What is Gluten Hydration?
Gluten hydration is the ability of gluten-forming proteins in flour to bind water to polar sites, establishing hydrophilic interactions between water molecules and side chains/surfaces of proteins.
Gluten provides better handling to the dough, and improved texture characteristics to the finished product. It’s at its best when there is enough water available to hydrate its polar sites, resulting in developed viscoelastic properties.
For optimal gluten hydration, there must be:
- Physical agitation via a mixing system to provide mechanical motion or work. This allows a direct contact between the flour particles and water
- Enough water to be absorbed by gluten and act as a plasticizer. Water bonds to hydrophillic sites in between protein chains, causing the structure of proteins to separate and allowing them to unfold.
How does gluten hydration work?
When wheat flour and water are mixed together, water hydrates the gluten-forming proteins gliadin and glutenin. Wheat flour particles are dense and hard in nature, and tend to resist penetration/diffusion of water. The mechanical action during mixing speeds up the diffusion process so the water molecules can migrate from the solution to the dry surface of the proteins.
When hydrated, gluten forms a viscoelastic mass that is responsible for the gas retaining properties of wheat dough (e.g., extensibility, elasticity and viscosity) and the springy texture of the final product. The ability of gluten proteins to hydrate directly affects their ability to function. Hydration depresses the glass transition of gluten and grants full mobility of protein chains at ambient temperatures.1
The development of gluten progresses from gluten lumps to gluten strands.2 The ability of gluten to hydrate affects how the dough transforms into an elastic material, and becomes functional. Inadequate gluten hydration not only takes a longer time to mix, but may negatively affect the volume of the product and create a short and crumbly texture.
Gluten hydration can be best obtained with aged flour in a sponge and dough or preferment system, with a long holding time (12-18 hours of bulk fermentation), or with high impact mixing technology.
A properly hydrated gluten network will:
- Allow the dough to be more extensible, stretchable and elastic
- Capture gas produced by yeast during fermentation and proofing
- Allow for a better sheeting and moulding of dough
- Improve cell structure of finished product, with more consistent shape and size
Control of gluten hydration
Mixing speed (energy input), mixing time, and dough temperature are factors that can be adjusted to control gluten hydration.
High intensity mixers (either in batch or continuous mode) can also be an option to modify and control gluten hydration. Such mechanisms quickly disperse and incorporate water by creating intense particle contact, thus increasing the hydration level of a dough.
- Cuq, Bernard, Joel Abecassis, and Stephanie Guilbert. “State Diagrams to Help Describe Wheat Bread Processing.” International Journal of Food Science and Technology 38.7 (2003), pp. 759–66.
- Auger, Fredric, Marie-Helene Morel, Jacques Lefebvre, Muriel Dewilde, and Andreas Redl. “A Parametric and Microstructural Study of the Formation of Gluten Network in Mixed Flour-water Batter.” Journal of Cereal Science 48.2 (2008), pp. 49–58.