Gluten in Flour

Gluten is a vital component in flour, and it is critical in breadmaking. Different wheat varieties have various levels of gluten, which helps determine their characteristics and suitability for use in bread products, noodles, and pasta.

Some flours will have a high gluten content, but others will be gluten-free. Therefore, testing for gluten is an important part of the science of baking.

What is Gluten?

Gluten is a network of protein molecules that provide stretch and spring to food products that use flour, such as bread, noodles, and pasta.

‘Flour’ is a generic term given to the powder formed from milling grains to a fine particle size. These grains are seeds made up of three parts:

∙      Bran

∙      Germ

∙      Endosperm.

Bran is the seed’s protective outer skin. The germ is the seed’s embryo. Endosperm is the germ’s starchy food supply. It is the endosperm that contains the native proteins that create gluten.

Two of these native proteins in wheat flour are:

∙      Glutenin

∙      Gliadin.

Different flours have different gluten forming potential, rather than actual gluten content, because gluten develops when you add water to flour.

Adding water initiates a chemical process and ultimately leads to gluten development.

When you grind wheat you destroy its seed structure, preventing germination. But the materials which would otherwise cause germination are still present in the flour. These enzymes will cause a series of chemical reactions once you add water to the flour.

This is what happens:

Starch molecules in the flour expand and glutenin protein molecules form long, curly chains that will bond with each other.

By mixing the combined flour and water, you encourage the creation of these bonds in the dough, giving it its spring-back elasticity.

But the other critical protein molecule, gliadin, acts to ensure you can shape this elasticity into workable shapes. Gliadin molecules retain their compact form even when water is added to them. This gives the dough another quality, extensibility – the ability to be stretched or stretched.

Consequently, it is the interaction of glutenin and gliadin that provides the conditions for gluten to be active in dough.

How Mixing and Proofing Help Gluten Develop

The basic goal of mixing is to hydrate the flour. While you can develop gluten in flour without mixing, it will ensure that you are dispersing water throughout the flour evenly. Mixing speeds up the hydration process, encouraging the formation of gluten.

Hydration encourages the glutenin and gliadin proteins to start binding together to form gluten.

However, although hydration is rapid, knitting the gluten proteins together to form a robust network does take time.

During mixing, and as the ingredients transform into dough, the protein chains grow in both number and length and create a kind of web.

This gluten network continues to strengthen during mixing until the dough is ready for proofing.

During proofing, while the dough rests, the enzymes continue to react, and the yeast starts to ferment. More molecules stick together, lengthening the gluten chains further still.

In bulk fermentation processes, bakers will fold dough to help the gluten strands align, helping the dough to expand.

When the gluten network has strengthened sufficiently, you can shape the dough. During this process of stretching, dividing, and shaping, the gluten strands will tighten and regroup themselves.

How Much Gluten is There in Flour?

Different flours will produce different amounts of gluten, depending on their gluten potential. The type of wheat grain used to make the flour, and, importantly, its protein content will determine gluten potential.

Broadly, there is hard wheat and soft wheat.

∙      Hard wheat has more protein and therefore produces flour with a higher gluten content

∙      Soft wheat has low protein and lower gluten content.

Millers can blend flours to achieve the gluten content they want for specific baking results.

∙      Soft wheat produces plain flour that is suitable for baking biscuits and pastries with a crumbly texture. This is also known as all-purpose flour. Typically, all-purpose flour has a gluten content of 8-11%.

∙      You can also get flour with an even lower gluten content of around 7% or 8%. This is cake flour, and it is ideal for baking lighter, more delicate cakes.

∙      Self-raising flour comes from a blend of hard and soft kinds of wheat. It already includes raising agents and has the same gluten levels as all-purpose flour.

At the other end of the scale are types of flour made from hard wheat varieties. These flours have a much higher gluten content.

∙      Bread flour or strong flour contains more gluten than other varieties, 12-14%, producing an elastic dough that traps more gas from yeast and produces lighter loaves. This strong flour is also used for baking pie crusts and pastries.

∙      There’s also gluten flour, made from hard wheat but with both bran and starch removed, and achieving a very high gluten content of between 75% and 80%. Typically, it is added to other flours to boost the gluten content of bread.

Some varieties of wheat do not have gluten-forming properties, including semolina. Baker's blend these with other wheat flours in various bread-making recipes.

Rye contains some gluten, but it is not the kind of gluten that forms a network. Grains such as rice and corn contain other proteins, rather than those that are gluten-producing.

Gluten-free flour is used in the production of various gluten-free products. With these flours, other ingredients need to provide elasticity and spring, instead of gluten.

Why Use Gluten-free Flour?

Some people have gluten intolerance - as many as one in 100 people in the UK have coeliac disease. This is an illness where the body’s immune system attacks its own tissues as a reaction to gluten.

Other people have wheat allergies and symptoms of gluten sensitivity.

Therefore, there is an ongoing demand for gluten-free products, including food baked with gluten-free flour.

This is a major reason why flour testing is a crucial part of baking and food production. But testing for gluten content is also critical for determining the characteristics of dough and, ultimately, the quality of finished products.

How Do You Test for Gluten in Flour?

The recognised global standard for testing gluten quality and quantity in flour is the Perten gluten index method. The index is the percentage of wet gluten remaining once you have forced it through a sieve using a centrifuge.

The gluten index defines whether the gluten quality in a sample is weak, normal, or strong. This allows for the classification of wheats with similar protein content, based on gluten values.

The Perten Glutomatic system tests flour, wheat, durum, and semolina for gluten content using the gluten index method.

This method is highly user-friendly, with easy sample preparation and only takes 10 minutes to complete a full test of each sample.

The calculation of results is fully automated and appears on the system’s touchscreen. The system also includes the Glutork 2000, which dries gluten completely for measuring dry gluten content and water binding.

This gluten-testing method supports various aspects of flour production and the baking supply chain, including:

∙      Grain trading and handling

∙      Flour milling

∙      Wheat breeding and classification

∙      Baking.

Gluten content influences a broad range of foodstuffs, from bread and baked goods to pasta.

Testing for gluten is also vital for specialist food manufacturers concerned with providing gluten-free products.

Using a standardised testing method, and one which is adaptable and suitable for different production sites enables fast, comprehensive quality control and quality assurance in flour production and application.

For more details about gluten testing, please contact Calibre Control.