Disulfide bonds: key to wheat protein functionality.

Disulfide bonds in wheat proteins are major factors that determine the properties of the proteins and their functionality in wheat flour. The gliadin proteins contain mostly intramolecular disulfide bonds. In contrast, the high-molecular-weight glutenins are formed by disulfide linkages of several diverse polypeptide chains which have been separated and characterized. The linkage of these proteins in a fairly linear array contributes to the unique viscoelastic properties of glutenin. The glutenin has been separated into two fractions differing in molecular weight. The amount of highest molecular weight component is correlated with the rheological behavior of the flours from different wheat varieties. Various oxidizing and reducing agents are widely used to alter the functional behavior of wheat proteins by the action on sulfhydryl and disulfide groups.