How wheat milling is made?

The wheat grain

To understand how flour is extracted, it is necessary to understand the wheat grain itself and its layers a little more in depth.

In the image below it is possible to notice all the layers of the wheat grain, the husk is subdivided into several sublayers reaching up to the aleurone, the husk being the main responsible for the bran extracted from the grinding, which together with the residue makes up 21-22% of the final fractions.

We also see the endosperm wich is the responsible for wheat flour, the white endosperm is rich in starch and proteins, the germ is the fattiest part of the grain, the extraction of flour varies depending on the operation but is generally made up of 78-79% of the final fractions of special and common flour.

In the grain we also have the pigment, which, like the smallest fragments of the shell, is the main factor in the increase in the ash content of the flour, directly affecting its color.

Now that we know that the endosperm is mainly responsible for wheat flour, we can analyze the process for forming the final product.

In a wheat mill, even if it is small, there is a large amount of diverse equipments installed, so a more succinct approach is needed, divided into smaller subsystems, which will facilitate understanding and explanation.

We can divide the general process into:

• Reception, pre-cleaning, feeding and storage of dirty wheat
• First cleaning, storage of moist wheat
• Dosage and second cleaning
• Grinding, control and weighing
• Transport, storage and extraction of flour
• Bagging and bulk loading of flour and bran

Reception, pre-cleaning, feeding and storage of dirty wheat

The reception of wheat has a variety of mechanical transport possibilities, including variations of bucket elevators, redlers and screw conveyors, then continues with pre-cleaning with a suction channel and filtering system to clean the grain as soon as it is unloaded from the truck and before storing it in the silos, we thus achieve better quality of the stored wheat over time, as the coarsest impurities are eliminated.

The wheat, which is still dirty, as only the largest impurities have been removed, is then sent to internal metal silos for the first cleaning.

First cleaning and storage of moist wheat

The first cleaning section removes contaminants such as impurities, seeds, stones, mycotoxins present in wheat husks and metals through the use of the cleaning machine, stone separator, polisher, suction channel, magnetic separator and aspiration system.

The light wheat fraction must be classified in the trieur or optical selector to guarantee a higher final quality of the product, eliminating oat grains, malformations and other cereals with shapes different from wheat.

After cleaning, the wheat needs to reach an exact moisture level before its griding, to guarantee maximum extraction and minimum ash content, then it is sent to the intensive dampener that controls the grain's moisture through the automatic damping system by automatically adding water to the grain, this is a high-precision electronic measuring device. As this is a very important stage in the process, as it determines the final quality of the ground product, our equipment was developed and improved in order to achieve high efficiency in this phase of the grinding process.

After humidifying the wheat, it will be stored in silos, where they remain for a while to homogenize the moisture in the grain. Just like dirty wheat silos, these silos have a system of multiple exits in their lower part that allows homogeneous extraction of the grain, ensuring that all grains have the same resting time.

Dosage and second cleaning

For dosing, it is recommended to use ponderal flow measurers when there is a need to mix different types of wheat.

The second cleaning section takes place through the scourer with a aspiration channel, this equipment removes even more impurities on the surface of the grain that were not removed by the polisher and other substances that are harmful, such as mycotoxins remaining from the first cleaning.

After cleaning equipment, the product will pass through a magnetic separator and a weighing scale for production control.

Grinding, control and weighing

In the griding section, the endosperm is separated from the husk to process the wheat into flour. After the roller mills, there are plansifters that separate the ground parts, sending the flour to a triple or double screw conveyor that takes the flour to the storage silos and the remaining of the grinding returns to the roller mills for the next break.

The vertical vibrating turbo sifters beat the bran to remove the last particles of flour before sending the bran to the storage silos and the sassors purify the semolina and send it back to the griding process, increasing the quality of the separation process. After extracting the flour, it goes through infestation destroyers and production control scales again.
 

Thunderoll Roller Mill The thunderoll roller mill is the perfect combination of quality and efficiency, it was designed for continuous and consistent operation for grain grinding.
Plansifter Grandsifter The plansichter is a machine that plays an important role in the flour production process, it provides a large sifting area in a limited space. The sieving process is done according to the grinding diagram.
Sassor The purifine purifier is used to clean and classify semolina after grain breaking in wheat griding diagrams.

Transport, storage and extraction of flour

The ground products are stored in different silos according to their purpose and the type of flour. During extraction they can be blended through a mixing system with electronic scales and mixer where it is possible to add micro ingredients such as vitamins or also move on to more complex pre-mixing systems for breads, cakes and other mixtures, we also have all the technology necessary to add value to the final product.

Bagging and bulk loading of flour and bran

Once the grinding and mixing processes are complete, the final product is ready for the end consumer, and can be bagged through the options of semi-automatic bagging machines for open-mouth, valved and big-bag bags and bulk loading systems, all evaluated according to the need of each operation.

It is possible to note that the wheat griding process is long and involves several variables, many technical aspects are too long for a brief explanation, so it is necessary to evaluate your demands together so that we can more assertively assist your needs.

Take the first step

We owe a lot to the mills for being part of the chain of our favorite foods, if you want to know more or get help and advice to make your work easier, get in touch with our experts, let us design while you produce.

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