Influence of droplet clustering on the rheological properties of emulsion-filled gels
Oliver, L. ; Berndsen, L. ; Aken, G.A. van; Scholten, E. - \ 2015
Food Hydrocolloids 50 (2015). - ISSN 0268-005X - p. 74 - 83.
large-deformation rheology - coronary-heart-disease - composite gels - saturated fat - viscoelastic properties - mechanical-properties - spheres
The aim of this work was to determine the effect and magnitude of fat droplet clustering on the rheological properties of emulsion-filled gels. To this end, we investigated experimentally the effect of fat hardness and emulsion droplet clustering in gelatin gels. Fat droplet clustering was induced or avoided by changing the temperature at which the emulsion was mixed with the gelatin. Rheological properties of the filled gels were investigated by uniaxial compression. The obtained experimental data show that next to changes in droplet hardness and matrix hardness, also droplet clustering contributes to the gel stiffness; even in the absence of discrete bonds between adjacent droplets. The experimental data was compared with the Kerner model, the Kerner model corrected by the effective volume fraction approach and the Kerner model considering an inhomogeneous distribution of the droplets. The Kerner model gives a good prediction for the gels filled with liquid droplets without clustering. The correction for an inhomogeneous distribution of the droplets best described the influence of emulsion droplet clustering in emulsion-filled gels, showing a quantitative evaluation on the role of droplet clustering in the rheological behaviour of emulsion-filled gels. This may provide guidelines for developing a strategy to control certain product properties.
A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species
Onoda, Y. ; Schieving, F. ; Anten, N.P.R. - \ 2015
Journal of Experimental Botany 66 (2015)9. - ISSN 0022-0957 - p. 2487 - 2499.
herbaceous plants - tissue stresses - mechanical-properties - maize leaf - biomechanics - organs - growth - perspective - irradiance - sunflower
Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiffness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers. Across a phylogenetically diverse range of 36 angiosperm species, the estimated Young’s moduli (a measure of stiffness) of mesophyll layers were much lower than those of the epidermis layers, indicating that leaf laminas behaved similarly to efficient sandwich structures. The stiffness of epidermis layers was higher in evergreen species than in deciduous species, and strongly associated with cuticle thickness. The ubiquitous nature of sandwich structures in leaves across studied species suggests that the sandwich structure has evolutionary advantages as it enables leaves to be simultaneously thin and flat, efficiently capturing light and maintaining mechanical stability under various stresses.
Coating formation during drying of ß-lactoglobulin: Gradual and sudden changes
Bouman, J. ; Vries, R.J. de; Venema, P. ; Belton, P. ; Baukh, V. ; Huinink, H. ; Linden, E. van der - \ 2015
Biomacromolecules 16 (2015)1. - ISSN 1525-7797 - p. 76 - 86.
diffusing-wave spectroscopy - concentrated colloidal suspensions - water-vapor sorption - mechanical-properties - film formation - protein films - wheat gluten - hydration - dynamics - solids
The drying dynamics of protein coatings is of importance for many applications. The main focus of research so far was to investigate macroscopic properties of protein coatings, leaving drying dynamics virtually unexplored. A unique combination of techniques is used to monitor drying of a coating containing the protein ß-lactoglobulin. The techniques used cover both macroscopic and microscopic aspects of the drying process. For all water fractions amenable to diffusing wave spectroscopy analysis (xw > 0.2 w/w), the tracer particles diffuse in the coating as in a Newtonian viscous medium. Magnetic resonance imaging shows both protein and water are distributed homogeneously over the coating during drying, up to water fractions above 0.2 w/w. When drying continues to lower water fractions, sudden transitions in drying behavior are observed by both dynamic vapor sorption and IR spectroscopy, which we suggest are due to changes in molecular interactions caused by dehydration of the protein backbone.
Dynamic texture perception and oral processing of semi-solid food gels: Part 1: Comparison between QDA, progressive profiling and TDS
Devezeaux de Lavergne, M.S.M. ; Delft, J.M. van; Velde, F. van de; Boekel, M.A.J.S. van; Stieger, M.A. - \ 2015
Food Hydrocolloids 43 (2015). - ISSN 0268-005X - p. 207 - 217.
emulsion-filled gels - sensory texture - rheological properties - mechanical-properties - temporal dominance - time - microstructure - sensations
Texture perception of food is a dynamic phenomenon depending on food properties and oral processing. Several sensory techniques enable to measure texture perception over time. The aim of this study was to compare quantitative descriptive analysis (QDA), temporal dominance of sensation (TDS) and progressive profiling in the assessment of dynamic texture of emulsion filled gels varying in fracture stress (low/high), fracture strain (low/high) and oil release (oil droplets bound/unbound to the gel matrix). The QDA results revealed that the variation of mechanical properties led to significant differences in texture properties perceived at first bite (firmness and brittleness). Texture attributes perceived at later stages of mastication showed significant differences between gels depending on the first bite properties e.g. soft gels were perceived as more melting. Progressive profiling showed that creaminess increased over eating time while firmness decreased. TDS results were in agreement with the other methods and additionally conveyed information on the succession of perceived attributes over time. The TDS sensory trajectories demonstrated that for all gels dynamic perception evolved in a similar fashion but samples with a high or low fracture strain differed at the end of oral processing. We conclude that texture perception of semi-solid gels is dynamic and can be measured by either of the three sensory methods. The mechanical properties of the gels influence the perception of texture attributes at first bite and at later stages of mastication. QDA, TDS and progressive profiling gave matching and complementary results in the assessment of dynamic sensory texture.
Effect of fat hardness on large deformation rheology of emulsion-filled gels
Oliver, L. ; Scholten, E. ; Aken, G.A. van - \ 2015
Food Hydrocolloids 43 (2015). - ISSN 0268-005X - p. 299 - 310.
coronary-heart-disease - protein isolate gels - composite gels - casein gels - viscoelastic properties - mechanical-properties - saturated fat - droplets - behavior - fracture
The aim of this work was to investigate the impact on the texture properties of emulsion-filled gels when saturated solid fat is replaced by unsaturated liquid oil. Whey protein aggregate, gelatin and micellar casein, were chosen to form different types of gel matrices and the fat hardness was varied by selection of the fat type and variation of the temperature. As emulsifier, either whey protein aggregates, whey protein or sodium caseinate was used. Texture properties of the filled gels were investigated by uniaxial compression. The fracture properties were affected by the presence of emulsion droplets, however the effect of fat hardness was small. The presence of emulsion droplets (either liquid or solid) increases the gel stiffness as compared to the emulsion-free gel, indicating that the droplets are an active part of the gel. An increase in solid fat content led to a moderate increase in gel stiffness for whey protein aggregate gels, which was in agreement with predictions according to the Palierne model for the effect of fat hardness on the stiffness of the filled gels. For the gelatin and micellar casein gels, the magnitude by which the gel stiffness increased as a function of the solid fat content was much larger than expected on the basis of this model. Microscopical observation suggested that this was caused by an inhomogeneous distribution of the fat droplets, due to droplet aggregation or/and concentration of the droplets in gel strands, which increases the effective volume fraction of the droplets in the matrix.
Incorporation of Mesoporous Silica Particles in Gelatine Gels: Effect of Particle Type and Surface Modification on Physical Properties
Perez-Esteve, E. ; Oliver, L. ; Garcia, L. ; Nieuwland, M. ; Jongh, H.H.J. de; Martinez-Manez, R. ; Barat, J.M. - \ 2014
Langmuir 30 (2014)23. - ISSN 0743-7463 - p. 6970 - 6979.
gate-like scaffoldings - controlled-release - filled gels - drug-delivery - polymer nanocomposites - rheological properties - mechanical-properties - nanoparticles - deformation - fracture
The aim of this work was to investigate the impact of mesoporous silica particles (MSPs) on the physicochemical properties of filled protein gels. We have studied the effect of the addition of different mesoporous silica particles, either bare or functionalized with amines or carboxylates, on the physical properties of gelatine gels (5% w/v). Textural properties of the filled gels were investigated by uniaxial compression, while optical properties were investigated by turbidity. The MSPs were characterized with the objective of correlating particle features with their impact on the corresponding filled-gel properties. The addition of MSPs (both with and without functionalization) increased the stiffness of the gelatine gels. Furthermore, functionalized MSPs showed a remarkable increase in the strength of the gels and a slight reduction in the brittleness of the gels, in contrast with nonfunctionalized MSPs which showed no effect on these two properties. The turbidity of the gels was also affected by the addition of all tested MSPs, showing that the particles that formed smaller aggregates resulted in a higher contribution to turbidity. MSPs are promising candidates for the development of functional food containing smart delivery systems, also being able to modulate the functionality of protein gels.
Pectic arabinan side chains are essential for pollen cell wall integrity during pollen development
Cankar, K. ; Kortstee, A.J. ; Toonen, M.A.J. ; Wolters-Arts, M. ; Houbein, R. ; Mariani, C. ; Ulvskov, P. ; Jorgensen, B. ; Schols, H.A. ; Visser, R.G.F. ; Trindade, L.M. - \ 2014
Plant Biotechnology Journal 12 (2014)4. - ISSN 1467-7644 - p. 492 - 502.
in-vivo expression - mechanical-properties - potato pectin - arabidopsis - gene - galactan - growth - biosynthesis - mutants - tubers
Pectin is a complex polysaccharide and an integral part of the primary plant cell wall and middle lamella, contributing to cell wall mechanical strength and cell adhesion. To understand the structure–function relationships of pectin in the cell wall, a set of transgenic potato lines with altered pectin composition was analysed. The expression of genes encoding enzymes involved in pectin acetylation, degradation of the rhamnogalacturonan backbone and type and length of neutral side chains, arabinan and galactan in particular, has been altered. Upon crossing of different transgenic lines, some transgenes were not transmitted to the next generation when these lines were used as a pollen donor, suggesting male sterility. Viability of mature pollen was severely decreased in potato lines with reduced pectic arabinan, but not in lines with altered galactan side chains. Anthers and pollen of different developmental stages were microscopically examined to study the phenotype in more detail. Scanning electron microscopy of flowers showed collapsed pollen grains in mature anthers and in earlier stages cytoplasmic protrusions at the site of the of kin pore, eventually leading to bursting of the pollen grain and leaking of the cytoplasm. This phenomenon is only observed after the microspores are released and the tapetum starts to degenerate. Timing of the phenotype indicates a role for pectic arabinan side chains during remodelling of the cell wall when the pollen grain is maturing and dehydrating.
Intraspecific variation of a desert shrub species in phenotypic plasticity in response to sand burial
Xu, L. ; Huber, H. ; During, H.J. ; Dong, M. ; Anten, N.P.R. - \ 2013
New Phytologist 199 (2013)4. - ISSN 0028-646X - p. 991 - 1000.
shade-avoidance responses - mechanical-properties - impatiens-capensis - shoot elongation - trifolium-repens - rumex-palustris - soil nutrients - plants - growth - stress
Shoot elongation is one of the main plastic responses of plants to burial, a ubiquitous stress factor in dry ecosystems. Yet, intraspecific variation in this response to burial and the extent to which this variation is functionally coordinated with variation in other trait responses are largely unknown. We subjected seedlings of the shrub Caragana intermedia from 18 maternal parents (i.e. different half-sib families) to repeated partial burial to investigate how burial affects shoot growth, stem mechanical traits and associated plasticity. Burial increased both stem elongation and diameter growth of plants, but decreased biomass production. Half-sib families had different rates of shoot elongation, and differed in their response to burial with respect to biomechanical stem properties. Across half-sib families, the magnitude of these responses in mechanical traits was positively correlated with the magnitude of the stem elongation response. These results indicate that plasticity in different stem traits in response to sand burial and intraspecific variation therein are functionally coordinated with respect to mechanical stability. The results emphasize the importance of considering functionally coordinated traits when analyzing phenotypic plasticity in plants.
PFG-NMR self-diffusion in casein dispersions: effect of probe size and protein aggregate size
Salami, S. ; Rondeau, C. ; Duynhoven, J.P.M. van; Mariette, F. - \ 2013
Food Hydrocolloids 31 (2013)2. - ISSN 0268-005X - p. 248 - 255.
dynamic light-scattering - sodium caseinate - mechanical-properties - electron-microscopy - gel microstructure - wave spectroscopy - micelles - suspensions - coagulation - milk
The self-diffusion coefficients of different molecular weight PEGs (Polyethylene glycol) and casein particles were measured, using a pulsed-gradient nuclear magnetic resonance technique (PFG-NMR), in native phosphocaseinate (NPC) and sodium caseinate (SC) dispersions where caseins are not structured into micelles. The dependence of the PEG self-diffusion coefficient on the PEG size, casein concentration, the size and the mobility of casein obstacle particles are reported. Wide differences in the PEG diffusion coefficients were found according to the casein particle structure. The greatest reduction in diffusion coefficients was found in sodium caseinate suspensions. Moreover, sodium caseinate aggregates were found to diffuse more slowly than casein micelles for casein concentrations >9 g/100 g H2O. Experimental PEG and casein diffusion findings were analyzed using two appropriate diffusion models: the Rouse model and the Speedy model, respectively. According to the Speedy model, caseins behave as hard spheres below the close packing limit (10 g/100 g H2O for SC (Farrer & Lips, 1999) and 15 g/100 g H2O for NPC (Bouchoux et al., 2009)) and as soft particles above this limit. Our results provided a consistent picture of the effects of diffusant mass, the dynamics of the host material and of the importance of the casein structure in determining the diffusion behavior of probes in these systems.
Bacterial cell surface deformation under external loading
Chen, Y. ; Norde, W. ; Mei, H.C. van der; Busscher, H.J. - \ 2012
mBio 3 (2012)6. - ISSN 2150-7511 - 8 p.
atomic-force microscopy - staphylococcus-aureus - mechanical-properties - adhesion - biofilms - model - viscoelasticity - peptidoglycan - contact - removal
Viscoelastic deformation of the contact volume between adhering bacteria and substratum surfaces plays a role in their adhesion and detachment. Currently, there are no deformation models that account for the heterogeneous structure and composition of bacteria, consisting of a relatively soft outer layer and a more rigid, hard core enveloped by a cross-linked peptidoglycan layer. The aim of this paper is to present a new, simple model to derive the reduced Young’s modulus of the contact volume between adhering bacteria and substratum surfaces based on the relationship between deformation and applied external loading force, measured using atomic force microscopy. The model assumes that contact is established through a cylinder with constant volume and does not require assumptions on the properties and dimensions of the contact cylinder. The reduced Young’s moduli obtained (8 to 47 kPa) and dimensions of the contact cylinders could be interpreted on the basis of the cell surface features and cell wall characteristics, i.e., surfaces that are more rigid (because of either less fibrillation, less extracellular polymeric substance production, or a higher degree of cross-linking of the peptidoglycan layer) had shorter contact cylinders and higher reduced Young’s moduli. Application of an existing Hertz model to our experimental data yielded reduced Young’s moduli that were up to 100 times higher for all strains investigated, likely because the Hertz model pertains to a major extent to the more rigid peptidoglycan layer and not only to the soft outer bacterial cell surface, involved in the bond between a bacterium and a substratum surface.
Soft matter approaches as enablers for food macroscale simulation
Datta, A.K. ; Sman, R.G.M. van der; Gulati, T. ; Warning, A. - \ 2012
Faraday Discussions 158 (2012). - ISSN 1359-6640 - p. 435 - 459.
multiphase porous-media - free-volume theory - moisture transport - mechanical-properties - mass-transfer - hydraulic conductance - model development - large-deformation - fluid transport - wetting liquid
Macroscopic deformable multiphase porous media models have been successful in describing many complex food processes. However, the properties needed for such detailed physics-based models are scarce and consist of primarily empirical models obtained from experiment. Likewise, driving forces such as swelling pressure have also been approached empirically, without physics-based explanations or prediction capabilities. Soft matter based prediction of properties will provide an additional avenue to obtaining properties and also provide a deeper and critical understanding of how these properties change with composition, temperature and other process variables.
Electrospinning versus fibre production methods: from specifics to technological convergence
Luo, C.J. ; Stoyanov, S.D. ; Stride, E. ; Pelan, E. ; Edirisinghe, M. - \ 2012
Chemical Society Reviews 41 (2012)13. - ISSN 0306-0012 - p. 4708 - 4735.
melt-blowing process - uniaxially aligned arrays - electrically forced jets - polymer nanofibers - bacterial cellulose - spider silk - carbon nanotubes - poly(ethylene-co-vinyl alcohol) - mechanical-properties - bending instability
Academic and industrial research on nanofibres is an area of increasing global interest, as seen in the continuously multiplying number of research papers and patents and the broadening range of chemical, medical, electrical and environmental applications. This in turn expands the size of the market opportunity and is reflected in the significant rise of entrepreneurial activities and investments in the field. Electrospinning is probably the most researched top-down method to form nanofibres from a remarkable range of organic and inorganic materials. It is well known and discussed in many comprehensive studies, so why this review? As we read about yet another "novel'' method producing multifunctional nanomaterials in grams or milligrams in the laboratory, there is hardly any research addressing how these methods can be safely, consistently and cost-effectively up-scaled. Despite two decades of governmental and private investment, the productivity of nanofibre forming methods is still struggling to meet the increasing demand. This hinders the further integration of nanofibres into practical large-scale applications and limits current uses to niche-markets. Looking into history, this large gap between supply and demand of synthetic fibres was seen and addressed in conventional textile production a century ago. The remarkable achievement was accomplished via extensive collaborative research between academia and industry, applying ingenious solutions and technological convergence from polymer chemistry, physical chemistry, materials science and engineering disciplines. Looking into the present, current advances in electrospinning and nanofibre production are showing similar interdisciplinary technological convergence, and knowledge of industrial textile processing is being combined with new developments in nanofibre forming methods. Moreover, many important parameters in electrospinning and nanofibre spinning methods overlap parameters extensively studied in industrial fibre processing. Thus, this review combines interdisciplinary knowledge from the academia and industry to facilitate technological convergence and offers insight for upscaling electrospinning and nanofibre production. It will examine advances in electrospinning within a framework of large-scale fibre production as well as alternative nanofibre forming methods, providing a comprehensive comparison of conventional and contemporary fibre forming technologies. This study intends to stimulate interest in addressing the issue of scale-up alongside novel developments and applications in nanofibre research.
The physics of tissue formation with mesenchymal stem cells
Higuera, G.A. ; Boxtel, A.J.B. van; Blitterswijk, C.A. van; Moroni, L. - \ 2012
Trends in Biotechnology 30 (2012)11. - ISSN 0167-7799 - p. 583 - 590.
bone-marrow - chondrogenic differentiation - mechanical-properties - bioreactor system - shear-stress - iron-oxide - in-vitro - expansion - proliferation - micro
Cells react to various forms of physical phenomena that promote and maintain the formation of tissues. The best example of this are cells of musculoskeletal origin, such as mesenchymal stem cells (MSCs), which consistently proliferate or differentiate under cues from hydrostatic pressure, diffusive mass transport, shear stress, surface chemistry, mechanotransduction, and molecular kinetics. To date, no other cell type shows greater receptiveness to macroscopic and microscopic cues, highlighting the acute sensitivity of MSCs and the importance of physical principles in tissue homeostasis. In this review, we describe the literature that has shown how physical phenomena govern MSCs biology and provide insight into the mechanisms and strategies that can spur new biotechnological applications with tissue biology.
Microcapsules with a pH responsive polymer: Influence of the encapsulated oil on the capsule morphology
Wagdare, N.A. ; Marcelis, A.T.M. ; Boom, R.M. ; Rijn, C.J.M. van - \ 2011
Colloids and Surfaces. B: Biointerfaces 88 (2011)1. - ISSN 0927-7765 - p. 175 - 180.
hollow polylactide microcapsules - premix membrane emulsification - internal phase-separation - mechanical-properties - shell microcapsules - emulsion droplets - lipophilic drugs - contrast agents - release - delivery
Microcapsules were prepared by microsieve membrane cross flow emulsification of Eudragit FS 30D/dichloromethane/edible oil mixtures in water, and subsequent phase separation induced by extraction of the dichloromethane through an aqueous phase. For long-chain triglycerides and jojoba oil, core–shell particles were obtained with the oil as core, surrounded by a shell of Eudragit. Medium chain triglyceride (MCT oil) was encapsulated as relatively small droplets in the Eudragit matrix. The morphology of the formed capsules was investigated with optical and SEM microscopy. Extraction of the oil from the core–shell capsules with hexane resulted in hollow Eudragit capsules with porous shells. It was shown that the differences are related to the compatibility of the oils with the shell-forming Eudragit. An oil with poor compatibility yields microcapsules with a dense Eudragit shell on a single oil droplet as the core; oils having better compatibility yield porous Eudragit spheres with several oil droplets trapped inside
A statistical analysis of fibre size and shape distribution after compounding in composites reinforced by natural fibres
Moigne, N. Le; Oever, M.J.A. van den; Budtova, T. - \ 2011
Composites Part A: Applied Science and Manufacturing 42 (2011)10. - ISSN 1359-835X - p. 1542 - 1550.
flax straw fibers - mechanical-properties - polypropylene composites - polymers - length - orientation - wheat - microstructure - morphology - strength
Using high resolution optical microscopy coupled with image analysis software and statistical methods, fibre length and aspect ratio distributions in polypropylene composites were characterized. Three types of fibres, flax, sisal and wheat straw, were studied. Number and surface weighted distributions were used to demonstrate the presence and amount of elementary fibres, fibre bundles and particles. A large number of small particles that are usually not taken into account were found. The obtained fibre length and aspect ratio distributions were successfully fitted by a two-parameter Weibull model. No significant effect of fibre concentration on the length and aspect ratio distributions was detected for 20% and 40% flax-based composite. Fibre type was found to be a very important parameter influencing size and shape distributions: flax is broken into long elementary fibres, sisal-based composite contains non-dispatched bundles and elementary fibres and wheat straw-based composite has bundles and large and small particles.
Virus inactivation by salt (NaCl) and phosphate supplemented salt in a 3D collagen matrix model for natural sausage casings
Wieringa-Jelsma, H. ; Wijnker, J.J. ; Zijlstra-Willems, E.M. ; Dekker, A. ; Stockhofe-Zurwieden, N. ; Maas, R. ; Wisselink, H.J. - \ 2011
International Journal of Food Microbiology 148 (2011)2. - ISSN 0168-1605 - p. 128 - 134.
swine-fever virus - complete nucleotide-sequence - mouth-disease - mechanical-properties - vesicular disease - hog - pathogenesis - intestines - diagnosis - pigs
Due to possible presence and spread of contagious animal viruses via natural sausage casings the international trade in these food products is subject to veterinary and public health requirements. In order to manage these restrictions we determined the effect of casing preservation on four highly contagious viruses for livestock: foot-and-mouth-disease virus (FMDV), classical swine fever virus (CSFV), swine vesicular disease virus (SVDV) and African swine fever virus (ASFV). We used an in vitro 3D collagen matrix model in which cells, infected with the four different viruses were embedded in a bovine collagen type I gel matrix and treated with either saturated salt (NaCl) or phosphate supplemented saturated salt at four different temperatures (4, 12, 20 and 25 °C) during a period of 30 days. The results showed that all viruses were faster inactivated at higher temperatures, but that stability of the various viruses at 4 °C differed. Inactivation of FMDV in the 3D collagen matrix model showed a clear temperature and treatment effect on the reduction of FMDV titres. At 4 and 12 °C phosphate supplemented salt showed a very strong FMDV inactivation during the first hour of incubation. Salt (NaCl) only had a minor effect on FMDV inactivation. Phosphate supplemented salt treatment increased the effect temperature had on inactivation of CSFV. In contrast, the salt (NaCl) treatment only increased CSFV inactivation at the higher temperatures (20 °C and 25 °C). Also SVDV inactivation was increased by phosphate supplemented salt, but salt (NaCl) treatment only resulted in a significant decrease of SVDV titre at a few time points. The ASFV results showed that both salt (NaCl) and phosphate supplemented salt were capable to inactivate ASFV within 48 h. In contrast to the other viruses (FMDV, CSFV and SVDV), ASFV was the most stable virus even at higher temperatures. The results obtained in this in vitro model underline the efficacy of a combined treatment using phosphate supplemented salt and storage at 20 °C or higher for a period of 30 days. This treatment may therefore be useful in reducing the animal health risks posed by spread of contagious animal viruses by international trade of natural sausage casings
Effect of differences in tendon properties on functionality of the passive stay apparatus in horses
Gussekloo, S.W.S. ; Lankester, J. ; Kersten, W. ; Back, W. - \ 2011
American Journal of Veterinary Research 72 (2011)4. - ISSN 0002-9645 - p. 474 - 483.
elastic energy-storage - mechanical-properties - flexor - forelimbs - limb - locomotion - ligaments - step - mass
Objective—To determine the effect of differences in structural and mechanical tendon properties on functionality of the passive stay apparatus in horses. Sample—5 forelimbs each from nondwarf Friesians, dwarf Friesians, and ponies. Procedures—Harvested forelimbs were loaded to test the passive stay apparatus. Tendons that stabilize the distal portion of the limb (superficial digital flexor tendon, deep digital flexor tendon, and tendo interosseus [suspensory ligament]) were isolated, and force-elongation data were obtained. Bone lengths, initial tendon lengths, and initial tendon cross-sectional areas were measured, and Young moduli were calculated. A model was used to determine whether joint angles could be explained by these 4 factors only. Results—Dwarf limbs were unable to stand passively under loading because tendons that prevent overextension of the distal limb joints were too long and compliant to prevent over-extension. Tendon properties of limbs of nondwarf Friesians appeared to be intermediate between those of ponies and dwarf Friesians. Conclusions and Clinical Relevance—Dysfunction of the passive stay apparatus in dwarf Friesians could be related to differences in structural and material properties of the tendons that result in hyperextension of the joints under loading. Nondwarf Friesians had intermediate tendon properties, which might be a breed-specific variation. Results indicated that certain tendon properties were associated with load failure of the stay apparatus and provided additional information about the functionality and requirements of the passive stay apparatus.
Biodegradable Polymeric Microcapsules: Preparation and Properties
Sawalha, H.I.M. ; Schroën, C.G.P.H. ; Boom, R.M. - \ 2011
Chemical Engineering Journal 169 (2011)1-3. - ISSN 1385-8947 - p. 1 - 10.
membrane emulsification technique - hollow polylactide microcapsules - ultrasound contrast agents - of-the-art - poly(lactic acid) - drug-delivery - mechanical-properties - immersion-precipitation - poly(l-lactic acid) - size distribution
Biodegradable polymeric microcapsules can be produced through different methods of which emulsion solvent-evaporation/extraction is frequently used. In this technique, the polymer (often polylactide) is dissolved in a good solvent and is emulsified together with a poor solvent into a nonsolvent phase. The solvent is then removed through the nonsolvent phase by evaporation. This results in solidification of the polymer around an internal droplet of the poor solvent. The poor solvent may be removed later when hollow capsules are required. This paper discusses the fundamental aspects of the formation process of hollow polylactide microcapsules and its effects on the physical and chemical properties of the capsules, with emphasis on the solidification process of the polymer and the resulting properties of the shell. The scope for improvement and adaptation of the current process, including new emulsification techniques, is also discussed. The main message of this paper is that the properties of the capsules can be optimized through the solidification process of the polymer which can be highly influenced by the proper choice of the nonsolvent and oil. Since this field is hardly investigated in literature, there is room for improvement, especially if the capsules can be produced with the newest emulsification technologies that are becoming available.
Interplay between product characteristics, oral physiology and texture perception of cellular brittle foods
Vliet, T. van; Primo Martin, C. - \ 2011
Journal of Texture Studies 42 (2011)2. - ISSN 0022-4901 - p. 82 - 94.
sensory texture - investigate differences - mechanical-properties - fracture-behavior - chewing behavior - cooked potatoes - jaw movement - crispness - mastication - hardness
Hard solid foods encompass a large variety of dry products as well as products with high water content. Most of these foods have a cellular structure, which is generally characterized by connected fairly rigid cell walls, enclosing a fluid material that may be liquid-like (fruit and vegetables) or a gas (mainly manufactured cellular foods). Typical for many hard solid products is their brittle fracture behavior, mostly accompanied by acoustic emission. The latter characteristic is essential for their crispy or crunchy character. Other main texture attributes are hardness and brittleness and for fruits and vegetables juiciness. The latter requires that the liquid content of the cells is released during mastication. Aspects of fracture behavior of cellular food products, oral processing of these products, and the interplay between product characteristics and perception of some main texture attributes (hardness and crispness) will be discussed. PRACTICAL APPLICATIONS It has become more and more clear that texture perception by consumers of hard solid (brittle) foods is based on the interplay between product structure, fracture behavior, oral processing and final grading by the brain. Better understanding of the relations between these aspects is essential for the production of healthy, tasteful food that is liked by consumers. This article focus on the interplay between physical properties of hard solid foods and oral processing in relation to the perception of selected texture attributes (hardness and crispness)
The potential of dry fractionation processes for sustainable plant protein production
Schutyser, M.A.I. ; Goot, A.J. van der - \ 2011
Trends in Food Science and Technology 22 (2011)4. - ISSN 0924-2244 - p. 154 - 164.
air classification - mechanical-properties - grinding characteristics - milling behavior - moisture-content - mixing behavior - wheat-flour - field peas - starch - separation
Wet fractionation processes are mainstream technology for producing plant-derived protein isolates. Unfortunately, wet fractionation involves consumption of copious amounts of water and energy. In addition, much of the (native) functionality of proteins is lost during processing. This paper reviews the potential of dry fractionation for producing protein-enriched ingredient fractions. Dry fractionation is extremely more energy efficient and is able to produce enriched fractions with retained (native) functionality. Hitherto, dry fractionation is most successfully applied to pulses and cereals, which is correlated to their specific tissue architecture and milling behaviour. Micromechanical studies on plant cell constituents and their interactions could improve milling processes and thus further develop dry fractionation. Moreover, the diversity of available protein fractions could be increased by development of fractionation techniques or innovative combinations thereof. Finally, expansion of scientific knowledge of dry-processed protein concentrates during product preparation is vital from application perspective. It is expected that the availability of a wide variety of protein concentrates with high (native) functionality will contribute to the development of better novel protein foods, provided that food technologists develop scientific tools to cope with the complex fractions