The Swallowing Characteristics of Thickeners, Jellies and Yoghurt Observed Using an In Vitro Model

Abstract

Drinks and foods may be thickened to improve swallowing safety for dysphagia patients, but the resultant consistencies are not always palatable. Characterising alternative appetising foods is an important task. The study aims to characterise the in vitro swallowing behaviour of specifcally formulated thickened dysphagia fuids containing xanthan gum and/or starchwith standard jellies and yoghurt using a validated mechanical model, the “Cambridge Throat”. Observing from the side,the model throat can follow an experimental oral transit time (in vitro-OTT) and a bolus length (BL) at the juncture of thepharynx and larynx, to assess the velocity and cohesion of bolus fow. Our results showed that higher thickener concentration produced longer in vitro-OTT and shorter BL. At high concentration (spoon-thick), fuids thickened with starch-based thickener showed signifcantly longer in vitro-OTT than when xanthan gum-based thickener was used (84.5 s±34.5 s and 5.5 s±1.6 s, respectively, p<0.05). In contrast, at low concentration (nectar-like), fuids containing xanthan gum-based thickener demonstrated shorter BL than those of starch-based thickener (6.4 mm±0.5 mm and 8.2 mm±0.8 mm, respectively,p<0.05). The jellies and yoghurt had comparable in vitro-OTT and BL to thickeners at high concentrations (honey-like and spoon-thick), indicating similar swallowing characteristics. The in vitro results showed correlation with published in vivo data though the limitations of applying the in vitro swallowing test for dysphagia studies were noted. These findings contribute useful information for designing new thickening agents and selecting alternative and palatable safe-to-swallow foods.