Binary Egg White and Collagen Protein Hydrogels: Mechanism of Formation, Physicochemical Properties, and Digestibility

Abstract

Dysphagia is characterized by difficulties in swallowing and chewing. Texture-modified soft foods are intended for patients with dysphagia to facilitate safe swallowing and meet nutritional requirements, with a primary focus on increasing protein intake. This study examined the feasibility of creating high-protein (35%) gel systems suitable for dysphagia patients by adjusting the levels of egg white protein and collagen hydrolysate. It was observed that increasing the concentration of egg white and decreasing the amount of collagen improved water-binding capacity (from 95.23% to 100%), hardness (0.85 N to 5.43 N), elasticity (higher G' moduli), and network protein content (from 89.59% to 96.33%), while structural recovery declined (from 54.89% to 36.85%). Based on the International Dysphagia Diet Standardization Initiative test, hydrogels are classified as Level 6, fulfilling texture safety standards for dysphagia management. This classification makes them more appropriate for patients with mild dysphagia. FTIR, DSC, and SEM analysis confirmed that the main network in the hydrogel composition is formed by egg white protein, with collagen serving more as an inactive filler. Hydrophobic interactions were dominant and primarily contributed to the stabilization of the gel network. The protein hydrolysis rate in hydrogels gradually declined as egg white concentration increased, resulting in a denser, firmer, and less porous structure that may reduce enzyme interactions. The findings offer a viable approach for designing tailored high-protein food formulations for dysphagia.