Gluten content, composition, and structural characteristics dominate chinese steam bun quality: Insights from varied...

Chinese steam bun (CSB), a 1,700-year-old staple food, remains highly valued for its nutritional and sensory qualities. Although gluten content influences CSB quality, the roles of gluten composition, structural organization, and intermolecular interactions remain less clearly defined. This study investigated these factors using seven wheat varieties, namely Canadian Spring (CS), Yongliang No.4 (Y4), You-mai 02-1 (Y2), Local Xinpu (LX), Hard Australian (HA), White Australian (WA), and French Wheat (FR), selected to capture gluten variability across diverse geographic origins. Wet gluten content (22.7%-37.0%, w/w) showed a non-linear relationship with specific volume, with moderate levels (32.3-33.1 g/100 g flour) being most favorable for dough expansion and bun volume. Glutenin content (r = 0.73) and the gliadin-to-glutenin ratio (r = 0.50) were positively correlated with specific volume. Secondary structure analysis showed that elevated antiparallel β-sheet and β-turn contents were positively associated with specific volume (r = 0.54 and r = 0.30, respectively), indicating the importance of a balanced gluten network with both stability and flexibility. In contrast, higher free sulfhydryl (SH) contents in WA and FR were associated with weaker gluten networks and lower specific volume (r = -0.44). Higher absolute zeta potential values, particularly in HA, were associated with a more organized gluten network and improved expansion performance (r = 0.49). These findings demonstrate that CSB quality depends not only on gluten quantity but also, more importantly, on gluten composition, structural characteristics, and intermolecular interactions.