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  • 51.
    Nyström, Magda
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Tamaddon Jahromi, HR
    Swansea University, UK.
    Webster, MF
    Swansea University, UK.
    Hyperbolic contraction measuring systems for extensional flow2017In: Mechanics of Time-Dependent Materials, ISSN 1385-2000, Vol. 21, no 3, p. 55-479Article in journal (Refereed)
    Abstract [en]

    In this paper an experimental method for extensional measurements on medium viscosity fluids in contraction flow is evaluated through numerical simulations and experimental measurements. This measuring technique measures the pressure drop over a hyperbolic contraction, caused by fluid extension and fluid shear, where the extensional component is assumed to dominate. The present evaluative work advances our previous studies on this experimental method by introducing several contraction ratios and addressing different constitutive models of varying shear and extensional response. The constitutive models included are those of the constant viscosity Oldroyd-B and FENE-CR models, and the shear-thinning LPTT model. Examining the results, the impact of shear and first normal stress difference on the measured pressure drop are studied through numerical pressure drop predictions. In addition, stream function patterns are investigated to detect vortex development and influence of contraction ratio. The numerical predictions are further related to experimental measurements for the flow through a 15:1 contraction ratio with three different test fluids. The measured pressure drops are observed to exhibit the same trends as predicted in the numerical simulations, offering close correlation and tight predictive windows for experimental data capture. This result has demonstrated that the hyperbolic contraction flow is well able to detect such elastic fluid properties and that this is matched by numerical predictions in evaluation of their flow response. The hyperbolical contraction flow technique is commended for its distinct benefits: it is straightforward and simple to perform, the Hencky strain can be set by changing contraction ratio, non-homogeneous fluids can be tested, and one can directly determine the degree of elastic fluid behaviour. Based on matching of viscometric extensional viscosity response for FENE-CR and LPTT models, a decline is predicted in pressure drop for the shear-thinning LPTT model. This would indicate a modest impact of shear in the flow since such a pressure drop decline is relatively small. It is particularly noteworthy that the increase in pressure drop gathered from the experimental measurements is relatively high despite the low Deborah number range explored.

  • 52.
    Nyström, Magda
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Tamaddon Jahromi, Hamid R.
    Swansea University, UK.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Webster, Michael F.
    Swansea University, UK.
    Extracting extensional properties through excess pressure drop estimation in axisymmetric contraction and expansion flows for constant shear viscosity, extension strain-hardening fluids2016In: Rheologica Acta, ISSN 0035-4511, E-ISSN 1435-1528, Vol. 55, no 5, p. 373-396Article in journal (Refereed)
    Abstract [en]

    In this study, hyperbolic contraction–expansion flow (HCF) devices have been investigated with the specific aim of devising new experimental measuring systems for extensional rheological properties. To this end, a hyperbolic contraction–expansion configuration has been designed to minimize the influence of shear in the flow. Experiments have been conducted using well-characterized model fluids, alongside simulations using a viscoelastic White–Metzner/FENE-CR model and finite element/finite volume analysis. Here, the application of appropriate rheological models to reproduce quantitative pressure drop predictions for constant shear viscosity fluids has been investigated, in order to extract the relevant extensional properties for the various test fluids in question. Accordingly, experimental evaluation of the hyperbolic contraction–expansion configuration has shown rising corrected pressure drops with increasing elastic behaviour (De=0∼16), evidence which has been corroborated through numerical prediction. Moreover, theoretical to predicted solution correspondence has been established between extensional viscosity and first normal stress difference. This leads to a practical means to measure extensional viscosity for elastic fluids, obtained through the derived pressure drop data in these HCF devices.

  • 53. Olsson, C.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rheological influence of non-gelling amylopectins on ?-lactoglobulin gel structures2000In: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 14, no 5, p. 473-483Article in journal (Refereed)
    Abstract [en]

    The effect of non-gelling potato amylopectin on the gel properties of a particulate ?-lactoglobulin gel was studied by small and large deformation rheology and by light microscopy. Two different techniques using small deformations, one measuring the modulus in shear and the other measuring the modulus in compression, have been compared. The fracture tests of the gels were performed in tension. The concentration of ?-lactoglobulin was kept constant at 6 wt%, and the amount of potato amylopectin was varied from 0 to 2 wt%. Two preparations of potato amylopectin, with different rheological behaviour, were used. The results illustrate the importance of a full theological characterisation, since small and large deformation tests responded different to the structure. Both the viscoelastic and the failure properties of ?-lactoglobulin gels changed on addition of potato amylopectin even at low concentrations. The effect of the potato amylopectin concentration on the rheological properties of the mixed system varied with the properties of the potato amylopectin. The higher viscosity (HV) potato amylopectin had a shear-thinning behaviour and a small yield stress, while the lower viscosity (LV) potato amylopectin had a lower viscosity with a Newtonian behaviour. The gels containing the LV potato amylopectin increased in the modulus of small deformations with increasing potato amylopectin concentration, while the stress at fracture was constant up to a concentration of 0.5 wt% potato amylopectin and then increased with increasing potato amylopectin concentration. For the gels containing the HV potato amylopectin the modulus of small deformations reached a maximum at 0.25 wt% potato amylopectin and then decreased with increasing potato amylopectin concentration. The stress at fracture was constant up to 0.5 wt% potato amylopectin and decreased at higher concentrations. The state of aggregation of ?-lactoglobulin was influenced both by concentration and properties of potato amylopectin. The higher the potato amylopectin concentration the larger the pores in the ?-lactoglobulin gel. (C) 2000 Elsevier Science Ltd.

  • 54. Oom, A.
    et al.
    Pettersson, Anders
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Taylor, J.R.N.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rheological properties of kafirin and zein prolamins2008In: Journal of Cereal Science, ISSN 0733-5210, E-ISSN 1095-9963, Vol. 47, no 1, p. 109-116Article in journal (Refereed)
    Abstract [en]

    The possibility of forming dough from kafirin was investigated and laboratory prepared kafirin was formed into a viscoelastic dough system. Measurements with Contraction Flow showed that dough systems prepared from kafirin and from commercial zein had the required extensional rheological properties for baking of leavened bread. The extensional viscosity and strain hardening of the kafirin and zein dough systems were similar to those of gluten and wheat flour doughs. The kafirin dough system, however, unlike the zein dough system rapidly became very stiff. The stiffening behaviour of the kafirin dough system was presumed to be caused by cross-linking of kafirin monomers. SDS-PAGE showed that the kafirin essentially only contained ?- and ?-kafirin, whereas the zein essentially only contained ?-zein. Since ?-kafirin contains more cysteine residues than the ?-prolamin it is more likely to form disulphide cross-links, which probably caused the differences in stiffening behaviour between kafirin and zein dough systems. Overall the kafirin dough system displayed rheological properties sufficient for baking of porous bread. Kafirin like zein appears to have promising properties for making non-gluten leavened doughs. © 2007 Elsevier Ltd. All rights reserved.

  • 55. Petersson, M.
    et al.
    Hagstrom, J.
    Nilsson, Katarina
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Kinetics of release from kafirin films2007In: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 21, no 8, p. 1256-1264Article in journal (Refereed)
    Abstract [en]

    Two separate studies were performed. The first studied release of two different preservatives (lactic acid and calcium propionate) from a biopolymer film to a model food with a water activity of aw=0.95. The second investigated the release of four sugars (fructose, maltose, raffinose and stachyose) with different molecular weights from a biopolymer film to a model food with water activities ranging from 0.85 to 0.95. In both studies, the biopolymer films containing the release components were made from kafirin and placed on the model food, consisting of a gel made of gelatine, sucrose and water with well defined water activity. The amount of preservatives and sugars released from the film to the gel were monitored over time using HPLC at different depths in the model food. The release of preservatives was rapid in both cases, and a gradient of released substances had already formed after 2 h in the model food. The gradients levelled out with time. Calcium propionate had a somewhat faster release than lactic acid. The water activity of the model food had a large impact on the release of sugars. A slow release was observed in the model food with aw=0.85, while a much more rapid release occurred in the model food with aw=0.95. There was a limited diffusion depth in the model food with aw=0.85, probably owing to a limited trial time, while the sugars in the model food with aw=0.95 diffused deeper into the model food until the film was depleted of available sugars. © 2006 Elsevier Ltd. All rights reserved.

  • 56. Petersson, M.
    et al.
    Loren, Niklas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Characterization of phase separation in film forming biopolymer mixtures2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 2, p. 932-941Article in journal (Refereed)
    Abstract [en]

    Enhanced, tailor-made films can be achieved by combining the good gas barrier of the hydrophilic high amylose maize starch (hylon) with the water resistance of the hydrophobic protein zein. Two polymers are not always miscible in solution, and the phase separation behavior of the mixture is therefore important for the final film structure and its properties. Phase separation of a mixture of these two biopolymers was induced either by cooling, which was observed as growing droplets of the hylon phase which in some cases also formed small aggregates, or by solvent evaporation and studied in real-time in a confocal laser scanning microscope. Solvent evaporation had a much stronger effect on phase separation. During the early stage of phase separation, hylon formed large aggregates and subsequently smaller droplets coalesced with other droplets or large hylon aggregates. The later part of the separation seemed to take place through spinodal decomposition. © 2005 American Chemical Society.

  • 57. Petersson, M.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Water vapour permeability and mechanical properties of mixed starch-monoglyceride films and effect of film forming conditions2005In: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 19, no 1, p. 123-132Article in journal (Refereed)
    Abstract [en]

    The effect on water vapour permeability (WVP) and mechanical properties of an addition of various amounts of an acetylated monoglyceride (Acetem) to native potato starch (NPS) films was studied. Phase separation was also evaluated by drying the films at different temperatures, since phase separation between starch and Acetem is affected by temperature. Films were gel-cast from a heated solution of NPS (3%). Five different concentrations (0-10%) of Acetem based on NPS were added to the solution and the films were dried at three different temperatures (23, 35 and 50°C). The film properties were evaluated by measuring thickness, moisture content (MC), WVP and mechanical properties and the results were then evaluated with multivariate analysis. The MC was slightly reduced in the films dried in higher temperatures, despite reconditioned samples, and the film thickness increased with an increasing amount of Acetem. The WVP of a pure NPS film was decreased by 27 and 37% with addition of 10% Acetem or high drying temperature, respectively. The mechanical properties were affected mainly by changes in Acetem concentration. A greater amount of Acetem decreased Young's modulus, stress at break and strain at break. Micrographs showed extensive phase separation in the films, but pure bilayer films were not formed. © 2004 Elsevier Ltd. All rights reserved.

  • 58.
    Petersson, Maria
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik. SCA Hygiene Products AB, Sweden; Chalmers University of Technology, Sweden.
    Gustafson, Inger
    SCA Hygiene Products AB, Sweden.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik. Chalmers University of Technology, Sweden.
    Comparison of microstructural and physical properties of two petroleum waxes2008In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 43, no 6, p. 1869-1879Article in journal (Refereed)
    Abstract [en]

    Microstructural and physical properties of two petroleum waxes, petrolatum and microcrystalline wax, were characterized in this work. Petroleum waxes are known to be hydrophobic and can be used in applications where a good moisture barrier is needed. In order to achieve a better understanding of different inherent properties of a wax, the two waxes in this work were characterized with infrared spectroscopy, confocal laser scanning microscopy, differential scanning calorimetry, rheology and X-ray diffraction. It was concluded from the results of infrared spectroscopy that the two waxes consisted only of saturated alkanes. Confocal laser scanning microscopy showed that the petrolatum sample had a more open microstructure with coarse crystals separated from each other than the microcrystalline wax, which appeared to have a more network-like crystalline structure consisting of somewhat finer crystals. Both waxes crystallized over a broad temperature range. Their crystallization characteristics were quite different, however, probably owing to a different oil content. According to modulated differential scanning calorimetry and rheological measurements the microcrystalline wax crystallized through a two-step process, whereas the petrolatum crystallized through only one step. 

  • 59.
    Petersson, Maria
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik. SCA Hygiene Products AB, Sweden; Chalmers University of Technology, Sweden.
    Gustafson, Ingrid
    SCA Hygiene Products AB, Sweden.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik. Chalmers University of Technology, Sweden.
    Ageing of two petroleum waxes2008In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 43, no 6, p. 1859-1868Article in journal (Refereed)
    Abstract [en]

    The effect of ageing at different storage conditions on the microstructure and melting properties of two petroleum waxes, petrolatum and microcrystalline wax, were investigated. The two waxes were stored for a maximum of 50 weeks at different temperatures. Samples were analysed before storage and removed from storage and analysed after different storage times. The effect of storage time and temperature was analysed with confocal laser scanning microscopy and modulated differential scanning calorimetry. Some alteration in the microstructure occurred with longer storage time. The amount of fine and irregular structures seen in the initial petrolatum samples decreased with storage time, and some shadowy, grey areas appeared. The microstructure of the microcrystalline wax stored at 23 °C became more diffuse and more, shadowy, grey areas appeared with time compared to samples stored at 50 °C. These showed coarser crystalline structures and fewer shadowy, grey areas. The results of confocal laser scanning microscopy and modulated differential scanning calorimetry analyses indicated that recrystallization occurred in both waxes during storage. The proposed recrystallization processes taking place during storage were most likely the same in all samples, but the recrystallization occurred to a greater extent in the microcrystalline wax samples stored at 50 °C.

  • 60.
    Qasi, Waqas
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Wiklund, Johan
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Ekberg, Olle
    Lund University, Sweden .
    Altskär, Annika
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Shear and extensional rheology of commercial thickeners used for dysphagia management2017In: Journal of texture studies, ISSN 0022-4901, E-ISSN 1745-4603, Vol. 48, no 6, p. 507-517Article in journal (Refereed)
    Abstract [en]

    People who suffer from swallowing disorders, commonly referred to as dysphagia, are often restricted to a texture-modified diet. In such a diet, the texture of the fluid is modified mainly by the addition of gum or starch-based thickeners. For optimal modification of the texture, tunable rheological parameters are shear viscosity, yield stress, and elasticity. In this work, the flow properties of commercial thickeners obtained from major commercial suppliers were measured both in shear and extensional flow using a laboratory viscometer and a newly developed tube viscometry technique, termed Pulsed Ultrasound Velocimetry plus Pressure Drop (PUV+PD). The two methods gave similar results, demonstrating that the PUV+PD technique can be applied to study flow during the swallowing process in geometry similar to that of the swallowing tract. The thickeners were characterized in relation to extensional viscosity using the Hyperbolic Contraction Flow (HCF) method, with microscopy used as a complementary method for visualization of the fluid structure. The gum-based thickeners had significantly higher extensional viscosities than the starch-based thickeners. The rheological behavior was manifested in the microstructure as a hydrocolloid network with dimensions in the nanometer range for the gum-based thickeners. The starch-based thickeners displayed a granular structure in the micrometer range. In addition, the commercial thickeners were compared to model fluids (Boger, Newtonian and Shear-thinning) set to equal shear viscosity at 50s−1 and it was demonstrated that their rheological behavior could be tuned between highly elastic, extension-thickening to Newtonian. This article is protected by copyright. All rights reserved.

  • 61.
    Qazi, Wapas
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food. Chalmers University of Technology, Sweden.
    Ekberg, Olle
    Skåne University Hospital, Sweden.
    Wiklund, Johan
    Incipientus Ultrasound Flow Technologies AB, Sweden.
    Mansoor, Rashid
    University of Oxford, UK.
    Stading, Mats
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food. Chalmers University of Technology, Sweden.
    Simultaneous X-ray Video-Fluoroscopy and Pulsed Ultrasound Velocimetry Analyses of the Pharyngeal Phase of Swallowing of Boluses with Different Rheological Properties2020In: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460Article in journal (Refereed)
    Abstract [en]

    The Ultrasound Velocity Profiling (UVP) technique allows real-time, non-invasive flow mapping of a fluid along a 1D-measuring line. This study explores the possibility of using the UVP technique and X-ray video-fluoroscopy (XVF) to elucidate the deglutition process with the focus on bolus rheology. By positioning the UVP probe so that the pulsed ultrasonic beam passes behind the air-filled trachea, the bolus flow in the pharynx can be measured. Healthy subjects in a clinical study swallowed fluids with different rheological properties: Newtonian (constant shear viscosity and non-elastic); Boger (constant shear viscosity and elastic); and shear thinning (shear rate-dependent shear viscosity and elastic). The results from both the UVP and XVF reveal higher velocities for the shear thinning fluid, followed by the Boger and the Newtonian fluids, demonstrating that the UVP method has equivalent sensitivities for detecting the velocities of fluids with different rheological properties. The velocity of the contraction wave that clears the pharynx was measured in the UVP and found to be independent of bolus rheology. The results show that UVP not only assesses accurately the fluid velocity in a bolus flow, but it can also monitor the structural changes that take place in response to a bolus flow, with the added advantage of being a completely non-invasive technique that does not require the introduction of contrast media. © 2020, The Author(s).

  • 62.
    Qazi, Waqas
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Ekberg, Olle
    Skåne University Hospital, Sweden.
    Wiklund, Johan
    Incipientus Ultrasound Flow Technologies AB, Sweden.
    Kotze, Reinhardt
    Incipientus Ultrasound Flow Technologies AB, Sweden.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing2019In: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460, Vol. 34, no 1, p. 21-833Article in journal (Refereed)
    Abstract [en]

    The characteristics of the flows of boluses with different consistencies, i.e. different rheological properties, through the pharynx have not been fully elucidated. The results obtained using a novel in vitro device, the Gothenburg Throat, which allows simultaneous bolus flow visualisation and manometry assessments in the pharynx geometry, are presented, to explain the dependence of bolus flow on bolus consistency. Four different bolus consistencies of a commercial food thickener, 0.5, 1, 1.5 and 2 Pa s (at a shear rate of 50 s −1 )—corresponding to a range from low honey-thick to pudding-thick consistencies on the National Dysphagia Diet (NDD) scale—were examined in the in vitro pharynx. The bolus velocities recorded in the simulator pharynx were in the range of 0.046–0.48 m/s, which is within the range reported in clinical studies. The corresponding wall shear rates associated with these velocities ranged from 13 s −1 (pudding consistency) to 209 s −1 (honey-thick consistency). The results of the in vitro manometry tests using different consistencies and bolus volumes were rather similar to those obtained in clinical studies. The in vitro device used in this study appears to be a valuable tool for pre-clinical analyses of thickened fluids. Furthermore, the results show that it is desirable to consider a broad range of shear rates when assessing the suitability of a certain consistency for swallowing. © 2019, The Author(s).

  • 63.
    Qazi, Waqas Muhammad
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Rheological modification of fluid foods for patients with dysphagia2016In: Annual Transactions of the Nordic Rheology Society, 2016, Vol. 24, p. 75-76Conference paper (Refereed)
    Abstract [en]

    Swallowing disorders, or dysphagia, is a growing problem especially as the population gets older. Fluid thickening is a well-established strategy for treating dysphagia, but the effects of thickening on the physiology of impaired swallowing are not fully understood and the relations to basic rheology are scarce. Commercial thickeners studied showed different behavior in both shear thinning, yield stress and first normal stress difference, and even larger differences in extensional viscosity.

  • 64.
    Qazi, Waqas Muhammad
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Wiklund, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Ekberg, Olle
    Lund University, Sweden.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    A swallowing model for efficient food product development2016In: The Materials Science Graduate Student Days 2016, 2016, p. 38-, article id P20Conference paper (Other academic)
    Abstract [en]

    Dysphagia refers to difficulties in swallowing, caused by conditions ranging from trauma to neurological disorders such as dementia. People suffering from dysphagia cannot adequately transfer food from the mouth to the stomach especially low viscosity, fluid foods. Texture modification is imperative to ensure safe passage of food from mouth into the stomach. Food products with elastic properties, i.e. high extensional viscosity, have been identified as helpful in promoting safe swallowing. However, this hypothesis is difficult to prove by clinical studies due to ethical issues and availability of suitable patients. Moreover, the problems of individual patients vary largely in nature and extent which further complicates the matter as identified in our previous research (1). We are currently constructing an in vitro human swallowing apparatus mimicking swallowing through the pharynx to the esophagus. The apparatus will have the pressure and ultrasound sensors to monitor real time flow properties of the bolus as it travels along the swallowing tract. This will enable us to measure relevant parameters during swallowing such as residence times and bolus velocity along the way. The model can be adjusted to different dysphagic conditions such as abnormal epiglottis closure. The goal of the project is to develop food products for safe swallowing and currently we are determining the rheological properties of commercial dysphagia thickeners, as well as model fluids. Two companies active in dysphagia foods are contributing (Fresenius Kabi and Findus). The shear and extensional properties have been shown to vary significantly, which has been correlated with fluid microstructure.

  • 65.
    Qazi, Waqas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Nyström, Magda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Ekberg, Olle
    Skåne University Hospital, Sweden.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Edible Boger fluid and its rheology at human physiological conditions2015In: Annual Transactions - The Nordic Rheology Society, ISSN 1601-4057, Vol. 23, p. 195-198Article in journal (Refereed)
    Abstract [en]

    Studies have shown that patients suffering from dysphagia have a slower oropharyngeal transit times than the healthy individuals. Therefore, elastic properties of liquids foods are hypothesized to be imperative for safe swallowing in those suffering from dysphagia. This makes the consideration of body temperature necessary while studying elastic fluids. Our result indicated that the elastic and viscous properties of the liquids products are considerably reduced when studied under the actual physiologic temperature conditions on the oral cavity and pharynx.

  • 66.
    Qazi, Waqas
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    In vitro models for simulating swallowing2019In: Dysphagia: Diagnosis and Treatment, 2019, p. 549-562Chapter in book (Other academic)
    Abstract [en]

    This chapter gives an overview of the in vitro models that are currently used for studying swallowing. The focus is on the construction, geometry, and performance of mechanical models. Swallowing simulations and mathematical modeling are also considered. The in vitro models that are concerned with the oral, pharyngeal, and esophageal phases of swallowing linked to bolus properties are discussed. The pharyngeal phase is given special consideration, as it is involved in both food transport to the stomach and air transport to the lungs, and therefore constitutes the most critical phase of swallowing.

  • 67.
    Qazi, Waqas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Wiklund, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Ekberg, Olle
    Lund University, Sweden.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    VALIDATION OF INLINE RHEOMETRY WITH THICKENER BASED LIQUIDS FOR DYSPHAGIA2016In: 6th ESSD Congress, 2016, article id 16.06Conference paper (Other academic)
  • 68. Richardson, G.
    et al.
    Bergenstahl, B.
    Langton, Maud
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    The function of ?-crystalline emulsifiers on expanding foam surfaces2004In: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 18, no 4, p. 655-663Article in journal (Refereed)
    Abstract [en]

    The expanding capacity and the stabilizing function of an ?-crystalline emulsifier on the bubble surfaces during and after expansion of a sugar foam were examined by volume measurements, confocal laser scanning microscopy (CLSM), freeze-etching and transmission electron microscopy (TEM) and oscillatory rheological measurements. 0.2-10% (w/w) emulsifier, either a polyglycerol ester mixed with monoglycerides (PGE/MG) in ?-gel form or sodium oleate in micellar form, was mixed into a 65% sucrose solution in a specially designed vessel at a pressure of 1-5 bar. The foam produced was expanded to ambient pressure before measurements were made. The total volume of the foam was shown to increase proportionally to the expansion with both emulsifiers. With PGE/MG, small bubbles were produced (1-4 ?m). With oleate, the bubbles became much larger (5-25 ?m) and more coalescence could be observed. The storage modulus of the foam was shown to depend on the bubble sizes, the volume fraction of air and also the emulsifier. The foam stabilized with PGE/MG was stiff at a high concentration of emulsifier, while the micelle forming emulsifier remained more liquid-like. A possible explanation was that the ?-crystalline PGE/MG emulsifier formed aggregates and caused an attractive bridging interaction between the bubbles, which resulted in a higher storage modulus. The micellar oleate did not cause any bubble bridging. © 2003 Elsevier Ltd. All rights reserved.

  • 69. Rindlav-Westling, A.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Gatenholm, P.
    Crystallinity and morphology in films of starch, amylose and amylopectin blends2002In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 3, no 1, p. 84-91Article in journal (Refereed)
    Abstract [en]

    Films of potato starch, amylose, and amylopectin and blends thereof were prepared by solution casting and examined using X-ray diffraction, light microscopy, transmission electron microscopy, and differential scanning calorimetry. Amylose films had a relative crystallinity of about 30% whereas amylopectin films were entirely amorphous. Blending of amylose and amylopectin resulted in films with a considerably higher degree of crystallinity than could be predicted. This is explained by cocrystallization between amylose and amylopectin and possibly by crystallization of amylopectin. The crystallized material gave rise to an endotherm detected with differential scanning calorimetry. The enthalpy and peak temperature of the transition also increased as the water content decreased. When the amylose proportion in the blends was low, separate phases of amylose and amylopectin were observed by light microscopy. At higher amylose proportions, however, the phase separation was apparently prevented by amylose gelation and the formation of a continuous amylose network. The amylose network in the films, observed with transmission electron microscopy, consisted of stiff strands and open pores and became less visible as the amylose proportion decreased. The water content of the films was dependent on the microstructure and the crystallinity.

  • 70. Rindlav-Westling, A.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Gatenholm, P.
    Structure, mechanical and barrier properties of amylose and amylopectin films1998In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 36, no 42038, p. 217-224Article in journal (Refereed)
    Abstract [en]

    The effect of film formation conditions on structure, mechanical properties and barrier properties of amylose and amylopectin films was studied. The films were prepared by solution-gel-casting of amylose and amylopectin from potato, with or without the addition of glycerol as plasticizer. Transmission electron micrographs showed that the network structure characteristic for the amylose gel was also found in the film state. The amylose films without glycerol plasticization exhibited a relatively high degree of B-type crystallinity, as revealed by wide-angle X-ray diffraction, whereas the unplasticized amylopectin films were amorphous. Although the addition of glycerol did not affect the crystallinity of the amylose films, glycerol-plasticized amylopectin formed B-type crystallinity, and the degree of crystallinity was dependent on the air humidity during film formation. The degree of crystallinity affected the mechanical properties of the amylopectin films, whereas the mechanical properties of the amylose films were influenced by the network microstructure. Oxygen and water vapour permeabilities were dependent neither on the degree of crystallinity in the films nor on the network structure. © 1998 Elsevier Science Ltd. All rights reserved.

  • 71.
    Sriviriyakul, Thana
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Bogren, Sara
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Schaller, Vincent
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Jonasson, Christian
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Blomgren, Jakob
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Ahrentorp, Fredrik
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Lopez-Sanchez, Patricia
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Berta, Marco
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Grüttner, Cordula
    micromod Partikeltechnologie GmbH, Germany.
    Zeng, Lunjie
    Chalmers University of Technology, Sweden.
    Stading, Mats
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Johansson, Christer
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nanorheological studies of xanthan/water solutions using magnetic nanoparticles2019In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 473, p. 268-271Article in journal (Refereed)
    Abstract [en]

    We show results of nanorheological studies of different concentrations of xanthan (non-Newtonian fluid) in water using magnetic nanoparticles (MNPs) together with the AC susceptibility (ACS) vs frequency method. For comparison we also show the ACS response for different concentrations of glycerol in water (Newtonian fluid). The ACS response is measured, and the data is modelled using dynamic magnetic models and different viscoelastic models. We study the ACS response (in-phase and out-of-phase ACS components) at different concentrations of xanthan in water (up to 1 wt% xanthan) and with a constant concentration of MNPs. We use MNP systems that show Brownian relaxation (sensitive to changes in the environmental properties around the MNPs). ACS measurements are performed using the DynoMag system. The Brownian relaxation of the MNP system peak is shifting down in frequency and the ACS response is broadening and decreases due to changes in the viscoelastic properties around the MNPs in the xanthan solution. The viscosity and the storage moduli are determined at each excitation frequency and compared with traditional macroscopic small amplitude oscillatory shear rheological measurements. The results from the traditional rheological and nanorheological measurements correlate well at higher xanthan concentration.

  • 72.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Edrud, S.
    Ekman, Susanne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Wendin, Karin
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rheological properties of a barium sulphate contrast medium.2007In: Transactions of the Nordic Rheology Society, Vol. 15, p. 267-268Article in journal (Other academic)
  • 73.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Large deformation properties of beta-lactoglobulin gel structures.1991In: Food Hydrocolloids, Vol. 5, no 4, p. 399-352Article in journal (Refereed)
  • 74.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Rheological behaviour of mixed gels of kappa-carrageenan-locust bean gum1993In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 22, no 1, p. 49-56Article in journal (Refereed)
    Abstract [en]

    Mixed gels of the K, Na and Ca-forms of ?-carrageenan and locust bean gum at a total polysaccharide concentration of 1% (w/w) were studied by dynamic viscoelastic measurements. Synergistic effects were only observed for mixed gels with K-?-carrageenan in ?0·1 m KCl. The composition favouring maximum synergy shifted from 90%-?-carrageenan in distilled water down to 35% K-?-carrageenan in 0·1 m KCl. Gels of K-?-carrageenan/locust bean gum did not show synergistic effects at high potassium concentration (0·2 m KCl). The typical behaviour of K-?-carrageenan at ?50 mm KCl dominated the rheological behaviour of the mixed systems even when the locust bean gum content was high. The synergistic effects probably originate from different mechanisms at low, 0-10 mm KCl, and high, 50-100 mm KCl, concentrations because of differences in the potassium-induced microstructure. The mixed gels with the Na or Ca-form of ?-carrageenan showed no synergy. Addition of locust bean gum caused the storage modulus to decrease and the phase angle to increase. The gels were weak, with G? < 170 Pa for the Na form and G? < 350 Pa for the Ca form. The mixed gels with both the Na and Ca forms had a broken frequency dependence of G?(f). © 1993.

  • 75.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Rheology and microstructure of mixed K-carrageenan-galactomannan gels.1995In: Annual Transactions of the Nordic Rheology Society, Vol. 3, p. 33-35Article in journal (Refereed)
  • 76.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Svenska livmedelsinstitutet.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Svenska livmedelsinstitutet.
    Viscoelastic behaviour of beta-lactoglobulin gel-structures.1990In: Food Hydrocolloids, Vol. 4, p. 121-135Article in journal (Refereed)
  • 77.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Langer, R.
    Mechanical shear properties of cell-polymer cartilage constructs1999In: Tissue engineering, ISSN 1076-3279, E-ISSN 1557-8690, Vol. 5, no 3, p. 241-250Article in journal (Refereed)
    Abstract [en]

    Cartilaginous constructs were created by using bovine chondrocytes on synthetic, biodegradable scaffolds made of fibrous polyglycolic acid (PGA). The constructs have previously been shown to resemble natural articular cartilage biochemically and histologically. The mechanical properties of articular cartilage mainly depend on the swollen extracellular matrix (ECM), which is a gel consisting of collagen fibers and proteoglycans in a fluid phase of water and electrolytes. The biomechanical properties of the constructs and the build-up of the ECM were studied using dynamic, nondestructive measurements in shear. A small, harmonic strain, ? ? 5 x 10-4, was applied to the sample, and the resulting stress was recorded and used for calculating the complex shear modulus G*. The applied strain was much smaller than that used in confined compression. The shear modulus G* correlated well with both the collagen and glycosaminoglycan content of the constructs but did not reach the same level as in natural cartilage. Collagen is the dominant component contributing to the shear strength of cartilage, and G* was shown to depend approximately quadratically on the collagen content of the constructs. The difference in G* between the constructs and natural cartilage was shown to depend on both the biochemical composition and the microstructure of the constructs.

  • 78.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Langton, Maud
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Inhomogenous biopolymer gels.1993In: Macromolekulare Chemie. Macromolecular Symposia, Vol. 76, p. 283-290Article in journal (Other academic)
  • 79.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Langton, Maud
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Inhomogenous fine-stranded beta-lactoglobulin gels.1992In: Food Hydrocolloids, Vol. 6, no 5, p. 455-470Article in journal (Refereed)
  • 80.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Langton, Maud
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Microstructure and rheological behaviour of particulate beta-lactoglobulin gels.1993In: Food Hydrocolloids, Vol. 7, no 3, p. 195-212Article in journal (Refereed)
  • 81.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Langton, Maud
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Small and large deformation studies of protein gels.1995In: Journal of Rheology, Vol. 39, no 6, p. 1445-1450Article in journal (Refereed)
  • 82.
    Stading, Mats
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Agriculture and Food.
    Lopez-Sanches, Patricia
    RISE - Research Institutes of Sweden (2017-2019), Bioscience and Materials, Agrifood and Bioscience.
    Challer, V.
    Johansson, C.
    Nano-rheometry for food oral processing2019In: Annual transactions of the nordic rheology society, 2019, Vol. 27, p. 117-120Conference paper (Refereed)
  • 83.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedelsforskning.
    Pettersson, A.
    Léufven, A.
    Mechanical properties and permeability of whey protein films.1996In: Annual Transactions of the Nordic Rheology Society, Vol. 4, p. 93-95Article in journal (Refereed)
  • 84.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design. Chalmers University of Technology, Sweden.
    Qazi, Waqas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Nyström, Magda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Berta, Marco
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Structure Design.
    Bulow, Margareta
    Skåne University Hospital, Sweden.
    Ekberg, Olle
    Skåne University Hospital, Sweden.
    Effect of shear vs. extensional flow during swallowing2015In: Annual Transactions - The Nordic Rheology Society, ISSN 1601-4057, Vol. 23, p. 63-65Article in journal (Refereed)
    Abstract [en]

    When we eat the swallowing is mainly an involuntary process. However, for an increasing number of the population the actual swallowing causes problems. The effect of elasticity on swallowing was thus evaluated. Edible model fluid foods were developed and the rheological properties were evaluated. The study indicated positive effects of fluid elasticity on the ease of swallowing for patients suffering from dysphagia.

  • 85.
    Stading, Mats
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rindlav-Westling, A.
    Gatenholm, P.
    Humidity-induced structural transitions in amylose and amylopectin films2001In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 45, no 3, p. 209-217Article in journal (Refereed)
    Abstract [en]

    The effect of humidity on the dynamic mechanical and barrier properties and on the microstructure of amylose and amylopectin films was studied. The films were solution-gel-cast, with and without glycerol as added plasticizer, and dried to equilibrium weight under various relative humidities (RH). The network microstructure of glycerol-plasticized amylose films was shown to change from dense and homogeneous to a more open structure with fluctuations in the pore size when the surrounding RH was increased. The structural change was attributed to plasticization of the amorphous areas by increased water content, leading to higher mobility in the network and subsequent inhomogeneous swelling. This structural change had a direct influence on the oxygen permeability, which drastically increased. The onset of the increase occurred at lower surrounding RH for the films containing glycerol, and these films also had higher oxygen permeability. Glycerol-plasticized amylopectin films with gradually increased crystallinity were prepared by varying the RH during film formation. Dynamic mechanical analysis at both varied temperature and RH showed that the increased crystallinity led to higher glass transition temperature, T g, and a smaller effect of the surrounding humidity on mechanical and barrier properties. The RH during the formation of glycerol-plasticized amylose films did not affect crystallinity or T g. These films formed at 70% RH were shown to have a marked heterogeneous network. © 2001 Elsevier Science Ltd.

  • 86.
    Stading, Mats
    et al.
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Waqas, Mohamad Qazi
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience. Chalmers University of Technology, Sweden.
    Holmberg, F
    Animato Konstruktions AB, Sweden.
    Wiklund, Johan
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Kotze, Richard
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Ekberg, O.
    Lund University, Sweden.
    A Device that Models Human Swallowing2019In: Dysphagia (New York. Print), ISSN 0179-051X, E-ISSN 1432-0460, Vol. 34, no 5, p. 615-626Article in journal (Refereed)
    Abstract [en]

    The pharynx is critical for correct swallowing, facilitating the transport of both air and food transport in a highly coordinated manner, and aberrant co-ordination causes swallowing disorders (dysphagia). In this work, an in vitro model of swallowing was designed to investigate the role of rheology in swallowing and for use as a pre-clinical tool for simulation of different routes to dysphagia. The model is based on the geometry of the human pharynx. Manometry is used for pressure measurements and ultrasonic analysis is performed to analyze the flow profiles and determine shear rate in the bolus, the latter being vital information largely missing in literature. In the fully automated model, bolus injection, epiglottis/nasopharynx movement, and ultrasound transducer positioning can be controlled. Simulation of closing of the airways and nasal cavity is modulated by the software, as is a clamping valve that simulates the upper esophageal sphincter. The actions can be timed and valves opened to different degrees, resembling pathologic swallowing conditions. To validate measurements of the velocity profile and manometry, continuous and bolus flow was performed. The respective velocity profiles demonstrated the accuracy and validity of the flow characterization necessary for determining bolus flow. A maximum bolus shear rate of 80 s−1 was noted for syrup-consistency fluids. Similarly, the manometry data acquired compared very well with clinical studies.

  • 87. Thorvaldsson, K.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Nilsson, Katarina
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Kidman, Siw
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Langton, Maud
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Rheology and structure of heat-treated pasta dough: Influence of water content and heating rate1999In: Lebensmittel-Wissenschaft + Technologie, ISSN 0023-6438, E-ISSN 1096-1127, Vol. 32, no 3, p. 154-161Article in journal (Refereed)
    Abstract [en]

    The migration of water and the influence of water content and heating rate on the rheological and structural formation of pasta dough were investigated. The dough used in the study had two different water contents, 39.5 and 41.0%, and was made using water and wheat flour. The samples, 15 x 15 x 2 cm in size, were heated from 25 to 80°C in a conventional oven at two different temperatures, 100 and 150°C, to achieve two different heating rates. During the heating the local water content was measured in the centre of the samples with a fibre-optic NIR instrument. The temperature was measured in the centre, halfway to the centre and at the surface. The rheology of the heat-treated samples was studied by means of tensile tests. Young's modulus, stress at maximum load and energy to break point were calculated. The micro structure of the samples was characterised by CLSM, confocal laser scanning microscopy, and the microstructural parameters were quantified using image analysis. The changes in rheological properties during heating were studied by means of DMA. Untreated dough samples were heated from 25 to 90°C with a heating rate of 5° C/min and a compressing oscillation of 1 Hz. The changes in phase angle ? and storage modulus E' were measured. The most important results were that no migration of water inside the pasta dough could be found. Both the water content and the heating rate affected the structural and rhelogical properties of the pasta dough. There was a maximum in E' vs. temperature, which shifted towards higher temperatures with decreasing water content. Young's modulus was affected by both the heating rate and the water content. Energy to break point and stress at maximum load were affected by the heating rate. The pore size was affected by the water content. The swelling temperature seemed to increase as the heating rate increased. © 1999 Academic Press.

  • 88.
    Undeland, Ingrid
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Influence of skinning on lipid oxidation in different horizontal layers of herring (Clupea harengus) during frozen storage1998In: Journal of the Science of Food and Agriculture, ISSN 0022-5142, E-ISSN 1097-0010, Vol. 78, no 3, p. 441-450Article in journal (Refereed)
    Abstract [en]

    This study was conducted to evaluate the effect of skinning and of compositional differences on the oxidative stability of various horizontal layers from herring (Clupea harengus) during frozen storage. Herring fillets, with and without skin, were stored at -18°C for 0, 3, 9, 16 and 28 weeks. After each storage period, the fillets were divided horizontally into three layers: 'under skin', 'middle part' and 'inner part'. Each layer was then extracted for total lipids, in which peroxide value (PV), absorbance at 234 nm (A234) and 268 nm (A268) as well as lipid-soluble fluorescent oxidation products (FP) were measured. Prior to storage, the fat content, fatty acid pattern and ?-tocopherol were also analysed. During storage of skinless fillets, the under skin layer increased most in PV, A234, A268 and FP (P < 0.05), followed by the inner and middle parts. In fillets stored with skin, the high oxidation rate of the under skin layer lipids was suppressed, but this layer still gave rise to the highest responses. Firstly, these results point to the protective properties of the skin and, secondly, to the unfavourable composition of the under skin layer: a lot of dark muscle; the silver surface; the highest fat content and the lowest level of ?-tocopherol. Concerning the fatty acid pattern in the three layers, the amount of C20 : 5, C18 : 1 and C20 : 1 in the fat gradually decreased from the under skin layer towards the inner part of the fillet, whereas the opposite was true for C22 : 6.

  • 89.
    Undeland, Ingrid
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Lingnert, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Influence of skinning on lipid oxidation in different horizontal layers of herring (Clupea harengus) during frozen storage1998In: Journal of the Science of Food and Agriculture, ISSN 0346-718X, Vol. 78, no 3, p. 441-450Article in journal (Refereed)
    Abstract [en]

    This study was conducted to evaluate the effect of skinning and of compositional differences on the oxidative stability of various horizontal layers from herring (Clupea harengus) during frozen storage. Herring fillets, with and without skin, were stored at -18 °C for 0, 3, 9, 16 and 28 weeks. After each storage period, the fillets were divided horizontally into three layers: `under skin', `middle part' and `inner part'. Each layer was then extracted for total lipids, in which peroxide value (PV), absorbance at 234 nm (A234) and 268 nm (A268) as well as lipid-soluble fluorescent oxidation products (FP) were measured. Prior to storage, the fat content, fatty acid pattern and ?-tocopherol were also analyzed. During storage of skinless fillets, the under skin layer increased most in PV, A234, A268 and FP (P<0.05), followed by the inner and middle parts. In fillets stored with skin, the high oxidation rate of the under skin layer lipids was suppressed, but this layer still gave rise to the highest responses. Firstly, these results point to the protective properties of the skin and, secondly, to the unfavourable composition of the under skin layer: a lot of dark muscle; the silver surface; the highest fat content and the lowest level of ?-tocopherol. Concerning the fatty acid pattern in the three layers, the amount of C20:5. C18:1 and C20:1 in the fat gradually decreased from the under skin layer towards the inner part of the fillet, whereas the opposite was true for C22:6.

  • 90. Wassell, P.
    et al.
    Wiklund, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Bonwick, G.
    Smith, C.
    Almiron-Roig, E.
    Ultrasound doppler based in-line viscosity and solid fat profile measurement of fat blends2010In: International journal of food science & technology, ISSN 0950-5423, E-ISSN 1365-2621, Vol. 45, no 5, p. 877-883Article in journal (Refereed)
  • 91.
    Wendin, Karin
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Ekman, Susanne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Bulow, M.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Johansson, D.
    Rothenberg, E.
    Objective and quantitative definitions of modified food textures based on sensory and rheological methodology2010In: Food & Nutrition Research, ISSN 1654-6628, E-ISSN 1654-661X, Vol. 54, p. 5134-Article in journal (Refereed)
    Abstract [en]

    Introduction: Patients who suffer from chewing and swallowing disorders, i.e. dysphagia, may have difficulties ingesting normal food and liquids. In these patients a texture modified diet may enable that the patient maintain adequate nutrition. However, there is no generally accepted definition of 'texture' that includes measurements describing different food textures. Objective: Objectively define and quantify categories of texture-modified food by conducting rheological measurements and sensory analyses. A further objective was to facilitate the communication and recommendations of appropriate food textures for patients with dysphagia. Design: About 15 food samples varying in texture qualities were characterized by descriptive sensory and rheological measurements. Results: Soups were perceived as homogenous; thickened soups were perceived as being easier to swallow, more melting and creamy compared with soups without thickener. Viscosity differed between the two types of soups. Texture descriptors for pâtés were characterized by high chewing resistance, firmness, and having larger particles compared with timbales and jellied products. Jellied products were perceived as wobbly, creamy, and easier to swallow. Concerning the rheological measurements, all solid products were more elastic than viscous (G? > G?), belonging to different G? intervals: jellied products (low G?) and timbales together with pâtés (higher G?). Conclusion: By combining sensory and rheological measurements, a system of objective, quantitative, and well-defined food textures was developed that characterizes the different texture categories. © 2010 Karin Wendin et al.

  • 92.
    Wiklund, Johan A.
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Pettersson, Anders Johan
    Chalmers University of Technology, Sweden.
    Rasmuson, Anders
    Chalmers University of Technology, Sweden.
    A comparative study of UVP and LDA techniques for pulp suspensions in pipe flow2006In: AIChE Journal, ISSN 0001-1541, E-ISSN 1547-5905, Vol. 52, no 2, p. 484-495Article in journal (Refereed)
    Abstract [en]

    For the first time, noninvasive measurements in pulp suspensions at consistencies ranging from 0.74%(w/w) up to 7.8%(w/w) have been performed simultaneously using ultrasound velocity profiling (UVP) and laser doppler anemometry (LDA) in an experimental pipe flow loop. Results show that both techniques can be used to determine the plug flow velocity with good agreement in much more concentrated pulp suspensions than what has been reported so far in the literature. Instantaneous velocity profiles have been obtained noninvasively in pipe flow using the UVP technique, and it is shown that combined with simultaneous pressure drop measurements, the UVP technique can be used to determine the yield stress in-line. Results further show that LDA works, with limited penetration depth of up to several millimeters, even in strongly opaque systems, such as in 7.8%(w/w) pulp. Deviating results were however obtained in the near wall region and more work is needed.

  • 93.
    Wiklund, Johan
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Birkhofer, B.
    Jeelani, S.A.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Windhab, E.J.
    In-Line rheometry of particulate suspensions by pulsed ultrasound velocimetry combined with pressure difference method2012In: Applied Rheology, ISSN 1430-6395, E-ISSN 1617-8106, Vol. 22, no 4, p. 5-Article in journal (Refereed)
    Abstract [en]

    The in-line rheometer concept based on the combination of the ultrasonic velocity profiling (UVP) technique and pressure difference (PD) measurements was utilized for investigating the influence of particle concentration and size distribution on the rheology of particulate suspensions in pipe flow under realistic industrial process conditions. Well defined model suspensions were used, consisting of 11mm and 90mm diameter polyamide particles suspended in rapeseed oil at concentrations ranging from 1 to 25% by volume. The variation of concentration and particle size distribution had the expected effects on the shear viscositiy of the investigated unimodal and bimodal suspensions. The in-line results showed that the investigated suspensions exhibit Sisko flow behavior and demonstrated that the UVP+PD method can be used to determine the flow behavior of complex fluids and suspensions, even at high solid concentrations, under industrial conditions in-line. The obtained inline results were in good agreement with measurement data obtained using a conventional rotational controlled-stress rheometer. Limitations of commercially available transducer technology were identified and other possible sources of inaccuracy of the UVP+PD method were investigated. Several improvements of the UVP+PD measurement method were proposed © Appl. Rheol.

  • 94.
    Wiklund, Johan
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Shahram, I.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Methodology for in-line rheology by ultrasound Doppler velocity profiling and pressure difference techniques2007In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 62, no 16, p. 4277-4293Article in journal (Refereed)
    Abstract [en]

    This paper describes a methodology for measuring rheological flow properties in-line, in real-time, based on simultaneous measurements of velocity profiles using an ultrasound velocity profiling (UVP) technique with pressure difference (PD) technology. The methodology allows measurements that are rapid, non-destructive and non-invasive and has several advantages over methods presented previously. The set-up used here allows direct access to demodulated echo amplitude data, thus providing an option to switch between time domain algorithms and algorithms based on FFT for estimating velocities, depending on the signal-to-noise ratio (SNR) and time resolution required. Software based on the MATLAB® graphical user interface (GUI) has been developed and provides a powerful and rapid tool for visualizing and processing the data acquired, giving rheological information in real-time and in excellent agreement with conventional methods. This paper further focuses on crucial aspects of the methodology: implementation of low-pass filter and singular value decomposition (SVD) methods, non-invasive measurements and determination of the wall positions using channel correlation and methods based on SVD. Measurements of sound velocity and attenuation of ultrasound in-line were introduced to increase measurement accuracy and provide an interesting approach to determine particle concentration in-line. The UVP-PD methodology presented may serve as an in-line tool for non-invasive, real-time monitoring and process control. © 2007 Elsevier Ltd. All rights reserved.

  • 95.
    Wiklund, Johan
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Application of in-line ultrasound Doppler-based UVP-PD rheometry method to concentrated model and industrial suspensions2008In: Flow Measurement and Instrumentation, ISSN 0955-5986, E-ISSN 1873-6998, Vol. 19, no 42067, p. 171-179Article in journal (Refereed)
    Abstract [en]

    The in-line ultrasound Doppler-based UVP-PD rheometry method was evaluated for non-invasive, real-time rheological characterization of complex model- and industrial suspensions. The method is based on the combination of ultrasound velocity profile (UVP) and pressure drop (PD) measurements. Experiments were carried out in pressure driven, steady shear flow at different volumetric flow rates in a flow loop, designed to mimic industrial conditions. Results showed that instantaneous velocity profiles and rheological properties could be monitored in real-time, in-line. A much wider range of model and industrial suspensions was covered compared to what has so far been reported in literature. Investigated suspensions differed in particle sizes, distributions, shapes and suspension characteristics. The agreement was good between shear viscosities measured in-line and off-line using conventional rheometers for particles smaller than the shear gap in the concentric cylinders. The UVP-PD method is applicable to suspensions for which conventional, off-line rheometers fail due to shear gap size restrictions. The UVP-PD method can be a valuable tool for process monitoring since rapid changes in rheology during processing can be monitored in real-time, in-line. © 2007 Elsevier Ltd. All rights reserved.

  • 96.
    Wiklund, Johan
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Tragardh, C.
    Monitoring liquid displacement of model and industrial fluids in pipes by in-line ultrasonic rheometry2010In: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 99, no 3, p. 330-337Article in journal (Refereed)
  • 97.
    Wiklund, Johan
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Trägårdh, C.
    Ultrasound doppler based in-line rheometry for processing applications.2007In: Transactions of the Nordic Rheology Society, Vol. 15, p. 135-139Article in journal (Other academic)
  • 98. Young, N.W.G.
    et al.
    Wassell, P.
    Wiklund, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Monitoring struturants of fat blends with ultrasound based in-line rheometry (ultrasonic velocity profiling with pressure difference)2008In: International journal of food science & technology, ISSN 0950-5423, E-ISSN 1365-2621, Vol. 43, no 11, p. 2083-2089Article in journal (Refereed)
    Abstract [en]

    Ultrasonic velocity profiling with pressure difference (UVP-PD) was demonstrated to be a successful, non-invasive, in-line measurement system for instantaneous velocity and rheological flow profiling of complex, opaque fat blends. Model systems of 25% Akomic, 75% rapeseed oil; and 25% Akomic, 74% rapeseed oil and 1% Grindsted® Crystalliser 110 were compared under real process conditions with UVP-PD. Results indicated that the sample containing the crystalliser had twice the viscosity of the control. These in-line results are in agreement with previous off-line results, and offer the chance to probe the mechanics of fat blend physics under real, dynamic conditions. © 2008 Institute of Food Science and Technology.

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