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What is Gluten & Gluten Replacer?

Gluten is the name of a protein matrix formed by 2 cereal flour’s proteins: Glutenin and Gliadin.  Glutenin has some effect on the elasticity of the dough. Gliadin affects the extensibility of the dough. For Gluten Matrix to be formed, glutenin and gliadin should be mixed with any water containing fluid and oxygen. This is done by mechanical action of mixing.

When flour is hydrated and continuously mixed, several chemical bonds (covalent disulfide, hydrogen, electrostatic, hydrophobic, Van Der Waals) are formed. All these chemical bonds are strong enough to hold high water content (up to %90 of flour weight) from dough state to baked product. Strongest and crucial chemical bond of a gluten matrix is disulfide bond between cysteine amino acids of glutenin and gliadin. Covalent disulfide bond is 7-16 times stronger than second strongest bond which is hydrogen or electrostatic. As the dough is mixed, sulfur ends of cysteine amino acids of glutenin and gliadin are continuously contacted to each other to form disulfide bonds. At the end of mixing, very strong web is established as folded layers of glutenin and gliadin. This web is called as gluten. It is mainly responsible to hold water/steam content and carbon dioxide gas produced by microbial fermentation as more time as possible till end of baking. When the temperature reach above 80 C, gluten structure becomes firm and final risen shape of bread is provided.

When the temperature reach above 80 C, gluten structure becomes firm and final risen shape of bread is provided.

Gluten takes great part in formation of final shape. That’s why, yeasted gluten free products have poor specific volume (volume per weight of product) compared with gluten containing ones. Specific volume of yeasted gluten free products is minimum 25% less than yeasted products having gluten. So, shape of gluten free products is less appealing than shape of conventional yeasted bakery products. However, unless gluten replacer is used in gluten free products, there would almost be no leavening (rising during baking). That is, final product would almost be flat!

Mostly used gluten replacers are proteins, gums and hydrocolloids. Egg white protein, milk protein, whey protein and vegetable protein concentrates (pea protein, soy protein) are examples of proteins that mimics gluten in term of building structure. Hydrocolloids or gums are a diverse group of long chain polymers characterized by their property of forming viscous dispersions and/or gels when dispersed in water. These materials were first found in exudates from trees or bushes, extracts from plants or seaweeds, flours from seeds or grains, gummy slimes from fermentation processes, and many other natural products. Occurrence of a large number of hydroxyl groups noticeably increases their affinity for binding water molecules rendering them hydrophilic compounds. The primary reason behind the ample use of hydrocolloids in gluten free products is their ability to modify the rheology of dough. This includes two basic properties of dough; that is, viscosity which helps entrapping gas produced by yeast and chewable texture formed by gelling due to oven heat. Mostly used gums and hydrocolloids are Psyllium Husk, Flaxseed, Chia Seeds, Bamboo Fiber, Guar gum, Xanthan gum, Pectin, Inulin, Carrageenan, Cellulose derivatives (CMC, HPC, HPMC, MC)

Source

Emily Buehler (2006), Ch 2.6: Gluten Structure. In; Bread Science – The Chemistry and Craft of Making Bread. Two Blue Books Hillsborough NC

Milani, Jafar & Maleki, Gisoo. (2012). Hydrocolloids in Food Industry. In; Food Industrial Processes – Methods and Equipment. 10.5772/32358

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