In recent years, there has been a growing awareness of the importance of consuming wholemeal products. And companies have taken on the challenge of producing higher-quality wholemeal products. In this post, we’ll analyse wholemeal flours, how to produce them, assess their quality, and explore the possibilities available to millers and manufacturers of wholemeal products. In a subsequent post, we’ll discuss the advantages of wholemeal products and how we can improve the quality of bread and other wholemeal products.

Wholemeal Flour

The first issue with wholemeal products is their definition. The reality is that each country tends to have a different definition of these products, and although they may be similar, they’re not always the same. Generally, the definition of wholemeal flour tends to coincide in most countries, but that of bread or other products is more variable. In the case of Spain, the regulations related to flours were updated in 2016, and in 2019 those related to bakery products. Nowadays, it’s clear that wholemeal flour is one that contains all components or parts of the grain. That is, it should contain both the endosperm (the central part from which white flour is obtained) and the bran and germ.

As most of you know, industrial flour production is based on the production of white or refined flours. In this process, the bran and germ are removed as thoroughly as possible. Since the production of wholemeal flours is very minor, milling designs are not usually modified to obtain wholemeal flours; instead, all fractions obtained in the milling process (including passes of white flour, bran, and germ) are mixed. It’s important to note that, in a milling process, for every 100 kg of wheat that enters, only about 75 kg of white flour is obtained. Therefore, to obtain wholemeal flour, it’s necessary to mix that 25% that is separated in the process, neither more nor less. Before the regulation change, in Spain, it was common to sell flour as wholemeal when bran or part of it was added, and the germ was not added. This was done because the germ contains a significant proportion of oil, and the shelf life of flours with germ (if not treated beforehand) was shorter due to possible rancidity. It was also common to mix only one type of bran, more or less coarse, depending on the client’s interests. In the milling process, different brans are obtained separately, from the coarsest (outer layer) to finer products, such as third and fourth brans. These brans, besides differing in particle size, also differ in composition since they come from different parts of the grain. Therefore, to obtain wholemeal flour, we cannot add only one of these types; instead, we must mix all types in the exact proportions obtained during milling.

It’s also possible, although less frequent, to produce wholemeal flours directly using other milling systems, such as stone mills. In these cases, to obtain a fine flour, it’s necessary to adjust the stones well. The final flours have a bran somewhat finer than usual in wholemeal flours obtained with roller mills. On the other hand, since a progressive milling is not carried out, it’s possible that the level of damaged starch in flours obtained by stone mill is higher, or their particle size somewhat larger. Some manufacturers are fond of flours obtained with this type of mill, and obviously, they lead to final products with differentiated characteristics. However, they usually have a higher cost, and their influence on the final product must be evaluated case by case.

What is generally accepted in the production of wholemeal flours is the removal of the outermost parts of the grain. This removal is usually done by friction in the grain cleaning process. In addition to removing adhered dirt (dust or mud), it also reduces problems with the presence of mycotoxins or residues of chemicals, which tend to accumulate in the outermost part. But the part of the grain that can be removed is limited to percentages around 2%. It should be noted that the grain is in contact with the environment, and therefore with moisture, dirt, products sprayed on the plant, etc. Thus, if there is any kind of microbial development, it usually occurs on the outer part of the grain and could leave mycotoxins on it. This problem is not common in Spain, in the case of wheat, due to the usual climatic conditions. But it can be in other countries or with other types of grains. Likewise, pesticides or other external substances would not penetrate the grain, but they could accumulate on the outer part. The presence of these substances depends a lot on the country of origin, the climatic conditions, and the allowed practices. The abrasive treatment of the grain also reduces the presence of lipases, enzymes that promote rancidity and concentrate on the outer parts, and therefore helps to improve the shelf life of the flour.

Quality Control of Wholemeal Flours

Quality control in mills is entirely focused on white flours, and mostly on protein quality, and its use for bakery and other products where the gluten network develops. However, the composition of the bran and its particle size can greatly influence the quality of these flours. Also, other parameters, such as their friability or even their colour. Therefore, in the case of evaluating the quality of wholemeal flours, we cannot rely solely on the quality of white flour, to which external parts are subsequently added.

Obviously, rapid analyses such as moisture or protein content can help us make a first screening or have a first idea. In the case of using NIR to perform these analyses, it’s necessary to know that calibrations for white flours are not useful for wholemeal flours, and we must perform a specific calibration. In the case of wholemeal flours, the presence of enzymes, which is usually more abundant than in the case of white flours, is very important. Therefore, the analysis of the falling number index, and some test that gives us an idea of possible proteolytic degradation, such as a extensogram with different resting times, can be very interesting. Particle size analysis is also a factor that can greatly influence the quality of flours and the consumer’s perception of the products obtained. In the case of wholemeal flours, the particle size of the bran will be especially important. Regarding the analysis of flour functionality, it’s possible to perform a farinogram, or similar analyses like those obtained with Chopin’s mixolab. But it’s not possible to obtain an alveogram with wholemeal flour. Or, rather, to obtain it, it’s necessary to modify the flour and introduce into the equipment a flour that is not the same as the one we are going to market, so this analysis is a bit “tricked,” and can give us misleading information. In the case of the farinogram, some caution is also required, as it’s possible to obtain somewhat anomalous curves, with two peaks. In these cases, the second peak should be considered, as the first one is usually related to the water absorption of the fibres, and the second one with the gluten development. In recent years, the analysis of these types of flours using the glutopeak has also been promoted due to the speed of this analysis. The reality is that, although all these analyses can be carried out, further study of their relationship with bread quality or for other types of processing is necessary. Some significant clients may also request analysis of mycotoxins and pesticides, depending on the intended use of such flours.

One of the issues with wholemeal flours, when it comes to preventing fraud, is that there is no analysis that guarantees that a flour is truly wholemeal. While it is true that this type of flour should have a minimum fibre content, this could be “rigged” by adding insoluble fibres, such as cellulose. The concentration of certain bioactive components or minerals should also be higher, but these could also be added. At present, at least in Spain, there are no specific analyses that this type of flour must comply with.

Permitted Practices

Although wholemeal flours must contain all parts of the grain, these can be modified in several ways. Thus, the miller can re-mill the bran to obtain a finer bran, which gives the final flour other properties. It is important to note that only the fine bran obtained in the milling process cannot be mixed alone (all obtained must be mixed), but the coarse or the entire bran to be added can be milled. The properties of the flour change significantly with this process but must be studied case by case. In some products, very fine bran gives a more pronounced feeling of dryness due to its greater water absorption capacity. In others, consumers like to find small pieces of visible bran. In general, this must be studied case by case.

We can also subject the bran, or the germ, or the grain before milling, to a thermal, dry, or wet treatment. This thermal treatment must be milder and affect only the outer layers of the grain if carried out on it since thermal treatments denature proteins and negatively affect the bread quality of gluten, in general. If the thermal treatment is carried out only on the bran or germ, it can be more intense. The main objective of these treatments is to reduce the enzymatic activity of the flours, and therefore the risk of rancidity or possible degradation of components during processing. It can also help reduce microbial load, but at least in Spain and in the case of wheat, this is usually not a problem. Finally, thermal treatments help to modify the flavour and aroma of the flour components, which can improve its organoleptic quality depending on the product in which they are incorporated. And we must not forget that, along with the bran, there is a small part of starch that will also receive this treatment. In the case of a hydrothermal treatment, we can pregelatinize that starch, greatly increasing the water absorption capacity of the flours.

Another possibility, somewhat more complex, is to ferment the bran. This method has been proposed both to improve the nutritional quality of bread and to improve its volume and texture. For this, we must moisten them and let certain microorganisms act. Factors such as temperature, type of microorganisms, or the duration of this process will influence the final result. Something similar can be achieved if we use sourdough when baking, but in this case, the action is on the entire flour, and therefore some conditions that could be interesting to modify the bran, and not so much for the rest of the flour, cannot be used.

Genetics

In general, when producing white flours, wheat varieties that provide good bread quality are sought. Therefore, we usually focus their selection and improvement on protein content and quality, fundamentally. However, genetics also determine the colour of wheat. Thus, there are varieties of lighter and darker colour. In fact, Americans differentiate white wheats (lighter) from red wheats (darker). In the case of wheats intended for the production of wholemeal flours, the same conditions (protein and bread quality) as in the rest cannot be neglected. But it would also be good to consider the colour of the wheats. Lighter wheats generate bran with less content of bitter substances, and therefore more pleasant for the consumer. Although it must also be said that darker ones contain a greater amount of antioxidant substances and are somewhat better nutritionally. But excessively whitish bran may raise doubts in consumers about whether the product is truly wholemeal. In any case, some regularity in these aspects can be good for generating more homogeneous flours.

Genetics can also influence the content of vitamins and minerals in whole grains and flours, but this is more difficult to control and convey to the consumer, so it is not usually taken into account.

Controversy

In recent years, there has been controversy in Spain regarding who should produce wholemeal flours. Should it be the flour millers, or can it be done by manufacturers of wholemeal products? In most cases, I believe it makes logical sense for flour millers to produce them, as they are familiar with their processes, know the quantities of bran (and its types), and germ that are generated. They are also the ones most capable of “reconstructing” the flours, including all parts of the grain. For the manufacturers of wholemeal products to do it themselves, they would need to receive all fractions separately, a more complex process for the flour miller, and store them separately (more complex for the manufacturer) and mix them exactly in the proportions indicated by the flour miller. Overall, it’s a much more complex system with no clear improvement. In these cases, having the manufacturer of bread or other wholemeal products produce them doesn’t seem to instil much confidence, and I believe it can only lead to a small degree of fraud by not achieving the correct mixture.

However, as we have discussed, it’s possible to modify bran using certain techniques, and this can be part of the baker’s secret. In these cases, it’s logical for the bread or other product manufacturer to prefer receiving the different components of the wholemeal flour separately, so they can modify them to their liking and not give away certain know-how to the flour miller. Overall, it’s a complex issue, as these modifications are not usually common.

To further expand your knowledge about wholemeal flours, I encourage you to consult the bibliographic review we published in 2020.

Bravo-Nuñez, A., Gutkosky, L.C., Gómez, M. (2020) Understanding whole wheat flour and its effect in breads. A review. Comprehensive Reviews in Food Science and Food Safety, 19:3241-3265. DOI: 10.1111/1541-4337.12625