Formation of homopolymers and heteropolymers between wheat flour and several protein sources by transglutaminase-catalyzed cross-linking

The effect of different protein sources (soy flour, lupin flour, egg albumin, gelatin powder, protein-rich beer yeast flour) on wheat dough functionality was tested by determining gluten index, texture properties, and thermomechanical parameters. Transglutaminase (TG) was also added to improve the dough functionality by forming cross-links. The presence of protein sources had a significant effect on the gluten index, with the exception of lupin flour. Gelatin and the presence of TG resulted in significant single effects on the texture properties of the wheat-protein dough. All the protein sources significantly modified the mixing characteristics of the dough or the thermal behavior. Capillary electrophoresis studies of the water-soluble, salt-soluble, and glutenin proteins indicated that interactions were mainly within proteins, thus homologous polymers. Scanning electron microscopy studies of the doughs made from blends of wheat and protein sources doughs supported the formation of heterologous structures in the wheat-lupin blends. The combination of TG and lupin would be a promising method to be used on the treatment of insect-damaged or weak flours, to increase the gluten strength.