Quality Enhancement and In Vitro Starch Digestibility of Wheat–Yam Composite Flour Noodles via Adding Different Improvers

The addition of Chinese yam powder (CYP) to wheat flour (WF) can compromise the elasticity of noodles due to weakening of the gluten network. To address this, we investigated the effects of TGase, vital wheat gluten (VWG), and egg white powder + sodium alginate (EWP + SA) on the quality of wheat yam composite flour noodles (color, cooking, textural, thermal properties, and in vitro starch digestibility). Our findings demonstrated that VWG, TGase, and EWP + SA exert distinct yet complementary effects on the quality of composite flour noodles. Combining TGase and VWG yielded the densest microstructure and better textural properties, including hardness, adhesiveness, and springiness. TGase and EWP + SA addition significantly increased slow digestible starch (SDS) content (G6: 33.81%) while reducing starch digestibility. These findings demonstrate that synergetic combinations of improvers, particularly TGase with VWG or EWP + SA, improve both the processing characteristics and nutritional quality of yam-based products.