Steady and Dynamic Shear Rheological Properties of Gum-Based Food Thickeners Used for Diet Modification of Patients with Dysphagia: Effect of Concentration

Comparison of Rheological and Tribological Properties of Cold Thickened Beverages for Dysphagia Management

This study investigated the rheological and tribological properties of cold beverages [bottled water (BW), sports drink (SD), orange juice (OJ), and whole milk (WM)] thickened with various concentrations (1%, 2%, and 3%, w/w) of xanthan gum-based food thickeners. All thickened beverages exhibited high pseudoplastic behavior, with increasing thickener concentration leading to higher viscosity and viscoelastic moduli and a lower flow behavior index. Thickened BW, SD, and WM exhibited typical Stribeck curves covering the boundary, mixed, and hydrodynamic lubrication regimes. However, thickened OJ displayed a different curve pattern comprising five regimes because of the presence of small pulp and gel particles. As the thickener concentration was increased, the maximum friction coefficient (μ) values of thickened BW, SD, and OJ decreased, whereas that of thickened WM increased because of the depletion flocculation of emulsion particles. The maximum μ values of thickened beverages, except for thickened WM, were positively correlated with n and tan δ values with increasing thickener concentration. Thus, the tribological characteristics of cold thickened beverages had a good relationship with their rheological properties, which were greatly influenced by the thickener concentration and beverage type.

Rheological, textural, and swallowing characteristics of xanthan gum-modified Riceberry porridge for patients with dysphagia

The incidence and prevalence of dysphagia worldwide are increasing yearly requiring a change in food texture to avoid malnutrition, dehydration, or sever complications. Riceberry porridges fortified with protein hydrolysate (1.5%), bio-calcium (589 mg), and thickened with xanthan gum (XG) of varying concentrations (0%, 0.255, 0.50%, 0.75%, 1.0%, and 2.0%) showed suitability for use in enriching diets of these patients. Porridges were examined using specified tests from the International Dysphagia Diet Standardization Initiative (IDDSI) and National Dysphagia Diet (NDD), and coupled with rheological, textural analyses, in vitro swallowing simulator and sensory analysis performed by a trained panel. Porridges with 0%-0.25% and 0.50%-2.0% XG were classified as IDDSI level 3 and 4, respectively, and apparent viscosities of porridges showed samples with XG displayed shear thinning behavior beneficial for patients with dysphagia. Increasing XG concentrations increased the consistency coefficient and decreased the flow behavior index (p < .05) with positive correlation of XG concentration with textural properties including firmness, consistency, cohesiveness, adhesiveness, and stickiness values. The relationship between instrumental measurements, in vitro and in vivo swallowing behavior showed high correlations with regards to XG concentration (r = .995). The findings indicate Riceberry porridges containing XG have significantly improved textural properties over those without XG for patients with dysphagia.

Improved physical and structural properties of high-protein powders by fluidized-bed agglomeration

High-protein powders (milk protein isolate (MPI) and soybean protein isolate (SPI)) were treated with maltodextrin solution (10% or 20%) or water as a binder and then subjected to fluidized-bed agglomeration. The MPI agglomerates were compared with the SPI agglomerates as a function of maltodextrin (MD) concentration. The particle size, wettability, and porosity values of SPI agglomerates were much higher than those of the raw powder when compared to the MPI agglomerates. The agglomerated protein powders with MD binder showed significantly higher solubility values than the raw powders. These tendencies were discernible in the morphological examination via SEM analysis. The dynamic modulus values of SPI agglomerates decreased with an increase in MD concentration from 10 to 20% whereas those of MPI agglomerates increased. These findings indicate that the physical, structural, and rheological properties of agglomerated high-protein powders are greatly influenced by the type of protein and the addition of MD binder.

Effect of Thickened Beverage and Swallowing Aid Jelly Used for Dysphagic Patients on the Disintegration of Orally Administered Tablets

Thickened beverages or swallowing aid jelly (SAJ), commonly used as tablet-swallowing aids for dysphagic patients, may influence the disintegration of orally administered tablets. With this in mind, we evaluated the disintegration times of therapeutic tablets immersed in thickened beverages or SAJ compared to immersion in ones without them. Thickened beverages and SAJs were prepared with various beverages (water, orange juice, and milk) using food thickeners and SAJ powders marketed in Korea. The tablet disintegration times were the same in thickened beverages and SAJs, and there was no statistically significant difference associated with the thickness levels of the thickened beverages. The disintegration times of Tylenol immersed in orange juice or milk were slightly higher compared to those immersed in water. Moreover, there was no difference in disintegration time when using the thickened beverages and SAJs. The disintegration times of Aspirin were similar in all of the thickened beverages or SAJs, and there were no differences between non-immersed and immersed tablets. These results demonstrate that the disintegration of Tylenol and Aspirin is not greatly affected by immersion in any of the thickened beverages and SAJs.

Polysaccharide-dextrin thickened fluids for individuals with dysphagia: recent advances in flow behaviors and swallowing assessment methods

The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide-dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide-dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future.

Effect of Molecules' Physicochemical Properties on Whey Protein/Alginate Hydrogel Rheology, Microstructure and Release Profile

The encapsulation of molecules with different physicochemical properties (theophylline, blue dextran, salicylic acid and insulin) in whey protein (WP) and alginate (ALG) microparticles (MP) for oral administration was studied. MP based on WP/ALG were prepared by a cold gelation technique and coated with WP solution after reticulation. Molecules influenced polymer solution viscosity and elasticity, resulting in differences regarding encapsulation efficiency (from 23 to 100%), MP structure and swelling (>10%) and in terms of pH tested. Molecule release was due to diffusion and/or erosion of MP and was very dependent on the substance encapsulated. All the loaded MP were successfully coated, but variation in coating thickness (from 68 to 146 µm) and function of the molecules encapsulated resulted in differences in molecule release (5 to 80% in 1 h). Gel rheology modification, due to interactions between WP, ALG, calcium and other substances, was responsible for the highlighted differences. Measuring rheologic parameters before extrusion and reticulation appeared to be one of the most important aspects to study in order to successfully develop a vector with optimal biopharmaceutical properties. Our vector seems to be more appropriate for anionic high-molecular-weight substances, leading to high viscosity and elasticity and to MP enabling gastroresistance and controlled release of molecules at intestinal pH.

A Thickening Agent Using Dioscorea japonica Powder Exhibits Suitable Properties for People with Dysphagia

In an aging society, the novel concept of added food functionality in a dysphagia diet is necessary for preventing diseases and maintain nutrition intake. The present study evaluated the utilization of Dioscorea japonica as a thickened liquid for people with dysphagia due to its unique physical properties and beneficial effects on chronic inflammation. The viscosity of the prepared thickened liquid using freeze-dried Dioscorea japonica powder was compared with those of xanthan gum and commercially available thickened liquids in selected conditions resembling to cooking. Dioscorea japonica powder showed high versatility, because the viscosity of its thickened liquid could be easily adjusted by modifying its blending amount and temperature. The thickened liquid of Dioscorea japonica had the most stable viscosity among the thickened liquids when NaCl was added and exhibited excellent resistance to α-amylase, similar to that of the other thickened liquids. The viscosity of the thickened liquid of Dioscorea japonica was relatively stable on changing the pH, but it was slightly unstable when the temperature changed. Overall, the thickened liquid of Dioscorea japonica powder has excellent viscosity stability, comparable to or better than commercially available thickened liquids, and is expected to be used as a new thickened liquid with added food functionality.

Testing and Development of Slightly Thick Infant Formula Recipes for Dysphagia Management: An Australian Perspective

Thickened feeds may be useful in supporting improved suck-swallow-breath coordination and airway protection in infants with dysphagia. Unfortunately, the stability of thickened feeds for infant formulas is unpredictable, which makes use of this strategy challenging. This study aimed to propose a set of Level 1 (slightly thick) recipes for Australian infant formulas/thickeners. A secondary aim was to test whether formula could be batch prepared. A set of powdered, ready-to-feed, and specialized formulas were mixed with two thickening products (Aptamil Feed Thickener® and Supercol®) and tested at 5-, 10-, 15-, 20-, 25-, 30-, and 45-min intervals using the International Dysphagia Diet Standardization Initiative (IDDSI) Flow Test. Formula/thickener samples were mixed following manufacturer instructions, but recipes were adapted to determine an ideal recipe for Level 1 (slightly thick) consistency that would be maintained over a feed. Samples were refrigerated, reheated after 12 h, and retested. Each combination was tested six times. Overall, 1,353 IDDSI Flow Tests were conducted using 14 formula/thickener combinations. In all combinations, recipe alterations were made using metric spoon measurements as opposed to the manufacturer-provided scoop. All samples were most variable at the 5-min timepoint. Formulas thickened with Supercol® generally reached a more stable consistency by 10 min, whereas formulas thickened with Aptamil Feed Thickener® were more stable by 15 min. Samples tested after 12 h were more variable with Aptamil Feed Thickener®. This study provides practical recommendations for clinicians working with infants requiring thickened feeds for dysphagia management. Further study under controlled laboratory conditions is required.

Rheological Properties and Stability of Thickeners for Clinical Use

The adaptation of liquids for patients with dysphagia requires precision and individualization in the viscosities used. We describe the variations of viscosity in water at different concentrations and evolution over time of the three compositions of commercial thickeners that are on the market (starch, starch with gums, and gum). By increasing the concentration in water, the viscosity of gum-based thickeners increases linearly, but it did not reach pudding texture, whereas the viscosity of the starch-based thickeners (alone or mixed with gums) rapidly reaches very thick textures. We modeled the viscosity at different concentrations of the four thickeners using regression analysis (R2 > 0.9). We analyzed viscosity changes after 6 h of preparation. The viscosity of gum-based thickeners increased by a maximum of 6.5% after 6 h of preparation, while starch-based thickeners increased by up to 43%. These findings are important for correct handling and prescription. Gum-based thickeners have a predictable linear behavior with the formula we present, reaching nectar and honey-like textures with less quantity of thickener, and are stable over time. In contrast, starch thickeners have an exponential behavior which is difficult to handle, they reach pudding-like viscosity, and are not stable over time.

Rheological Information of Pudding-Thick Liquids Prepared Using Commercial Food Thickeners Marketed in Korea for Dysphagic Patients According to the Manufacturers’ Guidelines

Food thickeners are commonly used to prepare thickened liquids for the management of dysphagia. The National Dysphagia Diet (NDD) thickness levels of thickened liquids prepared with commercial food thickeners are known to vary depending on the thickener type, recommended amount of thickener, thickener brand, and preparation instructions. Particularly, detailed preparation instructions must be provided by the manufacturers to achieve the correct thickness levels. However, the rheological information on product labels provided by manufacturers is typically not accurate. Here, various pudding-thick liquids were prepared by mixing commercial xanthan gum (XG)-based thickeners based on the manufacturers’ guidelines, and their rheological properties were characterized. Several thickened liquids prepared with four different XG-based thickeners (A-D) marketed in Korea did not meet the pudding-like criterion (> 1,750 mPa·s) based on the NDD guidelines. Significant differences in rheological parameter values (η_a,50, n, and G′) were also identified among the various thickened liquids. Only one thickener (thickener A) manufactured in Korea showed optimal results, which satisfied the pudding-thick viscosity range for various food liquids and also showed lower stickiness and enhanced bolus formation ability for easy and safe swallowing when compared to other thickeners (B, C, and D).

Institutionalized elderly are able to detect small viscosity variations in thickened water with gum-based thickeners: should texture classifications be reviewed?

BACKGROUND

The prevalence of dysphagia is very high in institutionalized elderly. Knowledge of the rheological and sensory characteristics of the various thickeners in elderly is limited, although it has been seen that there are differences between the rheological behaviors of gum-based thickeners with different composition. Moreover, we have not found sensory studies of viscosity in institutionalized elderly. Our hypothesis was that viscosity ranges established by the scientific societies, such as the National Dysphagia Diet Task Force (NDD), seem to be very wide and individuals might be able to detect small differences within the same texture range. The objectives of our study were 1) comparing the rheological characteristics of two commercial gum-based thickeners with different composition, dissolved in water under standard conditions, and 2) perform a sensory analysis (with both adults and institutionalized elderly) to detect different viscosities within the same texture (nectar and honey).

METHODS

Two commercial thickeners based on gums (NC and RC) were studied analyzing their viscosity in water with different concentrations (shear rate: 50 s^- 1; temperature: 22-25 °C). A sensory analysis involving 26 elderly and 29 adult controls was carried out to evaluate whether differences within nectar and honey textures among gum-based thickeners could be distinguished.

RESULTS

As the shear rate increases, viscosity decreases (non-Newtonian and pseudoplastic behavior). At the same concentration, each thickener produces a different viscosity (p < 0.05). Institutionalized elderly detected viscosity differences in nectar range of 49.9 (2.5) mPa·s (p < 0.05) and 102.2 (4.7) mPa·s (p < 0.0001). They also detected viscosity differences in honey texture range of 134.6 (9.7) mPa·s (p < 0.05) y 199.3 (9.2) mPa·s (p < 0.0001). Their caregivers also detected viscosity differences in both viscosity ranges (p < 0.0001) and with greater intensity than the elderly in honey texture (p: 0.016).

CONCLUSIONS

Our results suggest that the accepted viscosity ranges by NDD for the different textures might be too wide because institutionalized elderly and their caregivers are able to discern small differences in viscosity in nectar and honey textures. Gum-based thickeners with different composition showed differences in viscosity capacity, so they are not interchangeable.

Relationship between Syringe Flow Measurements and Viscosity of Nectar-Thick Beverages for Dysphagia Management

Commercial cold beverages thickened with a xanthan gum (XG)-based food thickener were examined at different thickness levels by using the simple, cost-effective syringe flow test (SFT) developed by the International Dysphagia Diet Standardization Initiative (IDDSI). We prepared cold thickened beverage (CTB) samples with different thickener concentrations and measured them by extrapolating the viscosity range (51–350 mPa·s) for nectar-like consistency. CTBs were also measured via the line-spread test (LST), and the flow distance value (cm) by LST and the volume remaining (mL) in the syringe by SFT was correlated with the apparent viscosity (η_a,50). Plots comparing η_a,50 with SFT or LST values showed good exponential relationships between the measurements. The SFT showed a better relationship (R² = 0.928) than LST (R² = 0.825), indicating that the former can predict the viscosity better in the range for nectar-like consistency. In particular, the SFT showed a significant difference (R² = 0.964) compared to the LST (R² = 0.709) for thickened protein-based beverages. These results suggest that the SFT using the IDDSI methodology is a more suitable instrument than the LST for accurately evaluating the viscosity of XG-based CTBs with nectar-like consistency.

Effect of Various Types of Sugar Binder on the Physical Properties of Gum Powders Prepared via Fluidized-Bed Agglomeration

Particle agglomeration of fine gum powders to improve their physical and morphological characteristics is of crucial importance. Changes in the physical properties of guar gum, locust bean gum, and carboxymethyl cellulose powders subjected to fluidized-bed agglomeration with various sugar types as the binder were examined. The agglomerates with sugar binders had much larger particles (D₅₀) and higher porosity (ε) than the corresponding fine gum powders, as confirmed by particle-size-distribution analysis and scanning electron microscopy. In particular, the carboxymethyl cellulose agglomerate exhibited much higher D₅₀ and ε values than the original fine gum powder, with sorbitol as the binder resulting in the highest D₅₀ and ε values. Except for guar gum with sorbitol as the binder, the guar gum and locust bean gum agglomerates with the other sugar binders showed lower Carr index and Hausner ratio values (thus exhibiting better flowability and lower cohesiveness) than the original powders, whereas those of the carboxymethyl cellulose agglomerates were higher. These findings indicate that the physical and structural properties of gum powders can be greatly improved according to the type of gum and sugar solution used in the agglomeration process.

Dysphagia-Related Health Information Improved Consumer Acceptability of Thickened Beverages

Most people tend to think that healthy foods do not taste good. This view could have a negative impact on the taste of the food that people eat for health. However, if health-related information is provided to avoid negative aspects, acceptability may improve. Thus, this study investigated changes in consumers’ sensory perception of thickened beverages before and after the provision of dysphagia-related health information. Sixty young (19–39 years old) and middle-aged (40–64 years old) consumers participated in two experiment sessions conducted one week apart. The first session proceeded without any information and the second provided information about dysphagia and the need for dietary modification before evaluation. Three beverages (orange juice, red bean water, and sports drink) were used in nectar-like (51–350 cP) and honey-like (351–1750 cP) forms; original beverage samples (0%) were used as the control. Consumers were asked about acceptability, liking the flavor, intensity, and general health interest (GHI). An analysis of variance was performed to show the change in flavor rating and acceptability between the two sessions. Although there were age-related differences in response to the samples, thickened beverages were rated as more acceptable, in terms of their characteristics (swallowing, viscosity, and mouthfeel) after the information was provided. There were no significant differences for the 0% samples. The mean GHI values were 3.97 ± 0.85 and 4.81 ± 0.68 for the young and middle-aged groups, respectively. High and low GHI groups were analyzed. The high GHI group showed significant differences in acceptability in the informed evaluation, whereas the low GHI group was not influenced by the information.

Texture-Modified Food for Dysphagic Patients: A Comprehensive Review

Food texture is a major food quality parameter. The physicochemical properties of food changes when processed in households or industries, resulting in modified textures. A better understanding of these properties is important for the sensory and textural characteristics of foods that target consumers of all ages, from children to the elderly, especially when food product development is considered for dysphagia. Texture modifications in foods suitable for dysphagic patients will grow as the numbers of elderly citizens increase. Dysphagia management should ensure that texture-modified (TM) food is nutritious and easy to swallow. This review addresses how texture and rheology can be assessed in the food industry by placing particular emphasis on dysphagia. It also discusses how the structure of TM food depends not only on food ingredients, such as hydrocolloids, emulsifiers, and thickening and gelling agents, but also on the applied processing methods, including microencapsulation, microgels as delivery systems, and 3D printing. In addition, we address how to modify texture for individuals with dysphagia in all age groups, and highlight different strategies to develop appropriate food products for dysphagic patients.

Cellulose derivatives agglomerated in a fluidized bed: Physical, rheological, and structural properties

Understanding the agglomeration of cellulose derivatives is crucial for the production of instant gum-based food thickeners. In the present study, physical, rheological, and structural properties of agglomerated water-soluble cellulose gums (CGs), such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), and methylcellulose (MC), were investigated at different concentrations of maltodextrin (MD) as a binder for fluidized-bed agglomeration. Among the CG agglomerates in the presence of MD, CMC exhibited better flowability and lower cohesiveness, showing lower Carr index and Hausner ratio values. The MC agglomerates with 20% MD exhibited higher porosity than the other CGs due to the size enlargement of MC particles, which was confirmed via scanning electron microscopy images and size distribution profiles. The dynamic moduli of the CG agglomerates were significantly decreased by the addition of MD and also decreased with increasing MD concentration. The tan δ values of the agglomerates increased with increasing MD concentration, indicating the enhancement of their viscous properties. These results suggest that the physical, rheological, and structural properties of cellulose derivatives with different types of CG can be greatly influenced by their agglomerate growths during fluidized-bed agglomeration of particles with the different concentrations of MD binder.

Rheological and Textural Properties of Apple Pectin-Based Composite Formula with Xanthan Gum Modification for Preparation of Thickened Matrices with Dysphagia-Friendly Potential

Modifying the consistency of a given edible fluid matrix by incorporating food thickeners is a common nursing remedy for individuals with dysphagia when adequate water consumption is a concern. As apple pectin (AP) offers nutraceutical benefits, properly formulated apple pectin (AP)-based thickeners featuring xanthan gum (XG) can be superior candidates for preparation of dysphagia-friendly matrices (DFMs). Our recruited DFMs exhibit fluid-like behavior (loss modulus > storage modulus, G" > G') at lower AP concentrations (2 and 5%, w/w); they turn into weak/critical gels (G' ≈ G") as the concentration becomes higher (9%). In contrast, XG-DFMs display gel-like attributes with G' > G", even at rather low concentrations (<1%) and become more resistant to sugar, Na+, and Ca2+ modifications. The composite matrix of AP1.8XG0.2 (constraint at 2%) exhibits a confined viscosity of 278 ± 11.7 mPa∙s, which is considered a DFM, in comparison to only AP- or XG-thickened ones. The hardness measurements of XG0.6 and AP1.2XG0.8 are 288.33 ± 7.506 and 302.00 ± 9.849 N/m2, respectively, which potentially represent a promising formulation base for future applications with DFMs; these textural values are not significantly different from a commercially available product (p > 0.05) for dysphagia nursing administrations.

Effect of Thermal Processing on Flow Properties and Stability of Thickened Fluid Matrices Formulated by Tapioca Starch, Hydroxyl Distarch Phosphate (E-1442), and Xanthan Gum Associating Dysphagia-Friendly Potential

The flow behavior of the administrated fluid matrices demands careful assessments for stability when consumed by individuals with dysphagia. In the present study, we incorporated tapioca starch (TS), hydroxypropyl distarch phosphate (HDP), and xanthan gum (XG) as thickeners into different nectars (300 ± 20 mPa.s) undergoing thermal processing and evaluated their stability. The thickened nectars presented better water holding and oil binding capacities at 25 °C than 4 °C, and the nectars with TS provided the best results for both capacities as well as the highest solubility index and swelling power (p < 0.05). All prepared nectars appeared to be shear-thinning fluids with yield stress closely fitting the power law and Casson models. XG-containing nectars presented a higher yield stress and consistency index. Matrices thickened by HDP exhibited a higher viscoelastic property compared to those thickened by TS during thermal processing. TS nectars presented viscous behavior, whereas HDP and XG nectars presented elastic behavior at 80 °C processing. The 3 min thermal processing HDP nectars remained stable and met dysphagia-friendly requirements under 4 °C storage for 28 days, regardless of the type of fluid base (distilled water, sport drink, or orange juice). The employed thickeners present adequate physicochemical properties to be potentially utilized for producing dysphagia-friendly formulations.

Agglomeration of galactomannan gum powders: Physical, rheological, and structural characterizations

Galactomannans (GM), such as guar gum (GG) and locust bean gum (LBG), are extensively used as a thickening agent in the food industry. In this work, the physical, rheological, and structural properties of GG and LBG agglomerated via a fluidized bed agglomerator with different concentrations of maltodextrin (MD) binder were investigated. Agglomerated GM at 40 % MD showed lower Carr index and Hausner ratio, indicating better flowability and lower cohesiveness. The GG showed larger particle sizes than LBG, which was confirmed via SEM images and size distribution profiles. The GM with MD exhibited improved rheological properties. The GG showed lower tan δ values than LBG, indicating the enhancement of their elastic properties. Results exhibit that the physical, rheological, and structural properties of GM can be greatly affected by their agglomerate growths during fluidized bed agglomeration of particles with varying concentrations of MD binder as well as the type of gum.

Validating the textural characteristics of soft fish-based paste through International Dysphagia Diet Standardisation Initiative recommended tests

One in every twelve people worldwide suffers from dysphagia that affects the swallowing mechanism and some patients require a special texture-modified food for their sustenance. Fish is a great source of nutrients and proteins, however the commercially dysphagia diet made from fish is limited. This study investigated the textural characteristics of a soft fish paste produced from steamed grass carp fillet with different the water addition, grinding cycles and ratio of starch with the mixture of steamed fillet and water, following International Dysphagia Diet Standardisation Initiative (IDDSI) guidelines and other instruments. The water addition and particle size affected the physical properties, and the starch had a certain masking effect on fishy odor. The mixture of steamed fish fillets and water (91:9 wt/wt) was ground in a colloid mill for 3 cycles. The fish paste was then sterilized by adding sugar, salt, and starch in the mixture (ratios of 0.5:100, 0.5:100, and 0.6:100, wt/wt, respectively) and mixing well. The paste conformed to Level 4-pureed and extremely thick of IDDSI framework. The fish paste product had a light fishy odor that was acceptable to sensory specialists.

Effect of Disintegrants on Prolongation of Tablet Disintegration Induced by Immersion in Xanthan Gum-Containing Thickening Solution: Contribution of Disintegrant Interactions with Disintegration Fluids

In clinical practice, a thickening solution is frequently used to allow easy swallowing of tablets by patients suffering from dysphagia. This study investigated the effect of the thickening solution on tablet disintegration. Model tablets containing different disintegrants were prepared and their disintegration times (DTs) measured using standard methods. We also performed an additional disintegration test on the model tablets after immersing them for 1 min in thickening solution containing xanthan gum (XTG-SOL) ("modified disintegration test"). The DTs of the test tablets were substantially prolonged by immersion in XTG-SOL. Furthermore, the effect of the XTG-SOL on the DTs differed depending on the type of disintegrant contained in the tablets. To investigate in more detail this prolongation of tablet disintegration, we examined the contribution of tablet properties to their DTs. The properties analyzed included contact angle, T₂ relaxation time, wetting time, and water absorption ratio. The contributions of these properties to the DTs were analyzed using multiple regression analysis. This analysis clarified that the tablet properties affecting DTs changed after immersion in XTG-SOL: wetting time significantly affected the DTs measured in the normal disintegration test, while T₂ was crucial for the DTs of tablets immersed in XTG-SOL. These findings provide valuable information for design of tablet formulations, and for clinical medication management for older patients with dysphagia.

Development of an Accurate Bedside Swallowing Evaluation Decision Tree Algorithm for Detecting Aspiration in Acute Respiratory Failure Survivors

BACKGROUND

The bedside swallowing evaluation (BSE) is an assessment of swallowing function and airway safety during swallowing. After extubation, the BSE often is used to identify the risk of aspiration in acute respiratory failure (ARF) survivors.

RESEARCH QUESTION

We conducted a multicenter prospective study of ARF survivors to determine the accuracy of the BSE and to develop a decision tree algorithm to identify aspiration risk.

STUDY DESIGN AND METHODS

Patients extubated after ≥ 48 hours of mechanical ventilation were eligible. Study procedures included the BSE followed by a gold standard evaluation, the flexible endoscopic evaluation of swallowing (FEES).

RESULTS

Overall, 213 patients were included in the final analysis. Median time from extubation to BSE was 25 hours (interquartile range, 21-45 hours). The FEES was completed 1 hour after the BSE (interquartile range, 0.5-2 hours). A total of 33% (70/213; 95% CI, 26.6%-39.2%) of patients aspirated on at least one FEES bolus consistency test. Thin liquids were the most commonly aspirated consistency: 27% (54/197; 95% CI, 21%-34%). The BSE detected any aspiration with an accuracy of 52% (95% CI, 45%-58%), a sensitivity of 83% (95% CI, 74%-92%), and negative predictive value (NPV) of 81% (95% CI, 72%-91%). Using recursive partitioning analyses, a five-variable BSE-based decision tree algorithm was developed that improved the detection of aspiration with an accuracy of 81% (95% CI, 75%-87%), sensitivity of 95% (95% CI, 90%-98%), and NPV of 97% (95% CI, 95%-99%).

INTERPRETATION

The BSE demonstrates variable accuracy to identify patients at high risk for aspiration. Our decision tree algorithm may enhance the BSE and may be used to identify patients at high risk for aspiration, yet requires further validation.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT02363686; URL: www.clinicaltrials.gov.

Standard Recipes for the Preparation of Thickened Barium Liquids Used in the Diagnosis of Dysphagia

Barium sulfate is commonly used to prepare contrast media for videofluorograpy. The flow characteristics of thickened liquids formulated for oropharyngeal imaging are known to be greatly affected by the addition of barium. In this study, thickened barium liquids were prepared by mixing a commercial xanthan gum (XG)-based thickener (Visco-up^®) at different concentrations (0.1%-3.0%) with barium powder (Baritop HD^®), and differences in the viscosity between thickened non-barium and thickened barium liquids were investigated. In addition, the thickness levels of thickened barium liquids, which are based on the National Dysphagia Diet (NDD) and International Dysphagia Diet Standardization Initiative (IDDSI) guidelines, were classified by measuring the viscosity (NDD) and gravity flow through a syringe (IDDSI) with 0.1%-3.0% thickener concentrations. The apparent viscosity (η_a,50) values of thickened barium liquids were much higher than those of thickened non-barium liquids, indicating that the addition of barium to the XG-based thickener resulted in further thickening. Standard recipes for preparing thickened barium liquids with desirable thickness levels were also established, showing the different thickener concentrations corresponding to the different NDD and IDDSI levels.

The impact of modification techniques on the rheological properties of dysphagia foods and liquids

Modifying food and the textures of food has been done for decades within the food science and technology field. More recently, modifying the texture of foods has been used to manage swallowing disabilities (dysphagia). Swallowing disabilities are often associated with dehydration and malnutrition, thus nutritional intervention has formed part of serving texture-modified diets. The question remains whether these modification techniques are viable for individuals with swallowing disabilities living in majority world countries. This study used two modification methods on a widely used specialized nutritious food (SNF) to determine whether it may be modified and used in dysphagia management. The techniques had to be ergonomic and economically appropriate for individuals with swallowing disabilities living in majority world countries. The International Dysphagia Diet Standardization Initiative's (IDDSI) standards were used to determine whether the texturally modified SNF is safe for swallowing. Rheological measurements were performed to determine apparent viscosity and structure recovery of each sample. The effects of two modification techniques, aeration and particle separation, on the rheological properties of the SNF were also measured and analyzed. It was determined that both milk and water could be used with this SNF to create a dysphagia diet, but only under certain conditions. The overall results indicated that heating the samples increased the apparent viscosity and exacerbated lumping. Room temperature samples had less lumps and could be classified to the desired levels of the IDDSI (Level 2 and Level 4). Using a whisk to aerate the samples reduced lumps significantly and using a sieve to separate particles of liquid samples eliminated lumps. This study provides new data on how texture modification techniques and the IDDSI framework could be adapted to individuals living in majority world countries. By using modification techniques that are ergonomic and economically viable and an SNF with longevity, this study could be useful in guiding future training of nursing staff and caregivers of individuals living in poverty or resource-constrained communities. This study also adds to the data on the rheological properties of dysphagia foods, although this study did not make use of commercial thickeners generally used in the modification of diets.

Effects of Cellulose Gums on Rheological Interactions in Binary Mixtures of Xanthan Gum and Locust Bean Gum

The effects of cellulose gums (CG), such as carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC), on the flow and dynamic rheological properties of binary mixtures of xanthan gum (XG) and locust bean gum (LBG) were examined at different XG/LBG/CG mixing ratios (50/50/0, 47.5/47.5/5.0, 45/45/10, and 42.5/42.5/ 15.0). All XG/LBG/CG ternary mixtures showed high shear-thinning behavior and the flow behavior index values of samples containing HPMC were lower than those of samples containing CMC. An increase in consistency index and apparent viscosity values was observed for ternary gum mixtures containing HPMC, indicating that the flow properties of the XG/ LBG binary mixture were affected by the content of HPMC. Storage modulus and loss modulus values of ternary gum mixtures decreased with an increase in CG content from 5 to 15%. The maximum viscoelasticity of XG/LBG/CG mixtures was observed at a mixing ratio of 47.5/47.5/5.0. These findings suggest that the rheological properties of XG/LBG binary mixtures were strongly influenced by the addition of CMC and HPMC.

Rheological studies on the effect of different thickeners in texture-modified chicken rendang for individuals with dysphagia

Texture-modified food has become an important strategy in managing dysphagia. Pureed food is proven to be the safest texture due to its high viscosity which can slow down the rate of the food bolus during swallowing. In this study, texture-modified chicken rendang was developed according to Texture C (smooth puree) as described by the Australian standard for texture-modified food. Samples were added with five different thickeners (sago starch, tapioca starch, modified corn starch, xanthan gum and carboxymethyl cellulose gum) at three different concentrations (10, 20 and 30% w/w). Their rheological effects were analyzed through dynamic and steady shear test. Results obtained reveals that samples contained xanthan gum have higher structure rigidity and shear thinning behaviour, while carboxymethyl cellulose gum provides the highest viscosity as well as yield stress than other samples. In terms of concentration, a strong dependence of structural rigidity and viscosity of all prepared samples with amount of thickeners added was observed. Overall, based on its rheological properties, the addition of carboxymethyl cellulose gum at 30% concentration was found to be the most suitable thickener, to be incorporated in the texture-modified chicken rendang. Selecting a suitable food thickener in developing food for individual with dysphagia plays an important role to ensure the right texture and consistency for their safe consumption.

Comparative study of IDDSI flow test and line-spread test of thickened water prepared with different dysphagia thickeners

The flow behaviors of thickened water samples prepared with six commercial instant thickeners (A-F) were investigated at different thickness levels using the inexpensive, simple, and visual clinical tools, such as a line-spread test (LST) and a syringe flow test developed by the International Dysphagia Diet Standardization Initiative (IDDSI). Both the flow distance value measured by the LST and the volume remaining in syringe by IDDSI flow test were compared with the apparent viscosity (η_a,50 ) values measured with a sophisticated computer-controlled rheometer. The η_a,50 values of thickened water samples increased as thickener concentration increased, whereas the flow distance (cm; LST) or remaining volume (ml; IDDSI flow test) were decreased. Plots comparing η_a,50 values to LST flow distances and IDDSI volumes revealed exponential relationships (R²  = 0.926 for the LST and R²  = 0.898 for IDDSI test) between the two measurements. Such lower determination coefficient (R² ) values (0.898) by IDDSI flow test seems to be due to the stickiness characteristics of starch component in starch-based thickeners (E and F), indicating that the syringe flow test is not suitable for starch-based thickeners. However, the thickened water samples prepared only with xanthan gum (XG)-based thickeners (A-D) showed strong relationships (R²  = 0.972 for the LST and R²  = 0.939 for IDDSI test). These results suggest that the LST is a more reliable method than the IDDSI test for evaluating the correct and desirable viscosity for the dysphagia diet, and that the IDDSI test provides a means to predict the rheometer-measured viscosity of water thickened with only XG-based thickeners. PRACTICAL APPLICATIONS: The effective management of dysphagia requires the thickened fluids prepared with the correct and desirable viscosity. In terms of clinical practice, it is very important to observe the comparison of LST with IDDSI flow test to determine a suitable method for estimating the correct viscosity of thickened fluids. Our results showed good relationships between the rheometer-measured viscosity and flow values measured by the LST and IDDSI test methods for the thickened water samples prepared with different foods thickeners. The IDDSI flow test may be useful as a clinical training tool for preparing thickened fluids with only XG-based thickeners to a target level of viscosity. These results presented in this study will provide clinicians, caregivers, and patients with valuable information for IDDSI flow test as an inexpensive and simple method for measuring the correct viscosity.

Optimizing Texture Modified Foods for Oro-pharyngeal Dysphagia: A Difficult but Possible Target?

Dysphagia is a swallowing disorder characterized by the difficulty in transferring solid foods and/or liquids from the oral cavity to the stomach, imparing autonomous, and safe oral feeding. The main problems deriving from dysphagia are tracheo-bronchial aspiration, aspiration pneumonia, malnutrition and dehydration. In order to overcome dysphagia-induced problems, over the years water and food thickening has been used, focusing specifically on viscosity increase, but limited results have been obtained. Elastic components and their effects on the cohesiveness on the bolus should be taken into account in the first place. We provide an analysis of dysphagia and suggest possible corrections to the protocols which are being used at present, taking into account rheological properties of food and the effect of saliva on the bolus. We reckon that considering such aspects in the dysphagia management market and healthcare catering would result in significant clinical risk reduction.

Rheological characterization of thickened protein-based beverages under different food thickeners and setting times

The effects of different setting times (15-120 min) on the rheological properties of cold thickened protein-based beverage (PBB) samples prepared with different xanthan gum (XG)-based food thickeners were examined. In this study, four commercial XG-based food thickeners (coded A-D) and three commercial PBB products (whole milk, skim milk, and soybean milk) were used to prepare thickened PBB samples at a 3% thickener concentration. The fastest increases in η_a,50 values of thickened PBB samples were observed at 15 min, and at longer time periods their η_a,50 values gradually increased or remained constant with an increase in setting time (15-120 min). The magnitudes of the rheological parameters (η_a,50 , K, G', and G″) of thickened PBB samples with thickener A were significantly higher compared with those with other thickeners (coded B, C, and D). The flow and dynamic rheological properties of thickened PBB samples prepared with different XG-based thickeners were significantly different (p < .05), demonstrating that their rheological properties were greatly affected by the type of PBB and thickener as well as the setting time.

PRACTICAL STATEMENTS

Food thickeners have been commonly used in the preparation of various thickened fluids with desirable rheological properties for dysphagic patients to elicit an optimal swallow response. However, among various thickened fluids, there is limited rheological information on cold thickened protein-based beverage (PBB) (e.g., whole milk, skim milk, and soybean milk) prepared with various xanthan gum (XG)-based thickeners. Our flow and dynamic rheological results showed that the flow and viscoelastic properties of the thickened PBB samples prepared with different food thickeners were dependent on the PBB type, thickener type, and setting time. These rheological results presented in this study will provide both thickener manufacturers and clinicians with valuable information for thickened PBB products with desirable rheological properties for safe and easy swallowing. New knowledge of the different rheological characterizations of thickened PBB can be practically applied to develop the commercial dysphagia thickeners suitable for PBB in food industry.

Effect of Maltodextrin on Physical Properties of Granulated Xanthan Gum Prepared by Fluidized-Bed Granulator

Fluidized-bed granulation has received considerable attention within the food process industry because granulated products often have improved flowability and appearance, and sometimes have specifically enhanced physical properties. In this study, the rheological properties of granulated xanthan gum (XG), commonly used as a main ingredient in food thickeners for dysphagia diets, were investigated at different concentrations (0, 5, 10, and 15 % w/w) of maltodextrin (MD) as a binder at different concentrations. Flowability and cohesiveness of granulated XG powder was also evaluated in terms of as Carr index (CI) and Hausner ratio (HR) were also investigated. The consistency index, apparent viscosity, storage modulus (G’) and loss modulus (G”) of granulated XG were significantly higher than those of non-granulated XG and granulated XG without binder (0 % MD). The tan δ values of granulated samples were lower compared with that of a non-granulated sample, indicating that their elastic properties were more pronounced because of the granulation. These rheological results also showed that there were no noticeable changes in flow properties between 0 % and 5 % MD concentrations, whereas the G’ and G” values at 10 % MD were much higher than those at other concentrations. The granulation process by MD binder also enhanced considerably flow characteristics of XG powder.