Sol-stage nano-reinforcement of bicontinuous bigels with chitin nanocrystals for thermally resilient 3D-printed dysphagia-friendly foods.

Abstract

Thermal exposure often causes structural collapse and melting-induced deformation in biphasic gels, restricting their application as 3D-printed dysphagia-friendly foods. In this study, chitin nanocrystals (ChNCs) were incorporated into low-acyl gellan gum (LAGG) sols to improve the recovery and printability of bicontinuous bigels (BCBG) after thermal treatment. After exposure at 85 °C for 10 min, the recovered BCBG containing 1.0% ChNCs (C1.0BGH) achieved the best balance between structural stability and processability. C1.0BGH effectively restricted oil-water migration, suppressed phase separation, and retained mechanical robustness (high creep recovery: 54.72 ± 1.64%; thixotropic recovery: 60.62 ± 0.12%). More importantly, the dimensional deviation of the printed constructs decreased from 29.33 ± 2.20% in BGH to 3.06 ± 0.40% in C1.0BGH. In addition, the selected spoon tilt and fork pressure assessments indicated that C1.0BGH partially met the texture criteria of International Dysphagia Diet Standardisation Initiative Level 5 (Minced and Moist). Mechanistically, atomic force microscopy and quartz crystal microbalance with dissipation analyses further revealed that ChNCs promoted a denser ChNCs-LAGG sol network, reducing surface roughness by 61.95% and pore area by 72.40%, and generating a tightly bound LAGG adsorption mass of 1294.06 ± 2.12 ng/cm2. These findings establish a precursor-state nano-engineering strategy for developing heat-processed, dysphagia-oriented 3D-printed foods with improved structural stability, printing fidelity, and texture suitability.