Interfacial thickness and roughness of sesame oil bodies by pH regulation for 3D printed dysphagia foods: Texture, rheology, and oral tribology.

For individuals with dysphagia, oral processing and easy swallowing characteristics are crucial. This study aimed to explore the mechanism by which pH regulates the interface membrane thickness and roughness of sesame oil bodies (SOBs) and its effects on the physicochemical properties, rheological behavior, textural characteristics, 3D printability, and applicability in dysphagia-friendly foods. SOBs were treated with four pH levels (5.5, 6.0, 6.5, and 7.0), and systematic characterizations were conducted. Results showed that pH significantly modified the composition of interface proteins in SOB, altered the secondary structure of interfacial proteins (α-helix and β-sheet contents) and intermolecular forces (electrostatic interaction, hydrogen bond), thereby regulating the interface membrane thickness. Among all groups, the SOB at pH 6.0 exhibited an optimal interface membrane thickness, which contributed to the highest consistency coefficient K (82.87 ± 2.45 Pa・sⁿ), excellent 3D printing accuracy (97.00 ± 0.42%) and stability (99.00 ± 0.47%), and textural properties that met the IDDSI 4 level (International Dysphagia Diet Standardization Initiative) criteria for dysphagia foods. Additionally, pH treatment led to changes in the roughness of the interface, which in turn affected oral friction. Appropriate oral friction was beneficial for individuals with swallowing difficulties during eating. This work provided a theoretical basis for the rational design of 3D printed customized foods for dysphagia patients by regulating interfacial properties via pH.