Understanding the Impact of Single-Helical Maize Amylose on Steamed Bun Hardness Enhancement

In this study, single-helical maize amylose (SHMAM) was successfully prepared via the sodium chloride-based eutectic solvent method. Incorporation of SHMAM into wheat flour for steamed buns significantly enhanced its hardness, with a 5% addition level yielding the maximum effect (hardness increased from 2318.7 ± 157.4 g to 3224.7 ± 98.1 g). Comprehensive structural characterization including FT-IR, XRD, DSC and 13C solid-state NMR revealed that during steaming hydrogen bonds formed between the C6 hydroxyl groups of SHMAM and sulfhydryl groups of Cys, α-amino groups of Lys, phenolic hydroxyl groups of Tyr, and ε-amino groups of Arg in glutenin. These interactions induced the conversion of β-sheets into α-helices and β-turns. As a result, a denser, more mechanically robust glutenin–starch network was formed, accompanied by a decreased water-holding capacity of glutenin and restricted interfacial water mobility between starch and glutenin phases. Collectively, these synergistic interactions enhanced dough compactness, stabilized the microstructural integrity of the dough matrix, and improved the hardness of the final steamed bun. This work establishes a novel, green, and scalable strategy for precisely modulating steamed bun texture, with broad implications for quality optimization in traditional wheat-based foods and potential benefits for dietary health.