Gluten's role in bread baking performance

Gluten composition

Gluten strength is an important factor in bread baking performance. It contributes to the ability of dough to rise and maintain its shape as it is baked.

There are several types of proteins that make up the total protein content in cereal crops, one of which is gluten. Gluten is a protein composite that accounts for 75 to 85% of the total protein content in bread wheat. Gluten component proteins are found in the endosperm of mature wheat grain, where they form a continuous framework around the starch granules.

Gluten is comprised of two protein groups: glutenin and gliadin. Glutenin contributes to the elastic character of gluten while gliadin contributes to extensibility. A balance between elasticity and extensibility is necessary for superior baking performance.

Gluten functionality in bread making

Gluten proteins are the most important protein group in bread making. Gluten forms when water is added to flour and is mixed. During mixing, a continuous network of protein forms, giving the dough its strength and elasticity. By holding gas produced during fermentation, the protein network allows bread to rise. It also allows the dough to maintain its shape. These two functions of the protein network are what give bread its chewy texture.

Hearth bread - right stronger gluten protein composition than left.
Hearth bread made from wheat differing in gluten strength. The loaf on the right indicates a stronger gluten protein composition than the loaf on the left.

Factors affecting gluten performance

There are several factors that can affect gluten performance.

Gluten strength is different in all varieties of wheat. The differences are caused by the unique number and combination of glutenin and gliadin polypeptides in each wheat variety, resulting in varieties with slightly better gluten strength than others. Bread that is baked using a “better” quality variety may have a higher loaf volume than bread baked with a “lesser” variety, even when both varieties have the same protein content.

Environmental conditions during the growing season can also have a large impact on gluten strength. Excessive rainfall, especially early in kernel development and during grain filling, can have a negative impact on gluten strength. Likewise, heat stress or frost prior to full maturity can halt formation of gluten protein components, resulting in weak dough properties. Some varieties are affected more by environmental conditions than others.

New varieties of Canadian wheat intended for bread making undergo 3 years of rigorous testing for their agronomic performance, disease resistance and end-use quality performance prior to being registered. There is a range of acceptable gluten strength within each class of wheat, and all new varieties must fall within that range during the 3-year test period. Once registered, they can then be delivered and sold as milling quality wheat.

Front and side view of 2 loaves of bread, one that has more volume than the other.
Pan bread made from wheat with different gluten strength.

Predicting milling and baking performance

When millers and processors buy Canadian bread wheat, they have expectations about how that wheat will perform when it is milled and baked. Wheat is visually inspected for a number of grading factors, which predict how wheat will perform. The effects of these factors on milling and baking performance are known and predictable because of scientific study. Furthermore, because registered Canadian wheat varieties meet end-use quality performance criteria, visual assessment for physical damage is an effective means of classifying and grading wheat.

Did you know?

Like a number of technical issues, such as milling quality and sprouting, gluten strength is a regular topic of interest for millers and processors, as well as for marketers and buyers. The Canadian Grain Commission stays in contact with these groups and responds to and investigates concerns raised about end-use quality performance. Through scientific analysis of harvest and export quality, we monitor factors affecting the processing qualities of wheat. We also conduct research to understand factors affecting processing performance.

Definitions

Class
In respect of grain, means any variety or varieties of grain designated by order of the Commission as a class for the purposes of this Act.

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