Binding of oxidised glutathione to dough proteins and a new explanation, involving thiol disulphide exchange, of the physical properties of dough

Abstract

Abstract The fate of oxidised glutathione (GSSG) mixed with dough has been investigated using 35 S‐labelied GSSG, It was found that over 50% of the label became bound by a disulphide bond to protein during the mixing of dough. The water‐soluble proteins bound more glutathione, especially in the initial stages of mixing, than did the gluten proteins. The binding was partly reversible under normal doughing conditions. A new hypothesis is presented concerning the role of thiol‐disulphide exchange reactions in affecting the theological properties of dough. The hypothesis recognises the apparent importance of thiol‐disulphide exchange reactions, but does not involve the polymerisation of proteins by disulphide linkages The change from dry flour to wet dough will necessitate conformational re‐arrangements in the proteins. The rate at which intramolecular disulphide bonds can be resorted will influence the rate of conformational re‐arrangement. Thiol groups will affect the kinetics of disulphide resorting. The hypothesis could account for the actions in dough of chemical improvers, thiol compounds, oxidising compounds, thiol‐locking reagents and GSSG.