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Superheated steam treatment (SST) can improve cereal-based foodstuff quality by altering the gluten properties. In the current study we investigate the effect of SST on the polymerization behavior, conformational rearrangement and microscopic characteristics of gluten, which contribute to determining the molecular mechanisms of SST that impact the gluten properties. Compared with native wheat gluten, SST was observed to induce an increase in sodium dodecyl sulfate (SDS) insoluble gluten. This indicates that SST promoted the polymerization behavior of gluten via the cross-linking of disulfide (SS) bonds. In addition, hydrogen bonds were observed to develop from the micro-environment variation of tryptophan (Trp) residue in the gluten. This consequently had a synergistic effect on the secondary structure, increasing the proportion of intermolecular β-sheets and α-helices. Furthermore, SST enhanced the molecular surface roughness and weakened the gluten network structure. This study could contribute to insight into the improvement of flour quality following SST. • Conformational rearrangement and microscopic properties of gluten were studied. • Superheated steam treatment buried the tryptophan residue and tyrosine doublet. • Superheated steam treatment rearranged disulfide conformation. • Superheated steam treatment roughened the surface micro-structure of gluten. [ABSTRACT FROM AUTHOR]

Wheat flour superheated steam treatment can improve the baking food quality by modifying the functionality of wheat flour. To reveal the underlying mechanism of improving wheat flour quality by superheated steam treatment, the gluten molecular rearrangement and polymerization behavior of wheat flour upon superheated steam were studied. Molecular size distributions of samples were analyzed using size exclusion (SE-HPLC) and electrophoresis, which illustrated that superheated steam treatment promoted the aggregation of gluten due to cross-links of disulfide (SS) bonds. Superheated steam treatment increased the SDS-insoluble proteins content from 63.07% (native wheat flour) to 93.32% (treated at 150 °C for 1 min). Infrared spectroscopy (FTIR) was used to calculate the different secondary structures percentages of gluten, suggesting that superheated steam treatment increased intermolecular β-sheet and α-helix while it decreased anti-parallel β-sheet, β-turn and β-sheet. Furthermore, thermo gravimetric analysis (TGA) and rheology suggested that superheated steam treatment enhanced gluten mass but weakened gel system due to molecular rearrangements of SS bonds and hydrogen bonds. [Display omitted] • Gluten polymerization behavior of wheat flour upon superheated steam were studied. • Superheated steam treatment induced gluten aggregation and SS bonds cross-links. • Superheated steam treatment weakened the wheat flour gel system. [ABSTRACT FROM AUTHOR]

Flavourzyme is a commercial peptidase, mainly with exopeptidase activity. In this study, effects of Flavourzyme addition (0–0.16 g/100 g) on properties of wheat dough and bread were systematically studied. Bread with a low concentration (0.01–0.08 g/100 g) of Flavourzyme addition had a large specific volume and soft texture with a uniform cell structure. The optimal Flavourzyme content was 0.04 g/100 g and the specific volume increased from 3.9 mL/g to 4.4 mL/g, the hardness decreased from 21.7 N to 13.3 N. The gas production capacity of yeast increased with low concentrations of Flavourzyme addition, promoting dough expansion. Flavourzyme had a clear hydrolysis effect on wheat gluten in dough and caused the depolymerization and unfolding of gluten structure, thus decreasing the strength and viscoelasticity of dough. Confocal laser scanning microscopy and scanning electron microscopy results further revealed that a low concentration of Flavourzyme had a slight effect on gluten. However, the gluten structure became discontinuous and open, which made the dough easily collapsed during fermentation, resulting in poor bread quality with high Flavourzyme content. The positive effects of appropriate amount of Flavourzyme addition on dough and bread properties indicated the potential of Flavourzyme as a bread improver by substituting chemical additives. • Moderate amount of Flavourzyme addition improved the quality of bread significantly. • The optimal addition of Flavourzyme is 0.04 g/100 g (based on wheat flour). • Dough expansion was enhanced with moderate Flavourzyme addition. • Moderate Flavourzyme addition did not cause obvious damage to gluten network. [ABSTRACT FROM AUTHOR]