Cassava Starch Improves Printability and Swallowability of Rapeseed Protein Gels for Dysphagia Foods

To create the CS-RP hybrid gels, samples were prepared with a fixed total solid content of 15% (w/w) and varying concentrations of CS (0%, 1%, 2%, 5%, 7%, 9%, and 15%). The ingredients were combined in purified water and heated at 90 °C for 30 minutes, then cooled at 4 °C for gel formation. The resulting gels were assessed for their printability using a specific 3D printer and software parameters.

The gels' rheological properties were analyzed to understand their behavior during printing. A series of tests measured viscosity, frequency response, and creep recovery to evaluate their print characteristics. For instance, the viscosity of the gels varied significantly; higher CS concentrations resulted in increased viscosity, which affected the gels' ability to maintain structural integrity during printing. The 2%-CS sample exhibited optimal printing quality, achieving a high accuracy of 97.37% and effectively retaining shape during and after the printing process.

Dynamic rheological testing confirmed that samples with lower CS concentrations (1% and 2%) had superior self-supporting capabilities due to their higher elastic modulus (G') compared to viscous modulus (G''). This trend indicates that moderate CS concentrations enhance printability and structural stability without compromising texture. Moreover, the ability to recover from deformation was strongest in the 2%-CS gel, indicating great potential for application in dysphagia diets.

Texture profile analysis showed that the 2%-CS gel also excelled in cohesive and chewable properties, making it suitable for individuals with swallowing difficulties. Additionally, low-field nuclear magnetic resonance (LF-NMR) analysis illustrated that semi-bound water contributed significantly to the gel's stability. FT-IR spectroscopy results indicated that the addition of CS did not change the fundamental structural interactions within the gel, but rather optimized the network strength through enhanced hydrogen bonding.

X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses demonstrated the predominant amorphous structure of the CS-RP gels and the gradual densification of the gel network as the CS content increased. IDDSI framework tests categorized the gels effectively for dysphagia, revealing that samples with CS concentrations between 2% and 9% showed minimal adherence and adequate swallowability.

Overall, the findings suggest that controlling the concentration of cassava starch in rapeseed protein gels can significantly enhance their printability and make them suitable for developing customized meals for dysphagia patients.