Proteins from intermediate wheatgrass (Thinopyrum intermedium) and their network in dough compared to wheat

Summary

Previous studies indicated that proteins of the perennial grain intermediate wheatgrass (Thinopyrum intermedium, IWG) form viscoelastic networks. However, their interactions have not been investigated extensively. Therefore, this study provides information on IWG proteins and their network from the macroscopic to the (macro)molecular level. Washing of IWG dough yielded a viscoelastic gluten-like material (containing 76.1 % protein) with similar extensibility to gluten (83.4 and 82.9 mm, respectively), though lower resistance to extension (0.176 and 0.867 N, respectively). IWG and bread wheat had comparable profiles of polymeric and monomeric proteins, as well as amino acid composition. Fractionation experiments coupled with gel electrophoresis showed that polymers in IWG were linked via SS-bonds, like glutenin polymers. Confocal laser scanning microscopy revealed continuous networks in IWG and wheat dough. However, IWG proteins formed honeycomb-like rather than fibrous structures. Accordingly, the IWG network was less irregular, reflected in lower lacunarity values than in wheat dough (0.07 vs. 0.11, respectively) when assessed via protein network analysis. Thus, although IWG proteins form a gluten-like network, its weak dough is most likely due to its microstructure. These findings increase our understanding of IWG proteins and their network, and thus the application potential in baked goods.