Gluten, its definition and origin
The history of gluten
In France and elsewhere, ‘gluten is a natural and historic component of our diet’.
Gluten comes from the classical Latin and means ‘glue, glue, gum’. After hydration, gluten is formed from plant proteins that are naturally present in cereals such as soft wheat, durum wheat, rye and spelt. Gluten is also present in barley, certain types of oats, kamut and malt. Find out more about gluten-based products here.
Gluten has been a dietary threat for some of us for centuries.
In fact, as early as 250 AD, the Greek physician Aretaeus of Cappadocia noted and described symptoms of malabsorption in some human beings after eating products containing gluten. This Greek physician called this inconvenience ‘koiliakos’, from the Greek word for ‘abdomen’, koelia. Since then, the amount of gluten, and wheat in particular, in our diet has only increased. Until the Middle Ages, the type of cereals that people grew contained a much smaller amount of gluten than we use today.
It wasn’t until 1856 that Francis Adams translated these pains using the term ‘cœliac’ or ‘celiac’. Then, in 1908, Carnegie Brown published the very first book to describe and explain coeliac disease.
This disease causes atrophy of the intestinal villi, which, according to the AFDIAG, means ‘destruction of the folds of the mucosa and connective tissue of the small intestine’. The only known cure for this disease is to completely eliminate gluten from the diet.
Gluten, its components and their impact on products
A more technical section: everything you need to know about gluten
Gluten is a sticky substance made up mainly of two proteins known as prolamins and glutenin. These are storage proteins that fall into different categories depending on the product/food used. Prolamins and glutenins are stored in the starch of various cereals.
Gluten proteins are prolamins because of the large number of glutamine and proline amino acid residues (a non-essential amino acid which is part of the composition of proteins) present in their primary structures. Prolamins are the main storage proteins in cereals. They differ from one gluten cereal to another.
The prolamine in wheat is gliadin, which is generally perceived as a protein in its own right. When w-5 gliadin meets glutenins, this creates gluten. Wheat w-5 gliadin has been shown to be the major gluten allergen, including wheat-dependent exercise-induced anaphylaxis.
Prolamine genes are present in the A, B and D genomes of wheat. As a result, the prolamin fractions are made up of more individual components in wheat than in barley and rye, for example.
Wheat prolamins are the most commonly identified gluten proteins: they are generally separated into two groups: the alcohol-soluble fraction known as ‘gliadins’ and the insoluble ‘glutenins’. Wieser H also demonstrated that gliadins contribute to the cohesion and extensibility of gluten, while glutenins play a role in maintaining the elasticity and resistance of gluten.
According to a study carried out in 2020 by Ross Albert B. et al, between 80% and 85% of bread-making wheat proteins are gluten, which determines the viscoelastic properties of the dough.
In barley, the main storage proteins are hordeins. These proteins, like gliadins, are alcohol-soluble prolamins, and are rich in glutamine and proline residues. However, they are low in charged amino acids. Their characteristics are very similar to those of wheat proteins.
The prolamins in rye are secalins, and those in oats are avenins. However, oats are different from other cereals in that their proline content is lower.
As confirmed by researcher Steven L. Kaplan in 2015, all these proteins enable the dough to rise. Gluten, in other words, gives elasticity to the dough, making it soft and tender. Wheat-based recipes get their chew from gluten, which forms when flour interacts with water. Gluten-free flours, on the other hand, are based on the starch of alternative cereals. When these substitutes are mixed with water, their structure and elasticity are different.
Research carried out during my final dissertation in July 2020.
Chloé