Effects of yellow onion skins extract on the structure and physicochemical properties of fresh noodles and gluten protein

This study explores the impact of yellow onion skin extract (YOSE) on fresh noodle quality and its interaction mechanism with wheat gluten protein. Results show that 0.25% and 0.5% (W/W) YOSE additions significantly improved noodle cooking properties, enhancing cooked noodle hardness, chewiness, tensile strength, and elongation. Scanning electron microscopy (SEM) revealed denser gluten networks at these concentrations, while higher doses (0.75%–1%) caused discontinuous and uneven structures. Total phenolic (TPC) and flavonoid (TFC) contents in cooked noodles increased significantly with YOSE (82.8%–271.4% for TPC; 75.8%–396.8% for TFC), boosting DPPH + and ABTS + radical scavenging rates by 1.7–6.1× and 2.5–7.4× versus controls, respectively. Sensory evaluation showed 0.25%–0.5% YOSE imparted warm golden color and complementary flavor, raising acceptability scores from 7.9 to 8.9. Fluorescence spectroscopy indicated reduced gluten protein fluorescence intensity, while free - SH content increased with higher YOSE. Fourier transform infrared (FTIR) analysis showed decreased α - helix and increased β - sheet structures, suggesting stabilized protein conformations in the gluten network. Collectively, YOSE significantly influences gluten protein structure, and low - level additions hold promise for enhancing wheat flour product quality. • Adding 0.5% of YOSE could improve the cooking characteristics of fresh noodles. • Adding 0.75% and 1% of YOSE had detrimental effects on fresh noodle quality. • Adding 0.5% of YOSE could improve the color, flavor and overall acceptability of fresh noodles. • YOSE enhanced antioxidant activity of fresh noodles. • YOSE increased the content of free sulfhydryl groups in gluten proteins. • YOSE stabilized the protein conformation within the gluten network.