Sodium alginate and zein co-modulation twin-screw extruded gluten-free potato noodles: Dough thermomechanical behavior, structural regulation, and quality enhancement

To address the quality limitations of gluten-free potato noodles caused by the lack of a gluten network, this study elucidates the influence of sodium alginate (SA, 0, 0.5, and 1.5%) and zein (0, 10, 15, and 20%), individually and in combination, on the thermomechanical properties of potato dough and the quality of twin-screw extruded noodles. Mixolab analysis showed that SA significantly increased water absorption, while zein delayed protein weakening ( P  < 0.05). Their combination enhanced dough's thermomechanical stability and starch gelatinization. At 0.5% SA and 10% zein, dough development time was minimized (0.70 min), and retrogradation resistance was optimal (C5–C4 = 0.63 Nm). Cooking loss was significantly reduced (16.41–30.71%) with SA at ≤1.5% and zein at ≤15%. Low-field nuclear magnetic resonance revealed their synergistic improvement of internal water distribution in noodles. Textural analysis indicated significantly reduced hardness, chewiness, and resilience for all SA-zein combinations except 1.5% SA with 20% zein, with maximum reductions (60.40%, 68.11%, and 38.18%) at 0.5% SA and 20% zein. Microscopy and quantitative network analysis confirmed that a moderate SA (<1.5%) promoted a continuous zein-starch network, whereas excess SA led to aggregation and structural deterioration. Color and in vitro digestion analyses revealed that SA and zein together enhanced redness and increased the content of rapidly digestible starch. In summary, at appropriate concentrations, the combination of SA and zein can synergistically improve noodle quality, thereby providing both theoretical and practical guidance for the rational design of gluten-free extruded noodles.