Other than serving as nutrient sources, wheat starch and wheat proteins (gluten) are added to foods because of the unique functionalities they impart. Oftentimes, modification is conducted on wheat starch to improve cooking or gelatinization characteristics, enhance paste clarity, viscosity and texture, increase adhesion properties, reduce enzyme digestibility, or improve processing tolerance such as stability to heat, shear, acid, or freeze-thaw treatments. Modified wheat starch can serve as a thickener, gelling agent, moisture retention agent, firming agent, texturizer, stabilizer, binding agent, coating agent, dusting agent, structure control agent, crisping agent or dietary fiber source. Some universities have successfully formulated Fibersym® RW in flour tortilla, white pan bread and sugar snap cookies for its functional attributes, as well as to serve as a nutritional fiber source.
In general, the functions of protein in foods are expressed in many ways such as water absorption, binding, solubility, viscosity, gelation, cohesion/adhesion, elasticity, emulsification, fat absorption, flavor binding or foaming. Wheat possesses one of the most unique plant proteins in the form of wheat gluten, because of its ability to form a viscoelastic dough, entrap leavening gasses, and yield bread after baking. Wheat protein essentially comprises two fractions, gliadin and glutenin, that exist in roughly equal amounts. The elastic property of wheat protein is associated with the glutenin fraction and the cohesive and extensible properties are attributed to gliadin.
Wheat protein can also undergo modification to change the elastic and extensible properties, increase solubility, improve emulsifying capacities, provide foaming capacities or impart unique texture. The resulting specialty wheat proteins can be classified as wheat protein isolates (Arise® products), hydrolyzed wheat gluten, or texturized wheat protein (TruTex™ products). In bakery applications, these specialty wheat proteins can increase dough absorption and reduce mix time. Furthermore, they can function in boosting protein content, raising bread volume, extending bread shelf-life (improved crumb softness over time), reducing microwave-induced toughening of breads and, in the case of TruTex, texturizing vegetarian foods and meat-extended products.