Fibres belong to the group of carbohydrates, but they are not assimilated as easily by the body. They are present in plant products, and their consumption has been associated with numerous nutritional benefits. For this reason, there is great interest in enriching baked goods, such as bread, with fibres. However, it is important to know what nutritional advantages they offer, what regulations govern these enrichments, and how fibres influence processes.

The topic of fibres is very complex, so in this entry, I have included many links so that readers can expand their knowledge on specific aspects if they are interested. I have tried to make the articles openly accessible, but it is not always possible. Due to the complexity of the topic, in the future, I will include specific entries about certain types of fibres or specific aspects of fibres. Therefore, this entry is more introductory than anything else, serving as a summary, clarifying some basic aspects.

Nutritional Benefits

A consumption of fibre between 20 and 35 grams per person per day is recommended, with ideally 5-10 grams of these being soluble fibre. However, generally, the consumption of fibre by the population is lower than these levels, although it depends greatly on countries and population groups. Increased fibre intake has been associated with a lower risk of contracting certain types of cancer, such as colon cancer, cardiovascular diseases, constipation, and obesity, among other ailments. In this regard, it is important to know that not all fibres have the same effect on different diseases, something that could be taken into account depending on the product being developed. Thus, fibres like inulin have a recognized prebiotic effect greater than others, beta-glucans or psyllium have a greater capacity to reduce cholesterol and the risk of cardiovascular diseases than other fibres, and wheat bran and psyllium fibres have a greater anti-constipation effect than other fibres. Even within the same type of fibre, aspects such as its molecular weight can influence these effects. Thus, for example, within beta-glucans, those with larger size or molecular weight have a greater beneficial effect on cholesterol and the reduction of cardiovascular diseases than those with smaller size. For this reason, oat beta-glucans are somewhat more beneficial than barley beta-glucans, and it is important to control the possible enzymatic hydrolysis of these beta-glucans (by the action of beta-glucanases) in processes. The purpose of this post is not to delve into these details, but they must be taken into account when developing a product with a specific nutritional purpose.

To delve further into the nutritional benefits of increased fibre consumption, you can refer to these articles (A and B). But I believe that the most significant aspect of increased fibre consumption can be found in this article, where those nutritional aspects that can most help reduce population mortality are detailed, or those practices that increase the risk of mortality. In addition to excessive sodium consumption, several of society’s major problems focus on the lower consumption of products with a high fibre content, such as whole grains, fruits and vegetables, and nuts and seeds. And while increased fibre consumption is less effective in reducing mortality than increased consumption of these products, it does have a clear effect on reducing mortality. In this other study, it is seen how, speaking only of carbohydrates, the increase in the percentage of fibre is one of the most effective positive health changes, much more clearly than the reduction of the glycaemic index.

Legislation

European legislation aims to promote increased fibre consumption and support products that contain appreciable amounts of this component. To this end, in Europe, it is allowed to include on the label a message stating that a product is a source of fibre “if the product contains at least 3 grams of fibre per 100 grams or, at least, 1.5 grams of fibre per 100 kcal.” On the other hand, it can be indicated that it has a high fibre content “if the product contains at least 6 grams of fibre per 100 grams or 3 grams of fibre per 100 kcal.” There are also approved health claims in various countries for the consumption of certain types of fibres. Specifically, in Europe, claims are approved for resistant starch, arabinoxylans produced from wheat endosperm, beta-glucans, rye fibre, wheat bran fibre, oat or barley grain fibre, glucomannans from konjac gum, guar gum, hydroxypropyl methyl cellulose, and pectins. In general, these claims refer to the reduction of glucose content in blood, maintenance of cholesterol levels, and the functioning of intestinal transit or stool volume. To include them, certain requirements must be taken into account. In other countries, there may be different legislation. The fibre content also helps to improve the score according to the Nutri-score code. In general, if a product receives a low score when considering the presence of sodium, simple sugars, saturated fats, and calories, more points can be deducted (something that improves the classification) based on the content of fibre and proteins.

Analysis

This is a very crucial point that many people are unaware of, and it is linked to the definition of fibre. Dietary fibre can be defined as the edible part of plants that resists digestion and absorption in the human small intestine and undergoes partial or total fermentation in the large intestine. Within this definition, many types of fibres are included, such as celluloses and their derivatives, hemicelluloses, resistant starch, inulin and polydextroses, pectins, gums, mucilages, and some other components. The issue is that some of the most commonly used methods for measuring dietary fibre do not include some of these compounds, such as inulin. The aim of this entry is not to discuss the analysis of dietary fibre, which would require a separate entry, but I do believe it is necessary to highlight that depending on the type of fibre a product contains and the analysis method used, we may encounter surprises. If you wish to delve deeper into these topics, you can do so in thisliterature review. It is also possible to differentiate between soluble and insoluble fibre, and both can be measured separately.

Influence on Processes and Final Product

This is the central part of this entry. The truth is that it is impossible to speak of a single functionality of different fibres, and fortunately, we have a multitude of fibres with very diverse properties. Therefore, we can incorporate different fibres to increase the fibre content of a product according to various needs. For example, if we want to incorporate a fibre that has little influence on the rheology of doughs and on the characteristics of the final product, we can resort to soluble fibres with little thickening power, such as polydextrose, oligofructose, or resistant starch. Similarly, if we want to increase the consistency of doughs, we should resort to fibres with high water absorption capacity and thickening power, such as beta-glucans, psyllium, or some gums (xanthan or guar, for example). In general, insoluble fibres like cellulose have a greater water retention capacity than flour, and if we replace flour with these fibres, we will observe that the dough is more consistent and hard, so we will need more hydration. This effect will be increased if we add fibres with a high water retention capacity, such as psyllium or xanthan, and the effect will be the opposite if we replace flour with a fibre with little thickening capacity. Therefore, it is necessary to study in each case, when reformulating, whether we should replace the flour or add additional fibre, and whether we should adjust the dough hydration.

If we want to reach very high levels of fibre, it can be very interesting to resort to blends of fibres with opposing effects. Thus, a mixture of cellulose (greater thickening power than flour) with a soluble fibre with little thickening power can be an alternative to maintain the consistency of doughs.

The fact that a fibre has a high water retention capacity when cold does not guarantee that after heating, it will maintain this water retention capacity. This is important if we want the fibre to help us retain water in the final product, improving the juiciness of the products or their shelf life. Although if the level of water retention is very high, we can go from products that tend to harden and dry out, to very juicy products but with a tendency to microbial development.

We also have fibres with special properties capable of gelling when cooled, such as pectins, carrageenans, or agar, for example. This type of fibre or gums are usually used in the production of dairy desserts, gels, or jams, for example. But in general, they are used in small percentages, more for their functionality than to achieve products with a high fibre content. In bread doughs or cake batters, they usually do not have much utility since those types of textures are not sought.

To further complicate matters, it must be said that within the different fibres, we can find very different properties depending on small changes in their composition. For example, oligofructoses present very different properties depending on the degree of polymerization or particle size. Suppliers know this and offer different types with different functionalities. Celluloses also have different properties depending on their shape and size, something that depends on their origin and the extraction process. The most well-known, such as those from wheat or oats, are usually elongated, but there are also rounded ones. And in the case of being elongated, the size of the fibre can be decisive in its application to a specific product. Similarly, there are different types of pectins, carrageenans, or hydroxypropyl methylcelluloses, among others.

In conclusion, there is some bad news, and that is that fibre enrichment is complex, requiring detailed study, and depends on the product we want to enrich and the type or types of fibre to be used. But there is also some very good news, and that is that we have a multitude of fibres available to adapt to our needs.

As you can see, the topic of fibres is very complex, and on the blog, we will have specific entries to discuss some of them or specific aspects.