Although Codonopsis pilosula (common name: Dangshen) is a widely used medicinal edible herb, but the structural divergence and functional specificity of polysaccharides from its intraspecific varieties remain understudied. Therefore, this study explores the structural characteristics and immunomodulatory activities of polysaccharides from two varieties of Codonopsis pilosula, namely, Codonopsis pilosula Nannf. var. modesta (Nannf.) L.T.Shen and Codonopsis pilosula (Franch.) Nannf. Crude polysaccharides were extracted via water extraction–ethanol precipitation and purified using DEAE-52 column chromatography to obtain homogeneous fractions WCP (6.444 kDa) and BCP (15.71 kDa). Structural analyses confirmed both to be fructans, but with distinct linkage patterns: WCP contains Fruf-(2→, Glcp-(1→, →1)-Fruf-(2→, →1,6)-Fruf-(2→ linkages, while BCP additionally harbors →6)-Fruf-(2→ linkages. This structural divergence correlates with the observed differences in their physical properties and biological activities. Using zebrafish models, WCP and BCP were found to increase the density of neutrophils and macrophages, while reducing the levels of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α (p < 0.05 vs. model group). These results support their immunomodulatory potential, providing a scientific basis for developing Codonopsis polysaccharide-based functional food ingredients.

Refined wheat staple foods are widely criticized for low dietary fiber and high postprandial glycemic response, making soluble dietary fiber fortification a promising strategy for cereal improvement. This study investigated how resistant dextrin (RD) modulates wheat starch, gluten, dough, and bread quality through multiscale interactions. In wheat starch, 6% RD gave the best overall balance, reducing 14-day retrogradation from 57.2% to 48.6%, delaying gelatinization, and restricting amylose diffusion, with hydrogen bonding identified as a major contributing interaction. In gluten, RD increased water-holding capacity but weakened network integrity, as evidenced by reduced moduli, a shift in thiol–disulfide balance, secondary-structure redistribution (increased β-sheet, decreased α-helix/β-turn), and suppressed glutenin polymerization, yielding a looser microstructure. In dough, SEM and rheological results suggested that moderate RD (4–6%) may form a hydrated, polysaccharide-rich phase that fills structural voids and improves matrix continuity, partially offsetting gluten weakening and enhancing viscoelasticity. Overall, this study establishes a quantitative relationship between RD addition level, multiscale macromolecular interactions in wheat matrices, and the processing performance and quality of bakery products.