Combined effects of Polygonatum cyrtonema flour and thermal treatment on the structural, rheological, and functional properties of wheat gluten.

BACKGROUND: Polygonatum cyrtonema flour (PCF) is increasingly incorporated into wheat products for nutritional enrichment. However, its quality effects are inconsistent and concentration-dependent, and the gluten modulation mechanism remains unclear. This study investigates the combined effects of PCF incorporation and thermal treatment on gluten structure and functionality using varying levels of 0 (PCF-0), 75 (PCF-75), 150 (PCF-150), and 300 g kg-1 (PCF-300) of PCF, followed by thermal treatment at 25, 60, and 95 °C. RESULTS: At 25 °C, PCF-300 increased free sulfhydryl (free - SH) by 94.7% and decreased surface hydrophobicity (H0) and fluorescence, disrupting covalent cross-linking, promoting hydrophobic interactions, and loosening secondary structure (branching -54.8%, strand width +113.3%), yielding a sparse network with reduced viscoelasticity, water-holding capacity (WHC), and emulsifying activity index (EAI). At 95 °C, heating reversed these effects: PCF-75 and PCF-150 promoted tight cross-linking, enhancing WHC (2.0 g g-1, +25.4%), EAI and emulsion stability index (+20.6-49.9%); PCF-300 preserved free - SH (H0 decline 10.8%) via steric hindrance, giving a flexible network. At 60 °C, PCF-150 and PCF-300 induced transient unfolding (fluorescence +21.7-29.4%) with local β-sheet formation, loosening the network. Oil-holding capacity decreased with PCF and heating (maximum -45.3% at PCF-300/25 °C). CONCLUSION: These antagonistic-to-synergistic effects enable targeted design: PCF-75 and PCF-150 at 95 °C enhance water retention and emulsification for clean-label baked goods; high-PCF heating reduces oil absorption for low-fat products; the 60 °C window offers a kinetic route for hydrophobic bioactive delivery, providing a mechanistic basis for rational PCF incorporation into healthier wheat foods. © 2026 Society of Chemical Industry.