Consistently Inconsistent: Commercially Available Starch-Based Dysphagia Products

Abstract

Individuals with dysphagia may be prescribed thickened fluids to promote a safer and more successful swallow. Starch-based thickening agents are often employed; however, these exhibit great variation in consistency. The aim of this study was to compare viscosity and the rheological profile parameters complex (G*), viscous (G″), and elastic modulus (G') over a range of physiological shear rates. UK commercially available dysphagia products at "custard" consistency were examined. Commercially available starch-based dysphagia products were prepared according to manufacturers' instructions; the viscosity and rheological parameters were tested on a CVOR Rheometer. At a measured shear rate of 50 s(-1), all products fell within the viscosity limits defined according to the National Dysphagia Diet Task Force guidelines. However, at lower shear rates, large variations in viscosity were observed. Rheological parameters G*, G', and G″ also demonstrated considerable differences in both overall strength and rheological behavior between different batches of the same product and different product types. The large range in consistency and changes in the overall structure of the starch-based products over a range of physiological shear rates show that patients could be receiving fluids with very different characteristics from that advised. This could have detrimental effects on their ability to swallow.

Commercial thickeners used by patients with dysphagia: Rheological and structural behaviour in different food matrices

“…The dynamic spectra indicated a predominance of elastic over viscous behaviour, as storage modulus was greater than loss modulus for both thickeners in the whole frequency range studied. That was in accordance with the studies performed by Payne et al (2011) and Cho et al (2012) in thickened beverages with starch-based and gum-based thickeners, respectively. Resource ® samples showed a weak gel-like behaviour with the mechanical spectra having the typical pattern of the starch pastes, reported by Payne et al (2011) and Quinchia et al (2011) among others.…”

“…That was in accordance with the studies performed by Payne et al (2011) and Cho et al (2012) in thickened beverages with starch-based and gum-based thickeners, respectively. Resource ® samples showed a weak gel-like behaviour with the mechanical spectra having the typical pattern of the starch pastes, reported by Payne et al (2011) and Quinchia et al (2011) among others. The Nutilis ® spectra were clearly different, with lower moduli values and a greater dependence on frequency, due to the fact that part of the starch was substituted for galactomannans, as it was previously observed by Dolz, Hern andez, and Delegido (2006).…”

“…Thickened fluids are classified into several levels of different consistency, or classes. The terminology used to describe them varies depending of the country (Andersen et al, 2013;Cichero, 2013;Payne, Methven, Fairfield, & Bell, 2011) but there is a certain agreement about establishing at least three levels of fluid thickness: nectar-syrup (mildly thick or stage 1), custard-honey (moderate thick or stage 2) and spoon-pudding (extremely thick or stage 3). Consistencies are classified on the basis of a range established for the values of viscosity measured at 50 s À1 , which is the shear rate considered to be representative of the swallowing process; although actually there is a large range of shear rates (from 1 to 1000 s À1 ) involved in the whole oral process of the bolus (National Dysphagia Diet Task Force, 2002;Payne et al, 2011;Zargaraan, Rastmanesh, Fadavi, Zayeri, & Mohammadifar, 2013).…”

“…Moreover, dynamic spectra obtained by small amplitude oscillation sweeps provide information related to internal structure of the substances (Payne et al, 2011). However, little information is available on dynamic rheological properties (Cho et al, 2012;Payne et al, 2011;Quinchia et al, 2011) as well as on microstructural properties of thickened beverages. These studies will allow an improvement on the understanding of the mechanical behaviour and the interactions between the major molecules of the thickened beverages.…”

Rheological Behaviors of Thickened Infant Formula Prepared with Xanthan Gum-Based Food Thickeners for Dysphagic Infants

“…It has been proposed that viscoelastic properties are potentially relevant for swallowing a food bolus because thickened liquids cannot be adequately defined by only a single viscosity value [9,16]. As shown in Fig.…”