal daily diet consisting of traditional products can easily satisfy the daily protein requirement, which is equal to 12-15% of the total calories of the day.
Cereals are not only sources of carbohydrates but already have a good percentage of protein in them. This quantity, combined with the proteins deriving from the protein sources of the main meals (meat, fish, eggs, cheeses, legumes) and from other sources such as dairy products, is more often than not sufficient. On the contrary, excessive consumption of proteins can become harmful to the body. Protein doughs must, therefore, always be included within a balanced and balanced food plan to avoid negative effects.
In any case, their consumption today is linked more to personal choices than to scientific evidence that demonstrates their real need. It has been noted that very often it is the impact of the media and commercial advertising of a product that makes it perceive as necessary, even when it is not at all.
Italian Society of Human Nutrition (SINU). LARN Tables 2014
Council for Agricultural Research and Analysis of the Agricultural Economy (CREA).Guidelines for healthy eating 2018
Council for Agricultural Research and Analysis of the Agricultural Economy (CREA). Food composition tables