Swallowing disorders, or dysphagia, affect a large part of the population due to factors such as degenerative diseases, medication side effects or simply age-related impairment of physiological oropharyngeal function. The management of dysphagia is mainly handles through texture-modified foods of progressively softer, smoother, moister textures, depending on the severity of the disorder. Rheological and physiological-related properties of boluses were determined for a group of five older persons (average age, 74) for a set of texture-modified foods: bread, cheese and tomato and the combination into a sandwich. The softest class was gel food, after which came a smooth timbale; both were compared to boluses of regular food. The subjects chewed until ready to swallow, at which point the bolus was expectorated and measured regarding saliva content, linear viscoelasticity and shear viscosity. The results were compared to those of a previously studied younger group (average age, 38). The general physiological status of the subjects was determined by hand and tongue strength, diadochokinesis and one-legged standing and showed that all subjects were as healthy and fit as the younger group. Age-related properties such as one-legged standing with closed eyes and salivary flow plus bolus saliva content were lower for the older group, but the average chews-until-swallow was surprisingly also lower. Consequently, bolus modulus and viscosity were higher than for the younger group. Overall, the intended texture modification was reflected in bolus rheological and physiological-related properties. Bolus modulus, viscosity, saliva content and chews-until-swallowed all decreased from regular food to timbale food to gel food. © 2023 The Authors.

Problems with swallowing or dysphagia is an increasing problem due to the ageing population. Investigation methods commonly require clinical techniques which are tedious and costly. An alternative analysis is to measure the swallowing time non-invasively through monitoring of swallowing sounds. GOKURI is an AI-powered, smartphone-based, neckband- type device for the assessment of the swallowing function. The present study investigated swallow sounds of food in comparison to those of water swallows. In total 19 healthy subjects were eating a full meal while their swallowing was recorded via the swallowing sensor. The results show that the time it takes for a person to swallow varies greatly. Nevertheless, the length of swallowing solid food differed significantly from water, which were slightly shorter to swallow (0.702s vs. 0.668 s respectively). This correlates well with our previous study where swallowing of water took shorter time compared to thicker Newtonian and a shear-thinning fluids.

We have developed a nano-rheological characterization tool to extract the frequency- and scale-dependent rheological properties of soft materials during oral processing. Taking advantage of AC susceptometry, the dynamic magnetization of magnetic nanoparticles blended in the matrix material is measured. The magnetic AC susceptibility spectra of the particles are affected by the viscosity and mechanical modulus of the matrix material and provide the rheological properties of the matrix. Commercially available iron-oxide magnetic nanoparticles with 80 and 100 nm particle sizes are used as tracers in the frequency range of 1 Hz–10 kHz. The AC susceptibility is measured using two differentially connected coils, and the effects of the sample temperature and distance with respect to the detection coils are investigated. The developed measurement setup shows the feasibility of remote nano-rheological measurements up to 2 cm from the coil system, which can be used to, e.g., monitor the texture of matrix materials during oral processing.

Root vegetables have unique techno-functional and nutritional properties however, their use in processed foods is limited to a few species, partially due to a lack of knowledge related to the impact of thermal treatments on the sensory properties. This study investigated the effect of steaming and boiling on the microstructure, mechanical properties, and sensory profile of three model root vegetables with distinct carbohydrate composition: Jerusalem artichoke (Helianthus tuberosus L.), parsnip (Pastinaca sativa), and beetroot (Beta vulgaris). Thermally treated Jerusalem artichoke and parsnip showed higher content of cell wall polysaccharides, particularly β-glucans (e.g. cellulose) and pectic components, compared to raw. Steaming produced more cell shrinkage and loss of cell-cell adhesion than boiling, leading to softer vegetables. Processed beetroot showed loss of cell turgor and drastic softening but not clear changes in overall carbohydrate content. The scores for several flavour and in-mouth attributes were higher for steamed vegetables compared to boiled. Our results give insights on the processability of root vegetables towards products with enhanced sensory and nutritional properties.

Hot-melt adhesives (HMA) are used for hobby as well as in industrial applications as a fast-setting alternative without solvents. They are used for corrugated boxes and in electronic devices to affix parts and wires, as well as for bookbinding as well as a glue in hygiene products. An edible HMA can be used for e.g. food decorations, for the childcare sector as a safe alternative to other glues as well as in packagings where corrugated boxes and paperboard cartons arc glued. We have developed an edible HMA based on sugars which can be applied by the same application techniques as conventional HMAs. The rheol. properties showed a similar melting behavior as a conventional HMA. A characterization of the mech. properties of the glue showed that the edible HMA was strong but fragile as compared to the more rubbery conventional HMA.

Food oral processing is the first step in the digestive process which prepares food forswallowing and digestion. The process only lasts a few seconds, yet it determines our complete perception of texture, taste and aroma of the product we are eating. This oral processing is an intricate combination ofvoluntary and involuntary actions, and it involves complex flow geometry, mass transport offluids and gases and signal processing and feedback from the brain. Any attempt of inserting measuring devices in the mouth will fail because the complete oral processing will be influenced. We have developed a remote, non-invasive determination technique using magnetic sensing of magnetic nanoparticles iron oxide particles. A small amount of these particles senses their surrounding texture through their rotation and the nano-viscoelasticity can therefore be picked up without disturbing the oral processing.

We have studied nanorheological properties (viscosity and shear moduli) of aqueous xanthan solutions, in the oscillation frequency range up to 10 kHz by using magnetic particles that undergo Brownian relaxation and frequency dependent AC susceptibility (ACS). We used two magnetic nanoparticle (MNP) systems with different mean particle sizes of 80 nm and 100 nm. The determined viscosity and shear modulus of the diluted xanthan solutions from the ACS measurement of the two particle systems agree with traditional oscillatory rheological measurements. However, there is a particle size dependency that could be explained by comparing particles sizes with the xanthan microstructure