Rheological characterization of polysaccharide thickeners oriented for dysphagia management: Carboxymethylated curdlan, konjac glucomannan and their mixtures compared to xanthan gum

Novel naturally sourced thickeners from food biopolymers have always gained significantly increasing attention, particularly in food areas where the edible safety of thickeners is highly requested. Polysaccharides are commonly used in thickening fluids, enabling on-demand management of dysphagia where the fluidal food must be adequately thickened for patients. To customize and develop dysphagia diets, understanding and controlling the rheological properties of thickeners is of crucial importance. Herein, rheological behaviors of a novel thickener of carboxymethylated curdlan potential for dysphagia, a traditional food thickener of konjac glucomannan (KGM), and their mixtures were investigated in both water and model nutrition emulsions. The well-known dysphagia thickener of xanthan gum was taken as the reference, to allow a direct comparison of the efficacy and applicability among these thickened fluids. Comprehensively rheological characterizations such as shear-thinning, yielding, viscoelasticity, creep, and relaxation response behavior showed that the carboxymethylated curdlan, similar to xanthan, demonstrated unique viscosity-enhancing ability in both water and emulsions, presenting promising feasibility as a novel dysphagia-oriented thickener. However, although KGM showed excellent thickening capacity in water as expected, a prominent viscosity-lowering phenomenon was observed in the presence of maltodextrin. Considering the feature of KGM as salutary dietary fibers, the antagonistic effect of maltodextrin on the viscosity of KGM solutions provides an advantage to incorporate more dietary fibers in dysphagia diet formula.