Tapioca starch-yeast protein 3D printing system for dysphagia: Different hydrocolloids regulate viscoelasticity and 3D printing accuracy through molecular interactions.

To develop easy-to-swallow foods for dysphagic individuals, this study prepared yeast protein (YP) and tapioca starch (TS) composite gel, and explored the effects of four hydrocolloids (HCs): flaxseed gum (FG), locust bean gum (LBG), xanthan gum (XG), and sodium alginate (SA) on their viscoelasticity, swallowing and 3D printing performances. All gels satisfied International Dysphagia Diet Standardization Initiative (IDDSI) Level 6 criteria. HCs raised 3D printing accuracy from 80.53% to 95.85%, correlating with increased viscoelasticity in the order: FG > XG > LBG > SA. Molecular analysis showed this stemmed from HCs' ability to increase hydrogen bond density in YP-TS gel. FG exhibited the highest hydrogen bond density due to abundant -OH and -COOH groups; XG had steric hindrance from side chains; LBG contained only -OH groups; SA had ionized -COO- groups. Thus, HC enhanced viscoelasticity and printability through hydrogen bonds in the order FG > XG > LBG > SA. This study offers a novel perspective for texture design of dysphagia foods.