Effects of Sodium Alginate on the Quality Attributes of Wet Instant Starch Noodle Cakes: From a Multi-Scale Perspective

This study aimed to investigate the potential of sodium alginate (SA) as a substitute for potassium alum (PA) to improve the quality of wet instant starch noodle cakes (WISNC). The effects of SA on the rheological properties of the starch dough, as well as the rehydration time, cooking performance, textural properties, multi-scale structure, and water distribution of the resulting WISNC, were systematically evaluated. The results demonstrated that the effects of SA on the quality attributes of WISNC were concentration-dependent, with 0.2% SA exhibiting the most pronounced improvement by effectively reducing cooking loss and shortening rehydration time while maintaining desirable textural properties. Rheological analysis showed that the addition of 0.2% SA effectively enhanced starch dough strength. Multi-scale structural analyses based on FTIR, Raman, XRD, DSC, and SEM revealed that an appropriate level of SA addition improved WISNC quality by promoting starch chain alignment and structural ordering, enhancing hierarchical structural organization, facilitating the formation of a more homogeneous starch–SA gel network, and mitigating freeze-induced structural damage caused by ice crystal formation. These findings provide mechanistic insights into starch–SA interactions and highlight the potential of SA as a functional alternative to PA for improving the quality attributes of WISNC.