Dysphagia thickeners in context of use: Changes in thickened drinks viscosity and thixotropy with temperature and time of consumption

Abstract

Dysphagia patients might need to thicken drinks. The viscosity of these thickened drinks varies among commercial thickeners and drinks compromising the ingesta safety. The aim of this study was to investigate how temperature and resting time affect the rheological properties of thickened drinks. Four commercial thickeners were used to thicken water, coffee, orange juice, and milk at two concentration levels used in dysphagia drinks (nectar and pudding). To study the effect of temperature, flow curves of thickened drinks at 10°C and 50°C were obtained and to study the effect of resting time, flow curves of thickened drinks at 25°C were obtained at different times (0, 30, and 60 min). All samples displayed shear‐thinning and time‐dependent behavior (thixotropy or antithixotropy). The effect of temperature on viscosity values and relative thixotropic area (RTA) depended on the thickener and the drink. Overall, apparent viscosity showed higher values at 50°C than 10°C, especially in thickeners containing starch and in drinks with higher soluble solids (milk and orange juice). This was attributed to the water absorption of pregelatinized starch granules favored by temperature. Antithixotropy was mainly observed at pudding concentration for the starch‐containing thickeners, and decreased with temperature. The effect of resting time on apparent viscosity and RTA depended also on the drink and thickener. Mostly, apparent viscosity values increased with resting time and antithixotropic behavior decreased. Both effects, increase in viscosity and decrease of antithixotropy with time, indicated that thickening action was being developed over the resting time.

Characterization of Dysphagia Thickeners Using Texture Analysis—What Information Can Be Useful?

“…To consider the suggested shears, in this study, the apparent viscosity values at 10, 50, and 300 s −1 of shear rate were obtained from the flow curves for the different thickeners and are presented in Table 8. Comparing the viscosity values at increasing shear rates, a decrease is observed; this is because dysphagia thickeners had a shear-thinning behavior, as described by other authors [8,26]. At nectar level, thickener A at 10 and 50 s −1 was the most viscous sample, followed by thickeners B, D and C. For pudding level, thickener A was the least viscous, whereas the other three had higher and similar viscosities for the selected shear rates.…”

“…The matrix in which drinks are dissolved and the temperature are important, as both factors have been shown to affect the final viscosity. For instance, in a previous work, it was elucidated that drinks with soluble solids (for example, milk and orange juice) had more viscosity than drinks without soluble solids (e.g., coffee) [ 26 ]. In this study, water was selected as it is the most used drink to calm thirstiness.…”

Rheology of liquid foods under shear flow conditions: Recently used models

“…Most rheometer software calculates the area of the hysteresis loop, which is proportional to the degree of thixotropy. In investigations on the effect of rice bran protein and fat content on the rheological properties of dairy desserts (Mohammadi et al, 2022), the effect of different thickeners in beverages for consumers with swallowing difficulties or dysphagia (Badia‐Olmos et al, 2022), and the effect of plant extracts containing flavonoids in topical formulations (Di Mambro & Fonseca, 2005), the area of the hysteresis loop is reported. A dimensionless thixotropic index, calculated as the area of the thixotropic loop to the area under the upward flow curve, was used to measure the degree of thixotropy of the aqueous solution of fenugreek gum (Wei et al, 2015).…”

“…Examples of this behavior are found in crystallized honey or concentrated noncolloidal suspensions. To date, few experimental data have been reported for this type of food fluids, in some cases, the downward flow curve returns above the upward flow curve, mainly in starch‐containing samples (Badia‐Olmos et al, 2022).…”

Origins of thirstiness sensation and current food solutions

“…Presentation of dysphagia drinks: Powders or ready to drink Thickeners for dysphagia in powder form are very versatile and can be added directly to different liquid matrixes without the need for a heating process. However, depending on the thickener ingredient (starch, gum, or a mixture), the medium (water, milk, coffee, or juices), the temperature, and the resting time, the final viscosity can differ (Badia-Olmos et al, 2022).…”