Gluten Explained

The current trend in gluten-free products has highlighted one thing: many consumers do not have a clear idea of what gluten is. We sometimes forget that wheat gluten is, in particular, that which permits the production of crusty or crunchy, leavened products such as breads, brioches, and croissants-not so bad after all. [1]

Let's look at the basics: Gluten is a group of proteins that includes glutenins, gliadins, and various albumins and globulins (Figure 1). Let us look more closely at the first two.

• Glutenins are very large proteins that are very resistant to elongation. They are what give the dough its elasticity and tenacity.
• Gliadins, on the other hand, give the dough its viscosity and extensibility.

The balance between these two types of large proteins confers unique characteristics on wheat dough. What we're talking about is called viscoelasticity (viscous + elastic) properties.

And it is really important because, depending on the characteristics of the gluten, we can make different kinds of products better. For example, manufacturing biscuits requires flour that is not very tenacious but is fairly extensible (viscous), whereas manufacturing brioches requires dough with high tenacity that is also very extensible. A tool such as the Alveograph is particularly suitable for measuring the viscoelastic properties of gluten in dough.

One important point is that it is increasingly well-known that gluten has the ability to bind to other components of the dough, and that this influences its viscoelastic behaviour. For this reason, while tests performed on gluten alone are of interest (so as to know the potential of isolated gluten), tests carried out on dough are actually much closer to the actual use conditions of flour.

What is the purpose of gluten in bread making?

In baking, the characteristics of gluten strongly affect the quality of the final product by acting at various times during manufacture:

• First, during kneading.
• Gluten begins by absorbing water. Due to kneading, the parts of the gluten come together, stick to each other, and end up forming the dough. There are two important points here: enough water needs to be added to allow the gluten network to form; and if you don’t knead or knead badly, the network cannot form.
• Once the network is developed, and as the kneading continues, the dough is able to incorporate air as mini-bubbles. These air bubbles are the source of future alveoli in the bread. Without them, there can be no beautiful, well-structured crumb. The structure of the crumb is therefore dependent on the quality of the kneading--and the properties of the gluten.
  
• When shaping the product
• Once the dough is kneaded, it is divided into parts and these pieces of dough are shaped--flattened for flat breads, lengthened for baguettes, or rounded. How the dough is able to lengthen (viscosity, extensibility) to make the product the right size without retracting (elasticity) depends largely on the specific characteristics of the gluten.
  
• During fermentation
• At this point, the yeast contained in the dough produces carbon dioxide. First, this gas enters into solution and is dissolved in the dough. But at some point (saturation) it will come out of the dough in gaseous form and find refuge...in the mini bubbles formed during kneading. For the bread to rise and to form a beautiful crumb, the dough needs to retain that gas. Under pressure, therefore, alveoli are formed. The size and appearance of these alveoli depends on the ability of the gluten to deform (viscosity, extensibility...) while retaining its structure (elasticity).
  
• At the beginning of baking
• The beginning of baking is a stressful moment for the dough, which is suddenly moved from one environment at 30°C to another at 220°C. The thing is that gluten, as a protein, is denatured around 60°C. In addition, the temperature increase when the bread is put in the oven which causes the gases to expand. If the gluten is too weak, all that gas escapes and the bread won’t have volume. If it’s too tough, it won’t let the alveoli grow, and once again, the bread won't have volume. It is perhaps at this point during manufacture that the qualities of gluten are most important. And this is undoubtedly what makes it unique.

With such impact on the process and quality of the finished products, it is not surprising that gluten has been (and still is) studied so much. Every day, great effort is made to create new varieties with specially adapted gluten.

This magical protein remains the one thing that enables the production of cereal products with so many shapes, textures, and flavours. Gluten is also a very valuable source of protein for those who do not suffer from intolerance.

[1] This article does not deal with the diseases associated with intolerance or allergy to gluten that affect a portion of the population, prohibiting them from consuming products containing gluten.