Effect of baked wheat germ on gluten protein network in steamed bread dough

The effect of baked wheat germ (BWG) on the gluten network structure in steam bread dough was investigated. The secondary structure, free sulphydryl (-SH) content, disulphide (-SS-) bonds content and microstructure of gluten were analysed to evaluate gluten structural changes. The addition of different amounts of BWG (0, 2, 4, 6, 8, 10, and 12%) in dough resulted in decreased content of α-helix and β-sheet structures, but increased random coils, which indicated that a disordered structure was formed. The presence of BWG increased the -SH content but decreased the -SS- bonds content, which indicated fracture of disulfide bonds. Confocal laser scanning microscopy (CLSM) analysis indicated that steamed bread dough containing BWG had larger-sized gas cell and granules of starch separated by the protein matrix, which weakened the gluten network structure. These changes may inevitably affect the viscoelastic properties of steamed bread dough.