Before I start, I must point out that this entry is based on the Spanish reality. But I believe that most of it is useful almost everywhere in the world.

The Objective

Flour users typically want it to work without worrying about much else. In some cases, larger companies may concern themselves with the quality parameters they need to control, as we have discussed in various entries on this blog. But we seldom think about the difficulties millers face in making good flour and the tools at their disposal to achieve this goal.

Flour mills usually produce various commercial flours that meet the needs of most of their customers. In general, these flours are distinguished by their protein content and strength, but other parameters can also be considered. For some large companies or special clients, specific custom flours can be developed based on their needs.

Perhaps the most important criterion for flour quality is consistency That is, if a customer needs flour with an alveographic strength of 250, they can likely work with one with a strength of 200, even if they must adapt. But it’s better if it’s always 200 rather than varying between 250 and 200 each time. Therefore, once the characteristics or quality parameters that a flour must meet are defined, achieving consistency becomes crucial, and this is possibly the most challenging part.

Regarding the protein quality of wheat and flour, in Spain, we are accustomed to working with alveographic parameters such as strength (W) or the balance (P/L) between tenacity (P) and extensibility (L). In other countries like Anglo-Saxon ones, quality measurement through farinographic analysis, considering dough absorption or stability during mixing, is more common. My recommendation is to consider both analyses to achieve greater consistency and reliability, although it is not always possible.

The Wheat

The first factor that millers deal with is the quality of the wheat. To obtain flour with a strength of 100, one must start with wheat with a strength of 100 (simplified to some extent). If you need to produce flours with different strengths, you must source different types of wheat. The protein content, hardness, and protein quality of wheat are determined by genetics and, therefore, by the variety. So, by buying wheat of a specific variety, you might have some confidence in obtaining a certain quality. However, it is often not that simple since marketed wheat is often a mixture of varieties, may not be the variety the seller claims it to be, and soil and climatic conditions also affect wheat quality. Agronomic practices such as fertilization, treatments, or harvest timing can also modify wheat quality.

With these considerations, millers must make a good purchase of wheat based on their needs, but they must also perform strict quality control when these wheats enter the mill. This quality control must consider aspects such as the presence of impurities, proteolytic degradation of wheat (caused by an attack of garrapatillo or other cereal bugs), or possible grain germination (analysed with the falling number index), which, if not meeting certain minimums, requires the batch to be rejected.

To obtain strong wheat, it is necessary for them to have a higher protein content, which is more costly because they have greater nutrient requirements from the soil than weak wheats. Thus, strong wheats usually have a lower agronomic yield than weak ones. Proper fertilization can help, but this also comes with a cost. Therefore, strong wheats tend to be more expensive, both due to their lower agronomic yield and the need for certain practices.

To achieve strong wheat at a lower cost, geneticists have strived to obtain greater strength with lower protein content, and hence higher yield. This is achieved by carefully selecting the type of proteins (protein bands in electrophoretic analysis) present in that wheat. Although this is possible, and stronger wheats with lower protein content can be obtained, it has led to an increase in the alveographic P/L value. In other words, these are stronger but less extensible wheats. Therefore, acquiring stronger wheats comes with a higher cost, and obtaining wheats with the same strength but lower P/L values is also more expensive.

Another factor that millers must consider is the hardness of wheat. Hard wheat is more energy-consuming to grind, and this process generates more damaged starch compared to soft wheat. In general, wheats with higher protein content and greater strength tend to be harder, and this needs to be managed within limits. However, it doesn’t make much sense to grind a weak and hard wheat to obtain quality flours. Nevertheless, excessively soft wheats can also cause problems because endosperm particles can tend to flake off. Some soft wheats, which are very extensible and thus highly valuable, may be too soft to be ground separately and need to be blended with slightly harder wheats to mill properly through the mill.

The Situation in Spain

Speaking of the situation in Spain, it must be mentioned that Spain is a wheat and cereal-deficient country, and we must import nearly half of the wheat we consume. Farmers face the dilemma of whether to go for low-quality but high-yield wheats or high-quality wheats (higher protein and strength) with lower yields. I should clarify that when I talk about high-quality wheats, I mean those for which a higher price is paid. We cannot speak of wheat or flour quality, as good flour for one product can be detrimental for another. For instance, we can talk about flour quality for biscuits or bread (it is different). But usually, we refer to high-quality wheats or flours as those with higher strength and, if possible, lower P/L values, as these are the most valued and best-paid.

It’s important to note that low-quality wheats always have a guaranteed price, which is what animal feed producers are willing to pay, and factors like strength or extensibility don’t affect them. However, high-quality wheats, although better paid, have a price determined by the international market, and this can be more variable depending on the availability of such wheats each year, making it less predictable. Moreover, any problems in the production of high-quality wheats that reduce their quality (pests, weather issues, etc.) automatically reduce what you’ll receive for that wheat, which has cost more to produce than if you had gone for low-quality wheat.

In my opinion, growing high-quality wheats is ultimately rewarding, but it requires a more professional farming mindset and long-term thinking. If a farmer wants to play it safe, thinks short-term, and avoids risks, it’s easier to opt for low-quality wheats intended for animal feed, which can sometimes be sold to a mill. This reality has resulted in a shortage of high-quality wheats in Spain.

Additionally, there isn’t much professionalism in warehouses that purchase this type of wheat and create larger lots (with some honourable exceptions), and in some cases, they mix wheats suitable for milling and use in mills with others that not only have problems but also extend these problems to the entire batch. This is because, in many cases, they are intended for animal feed. All of this poses significant problems for mills, which do not have access to quality wheats in Spain or homogeneous batches, something highly valued. In contrast, when looking for wheat imports, commercial companies tend to be more professional, at least when it comes to wheats intended for human consumption, and they guarantee the quality and homogeneity of large lots.

Reception, Classification, and Blending

So, once a mill has identified the wheats, it has conducted preliminary analyses in some cases, and decided to purchase them, they must receive them. During the reception, representative samples of the whole lot must be taken and reanalysed (unfortunately, the received wheat does not always match what was previously analysed), although this depends on the relationship with the supplier. It’s important to keep in mind that wheat strength can vary between alveographic values of 80 and 400, in most cases. And we cannot store wheat with different strengths in a single silo, as this would mean missing the opportunity to produce specific flours. Therefore, a good mill will perform as complete an analysis as possible of the received wheats and separate them by quality to the best of their ability, which is related to the number of wheat silos available.

Even with good classification, in the same silo, there will be wheats of different qualities. These differences will be much smaller the more wheat silos the mill has, but achieving total homogeneity is impossible. Thus, to obtain flour with a specific strength, it is usually not advisable to grind wheat from a single silo but to mix them, minimizing possible differences. To understand this, if we have a silo with wheats close to a strength of 200, another with values close to 100, and another with values close to 300, it would be more effective to mix them in equal proportions from all three silos to obtain flour with a strength of 200. This is because each silo has different stratified samples, and it would be a coincidence for lower or higher strength batches to match in all silos. Therefore, proper blending helps obtain flours closer to the desired quality. However, good mills do not produce commercial flours this way; instead, they produce standard flours that are distributed among flour silos. To make commercial flours, they usually remix standard flours to minimize these inevitable differences.

In summary, to obtain good flour, you need a good laboratory, spend a lot of time analysing the wheat (and flour), have many wheat silos for proper classification and separation, and also have a large number of flour silos to have numerous standard flours available and ensure proper wheat and flour blending.

Grinding Passes

During the grinding process, millers have few options to modify flour quality, but they must be careful not to spoil it with poor regulation of the mills and various equipment, which could lead to higher energy consumption or increased damaged starch content. It’s important to note that in modern milling processes, flour is gradually obtained, little by little. Thus, different proportions of the final flour are obtained as the process advances. This is referred to as grinding passes (or streams), and although they are all somewhat similar, there can be significant differences between them. A good miller understands the differences in aspects such as particle size, contamination with external parts of the grain, protein content, and others, among different grinding passes (or streams). A common factor in almost all processes is that the final grinding passes, both in the break and compression phases, tend to be more contaminated with external parts of the grain since we are pushing the grinding to its limits. These passes have a slightly darker colour, more ash content, more protein, and higher enzymatic content. These differences also translate into a higher P/L value. Therefore, if a customer wants whiter flours or flours with lower ash content or more extensible, the miller can separate these fractions. But, obviously, this comes with a cost.


Finally, millers can incorporate some type of additive or enzyme into the flour to modify its functionality. Regarding additives, in Spain, the use of monocalcium phosphate and ascorbic acid has been common. The latter is an additive with an oxidizing function, which increases the strength of doughs and their ability to retain gases produced during fermentation. However, almost all dough improvers incorporate ascorbic acid or another oxidizing product, so if the flour has gained strength using this product, it is possible that the dough improver may not show its full potential. As for phosphate, it is a chelating or ion-sequestering agent that minimizes the action of proteases injected by the “garrapatillo”. This pest is typical in Mediterranean countries and should not be a concern in other parts of the world. Many millers claim to use it not because they include wheats attacked by the “garrapatillo” but as a precaution (in case a batch of wheat with “garrapatillo” has not been detected). In any case, what a good miller should do is ensure that no wheat with this problem enters their facilities and refrain from using this additive. Therefore, as a customer, I recommend demanding unadditized flours, partly to force millers to work correctly and partly to achieve a complete improvement effect when doughs are subsequently treated with additives.

A special case is constituted by fortified flours, or flours enriched with certain nutrients, depending on the regulations of different countries.

However, millers can also incorporate enzymes into their flours. Enzymes do not need to be declared, or there is no legal obligation to do so. Nowadays, most of the additives used in baking can be replaced by enzymes. For instance, ascorbic acid can be substituted with glucose oxidase, and emulsifiers can be replaced by lipases. The fermentative capacity of a flour can also be improved by adding amylases or extensibility by including certain proteases or hemicellulases. In this case, a good relationship between flour seller and end-user is recommended to provide transparency regarding the use of enzymes in different flour batches, allowing purchase decisions to be made with all the information.

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