Dysphagia has emerged as a serious health issue facing contemporary society. Consuming thickened liquids is an effective approach for improving the swallowing safety for dysphagia patients. The thickening effect of chia seed gum (CSG), a novel thickener, in different dispersing media (water, orange juice, and skim milk) was investigated. Moreover, the potential application of CSG for dysphagia management was evaluated by comparison with xanthan gum (XG) and guar gum (GG). The thickened liquids prepared with 0.4 %-1.2 % (w/v) CSG, XG, and GG could be classified into levels 1-4, 2-4, and 1-3, respectively, according to the International Dysphagia Diet Standardization Initiative (IDDSI) framework. All the thickened liquids displayed shear-thinning characteristics that facilitated safe swallowing. The viscosities (η50) of CSG dissolved in water (0.202-1.027 Pa·s) were significantly greater than those of CSG dissolved in orange juice (0.070-0.690 Pa·s) and skim milk (0.081-0.739 Pa·s), indicating that CSG had a greater thickening effect in water than in orange juice and skim milk. Compared with those prepared with GG, the thickened liquids prepared with CSG and XG exhibited greater viscoelasticity, better water-holding capacity, and more compact networks. The findings suggested that CSG can be used as a potential thickener for thickening liquid foods to manage dysphagia.

A dysphagia diet is a special eating plan. The development and design of dysphagia foods should consider both swallowing safety and food nutritional qualities. In this study, the effects of four food supplements, namely vitamins, minerals, salt and sugar, on swallowing characteristics, rheological and textural properties were investigated, and a sensory evaluation of dysphagia foods made with rice starch, perilla seed oil and whey isolate protein was carried out. The results showed that all the samples belonged to foods at level 4 (pureed) in The International Dysphagia Diet Standardization Initiative (IDDSI) framework, and exhibited shear thinning behavior, which is favorable for dysphagia patients. Rheological tests showed that the viscosity of a food bolus was increased with salt and sugar (SS), while it decreased with vitamins and minerals (VM) at shear rates of 50 s-1. Both SS and VM strengthened the elastic gel system, and SS enhanced the storage modulus and loss modulus. VM increased the hardness, gumminess, chewiness and color richness, but left small residues on the spoon. SS provided better water-holding, chewiness and resilience by influencing the way molecules were connected, promoting swallowing safety. SS brought a better taste to the food bolus. Dysphagia foods with both VM and 0.5% SS had the best sensory evaluation score. This study may provide a theoretical foundation for the creation and design of new dysphagia nutritional food products.

The effects of Astragalus polysaccharide (APS) on rheological, textural, water-holding, and microstructural properties of mung bean starch (MBS)/flaxseed protein (FP) composite gels were investigated. Results showed that the storage modulus (G\') of gels with APS were significantly lower than that of the control gel, while different concentrations of APS possessed diverse effects on the hardness, gumminess and cohesiveness of the gels. Adding APS significantly improved the water retention capacity by trapping more immobilized and free water in the gel network. Microstructurally, the MBS/FP/APS composite gels displayed a complex network with reduced pore size compared with that of the control gel (MBS/FP). International dysphagia diet standardization initiative (IDDSI) tests suggested that gels with APS contents below 0.09 % could be classified into level 6, while gel with 0.12 % APS could be categorized as level 7. Mechanistically, APS could influence the interactions between starch and protein within the tri-polymeric composite systems by affecting starch gelatinization and hydrogen bonding, further contributing to the formation of strengthened gel network and the change of gel properties. These results suggest that the macromolecular APS can improve the structural and textural properties of the starch-protein composite systems, and impart various functional properties to the FP-based gel foods.

Effects of calcium gluconate (CG), calcium lactate (CL) and calcium dihydrogen phosphate (CDP) on the structural and functional properties of mung bean starch (MBS)-flaxseed protein (FP) composite gels were investigated to explore the feasibility of developing dysphagia food. The water-immobilizing, rheological and structural properties of MBS-FP composite gels adding different calcium salts (10, 30, and 50 mmol/L) were analyzed by low-field nuclear magnetic resonance measurement, rheological and textural analyses, fourier transform infrared spectroscopy, scanning electron microscopy and confocal laser scanning microscopy. Results showed that calcium salts imparted various soft gel properties to the composite gels by influencing the interactions between MBS and FP. Calcium salts could affect the conformation of amylose chains, accelerate the aggregation of FP molecules, and increase the cross-linking between starch and protein aggregates, resulting in the formation of large aggregates and a weak gel network. Consequently, calcium salts-induced composite gels showed lower viscoelastic moduli and gel strength than the control gel. In particular, different calcium salts had various impacts on the gel properties due to their diverse ability forming hydrogen bonds. Compared with CL and CDP, the gels containing CG presented the higher viscoelastic moduli and hardness, and possessed an irregular cellular network with the increased pore number and the decreased wall thickness. The gel containing 50 mmol/L CL had the highest water-holding capacity, in all the gels tested, by retaining more immobilized and mobile water in the compact gel network with larger cavities. The gels adding CDP presented lower hardness and gumminess due to the obvious lamellar structure within the network. International dysphagia diet standardization initiative (IDDSI) tests indicated that the gels adding CG and CL could be categorized into level 6 (soft and bite-sized) dysphagia diet, while the samples adding CDP could be classified into level 5 (minced and moist). These findings provide insights for the development of the novel soft gel-type dysphagia food.

Thickened fluids are commonly used in the medical management of individuals who suffer from swallowing difficulty (known as dysphagia). International Dysphagia Diet Standardization Initiative (IDDSI) developed a standardized terminology and description for texture-modified foods and thickened fluids to allow dysphagia patients to receive the correct consistency of food/drink. Syringe flow test and fork drip test are suggested by IDDSI to identify the drink category (IDDSI Levels 1-4). These practical methods are widely welcomed by carers and patients because of their simplicity. However, these methods are not most feasible for industrial applications, where objective measurements are required for industry for the purpose of quality control of such products. Therefore, our aim in this work was to develop quantitative and objective measurements that best describe IDDSI level category for use as an objective framework. Two measuring techniques, syringe flow test and fork drip test, recommended by IDDSI were evaluated in two different sets of experiment. Participants were recruited to categorize fluid samples of known texture parameters using syringe flow test and fork drip test techniques. The apparent stress measured from Ball-Back Extrusion (BBE) technique for each of the fluid category (IDDSI Levels 1-4) was calculated. Bands of apparent stress for each of the fluid category were developed from two measuring techniques, syringe flow test and fork drip test. An inconsistency was observed between these two measuring techniques for IDDSI Level 3 fluid due to different dominating factors in the two tests. However, we proposed to combine the results from the two experiments to develop a quantitative range for each IDDSI Level as objective complements to the IDDSI Framework. Thickened fluid manufacturers are encouraged to follow the proposed guidelines presented once they are clinically validated and use them fine-tune their products, thus enhancing the safety of individuals with dysphagia.

Texture-modified foods and thickened fluids play a major role in clinical treatment for individuals who suffer from swallowing difficulties (known as dysphagia). International Dysphagia Diet Standardization Initiative (IDDSI) developed a standardized terminology and description for texture-modified foods and thickened fluids to allow dysphagia patients to receive the correct consistency of food/drink. While the IDDSI framework provides a consistent texture description (Levels 0-7) and is widely accepted as an international standard, testing and assessment of IDDSI texture level are qualitative in nature and subjective in manner. These methods were proposed primarily for use by frontline carers, but are not most ideal for industrial purposes of quality control of such products. Therefore, the main aim of this work was to develop a quantitative instrumental method that best describes IDDSI levels as an objective framework. A set of test samples, including commercially available instant mashed potato, baby rice cereal, and cooked potato cubes of varying texture, were prepared. Two IDDSI measuring techniques, fork pressure test and spoon tilt test, were used to evaluate texture grades of these samples. Puncture and compression tests based on texture analyzer were used to assess cohesiveness, adhesiveness, firmness, and hardness for each food category (Levels 4-7). Thresholds of cohesiveness and adhesiveness, as well as bands of acceptable firmness and hardness for each food category were clearly identified and are proposed as objective complements to the IDDSI framework.

The International Dysphagia Diet Standardization Initiative (IDDSI) proposed the flow test (FT) as a simple method for measuring the viscosity of thickened liquids. However, the FT specifies the use of a particular syringe type (BD-Slip), which is unfortunately not easily available in Japan. Therefore, the current study primarily aimed to investigate the effects of the internal syringe shape on IDDSI FT and identify the most suitable syringe available in Japan for xanthan gum-based thickened liquids. Accordingly, four syringes, namely, Luer slip tip, Luer-Lok tip, TERUMO, and NIPRO syringes, were used to examine FT value with water and nine different water viscosity levels. The correlation and systematic errors on residual FT values between the BD-Slip syringe and the other three syringes were analyzed. The two-dimensional internal shapes of the four syringes were measured using industrial computed tomography (CT) scanning. Based on the results of our FT, TERUMO had the smallest error range among the three syringes, without systematic errors. On a CT scan, three of five tip-shape parameters showed the smallest difference between BD-Slip and TERUMO syringe. Therefore, TERUMO had the smallest FT error range compared with that in BD-Slip tip syringe, indicating that TERUMO could be used as a substitute for BD-Slip when performing IDDSI FT with xanthan gum-based thickened water in Japan.

With the speeding tendency of aging society, the population experienced dysphagia is increasing quickly. Desirable dysphagic diets should be safe, visually appealing and nutritious. 3D printing allows for creation of personalized nutritious foods with regular-like appearance. Shiitake mushroom, rich in protein and bioactive compounds, is suitable for elderly, but its hard texture was not friendly to the elderly with dysphagia. This study investigated the feasibility of production of dysphagic product using shiitake mushroom by 3D printing with various gums addition, including arabic gum (AG), xanthan gum (XG) and k-carrageenan gum (KG) at concentrations of 0.3%, 0.6% and 0.9% (w/w). Data suggested that XG and KG incorporation significantly increased inks\' mechanical strength by decreasing water mobility and promoting the formation of hydrogen bond, enabling 3D printed objects with great self-supporting capacity. The XG containing and KG-0.3% samples were categorized into level 5-minced and moist dysphagia diet within international dysphagia diet standardization initiative (IDDSI) framework. AG addition decreased mechanical strength and viscosity, hardness and self-supporting capacity of 3D printed constructions. AG-0.3% and AG-0.6% samples could not be classified as dysphagia diets based on IDDSI tests. This study provides useful information for dysphagia diet development with appealing appearance by 3D printing.

Dysphagia is a highly prevalent eating and swallowing disorder among elderly people, impacting negatively on the health and well-being of those afflicted. With increasing populations of elderly people, food industries are under growing pressure to produce appropriately texture-modified food for safe consumption by these vulnerable populations. Recently published International Dysphagia Diet Standardisation Initiative (IDDSI) framework provides a new global guideline on texture modification and standardization for dysphagia patients. This work was designed to test the feasibility of IDDSI framework for clinical applications by assessing the correlation between swallowing capability of dysphagia patients and the IDDSI texture levels. Altogether 26 elderly subjects were recruited and assessed for their dysphagia grades using the Water Drinking Test. Subjects were provided with fluid samples constituted at different consistencies from a commercial product and swallowing performance (time of swallowing, number of swallows, and number of coughs) was monitored and recorded. Correlations among swallowing capability parameters were observed. Most importantly, results from this work clearly demonstrated that the severity of dysphagia by water-based swallow tests correlates positively with the IDDSI fluid thickness aimed at reducing dysphagia symptoms in those patients, confirming the reliability and feasibility of IDDSI framework for clinical applications.
Swallowing disorder or dysphagia occurs commonly among many elderly people and imposes negative impacts on their health and well-being. Medical professionals can diagnose eating and swallowing capability in a qualitative manner, but have difficulty in making diet recommendation because of the lack of texture guidance. This work confirmed the feasibility of IDDSI framework for clinical and bedside applications. The correlation between the capability grades of swallowing and IDDSI texture levels established in this work provides a useful measure for such applications.