Structure-function design of 3D-printable whole lotus root-Schizophyllum commune composite gels for dysphagia foods with reduced starch digestibility

Abstract Designing foods for older adults with coexisting dysphagia and impaired glycemic control requires simultaneous control of bolus texture, printability, and starch digestibility. Here, whole lotus root powder (WL) was combined with Schizophyllum commune powder (SC; 0–32%, w/w relative to WL) to construct 3D-printable composite gels. Rheology, printing stability, texture, water mobility, molecular interactions, microstructure, in vitro starch digestion, and International Dysphagia Diet Standardization Initiative (IDDSI) tests were integrated to establish composition-structure-function relationships. SC reduced the storage and loss moduli, indicating partial disruption of the continuous starch network, but increased post-shear recovery from 13.1% to 28.2%. At SC contents of at least 24%, particle filling, water immobilization, and interfacial interactions increased hardness and resistance to deformation. FTIR, LF-NMR, CLSM, and microscopy collectively showed that SC altered hydrogen-bonding, redistributed water, inhibited short-range starch ordering, and produced a more densely packed composite skeleton despite reduced continuity of the starch-rich phase. These changes decreased glucose release and reduced 180-min starch hydrolysis from 13.03% to 9.33% (28.4%). The estimated glycemic index decreased from 65.60 to 52.76 at 32% SC, while all formulations met the qualitative IDDSI Level 5 criteria evaluated in this study. Thus, SC enabled a tunable balance among extrusion, structural recovery, oral texture, and starch digestibility, providing a structure-guided strategy for developing 3D-printed dysphagia-oriented foods. Clinical swallowing safety and postprandial glycemic responses require further validation.