Instrumental characteristics from extensional rheology and tribology of polysaccharide solutions

Abstract

Instrumental characteristics from extensional rheology and tribology for aqueous xanthan gum (XG) and locust bean gum (LBG) solutions were studied in the presence or absence of simulated saliva. Extensional viscosity was calculated from the filament shrinkage behavior using a capillary breakup extensional rheometer, whereas the friction coefficient was measured using a set‐up consisting of polydimethylsiloxane substrate and a glass ball bearing on a rotational rheometer. Increase in extensional viscosity was detected immediately after initiation of extensional flow, particularly XG, and also immediately before the filament rupture, particularly LBG. Extensional viscosity tended to decrease with increased addition of simulated saliva for XG, while to increase for LBG. In both cases, effect of cations in the saliva was greater than that of mucin. From the shape of the Stribeck curve (i.e., dependence of the friction coefficient on the entrainment speed) and comparison of the friction coefficient itself, lubricity of XG was greater than that of LBG. Simulated saliva added decreased the friction coefficient for each polysaccharide through functions of cations rather than mucin. Extensional viscosity and tribological measurements revealed mechanical properties of polysaccharide solutions which cannot be determined or quantified by shear viscosity alone.

Rheology for Safe Swallowing 3

“…It was found that η e for both XG and LBG decreased and then increased with increasing Hencky strain but the increase of η e was more noticeable for LBG, which might be explained by the difference in chain stiffness of XG and LBG 270) . Since LBG is more flexible than XG the coil-stretch transition occurs more clearly than in XG.…”

“…In relation to this, "structured fluid" having the yield stress leads to the formation of one coherent bolus that is then swallowed in one go, presenting a rheological nature for swallowing ease. Funami and Nakauma 270) reported that perceived sliminess had the highest correlation with the friction coefficient at the point E in the Stribeck curve, which corresponds to entrainment speed of 6 × 10 −3 m/s. According to a flow simulation study 271) the bolus flow for non-Newtonian fluids (xanthan gum and guar gum used in Nishinari et al 199) with the viscosity more than 10 times higher than the solutions used 270) was ~ 0.3 m/s at the palate, 0.3 ~ 0.5 m/s at the pharynx, and 0.1 ~ 0.4 m/s at the larynx/esophagus, depending on feeding volume from 5 to 10 ml.…”

“…According to a flow simulation study 271) the bolus flow for non-Newtonian fluids (xanthan gum and guar gum used in Nishinari et al 199) with the viscosity more than 10 times higher than the solutions used 270) was ~ 0.3 m/s at the palate, 0.3 ~ 0.5 m/s at the pharynx, and 0.1 ~ 0.4 m/s at the larynx/esophagus, depending on feeding volume from 5 to 10 ml. Then, it was concluded that the sliminess should be perceived through relatively slow movement of bolus at the palate than bolus flow velocities at the pharynx and larynx/esophagus 270) .…”

“…Extensional viscosity η e of solutions of xanthan gum (XG) and locust bean gum (LBG) was studied recently 270) .…”

Food texture and texture modification for dysphagia management

“…In organizing this special issue, our main consideration has been on the fundamental principles and feasible techniques of texture modification for adult dysphagia. For this purpose, a number of leading scientists have been approached for a contribution in topics including the effect of bolus rheology of texture-modified foods on the degree of modification (Stading, 2021a); relationship between masticatory variables and bolus characteristics of meat with different textures (Pematilleke, Kaur, Adhikari, & Torley, 2021); textural properties and muscle activities during mastication of normal and ultrasonically softened sticky rice (Wattanapan, Saengnil, Niamnuy, Paphangkorakit, & Devahastin, 2021); extensional rheology and tribology of polysaccharide solution (Funami & Nakauma, 2021); the physical properties of texture-modified foods (Stading, 2021b); the effect of the rheological properties of thickened fluids on the in vitro swallowing of solid oral dosage forms (Lavoisier, Shreeram, Jedwab, & Ramaioli, 2021); and microwave treatment to modify textural properties of high-protein gel applicable as dysphagia food (Pure, Yarmand, Farhoodi, & Adedeji, 2021).…”