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There is an increasing proof of the relevance of rheology on the design of fluids for the diagnosis and management of dysphagia. In this sense, different authors have reported clinical evidence that support the conclusion that an increase in bolus viscosity reduces the risks of airway penetration during swallowing. However, this clinical evidence has not been associated yet to the definition of objective viscosity levels that may help to predict a safe swallowing process. In addition, more recent reports highlight the potential contribution of bolus extensional viscosity, as elongational flows also develops during the swallowing process. Based on this background, the aim of this review paper is to introduce the lecturer (experts in Dysphagia) into the relevance of Rheology for the diagnosis and management of oropharyngeal dysphagia (OD). In this sense, this paper starts with the definition of some basic concepts on Rheology, complemented by a more extended vision on the concepts of shear viscosity and elongational viscosity. This is followed by a short overview of shear and elongational rheometrical techniques relevant for the characterization of dysphagia-oriented fluids, and, finally, an in-depth analysis of the current knowledge concerning the role of shear and elongational viscosities in the diagnosis and management of OD (shear and elongational behaviors of different categories of dysphagia-oriented products and contrast fluids for dysphagia assessment, as well as the relevance of saliva influence on bolus rheological behavior during the swallowing process). [ABSTRACT FROM AUTHOR]

Thickened fluids are a therapeutic strategy for oropharyngeal dysphagia (OD). However, its therapeutic effect among different phenotypes of OD patients has not yet been compared. We aimed to assess the therapeutic effect and α-amylase resistance of a mixed gum/starch thickener [Fresubin Clear Thickener® (FCT)] on four phenotypes of OD patients: G1) 36 older; G2) 31 head/neck cancer (HNC); G3) 30 Parkinson's disease; and G4) 31 chronic post-stroke. Therapeutic effect of FCT was assessed during videofluoroscopy using the Penetration-Aspiration Scale (PAS), for 5/20 mL boluses, at four levels of shear-viscosity (<50, 250, 1000 and 2000 mPa·s). The effect of α-amylase was assessed after 30 s of oral incubation. Patients had high prevalence of VFS signs of impaired efficacy (98.44%) and safety (70.31%) of swallow with a severe PAS score (4.44 ± 0.20). Most severe OD was in HNC (80.6% unsafe swallows). FCT showed a strong therapeutic effect on the safety of swallow at a range between 250–1000 mPa·s (74.19–96.67%, safe swallows in G1, G3, G4, and 58.06% in G2), without increasing pharyngeal residue. Viscosity was unaffected by α-amylase. Increasing shear-viscosity with FCT causes a strong viscosity-dependent therapeutic effect on the safety of swallow. This effect depends on the phenotype and is similar among older, Parkinson's and post-stroke patients. [ABSTRACT FROM AUTHOR]

The objective was to study the effect of cross-linking on in vitro amylase resistance of regular corn (RC), faba bean (FB), and field pea (FP)starches in their native and gelatinized states, by three different phosphorylation methodologies. Phosphorylation was carried out by the following three methods: a) POCl 3 -aqueous: 1–2% phosphoryl chloride (POCl 3, v/w) in aqueous slurry at 25 °C; b) STMP-semidry: 2–4% sodium trimetaphosphate/sodium tripolyphosphate (STMP/STPP 99:1, w/w) in a semidry state at 130 °C; and c) STMP-aqueous: 5–12% STMP/STPP (99:1. w/w) in aqueous slurry at 45 °C. The modified starches were characterized for morphology, phosphorus content (% P, w/w), degree of crosslinking (DC) and amylase resistance (AR). Phosphorylation imparted minor differences in the starch granular morphology. The %P and DC of modified starches increased with increasing chemical concentration. The % P (0.01–0.19%, w/w) significantly differed with starch sources (FP > FB > RC) and the method of phosphorylation (STMP-semidry > STMP-aqueous > POCl 3 -aqueous). However, the DC did not follow the same trend as % P, where POCl 3 -aqueous showed the greatest. The POCl 3 -aqueous method had a greater impact than both STMP methods on AR with decreasing rapidly digestible starch (RDS) levels and increasing resistant starch (RS) levels in ungelatinized starches. In gelatinized starches, all three phosphorylation methods increased AR. These changes were more pronounced with STMP-semidry. The results showed that crosslinking by three phosphorylation techniques had a significant influence on AR of starch, and the correlation between AR and DC was different among starch types (r = 0.627–0.910) and phosphorylation methodologies (r = 0.590–0.799). Image 1 • Phosphorylated pulse starches contained higher phosphorus than corn counterparts. • STMP-semidry starch contained highest phosphorus than STMP-aqueous and POCl 3 -aqeous starch. • Amylase resistance had relatively higher correlation with degree of crosslinking than phosphorus content. • The effect of phosphorylation on amylase resistance was influenced more by starch types than phosphorylation methods. [ABSTRACT FROM AUTHOR]