Time-dependent thixotropy of dysphagia management-oriented polysaccharide solutions

Abstract

During dysphagia management, the required foods are often thixotropic yield fluids (YSFs) in which polysaccharide gums are used as thickeners or gelling agents. Thixotropy is a prevalent hysteresis phenomenon in YSFs, so it always occurs as an apparently time-dependent stress or modulus response. The yielding behavior of the food bolus is inseparable from the mastication and swallowing process, among which time-dependent thixotropy is integral. Nevertheless, standardizing and generalizing the thixotropy levels has always been a challenge in the manufacturing application of YSFs. Moreover, the existing thixotropic approaches cannot guarantee the accuracy and comparability of the measurement process due to technicalities. Along these lines, in this work, the thixotropic stress-shear rate hysteresis loops were investigated based on the utilization of dysphagia management-oriented model polysaccharide solutions that exhibited different time-dependent thixotropy levels. More specifically, xanthan gum (XG), carboxymethylated curdlan (CMCD), and konjac glucomannan (KGM) solutions were selected to mimic dysphagia diet construction, whereas the relationship between their technically mechanical properties and structural changes was analyzed. Compared with the KGM solutions, both XG and CMCD solutions presented significant thixotropy levels with different timescale responses and concentration dependence. The recorded discrepancy in their loop area and shape were attributed to their different intermolecular association and networks.