Soft wheat: each step taken in the mill, from selection to cleaning

Soft wheat each step taken in the mill

Since we have made the craft of milling our profession, we know that many people tend to think that wheat is unique as a plant, and that the flour extracted from wheat is too of one type only.

With this in-depth analysis we intend to disprove this non sequitur, starting at the beginning of a typical day. At breakfast-time , do you prefer to start your day by dipping biscuits in your latte or with the classic cappuccino and a croissant?

Consider these confectionery products as the protagonists. The biscuit is flat with a compact structure; the croissant, on the other hand, is well risen with air pockets inside in which to house a shiny spoonful of jam. The question arises spontaneously: “from where do these very different forms originate?“.

Although we tend to think that they have the same origin, the biscuit and the croissant are made with types of flour produced from grain with completely different characteristics, as you can see in our recipes for wholemeal shortcrust pastry and pain au chocolat.

The selection of the raw materials: the role of the miller

The discursive tone of the initial lines served to introduce a topic which, in the daily life of the miller, is actually much more complex. The miller is responsible for selecting the specific grain which, on the one hand, will give the biscuit factory a flour with a low protein content, allowing it to obtain biscuits with a compact but crumbly texture, like our Sebòn Biscuits and Shortbread; on the other hand, to the croissant producer, a flour with specific strength values that will allow the creation of a well-developed and flaky product, like our Sebòn Croissant.

The chapter on the selection of raw materials is the first and most important in the book of milling, which despite having remained an ancient process conceptually, is today carried out with innovative machinery and in environments that follow the highest standards of health, safety and hygiene.

Milling is an ancient process, the flour produced by a mill must be the same as it always has been. There are, however, determining variables: the choice of raw materials and the sensitivity of the miller who looks after and regulates the machinery.

The selection of the wheat is one of the most challenging phases in our profession because it requires in-depth knowledge of the various types of wheat, their properties and characteristics. Each variety, in fact, has particular milling characteristics and these translate into different types of flour which, in turn, have different properties and uses (here is our guide on how to choose the best flour).

Returning to the introductory example, we can therefore:

  • obtain the most suitable flour for the production of biscuits only by grinding a low protein grain, with alveographic characteristics of modest strength and high extensibility;
  • obtain flour for croissants from grain with a high protein content and very high alveographic characteristics.

chicchi di grano tenero varietà selezione molino

Figure 1: On the left a soft wheat rich in protein, note the small, dark, elongated grains. On the right a soft wheat low in protein, note the lighter, stockier, bulkier grains.

chiccho di grano tenero sezione guida approfondimenti

Figure 2: On the left, the cross-section of a grain of soft wheat rich in protein, note the vitreous body. On the right, the cross-section of a grain of soft wheat low in protein, note the more floury body.


The origin of soft wheat: a much debated topic

Today the question of the origin of wheat among those in the food sector is the one that most involves public opinion. Considering the fact that Italian production is not sufficient for national needs. It is equally undeniable that grain that comes from other parts of the world, such as the rest of Europe and North America, have very different properties due to the differences in climate and the soil in which they are grown. It is the miller’s expertise that is the determining factor in enhancing its potential, where necessary.

We at Mulino Padano are particularly sensitive to the question of national home-grown wheat. In fact, as long ago as 2005, we were the first company in Italy to develop a project that aimed to produce a range of flours using only 100% Italian wheat and today our Scelte di Campo range has a certified supply chain. This is only possible because our mill is located right on the banks of the river Po, in the area that produces the best Italian soft wheats.

From delivery to grain cleaning

Having talked about the origin of the raw materials, let’s take a look at the grain’s journey through the mill, starting with the quality control and acceptance phases.

Step 1: the arrival of the grain at the mill

As soon as a delivery of soft wheat arrives at the mill, it is immediately subjected to two rigorous checks:

  • an initial olfactory investigation to exclude unsuitable odours
  • a visual inspection to evaluate the quantity of foreign bodies not eliminated by the combine harvester, such as straw, seeds of other cereals and dust.

Failure to pass this first control phase unquestionably leads to the rejection of the goods.

Step 2: the measurement of the specific weight of the grain

These initial evaluations are followed by the measurement of the specific weight of the grain, a judgment that determines the milling capacity of the cereal. This step is important: if the specific weight is below the reference value, it can lead to the rejection of the goods.

Step 3: analysis of the quality of the grain

Upon entry the quality of the grain is analyzed. In this phase we examine the protein content and other parameters, which must be directly proportional. If they correspond to the values typical to the variety, the acceptance phase of the wheat is considered complete.

analisi grano tenero accettazione molino

Figure 3: Some of the analysis carried out on wheat in the acceptance phase.

Step 4: ensiling and pre-cleaning of the grain

If the first 3 steps are passed, the cereal begins its journey towards ensilage by passing through a machine which, by screening and suction, carries out the pre-cleaning process, making the grain suitable for storage in silos.

In our mill, the entire receiving, unloading and ensiling phase of the grain is controlled and recorded by a cutting-edge, fully computerized traceability system, which allows the reconstruction of the entire production chain of a batch of flour.

Step 5: evaluation of rheological values

At this point, with a special laboratory mill, our analysts grind the samples taken from each separate accepted load of grain and, with the appropriate laboratory machinery (such as Chopin’s Alveograph, to mention only the most well-known), measure the rheological values that define the behavior of the flour during kneading and leavening.

Step 6: cleaning the grain

Now that all the characteristics of the silage grain are known, it is ready to be cleaned of any impurities. The first cleaning process is followed by a second, upon completion of which the batch of wheat enters the final processing phase, grinding by way of cylinders or stone.

The grain’s journey through the optical sorter

During the cleaning process the cereal is freed from any impurities with which it has coexisted since harvest by means of air suction, beating and sieving machines. These systems, although based on principles developed in the second half of the nineteenth century (when the milling industry experienced a major revolution with the introduction of counter-rotating cylinder grinding), are now cutting edge and feature differentiated speed systems, with oscillating table tumblers and semolina screening machines.

Innovation in the grain cleaning process has reached a turning point in recent years with the introduction of optical selection machines. These machines are capable of “photographing” each grain in the cereal flow and discarding those that are broken, shriveled or blackened.

How the optical sorter works

Up until the early 2000s, the cleaning areas of modern mills functioned more or less as they always had, identifying waste by the weight and size of the grain. In this way, foreign bodies that were lighter than a grain of wheat, such as a straw, was discarded, as were foreign bodies that were larger than the grain. Conventional cleaning, still commonly used in many mills today, is not able to discard any grain which, despite having the same size and weight as good grain, has chromatic defects. These defects not only compromise the aesthetics of the flour (with important repercussions on some types, such as fresh pasta flour), they can also lead to an increase in contaminants in the finished product because, often, chromatic variations in the grain are an indication of attacks by mold or fungi.

To defend ourselves from this threat, we have installed a cutting edge optical sorter in our mill, through which all the wheat grain passes twice before milling.

This machine distributes the grain in a homogeneous flow, illuminates it with special lamps and photographs it with high-resolution cameras. In this way, even the smallest anomaly is highlighted and the grain identified as “bad” is automatically discarded by a concentrated air flow. 

selezionatrice ottica grano tenero

Figure 4: The grain inside the optical sorter.

chicchi scartati selezionatrice ottica grano tenero

Figure 5: Soft wheat grains rejected by the optical sorter due to the presence of colour defects.

Let’s recap the steps of selecting and cleaning soft wheat

In a nutshell:

  • the choice of wheat varies according to the type of baked product you wish to obtain
  • rheological characteristics vary from grain to grain
  • depending on its origin, due to the different climates and soils in which it are grown, grain can have very different properties
  • from its arrival at the mill to its cleaning, the grain is subjected to rigorous controls aimed at eliminating impurities and verifying the correctness of the cereal’s characteristics
  • a crucial step, still not widespread in most mills, is the use of an optical sorter, which rejects grain that is unsuitable for grinding.

In a mill that is in step with the times, an apparently elementary natural product such as wheat is subjected to numerous, technologically advanced checks, all aimed at guaranteeing the maximum health value and food safety of the flour produced. The great attention that is paid to the wheat is motivated by the fact that it is the one and only ingredient in the flour. Making a wrong choice or not taking proper care of it would nullify the effort dedicated to all the subsequent processing phases.