Effect of Polyphenols Extracted from Rosa roxburghii Tartt Pomace with Different Particle Sizes on Quality and Biological Activity of Noodles: A View of Molecular Interaction

The retention of polyphenols in thermally processed noodles is constrained by interactions with starch and glutenin, critically impacting functional properties (antioxidant activity, starch digestibility modulation) and quality attributes. Current understanding lacks quantitative links between initial pomace particle size, polyphenol behavior throughout processing, and the resulting noodle properties. This study systematically investigated how <i>Rosa roxburghii</i> pomace particle size (0.1-250 μm), fractionated into five ranges, governs polyphenol extractability, retention in fresh/boiled noodles, and their functional and quality outcomes. Mathematical modeling established quantitative particle size-property relationships. The results indicated that polyphenol release was maximized at the 1-10 μm particle size. Total phenolic retention in boiled noodles was highest with 0.1-1 μm pomace, while the retention of specific phenolics peaked with 60-80 μm pomace. Fresh noodle hardness and gumminess decreased significantly, particularly with extracts from 1 to 40 μm pomace, whereas boiled noodles showed increased chewiness/adhesiveness. All polyphenol-enriched noodles exhibited suppressed starch digestibility and enhanced antioxidant capacity. Robust quadratic regression models predicted key properties based on particle size. Molecular interactions (hydrogen bonding, hydrophobic contacts, π-cation stacking, salt bridges) between key phenolics (EGCG, hydroxybenzoic acid, gallic acid, quercetin, and isoquercitrin) and the gluten-starch matrix, critically involving residues Arg-86 and Arg-649, were identified as the underlying mechanism. These results demonstrate that precise control of pomace particle size regulates extract composition and molecular binding dynamics, providing a strategic approach to optimize functional noodle design.