Structure and functional properties of Dendrobium officinale polysaccharide-hemp seed protein gels for dysphagia diets as regulated by alkali concentration and temperature.

Dysphagia is highly prevalent among older adults and increases the risks of malnutrition, dehydration, and aspiration pneumonia, highlighting the need for safe and nutritionally adequate texture-modified foods. Polysaccharide-protein gels are promising candidates for this purpose, but precise control of their rheological properties and structural stability remains challenging. Here, we systematically investigated how alkali concentration (Na2CO3, 0.5-2.5%, w/v) and thermal treatment (25-85 °C) regulate the gelation, structure, and functional performance of Dendrobium officinale polysaccharide-hemp seed protein (DOP-HSP) gels for dysphagia-oriented foods. Among the tested conditions, 1.5% Na2CO3 and 55 °C were identified as the most favorable treatment, as indicated by the highest water-holding capacity at 1.5% Na2CO3 (75.25 ± 2.63%) and an increase in hardness from 46.04 ± 1.32 g to 65.71 ± 1.47 g after 55 °C. All gels belonged to the international dysphagia diet standardisation initiative (IDDSI) level 5 and maintained Caco-2 cell viability above 90% at 25-100 mg/mL, indicating their potential suitability for dysphagia-oriented foods and favorable preliminary cytocompatibility. Moderate alkali treatment and heating likely promoted HSP unfolding and structural modification of DOP, strengthening disulfide bonding, hydrogen bonding, and hydrophobic interactions. These changes resulted in denser gel structures, improved stability and antioxidant activity, and altered in vitro digestibility. By contrast, excessive alkali or thermal treatment weakened intermolecular interactions and impaired network integrity. Overall, this study clarifies the relationships among processing conditions, gel network organization, and functional performance in DOP-HSP gels, guiding the rational design of plant-based texture-modified foods for dysphagia management.