Superheated Steam Modified Finger Millet Starch for 3D Printed Dysphagia-Friendly Foods

Abstract

Objective: Modification of finger millet starch (FMS) using superheated steam (SHS) to improve functionality and printability for the development of dysphagia-friendly 3D-printed foods. Methodology: Finger millet starch was treated using SHS at 140°C and 160°C for 5, 10, and 20 minutes. Native and treated starch samples were analyzed for structural (SEM, XRD, FTIR), functional (solubility, swelling power), pasting behaviour, rheology, tribology, and textural properties. Based on functional performance, the optimized starch gel was tested for 3D printing suitability by varying starch concentration, gelatinization temperature, nozzle diameter, and nozzle height. A fork pressure test was performed to evaluate compatibility with IDDSI Level 6 soft & bite-sized food requirements. Results and Conclusions: SHS-treated starch showed enhanced solubility, swelling, peak viscosity, and crystallinity. SS-treated samples demonstrated improved lubrication behaviour with reduced coefficient of friction, ensuring smooth swallowability. Rheology confirmed a higher elastic modulus (G'), indicating stronger gel networks suitable for 3D printed structural stability. Texture profiling revealed higher hardness and cohesiveness with reduced adhesiveness. Optimized printing conditions were identified at 20% starch concentration, 75°C gelatinization, 5 mm nozzle diameter, and 3 mm nozzle height. SHS treatment (SS_160_20) met IDDSI Level 6 criteria in the fork pressure test, proving suitability for dysphagia diets. Therefore, SHS is a clean-label modification approach that enables functional starches for safe, personalized 3D-printed foods. Future research can integrate SHS-modified starches into 3D printing to develop next-generation, personalized dysphagia-safe foods.