Enhancing the oral disintegration of milk protein puffs for dysphagia via calcium chelators

Orally self-disintegrating protein puffs provide high-quality protein for individuals with swallowing difficulties, yet current formulations rely on synthetic phosphate-based calcium chelators that conflict with demand for clean-label products. This study evaluated the efficacy of natural calcium chelators (casein phosphopeptide (CPP) and citric acid (CA)) and synthetic chelators (sodium hexametaphosphate (SHMP) and sodium tripolyphosphate (STPP)) in milk protein (MPC) puffs produced via supercritical fluid extrusion. The inclusion of chelators led to an increase in pore size and more disrupted surface morphology in the puffs. MPC-CPP puffs achieved water diffusion coefficients (5.23 × 10^-7 m²/s) comparable to MPC-SHMP puffs (5.89 × 10^-7 m²/s), while MPC-CA puffs exhibited significantly lower values. Chelation efficiency demonstrated that CPP rivaled synthetic chelators, whereas CA showed limited effectiveness. Molecular docking simulations revealed that synthetic chelators engaged β-casein primarily through ionic interactions, while CPP established combined hydrogen bonding and hydrophobic interactions. Fourier transform infrared spectroscopy confirmed that all chelators induced phosphate group shifts and increased random coil content relative to control samples, indicating disruption of the calcium-stabilized protein network. The results established that CPP achieved competitive disintegration performance through calcium sequestration and amphiphilic intercalation into casein micelles. This interaction induced protein unfolding, which facilitated the formation of a porous and rapidly hydrating matrix. These findings demonstrate that casein-derived CPP represents a natural alternative to synthetic phosphate chelators, which can offer the additional benefit of enhanced calcium bioavailability in high-protein products.