Molecular and physico-chemical basis of breadmaking : Properties of wheat gluten proteins : A critical appraisal

Wheat gluten consists mainly of the storage protein of wheat endosperm, i.e., gliadin and glutenin. Upon hydration and during processing, gliadin and glutenin interact to form a unique viscoelastic gluten network, which is envisaged as being necessary for holding the gases and for producing a light porous crumb textured bread. Recent work has confirmed that the elastic properties of gluten are due to the glutenin fraction, whilst the viscous properties come from the gliadin fraction. An appropriate balance in the amount of these two major protein components of wheat gluten is required for achieving the desired bread quality. Variations in the composition and physical properties of the glutenin polypeptides appear to be largely responsible for the differences in the gluten viscoelasticity and breadmaking potential among wheat cultivars. Recently, exploratory results have indicated an association of gliadin polypeptides with breadmaking quality. Using improved protein separation and purification techniques, physical methods and genetic engineering, a beginning has been made to understand the structure-functional relationship of wheat gluten proteins, but much remains to be explored in the years to come.