Rheological Characteristics of Cold Thickened Beverages Containing Xanthan Gum-Based Food Thickeners Used for Dysphagia Diets

Cold beverages are commonly thickened with commercial gum-based food thickeners for consumption by patients with dysphagia. In this study, the rheological properties of a thickened water and five thickened beverages (orange juice, apple juice, grape juice, whole milk, and a sport drink) that were prepared with four commercial instant xanthan gumebased thickeners (coded A-D) were investigated at a 3% thickener concentration. All thickened samples showed high shear-thinning behavior with yield stress at the serving temperature of 8 degrees C. The magnitudes of apparent viscosity (eta(a,50)), consistency index (K), storage modulus (G'), and loss modulus (G '') of the thickened beverages, except for water, with food thickener A were significantly higher compared with other thickeners (B, C, and D) (P<0.05). The largest increases in K values for thickened beverages were observed at 1-hour storage, and at longer times their K values, except for milk, remained approximately constant. Rheological parameters demonstrated statistically significant differences in flow and dynamic behaviors between the cold thickened beverages prepared with the xanthan gum-based food thickeners (P<0.05), indicating that their rheological properties are strongly influenced by the dispersing medium, the type of food thickener, and storage time. In particular, appropriately selecting a commercial food thickener for preparing thickened beverages seems to be of importance for managing dysphagia.