Rheological aspects of dysphagia-oriented food products: A mini review

Insights into the digestive processes of normal and high-amylose rice using realistic boluses formed in the bio-inspired oral mastication simulator (iBOMS-III)

Mastication is essential for preparing food bolus for swallowing and digestion. This study employed the bio-inspired oral simulator (iBOMS-III) to investigate the effects of mastication on physical properties and starch hydrolysis of normal rice (NR) and high-amylose rice (HR), while validating its results through comparison with in vivo data from human subjects. The median particle size (d50) of NR (1.266, 0.931, 0.776 mm) and HR (1.32, 1.04, 0.928 mm) boluses from iBOMS-III at 12, 14, and 20 cycles closely matched human boluses at the swallowing threshold, particularly after 14 and 20 cycles. Starch hydrolysis in NR increased from 76.6 % to 91.3 %, while HR hydrolysis ranged from 63.4 % to 73.3 %. Boluses from iBOMS-III with 14 and 20 cycles showed starch digestibility consistent with in vivo data (84.2 % for NR, 71.3 % for HR). These findings demonstrate that iBOMS-III effectively replicated human mastication behaviors, producing boluses comparable to those observed in vivo.

Ultrasound treatment on commercial pea protein isolates systems: Effect on structure, rheology and gelling properties

Pea protein has attracted great attention due to its capability to meet the growing requirements from consumers for desired nutrition and texture from plant protein. Hence, the current study aimed to investigate the effects of different ultrasonic treatment parameters (power and duration) on the gelling characteristics of commercial pea protein isolates (PPIc). The findings demonstrated that by manipulating the ultrasonic power and treatment duration, great enhancement of the solubility, adhesiveness and formation strength of PPIc gel can be realized. The reduction in particle size was positively correlated with higher power and longer treatment durations. Interestingly, no direct correlation between average particle size, solubility, turbidity, and ζ-potential was observed. Additionally, the ultrasound-modified PPIc in this study exhibited comparable characteristics to laboratory-prepared pea protein isolates, in terms of solubility, water-holding capacity, and gel strength. Overall, manipulating ultrasonic parameters presents a feasible method to customize the texture of pea-protein-based substitute.

Effectiveness of diet modification on dietary nutrient intake, aspiration, and fluid intake for adults with dysphagia: a meta-analysis of randomized controlled trials

OBJECTIVES

To determine and explore the effectiveness of diet modification on dietary nutrient intake, aspiration, and fluid intake in adults with dysphagia.

PARTICIPANTS

Adults with dysphagia.

DESIGN

A meta-analysis of randomized controlled trials (RCTs).

METHODS

We conducted a comprehensive literature search in EMBASE, Cochrane Library, Ovid-Medline, CINAHL, Web of Science, PubMed, and reference lists until November 2023. Quality of the included studies was assessed by the Cochrane Risk of Bias Assessment tool 2.0. Data analysis was performed using Comprehensive Meta-analysis 3.0 for pooled Hedges' g and odds ratios (ORs) with corresponding confidence interval (CI) adopting a random-effects model. A X2- based test using Cochran's Q (P < 0.10) and I2 statistics evaluated heterogeneity.

RESULTS

In total, 16 RCTs from among 3,854 studies retrieved from the literature search with 1812 adults with dysphagia were included in this meta-analysis. Texture-modified diets revealed a significant small effect on increasing energy intake (g: 0.37, 95% CI = 0.05-0.68) and a medium effect on increasing protein intake (g: 0.56, 95% CI = 0.13-0.99). Thickened fluids revealed a significantly reduced risk of aspiration (OR: 0.59, 95% CI = 0.44-0.79), and thickened fluids combined with water protocol revealed a significant large effect on increasing fluid intake (g: 3.96, 95% C = 0.75-7.16).

CONCLUSIONS

The findings of this meta-analysis demonstrated that texture-modified diets increase dietary intake of energy and protein for adults with dysphagia. In addition, thickened fluids reduced the risk of aspiration while thickened fluids combined with water protocol increased fluid intake in adults with dysphagia.

Relationship between rheological properties, sensory perception, and overall acceptability of thickened liquids for dysphagia in young and old healthy individuals

This study investigated the relationship between rheological properties, sensory perception, and overall acceptability in healthy young and old groups for dysphagia thickened liquids. Unflavored (UTL) and flavored (FTLP) thickened liquids were prepared using tap water or pomegranate juice at 10 different viscosity levels. The rheological properties were then evaluated via syringe flow test and line spread test (LST). When the apparent viscosity levels of UTL and FTLP were similar, the syringe test and LST results were also similar, indicating consistent flow behavior. Sensory perception evaluations showed that the young group better distinguished viscosity differences between stages compared to the old group. Regarding overall acceptability, the old group preferred samples with higher apparent viscosity than the young group. Principal component analysis and k-means cluster analysis were used to explore correlations between variables and classify thickened liquids into four groups. This can serve the foundation for standardized texture grades of dysphagia thickened liquids, considering rheological characteristics and sensory profiles.

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.

Paediatric Solid Oral Dosage Forms for Combination Products: Improving In Vitro Swallowability of Minitablets Using Binary Mixtures with Pellets

There is a growing interest in enhancing the acceptability of paediatric pharmaceutical formulations. Solid oral dosage forms (SODF) are being considered as an alternative to liquid formulations, but they may compromise palatability as large volumes may be required. We hypothesised that a binary mixture of paediatric SODF, designed to increase the formulation maximum packing fraction, could reduce the suspension viscosity and facilitate swallowing. Using the Paediatric Soft Robotic Tongue (PSRT) - an in vitro device inspired by the anatomy and physiology of 2-year-old children - we investigated the oral phase of swallowing for multi-particulate formulations, i.e., pellets (350 and 700 µm particles), minitablets (MTs, 1.8 mm), and their binary mixtures (BM), by evaluating oral swallowing time, the percentage of particles swallowed, and post-swallow residues. We also conducted a systematic analysis of the effect of feeding method, bolus volume, carrier type, particle size, and particle volume fraction on pellets swallowability. The results demonstrated that the introduction of pellets affected the flowing ability of the carriers, increasing shear viscosity. The size of the pellets did not appear to influence particle swallowability but raising the particle volume fraction (v.f.) above 10% resulted in a decrease in the percentage of particles swallowed. At v.f. 0.4, pellets were easier to swallow (+ 13.1%) than MTs, being the administration method used highly dependent on the characteristics of the multi-particulate formulation under consideration. Finally, mixing MTs with only 24% of pellets improved particle swallowability, achieving swallowing levels similar to those of pellets alone. Thus, combining SODF, i.e., MTs and pellets, improves MT swallowability, and offers new possibilities for adjusting product palatability, being particularly attractive for combination products.

Rheological Issues on Oropharyngeal Dysphagia

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).

Feasibility of hydrocolloid addition for 3D printing of Qingtuan with red bean filling as a dysphagia food

Glutinous rice flour, the main component of Qingtuan, has increased adhesiveness after gelatinization and hardness after aging; this results in great challenge in swallowing if for patients with dysphagia. Dual nozzle 3D printing has great potential for developing innovative Chinese pastries with fillings that conform to dysphagia diets. In this experimental study, the gelatinization and retrogradation behavior of glutinous rice starch was improved by designing printing inks of optimal properties made with different soluble soybean polysaccharide (SSPS) additions (0%, 0.3%, 0.6%, 0.9%). The internal structure of Qingtuan was modified by adjusting different filling densities (75%, 100%) in combination with the dual nozzle 3D printing. The objective of these tests was to enhance the texture of Qingtuan so that it meets the requirements of International Dysphagia Diet Standardization Initiative (IDDSI). The experimental results showed that 0.9% SSPS addition could effectively reduce the hardness and adhesiveness of the Qingtuan, which met the Level- 6 -soft & bite-sized standard while lower filling density lowers both hardness and adhesiveness.

Easy-to-swallow mooncake using 3D printing: Effect of oil and hydrocolloid addition

3D printing is a promising technology for food production, capable of producing and developing personalized food products. In recent years, research on the application of 3D printing technology to create easy-to-swallow foods for the elderly with dysphagia has received extensive attention. In this study, we applied dual nozzle 3D printing technology to develop an easy-to-swallow mooncake food using a traditional Chinese food, mooncake, as a model system. We optimized the printing dough ink formulation by setting up soybean oil gradient experiments and Arabic gum gradient experiments, and then we applied the optimized dough ink as the crust of the mooncake to produce easy-to-swallow mooncakes. The experimental results show that the addition of 2.5 g of soybean oil and 0.125 g of Arabic gum could improve the texture of the dough product and reduce its hardness and adhesiveness. The mooncake produced with this crust dough ink was rated in the IDDSI texture level four, which met expectations. Therefore, this work provides insights into the development of easy-to-swallow food products.

Development and Characteristics of Plant-Based Product Prototypes for Oro-Pharyngeal Dysphagia Diet

Patients with dysphagia diseases require food with acceptable textural characteristics. Additionally, due to the consumption of smaller portions, these patients receive insufficient amounts of nutrients. Therefore, this study aimed to develop plant-based purée as a meal for an oro-pharyngeal dysphagia (OD) diet, enriched with proteins, fiber and antioxidant vitamins. The suitability of three protein sources-soy protein isolate, whey protein isolate and brown pea protein concentrate-was tested through evaluation of their effect on the rheological properties of protein-enriched plant-based purées for OD diets. Based on the rheological analysis, whey protein was selected for incorporation into the new product formulations. Two prototypes of soups and two prototypes of desserts produced in this study demonstrated acceptable textural properties and high nutritional value.

Meat texture modification for dysphagia management and application of hydrocolloids: A review

Dysphagia is a medical condition that describes the difficulty of swallowing food, and texture modified food (TMF) is the best intervention for dysphagia. The relevant guidelines to identify dysphagia food are provided by the International Dysphagia Diet Standardization Initiative (IDDSI). Developing texture modified meat is a challenging task due to its fibrous microstructure and harder texture. Various meat tenderization attempts are therefore evaluated in the literature. Meat texture modification for dysphagia is not just limited to tenderization but should be focused on safe swallowing attributes as well. The application of hydrocolloids for designing TMF has a major research focus as it is a cost-effective method and offers an opportunity for careful control. The present review focuses on the meat texture modification attempts that have been used in the past and present, with special attention to the use of hydrocolloids. Several studies have shown improvements in texture upon the addition of various hydrocolloids; however, few studies have attempted to develop texture modified meat for people with dysphagia. This area has to be further developed along with the sensory evaluations conducted with the dysphagia population, to validate the industrial application of hydrocolloids to TMF.

Review of the effect of amylase-resistant dysphagia products on swallowing safety

PURPOSE OF REVIEW

Thickened fluids are a widely utilised compensatory management strategy for people with impaired swallowing (dysphagia). Over recent years there has been a shift in practice to offer gum-based instead of starch-based products. A key marketing message has been that gum-based thickeners with amylase-resistant properties are superior in promoting 'safer swallowing'. This review sought evidence to evaluate the effect of amylase-resistant products on swallowing safety.

RECENT FINDINGS

No studies directly compared the effect of amylase-resistant products with usual care or products without amylase resistance. Five studies cited amylase-resistant properties and compared gum-based to starch-based dysphagia products or thin fluids. Swallowing safety was frequently judged subjectively with rating scales. Swallowing biomechanics were not included and clinically meaningful outcomes, such as incidence of aspiration pneumonia, were not reported. A scoping review of the grey literature found little evidence that amylase-resistant properties of dysphagia products were of significant concern to clinicians or patients.

SUMMARY

Despite references to the 'importance' of amylase-resistant properties of dysphagia products there is no evidence that this property improves swallowing safety. Further research is needed using objective and clinically meaningful outcome measures to allow clinicians and patients to make informed decisions for dysphagia management.

Preparation and Performance of Thickened Liquids for Patients with Konjac Glucomannan-Mediated Dysphagia

The present study sought to characterize the rheological and thickening properties of Konjac glucomannan (KGM) and prepare thickening components for special medical purposes using KGM and maltodextrin as the primary raw materials and guar gum (GG), xanthan gum (XG), locust bean gum (LBG), and carrageenan (KC) as the supplemented materials. The formulation and preparation processes were optimized through single factor experiments taking sensory evaluation as an indicator. The results confirm that KGM had excellent thickening performance, reaching about 90 times its own mass. The optimal formulation process of the thickening components based on KGM was as follows: the mass concentration of the compound thickener (KGM/GG/XG/LBG/KC = 13:2:2:2:1) was 5.0–7.0 mg/mL; the maltodextrin concentration was 10.0 mg/mL; the brewing temperature of the thickening component was 60 °C with no restriction on consumption time. The rheology test results revealed that the thickening components had shear thinning characteristics, which could provide three different thickening effects of nectar-thick level (350 mPa·s), honey-thick level (1250 mPa·s), and pudding-thick level (1810 mPa·s) suitable for people with different degrees of chewing disorders. Overall, this study provides a theoretical basis and technical reference for KGM as a dietary nutrition support for patients with dysphagia.

Evaluation of thickened liquid viscoelasticity for a swallowing process using an inclined flow channel instrument

An inclined flow channel instrument that can be developed to be a structurally simple and easy-to-use rheometer was applied to control the thickness, specifically the viscosity and elasticity, of liquids thickened to support swallowing in nursing-care practice. Aqueous solutions containing salt or acid, which might be used as ingredients in drinks, were thickened with a commercial thickener. The thickener efficacy decreased because of the salt or acid in liquid phase. Analysis of the flows in the instrument by experimentation yielded a dimensionless relation representing changes of the Deborah number in the flow process, as indicated by the relative flow length, considering the shear rate in oral processing. One unique methodology to evaluate the viscoelasticities of thickened liquids during the swallowing process was presented utilizing the measurements such as elapsed time and velocity in the instrument.

Correlation between Instrumental and Sensory Properties of Texture Modified Carrot Puree

This study was undertaken to determine the correlation between instrumental and sensory evaluation on texture modified carrot puree. Texture modified foods (TMF) are prescribed to dysphagia individuals to aid in the oral manipulation and facilitate swallowing of food. There is a lack of correlation between instrumental measurements and sensory attributes on TMF. Understanding this correlation will aid in the formulation of safe foods with desired sensory properties for dysphagia patients. Instrumental measurements of carrot purees were performed by back extrusion method using a texture analyser and the attributes obtained were firmness, consistency, cohesiveness and adhesiveness. Quantitative Descriptive Analysis (QDA) with eight trained panellists was employed to characterize the texture of the carrot puree based on seven sensory attributes: Firmness, viscous, adhesive (mouth), smoothness, adhesive (throat), rate of breakdown, difficulty to swallow. Five thickeners, namely gellan gum, xanthan gum, Suberakaze, UNI-PURE® Dys-sperse instant thickener, ULTRA-SPERSE® M Starch were evaluated against carrot puree without any thickener as control. The correlation results obtained from texture analysis and sensory evaluation were statistically significant (p < 0.05). The firmness attributes from instrumental and sensory results were positively correlated. The consistency parameter was positively correlated to sensory attribute viscous and negatively correlated to smoothness. The sensory attribute rate of breakdown was negatively correlated to instrumental parameter of cohesiveness. Lastly, instrumental adhesiveness was positively correlated to sensory attributes adhesive to mouth and throat, and difficulty to swallow. The correlation results showed a well-designed instrumental technique can be used to understand the impact of thickeners on TMF for dysphagia subjects. This article is protected by copyright. All rights reserved.

3D Printing of Shiitake Mushroom Incorporated with Gums as Dysphagia Diet

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.

Safety and Efficacy of Specially Designed Texture-Modified Foods for Patients with Dysphagia Due to Brain Disorders: A Prospective Study

Providing texture-modified food for patients with dysphagia is a cornerstone of dysphagia treatment. This study aimed to evaluate the safety and efficacy of a specially designed texture-modified food that can be easily swallowed while maintaining the unique taste by adjusting hardness and adhesiveness in patients with brain disorders using a videofluoroscopic swallowing study. We included 101 patients with oropharyngeal dysphagia due to brain disorders who were referred to the rehabilitation department. To evaluate the safety and efficacy of a specially designed texture-modified food, rice gruel was compared with a regular instant rice porridge, and bulgogi mousse was compared with ground bulgogi, which normally serves as a texture-modified diet for patients with dysphagia in our hospital during the videofluoroscopic swallowing study. The Penetration–Aspiration Scale score, oropharyngeal transit time, number of swallows required to maximally eliminate food materials from the oropharyngeal space, and vallecular and pyriform sinus residue after swallowing scale score were compared. Rice gruel required a shorter oropharyngeal transit time and fewer number of swallowing per the given amount of food than regular instant rice porridge; however, no statistical difference was found in the vallecular and pyriform sinus residue after swallowing scale scores and the Penetration–Aspiration Scale scores. Bulgogi mousse required more swallowing and had lower Penetration–Aspiration Scale scores than ground bulgogi; however, no significant difference was found in the oropharyngeal transit time and the vallecular and pyriform sinus residue after swallowing scale scores. The study foods were safe and efficacious compared to control foods usually provided for patients with dysphagia from various brain disorders.

Exploring Tools for Designing Dysphagia-Friendly Foods: A Review

Dysphagia is a medical condition that affects normal swallowing. To prevent the risk of aspiration or choking, thickened fluids and texture-modified foods have been used for dysphagia management with the goal of slowing down the flow of liquids and protecting the airway. This article summarizes the available information about the rheological and textural parameters, the characterization of the most-used thickeners and the application of alternative texture modification technologies that are crucial to developing safe dishes for people who suffer from swallowing difficulties. Regarding rheological and textural measurements, fundamental and empirical methods are described.

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.

Rheological and Nutritional Assessment of Dysphagia-Oriented New Food Preparations

Dysphagia that involves difficulty swallowing food and liquids is a symptom of different diseases. In some cases, patients who experience this symptom should be fed with modified consistency foods. Dysphagia is often accompanied by malnutrition and dehydration and an interesting approach to dealing with these conditions is to provide patients with nutrient-rich foods. In this study, two new food formulations for dysphagia patients are proposed: a cereal-based protein meal and a vegetable cream. The nutritional and rheological characteristics of the two innovative preparations were assessed and compared with those of commercial products. The proposed protein meal formulations meet the criteria for the “high protein” claim and the vegetable cream meets those of the “source of fiber” claim. The rheological investigation revealed that the flow properties of the innovative formulations were comparable to those of the commercial ones. Based on these preliminary outcomes, this investigation represents an interesting perspective potentially valuable to enlarge the offer of possibilities for people suffering from swallowing disorders.

Food Texture Design by 3D Printing: A Review

An important factor in consumers’ acceptability, beyond visual appearance and taste, is food texture. The elderly and people with dysphagia are more likely to present malnourishment due to visually and texturally unappealing food. Three-dimensional Printing is an additive manufacturing technology that can aid the food industry in developing novel and more complex food products and has the potential to produce tailored foods for specific needs. As a technology that builds food products layer by layer, 3D Printing can present a new methodology to design realistic food textures by the precise placement of texturing elements in the food, printing of multi-material products, and design of complex internal structures. This paper intends to review the existing work on 3D food printing and discuss the recent developments concerning food texture design. Advantages and limitations of 3D Printing in the food industry, the material-based printability and model-based texture, and the future trends in 3D Printing, including numerical simulations, incorporation of cooking technology to the printing, and 4D modifications are discussed. Key challenges for the mainstream adoption of 3D Printing are also elaborated on.

Influence of physical properties on the taste and flavor of strawberry jam

This study investigated the influence of the type and concentration of pectin on the sensory attributes and physical properties of a model strawberry jam. The methods used for the sensory evaluation and determination of physical characteristics that affect human taste and flavor perception are outlined. Increasing pectin concentration altered the solid (elastic) properties of the model strawberry jam. Each sensory attribute showed high correlation with various physical properties as determined by viscosity measurements. These results allowed us to predict the human oral cavity conditions during taste and flavor perception. From this study, it is clear that humans assess the physical properties of foods by the tongue movements and adjustments in the oral cavity conditions according to the taste and flavor characteristics.

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.

A novel soft surimi gel with functionality prepared using alcalase for people suffering from dysphagia

In this study, effects of alcalase on physical properties, pepsin digestibility, and antioxidative activity in the heat-induced surimi gel were investigated to develop a novel gel product for people with dysphagia. The heat-induced gelation profile of surimi showed that alcalase activity was maximized at approximately 37 °C. The surimi gel attained an appropriate texture for people with dysphagia, when a combination of 0.3-0.5% alcalase and two-step heating at 37 °C and 90 °C was used. Adding alcalase effectively promoted proteolysis, resulting in softening of the gel. Furthermore, the gel with 0.5% alcalase showed improved pepsin digestibility, when heated at 37 °C and 90 °C. Its antioxidative activity was enhanced by adding 0.5% alcalase. Therefore, a combination of 0.5% alcalase and the two-step heating at 37 °C and 90 °C was useful in improving the physical and functional properties of the surimi gel for people with dysphagia.

Cardiac and Metabolic Impact of Functional Foods with Antioxidant Properties Based on Whey Derived Proteins Enriched with Hemp Seed Oil

The impaired ability to feed properly, evident in oncologic, elderly, and dysphagic patients, may result in malnutrition and sarcopenia. Increasing the consumption of dietary proteins by functional foods and enriching their composition by adding beneficial nutrients may represent an adjuvant therapy. We aimed to evaluate the safety and the positive effects of a standard diet (SD) supplemented with whey-derived protein puddings (WDPP), with appropriate rheological properties, and hemp seed oil (HSO), rich in polyphenols. Rats were assigned to SD, WDPP, WDPP plus hemp seed oil (HSOP), and HSO supplemented diets for eight weeks. “Anthropometric”, metabolic, and biochemical variables, oxidative stress, tissue injury, liver histology, and cardiac susceptibility to ischemia/reperfusion were analyzed. All the supplementations did not induce significant changes in biochemical and metabolic variables, also in relation to glucose tolerance, and livers did not undergo morphological alteration and injury. An improvement of cardiac post-ischemic function in the Langendorff perfused heart model and a reduction of infarct size were observed in WDPP and HSOP groups, thanks to their antioxidant effects and the activation of Akt- and AMPK-dependent protective pathways. Data suggest that (i) functional foods enriched with WDPP and HSOP may be used to approach malnutrition and sarcopenia successfully under disabling conditions, also conferring cardioprotection, and that (ii) adequate rheological properties could positively impact dysphagia-related problems.

Are Medication Swallowing Lubricants Suitable for Use in Dysphagia? Consistency, Viscosity, Texture, and Application of the International Dysphagia Diet Standardization Initiative (IDDSI) Framework

Medication lubricants are thick liquids or gels that are designed to aid swallowing of solid oral dosage forms. Tablets and capsules are placed within a spoonful of the product for swallowing. The aim of this study was to describe and compare commercially available medication lubricants in terms of textural suitability for patients with dysphagia. Twelve medication lubricants were characterised according to the International Dysphagia Diet Standardisation Initiative (IDDSI) framework. Apparent viscosity, yield stress, thickness consistency, and various texture features were compared. Gloup Forte was the only medication lubricant classified as IDDSI level 4 (pureed/extremely thick) at room (24 °C) temperature. Four other Gloup products were IDDSI level 3 (liquidised/moderately thick) at room temperature but testing at 4 °C or pouring from the container instead of using the pump dispenser resulted in classification as IDDSI level 4. The IDDSI Flow test would have classified MediSpend and Slo Tablets as IDDSI level 3, but their very low yield stress led to these fluids flowing too quickly through the prongs of a fork and so these were classified as <3. Severo was IDDSI level 2. Heyaxon and the two versions of Magic Jelly tested contained lumps, and Swallow Aid had exceptionally high viscosity, hardness, adhesiveness, and gumminess, classifying them as IDDSI Level 7 (“regular textures”) and therefore as unsuitable for people with dysphagia according to IDDSI. This study provides valuable information to help with the selection of a safe medication lubricant with appropriate thickness level suited to each individual with dysphagia.

Consistencies and terminologies - the use of the International Dysphagia Diet Standardization Initiative

Introduction

Introduction: this study aimed to verify the ability of speech therapists to identify, sort and name the different consistencies used in neurogenic oropharyngeal dysphagia (NOD) management, and to compare the results with the terms proposed by the International Dysphagia Diet Standardization Initiative (IDDSI). Methods: this research was approved by the ethics committee. Sixty speech therapists who work with NOD patients sorted 5 commercial foods from thinnest to thickest to match IDDSI levels 0 to 4, and then used a term to designate each consistency. Results: most subjects (76.66%) sorted the foods properly. Terminologies were divergent at all levels. For level 0, practitioners assigned 3 different terms. For level 1, 24 different terms were reported; for level 2 there were 25 terms, 23 terms for level 3, and 18 terms for level 4. Level 0 (IDDSI - thin) was designated by most participants as liquid; level 1 (IDDSI - slightly thick) was referred to as semi-thickened liquid; level 2 (IDDSI - mildly thick) as thickened liquid; level 3 (IDDSI - moderately thick) as honey; and level 4 (IDDSI - extremely thick) as pasty by most subjects. A reduced number of participants used terms in accordance with IDDSI. Level 0 was appropriately named by 5 subjects (8.33%); levels 1, 2 and 4 by 2 practitioners each (3.33%); and level 3 by 1 professional (1.66%). None of the subjects named all 5 IDDSI levels correctly. Conclusion: most practitioners progressed consistencies properly. There was a diversity of terminologies used for the same consistency at all levels, with no standardization.

Evaluation of non-Newtonian Viscosities of Liquid Foods in Swallowing Process Using Inclined Flow Channel Instrument

To evaluate the non-Newtonian viscosities of liquid foods thickened for assistance of swallowing in nursing-care practice, an inclined flow channel instrument was investigated for development into a structurally simple and easy-to-use viscometer. Experimental analysis of the flows of Newtonian and non-Newtonian test liquids in the instrument derived a dimensionless relation expressing changes of the friction coefficient in the flow process which was indicated by the relative flow length, considering the shear rate level in the swallowing process. A methodology to evaluate uniquely the viscosities of liquid foods undergoing the swallowing process was presented using the measurements such as the flow length and velocity in the instrument.

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.

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.

Relationship between sensory analysis for texture and instrument measurements in model strawberry jam

The primary objective of this study was to investigate the correlations between instrument measurements and sensory attributes of strawberry jam. For this purpose, a series of low sugar strawberry jams were prepared by using different contents of pectin from different sources, which were evaluated by sensory analysis for sensory attributes and by instrument measurements for specific physical properties. Model strawberry jams showed an elastic behavior that increased with higher low-methoxyl (LM) pectin content. These results showed that the apparent viscosity from viscosity measurements was highly correlated with each sensory attribute. As jam is a non-Newtonian fluid, the apparent viscosity was dependent on the shear rate. Moreover, the secondary objective of this study was to discern the physical properties affecting human texture perception based on these relationships. Hence, the instrumental texture perception based on the oral cavity condition was able to predict human texture perception based on the shear rate, which was obtained from the apparent viscosity. These results indicated that human texture perception is judged by apparent viscosity as determined by controlling tongue movement and oral cavity condition (e.g., temperature, saliva, and shear rate).

PRACTICAL APPLICATIONS

We could demonstrate the importance of texture measurement using replicated oral processing for each sensory attribute. Specifically, viscosity measurement results indicated that shear rate is a very important factor for texture perception. Moreover, our findings clarified that human texture perception is modified by apparent viscosity corresponding to shear rate. We anticipate that this technology might be applied as a measure of apparent viscosity to control texture for jam quality improvement.

Clinical applications of IDDSI framework for texture recommendation for dysphagia patients

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.

PRACTICAL 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.