Effect of Curdlan on the Structural Stability and Thermal Processing Properties of Mycelium-Based Gels Used in 4D-Printed Meat Analogs

This study investigated the effects of curdlan (CUR) on the structural stability and thermal processing properties of Pleurotus eryngii mycelium–soy protein isolate–cassava starch gels used as bio-ink scaffolds for 4D-printed meat analogs. Bio-inks containing different CUR concentrations (0–5%, w/w) were prepared, and their rheological properties, 3D printability, microstructure, and water distribution were systematically evaluated. The fermented meat analogs were then subjected to steaming and baking to assess cooking loss, dimensional shrinkage, and textural properties. The results showed that CUR significantly increased the yield stress and structural recovery of the bio-inks while maintaining high height retention (>87%), thereby providing a favorable scaffold for mycelial growth and subsequent product formation. During thermal processing, CUR effectively mitigated structural collapse, which may be attributed to its heat-induced thermally irreversible gelation and the formation of an internal supporting network that resisted matrix contraction and dehydration. In particular, the addition of 5% CUR reduced cooking loss from 12.83% to 7.35% during steaming and from 42.52% to 38.59% during baking, while reducing shrinkage to 9.29% and 18.00%, respectively. In addition, hardness, springiness, and chewiness were significantly improved after cooking. Overall, CUR functioned not only as a rheological modifier for extrusion printing but also as a heat-activated internal supporting network during cooking, owing to its thermally irreversible gelation.