Effects of barium sulfate on rheological properties and IDDSI flow consistency of liquid stimuli prepared using commercial thickening powders

During videofluoroscopic swallowing study (VFSS), barium sulfate (BaSO4 ) is commonly added into food samples as a radiopaque contrast media for bolus visualization and examination. Accordingly, the consistency and flow behavior of barium stimuli can differ significantly from their non-barium counterparts. Such differences may have a subsequent impact on the validity of VFSS. Therefore, in this study, effects of barium sulfate on the shear and extensional rheological properties and IDDSI (International Dysphagia Diet Standardization Initiative) flow consistency of liquids prepared using various commercial thickening powders were investigated. Results showed that all barium stimuli exhibited shear thinning behavior but with significantly higher shear viscosity compared to the non-barium counterparts. A shift factor of viscosity at shear rate 50 s-1 with values in range of 1.21-1.73 could be used to describe the increase in the viscosity for samples thickened with gum-based thickeners. However, the change in the viscosity was not invariant for the stimuli prepared starch-based thickener. The addition of BaSO4 had a negative impact on extensional properties of samples by demonstrating a faster filament rupture. The extent of impact on the decrease in filament breakup time was more pronounced in xanthan > guar gum ≈ tara gum-based thickeners. Based on the IDDSI flow test, no significant effect of BaSO4 was found on the gum-based thickeners, whereas there was a marked effect in the starch-based sample. These results can be used beneficially to assist clinicians in the dysphagia diagnosis for matching rheological properties of the barium stimuli to enhance effectiveness dysphagia interventions.

Influence of food oral processing, bolus characteristics, and digestive conditions on the protein digestibility of turkey cold meat and fresh cheese

During mastication, foods are progressively transformed to achieve swallowable boluses and their characteristics are crucial for the subsequent digestion events. The main goal of this work was to evaluate the impact of food oral processing, bolus properties, and different digestive conditions on the protein digestibility of turkey cold meat and fresh cheese. In vivo normal and deficient masticated food boluses were prepared by a young volunteer. Besides, three digestion models were used to simulate the different physiological conditions frequently observed in adults and the elderly, presenting good or poor oral health: i) Normal Masticated-Normal Digested model; ii) Deficient Masticated-Normal Digested model; and iii) Deficient Masticated-Elderly Digested model. The oral processing behaviour (number of chews, chewing time, chewing rate, and saliva uptake), bolus particle size, textural and viscoelastic properties of boluses, and protein digestibility of samples were determined. Results showed that deficient masticated boluses exhibited lower amounts of saliva uptake and greater particle sizes, hardness, stiffness, and rigidity, notably in deficient masticated turkey cold meat boluses. Moreover, the worst digestive scenario (Deficient Masticated-Elderly Digested model) negatively impacted on the proteolysis extend of samples, especially for total soluble proteins and soluble peptides contents. The current study demonstrates that the oral processing behaviour and degree of food fragmentation impacted on the granulometric, texture, and viscoelastic properties of both food boluses, whereas the worst digestive scenario commonly observed in the elderly reduced the proteolysis extend of the products evaluated.

Role of continuous phase and particle properties on the sensory perception of root vegetable purées evaluated by an expert panel and naïve consumers

Textural properties play an essential role in the development of food products. The complexity of textural attributes has been traditionally overcome with extensive panelist training and the use of generic descriptive analysis. A better understanding on the use of rapid methods with naïve consumers to evaluate texture attributes in complex food products is still needed. The present study aimed to investigate the (i) role of different continuous phases and particle properties (i.e., size and hardness) on the mouthfeel perception of root vegetable purées and (ii) the effect of panel expertise (sensory experts vs. naïve consumers) using Rate-All-That-Apply (RATA). The study included six purées made of two different continuous phase (based on Jerusalem artichoke which is rich in inulin and, parsnip which is rich in starch) and three types of beetroot particles (raw, cooked, and comminuted beetroot). Results showed that both panels were able to discriminate and profile in a similar manner. However, sensory experts showed higher ability to discriminate between samples regarding the particle's attributes whereas consumer's sample discrimination was influenced by attributes such as "ease of swallow" and "creaminess." For the expert panel, the presence of hard particles was a clear factor driving the differences between samples. Our results highlighted the contribution of both continuous and dispersed phases to design the texture profile of particulate semisolid plant-based foods.

Improved system for measuring rheological properties of thickened liquid using an inclined parallel plate and optical sensor

The purpose of this study was to improve the method of using an inclined parallel plate (IPP) in directly estimating the yield stressτ iy and evaluating the properties of a thickened liquid. The flow curve of the relationship between the shear rate and shear stress of a liquid thickened with a xanthan gum agent was predicted using the Herschel-Bulkley fluid model ( τ = τ y + k γ ˙ n - 1 ). We supposed that the yield stressτ y and the result of a line spread test (LST) indicate the deformation state and the flow state of shear stress ( k γ ˙ n - 1 ), respectively.τ iy , the yield stressτ ry estimated adopting a rotational viscometer and LST, was investigated for three liquids thickened with xanthan gum at four concentrations (C) at intervals of 0.5 wt% within the range 0.5-2.0 wt%. Linear plots of the relations of C versusτ iy andτ ry and the LST show that with an increase in C , the resistance force (τ ry andτ iy ) increases until flow starts, after which viscosity increases. We suggest that yield stressτ iy estimated with the IPP method effectively indicates the rheological properties of thickened liquids.

Comparison between the use of hydrocolloids (xanthan gum) and high-pressure processing to obtain a texture-modified puree for dysphagia

Enriched lentil protein vegetable purees (10% zucchini, 10% carrots, 2.5% extra virgin olive oil and 21.8% lentil protein concentrate) suitable for people with dysphagia were developed with 0.8% xanthan gum (XG) or 600 MPa/5 min high pressure processing (HPP) treatment with the aim of comparing their rheological and textural properties. Selection of the appropriate XG % and HPP conditions was made by performing initial pilot trials. Purees showed a good nutritional profile (12% protein, 3.4% fiber, 100 Kcal/100 g), being adequate for people with dysphagia. Microbiological testing of HPP treated purees indicated that it has a good shelf-life under refrigerated conditions 14 days). Both types of purees showed a gel-like character (tan delta 0.161-0.222) and higher firmness, consistency and cohesiveness than control samples. Comparing XG and HPP samples at time 0, HPP treated purees showed the highest stiffness ( G'), the lowest deformability capacity (yield strain_LVR) and the lowest structural stability (yield stress_LVR). With storage, HPP treatment samples showed significant increases in all rheological and textural parameters. These results confirm the suitability of HPP as an alternative technology to hydrocolloids for the obtained dysphagia dishes.

Determination of Physicochemical, Textural, and Sensory Properties of Date-Based Sports Energy Gel

Applying energy supplements in gel form may circumvent gastric discomfort and thus it is a practical alternative. The main objective of this investigation was to develop date-based sports energy gels consisting of highly nutritious ingredients such as black seed (Nigella sativa L.) extract and honey. Three date cultivars (Sukkary, Medjool, and Safawi) were used and characterized for their physical and mechanical properties. The sports energy gels were prepared with addition of xanthan gum (0.5% w/w) as the gelling agent. The newly developed date-based sports energy gels were then analysed for proximate composition, pH level, colour, viscosity, and texture profile analysis (TPA). A sensory test was also conducted with 10 panellists who analysed the appearance, texture, odour, sweetness, and overall acceptability of the gel using a hedonic scale. The results showed that different types of date cultivars affect the physical and mechanical properties of the new developed gels. The outputs of the sensory evaluation revealed that the date-based sports energy gel prepared from Medjool received the highest mean score, followed closely by those prepared from Safawi and Sukkary, indicating that, overall, all three cultivars are acceptable to consumers, but the date-based sports energy gel prepared from Medjool is the most preferred one.

Textural characterization of calcium salts-induced mung bean starch-flaxseed protein composite gels as dysphagia food

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.

Instrumental and sensory techniques to characterize the texture of foods suitable for dysphagic people: A systematic review

The interest to characterize texture-modified foods (TMFs) intended for people with oropharyngeal dysphagia (OD) has grown significantly since 2011. Several instrumental and sensory techniques have been applied in the analysis of these foods. The objective of the present systematic review was to identify the most appropriate techniques, especially for the food industry and clinical setting. The search was carried out in three online databases according to the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA). Across the multiple trials reviewed, Texture Profile Analysis and the Uniaxial Compression Test were most used as the instrumental technique for solid foods, and the Back Extrusion Test for fluid and semisolid foods. All trials used descriptive analysis as the sensory technique. However, the experimental conditions of the trials lacked standardization. Consequently, the results of the trials were not comparable. To properly characterize the texture of TMFs intended for OD by each technique, an international consensus is needed to establish standardized experimental conditions. Methods based on these techniques should also be validated by collaborative studies to verify repeatability, replicability, and reproducibility.

A method for evaluating time-resolved rheological functionalities of fluid foods

We have developed an effective method for evaluating time-resolved rheological functionalities of swallowed foods using ultrasonic spinning rheometry (USR). USR can obtain variations over time in the rheological properties of fluids despite the fluids being in heterogeneous and non-equilibrium conditions. In addition, USR can evaluate time variations of shear-thinning property changing in a few seconds. Demonstrations were conducted with typical thickener solutions: starch, guar gum, and xanthan gum-based solutions, with alpha-amylase as a digestive enzyme. The flow curve of the starch-based solutions lowered with time, and a few minutes after addition of the amylase, the viscosity dropped to one-hundredth of the original value. In contrast, the guar gum and xanthan gum-based solutions maintained the original viscosities as generally known. Applying the power law fitting to series of these flow curves, the time variation of the shear thinning property is quantitatively characterized by the plots on typical K-n space, where K and n are parameters in the model, consistency index and power law exponent. The qualitative characteristics of the thickeners are successfully quantified in the K-n space, and this will be a practical tool for evaluating the time-resolved rheological properties of swallowed foods.

Variations of the viscous properties of a sponge cake artificial bolus with some physiological parameters

Artificial boluses were prepared from sponge cake by grinding the food to a given particle size and hydrating with artificial saliva. The shear viscosity of the artificial food bolus was then measured by capillary rheometry, and its variations with shear rate were studied as a function of four main factors: bolus water content, particle size, temperature and saliva viscosity. The flow curves can be fitted according to the Herschel-Bulkley model, which allows for the derivation of two main properties: yield stress and consistency. Saliva plasticizing coefficients are defined by the variations of these properties as a function of the water content. Their value, close to 12, is in good agreement with values obtained for molten starch (10 < α < 20). Particle size has little influence, whereas the effect of temperature and saliva viscosity is not monotonous. They underline the complexity of the structure of the bolus and the interplay between the saliva, acting as a lubricant and a swelling agent. Finally, the extensional viscosity of the artificial bolus is also determined by capillary rheometry, and it is shown to be of importance when comparing the viscous properties of the artificial bolus with those of real ones from literature.

Food polysaccharides and roles of rheology and tribology in rational design of thickened liquids for oropharyngeal dysphagia: A review

In today's market environment, an aging society is recognized as one of the megatrends in the world. The demographic change in the world population age structure has driven a huge demand in healthcare products as well as services that include the technological innovation for the health and wellness of the elderly. Dysphagia or swallowing difficulty is a common problem in the elderly as many changes in swallowing function come with aging. The presence of a strong relationship between swallowing ability, nutritional status, and health outcomes in the elderly leads to the importance of dysphagia management in the population group. Modification of solid food and/or liquid is a mainstay of compensatory intervention for dysphagia patients. In this regard, texture-modified foods are generally provided to reduce risks associated with choking, while thickened liquids are recommended for mitigating risks associated with aspiration. In this review, we discuss thickened liquids and other issues including the importance of their rheological and tribological properties for oropharyngeal dysphagia management in the elderly. The review focuses on both commercial thickeners that are either based on modified starch or xanthan gum and other potential polysaccharide alternatives, which have been documented in the literature in order to help researchers develop or improve the characteristic properties of thickened liquids required for safe swallowing. Furthermore, some research gaps and future perspectives, particularly from the nutrition aspect related to the interaction between thickeners and other food ingredients, are suggested as such interaction may considerably control the rate of nutrient absorption and release within our body.