Rheological and Physicochemical Properties of a Functional Apple Drink and Its Clinical Impact on Dysphagia Management

Modification of liquid viscosity using commercial thickeners is a recognized strategy to ensure safe swallowing for patients with oropharyngeal dysphagia. This study investigated the rheological, physicochemical, and sensory properties of functional apple drinks formulated for dysphagia management. Various concentrations of gellan gum (0.042% to 0.050%), inulin (3.5%), maltodextrin (3%), and stevia were tested to optimize the viscosity and sensory characteristics of the drinks. The results indicated that gellan gum concentrations of 0.045%-0.047% and 0.048%-0.050% achieved viscosities corresponding to IDDSI Levels 1 and 2, respectively, making the drinks suitable for dysphagia patients. All samples exhibited time-independent, non-Newtonian, shear-thinning behavior, with the Herschel-Bulkley model providing the best fit for describing flow properties (R² > 0.93). Higher gellan concentrations enhanced apparent viscosity (ηa,50), consistency index (κ), yield stress (σ0), and viscoelastic moduli (G' and G″). Physicochemical properties such as acidity, pH, Brix, and color remained stable during 15 days of refrigerated storage. Clinical trials demonstrated a significant improvement in swallowing function among patients who consumed the thickened drinks. These findings highlight the potential of low-acyl gellan gum to develop functional beverages tailored for dysphagia management, providing both safety and sensory appeal.