The Effects Of Sucrose On The Mechanical Properties Of Acid Milk Proteins-κ-carrageenan Gels

Mechanical properties have been widely correlated with textural characteristics to determine the interactions during the process formation of dairy gel. These interactions are strongly affected by process conditions and system composition. In the present study, the rheological of acid-induced protein dairy gels with (2(7-3)) and without (2(6-2)) sucrose and subjected to small and large deformations were studied using an experimental design. The independent variables were the sodium caseinate, whey protein concentrate (WPC), carrageenan and sucrose concentrations as well as stirring speed and heat treatment time and temperature. Mechanical deformation tests were performed at 0.1, 1, 5, and 9 mm/s up to 80% of initial height. A heavy dependence of rupture stress on increasing crosshead speed and the formation of harder gels with the addition of sucrose were observed. Moreover the elastic and viscous moduli, obtained by fitting the Maxwell model to stress relaxation data, increased with increasing addition of sucrose. These results can be explained by preferential hydration of the casein with sucrose, causing an induction of casein-polysaccharide and casein-casein interactions.2315565Antipova, A.S., Semenova, M.G., Belyakova, L.E., Effect of sucrose on the thermodynamic properties of ovalbumin and sodium caseinate in bulk solution and at air-water interface (1999) Colloids and Surfaces B - Biointerfaces, 12, p. 261Antipova, A.S., Semenova, M.G., Effect of sucrose on the thermodynamic incompatibility of different biopolymers (1995) Carbohydrate Polymers, 28, p. 359Arakawa, T., Timasheff, S.N., Stabilization of protein-structure by sugars (1982) Biochemistry, 21, p. 6536Belyakova, L.E., Antipova, A.S., Semenova, M.G., Dickinson, E., Merino, L.M., Tsapkina, E.N., Effect of sucrose on molecular and interaction parameters of sodium caseinate in aqueous solution: Relationship to protein gelation (2003) Colloids and Surfaces B - Biointerfaces, 31, p. 31Bertola, N.C., Bevilacqua, A.E., Zaritzky, N.E., Changes in rheological and viscoelastic properties and protein breakdown during the ripening of "Port salut argentino" cheese (1991) International Journal of Food Science and Technology, 26, p. 467Braga, A.L.M., (2002) Characterization of Macromolecular Interactions in Acidified Caseinate-Xanthan-Sucrose Gels: Rheological and Thermal Analysis., , Master' Thesis, School of Food Engineering, State University of Campinas (In Portuguese)Capron, I., Nicolai, T., Durand, D., Heat induced aggregation and gelation of β-lactoglobulin in the presence of κ-carrageenan (1999) Food Hydrocolloids, 13, p. 1Dickinson, E., Merino, L.M., Effect of sugars on the rheological properties of acid caseinate-stabilized emulsion gels (2002) Food Hydrocolloids, 16, p. 321Farrell, H.M., Pessen, H., Brown, E.M., Kumosinski, T.F., Structural insights into the bovine casein micelle-small-angle x-ray-scattering studies and correlations with spectroscopy (1990) Journal of Dairy Science, 73, p. 3592Fly, J.A., Clarke, P.T., Du Parquet, H., Toyne, S., Augustin, M.A., Use of glucono-delta-lactone in manufacture of yogurt (1997) The Australian Journal of Dairy Technology, 52, p. 20Hemar, Y., Hall, C.E., Munro, P.A., Singh, H., Small and large deformation rheology and microstructure of κ-carrageenan gels containing commercial milk protein products (2002) International Dairy Journal, 12, p. 371Ju, Z.Y., Kilara, A., Textural properties of cold-set gels induced from heat-denatured whey protein isolates (1998) Journal of Food Science, 63, p. 288Koh, M.W.W., Merino, L.M., Dickinson, E., Rheology of acid-induced sodium caseinate gels containing added gelatin (2002) Food Hydrocolloids, 16, p. 619Kulmyrzaev, A., Bryant, C., McClements, D.J., Influence of sucrose on thermal denaturation, gelation, and emulsion stabilization of whey proteins (2000) Journal of Agriculture and Food Chemistry, 48, p. 1593Lucey, J.A., Singh, H., Formation and physical properties of acid milk gels: A review (1998) Food Research International, 30, p. 529Mleko, S., Li-Chan, E.C.Y., Pikus, S., Interactions of κ-carrageenan with whey proteins in gels formed at different pH (1997) Food Research International, 30, p. 427Mleko, S., Rheological properties of milk and whey protein desserts (1997) Milchwissenschaft, 52, p. 262Mora-Gutierrez, A., Farrell, H.M., Sugar-casein interaction in deuterated solutions of bovine and caprine casein as determined by oxygen-17 and carbon-13 nuclear magnetic resonance: A case of preferential interactions (2000) Journal of Agriculture and Food Chemistry, 48, p. 3245Mora-Gutierrez, A., Kumosinski, T.F., Farrell Jr., H.M., Oxygen-17 nuclear magnetic resonance studies of bovine and caprine hydration and activity in deuterated sugar solutions (1997) Journal of Agriculture and Food Chemistry, 45, p. 4545Mulvihill, D.M., Kinsella, J.E., Gelation of ß-lactoglobulin. effects of sodium chloride and calcium chloride on the rheological and structural properties of gels (1988) Journal of Food Science, 53, p. 231Nakamura, K., Shinoda, E., Tokita, M., The influence of compression velocity on strength and structure for gellan gels (2001) Food Hydrocolloids, 15, p. 247Oakenfull, D., Miyoshi, E., Nishinari, K., Scott, A., Rheological and thermal properties of milk gels formed with K-carrageenan. I. sodium caseinate (1999) Food Hydrocolloids, 13, p. 525Ribeiro, K.O., Rodrigues, M.I., Sabadini, E., Cunha, R.L., Mechanical properties of acid sodium caseinate - κ-carrageenan gels: Effect of co-solute addition (2004) Food Hydrocolloids, 18, p. 71Roefs, S.P.F.M., Degrootmostert, A.E.A., Van Vliet, T., Structure of acid casein gels. 1. formation and model of gel network (1990) Colloids and Surfaces A, 50, p. 141Schkoda, P., Hechler, A., Kessler, H.G., Effect of minerals and pH on rheological properties and syneresis of milk-based acid gels (1999) International Dairy Journal, 9, p. 269Schorsch, C., Jones, M.G., Norton, I.T., Thermodynamic incompatibility and microstructure of milk protein/ locust bean gum/sucrose systems (1999) Food Hydrocolloids, 13, p. 89Serpelloni, M., Lefevre, P., Dusautois, C., Glucono-delta-lactone in milk ripening (1990) Dairy Industries International, 55, p. 35Spiegel, T., Whey protein aggregation under shear conditions - Effects of lactose and heating temperature on aggregate size and structure (1999) International Journal Food Science and Technology, 34, p. 523Steffe, J.F., (1996) Rheological Methods in Food Process Engineering, pp. 1-93. , Freeman Press, East LansingThybo, A.K., Nielsen, M., Martens, M., Influence of uniaxial compression rate on rheological parameters and sensory texture prediction of cooked potatoes (2000) Journal of Textures Studies, 31, p. 25Tziboula, A., Home, D.S., Influence of milk proteins on kappa-carrageenan gelation (1999) International Dairy Journal, 9, p. 359Verheul, M., Roefs, S.P.F.M., Structure of whey protein gels, studied by permeability, scanning electron microscopy and rheology (1998) Food Hydrocolloids, 12, p. 17Walkenström, P., Windhab, E., Hermansson, A.M., Shear-induced structuring of particulate whey protein gels (1998) Food Hydrocolloids, 12, p. 45

Espacos migratorios e problematica ambiental no Mercosul

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ANÁLISE DOS PARÂMETROS GEOMORFOLÓGICOS E DA DINÂMICA FLUVIAL: O CASO DO BAIXO CURSO DO RIO TIETÊ (SP)

Partindo-se da necessidade de maior abrangência em mapeamentos geomorfológicos da dinâmica fluvial para o levantamento da sensibilidade ambiental a derramamentos de óleo, esta pesquisa, valendo-se de técnicas tradicionais de mapeamento geomorfológico, propõe a confecção de um mapa o qual possa colaborar com estes estudos. Para isso, foi necessário identificar e mapear as feições geomorfológicas a fim de avaliar o significado destas em termos de sua sensibilidade em um trecho do Rio Tietê

Theory of Stellar Oscillations

In recent years, astronomers have witnessed major progresses in the field of stellar physics. This was made possible thanks to the combination of a solid theoretical understanding of the phenomena of stellar pulsations and the availability of a tremendous amount of exquisite space-based asteroseismic data. In this context, this chapter reviews the basic theory of stellar pulsations, considering small, adiabatic perturbations to a static, spherically symmetric equilibrium. It starts with a brief discussion of the solar oscillation spectrum, followed by the setting of the theoretical problem, including the presentation of the equations of hydrodynamics, their perturbation, and a discussion of the functional form of the solutions. Emphasis is put on the physical properties of the different types of modes, in particular acoustic (p-) and gravity (g-) modes and their propagation cavities. The surface (f-) mode solutions are also discussed. While not attempting to be comprehensive, it is hoped that the summary presented in this chapter addresses the most important theoretical aspects that are required for a solid start in stellar pulsations research.Comment: Lecture presented at the IVth Azores International Advanced School in Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta, Azores Islands, Portugal in July 201

In vitro and in vivo ocular biocompatibility of electrospun poly(ɛ-caprolactone) nanofibers.

Biocompatibility is a requirement for the development of nanofibers for ophthalmic applications. In this study, nanofibers were elaborated using poly(ε-caprolactone) via electrospinning. The ocular biocompatibility of this material was investigated. MIO-M1 and ARPE-19 cell cultures were incubated with nanofibers and cellular responses were monitored by viability and morphology. The in vitro biocompatibility revealed that the nanofibers were not cytotoxic to the ocular cells. These cells exposed to the nanofibers proliferated and formed an organized monolayer. ARPE-19 and MIO-M1 cells were capable of expressing GFAP, respectively, demonstrating their functionality. Nanofibers were inserted into the vitreous cavity of the rat's eye for 10days and the in vivo biocompatibility was investigated using Optical Coherence Tomography (OCT), histology and measuring the expression of pro-inflammatory genes (IL-1β, TNF-α, VEGF and iNOS) (real-time PCR). The OCT and the histological analyzes exhibited the preserved architecture of the tissues of the eye. The biomaterial did not elicit an inflammatory reaction and pro-inflammatory cytokines were not expressed by the retinal cells, and the other posterior tissues of the eye. Results from the biocompatibility studies indicated that the nanofibers exhibited a high degree of cellular biocompatibility and short-term intraocular tolerance, indicating that they might be applied as drug carrier for ophthalmic use

Rheology of supersaturated sucrose solutions

Sucrose solutions, with concentrations near or superior to saturation, present high potentialities for the candy and pastry industries. Creep measurements under small stresses were done to obtain the rheological properties of highly concentrated sucrose solutions, since such solutions could be in a metastable state and tend to crystallise. The viscosities of these solutions, from 70.0% to 85.2% (w/w), were determined experimentally at different temperatures, from 0 to 90 C. The temperature dependence of viscosity was studied using experimental and published data for, respectively, high and low concentrations (<70% (w/w)). Results showed that the Arrhenius model describes better the temperature dependence of viscosity for concentrations under saturation and in the high concentration regime the WLF model had a better predicting ability. The effect of concentration on viscosity was observed and included in the Arrhenius and WLF models parameters. The proposed models were able to successfully describe the data in the corresponding concentration range. These results can be used in predicting the viscosities of syrups for either process design or new products formulation

Anti-Inflammatory Effect of Dexamethasone Controlled Released From Anterior Suprachoroidal Polyurethane Implants on Endotoxin-Induced Uveitis in Rats.

Targeted drug delivery to the ocular tissues remains a challenge. Biodegradable intraocular implants allow prolonged controlled release of drugs directly into the eye. In this study, we evaluated an anterior suprachoroidal polyurethane implant containing dexamethasone polyurethane dispersions (DX-PUD) as a drug delivery system in the rat model of endotoxin-induced uveitis (EIU). In vitro drug release was studied using PUD implants containing 8%, 20%, and 30% (wt/wt) DX. Cytotoxicity of the degradation products of DX-PUD was assessed on human ARPE-19 cells using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) test. Short-term ocular biocompatibility of suprachoroidal DX-PUD implants was evaluated in normal rat eyes. Endotoxin-induced uveitis was then induced in rat eyes preimplanted with DX-PUD. Clinical examination was performed at 24 hours; eyes were used to assess inflammatory cell infiltration and macrophage/microglial activation. Cytokine and chemokine expression in the iris/ciliary body and in the retina was investigated using quantitative PCR. Feasibility of anterior suprachoroidal PUD implantation was also tested using postmortem human eyes. A burst release was followed by a sustained controlled release of DX from PUD implants. By-products of the DX-PUD were not toxic to human ARPE-19 cells or to rat ocular tissues. Dexamethasone-PUD implants prevented EIU in rat eyes, reducing inflammatory cell infiltration and inhibiting macrophage/microglial activation. Dexamethasone-PUD downregulated proinflammatory cytokines/chemokines (IL-1β, IL-6, cytokine-induced neutrophil chemoattractant [CINC]) and inducible nitric oxide synthase (iNOS) and upregulated IL-10 anti-inflammatory cytokine. Polyurethane dispersion was successfully implanted into postmortem human eyes. Dexamethasone-PUD implanted in the anterior suprachoroidal space may be of interest in the treatment of intraocular inflammation

Invasion genetics of the mummichog (Fundulus heteroclitus): recent anthropogenic introduction in Iberia

Human activities such as trade and transport have increased considerably in the last decades, greatly facilitating the introduction and spread of non-native species at a global level. In the Iberian Peninsula, Fundulus heteroclitus, a small euryhaline coastal fish with short dispersal, was found for the first time in the mid-1970s. Since then, F. heteroclitus has undergone range expansions, colonizing the southern region of Portugal, southwestern coast of Spain and the Ebro Delta in the Mediterranean Sea. Cytochrome b sequences were used to elucidate the species invasion pathway in Iberia. Three Iberian locations (Faro, Cádiz and Ebro Delta) and 13 other locations along the native range of F. heteroclitus in North America were sampled. Results revealed a single haplotype, common to all invasive populations, which can be traced to the northern region of the species’ native range. We posit that the origin of the founder individuals is between New York and Nova Scotia. Additionally, the lack of genetic structure within Iberia is consistent with a recent invasion scenario and a strong founder effect. We suggest the most probable introduction vector is associated with the aquarium trade. We further discuss the hypothesis of a second human-mediated introduction responsible for the establishment of individuals in the Ebro Delta supported by the absence of adequate muddy habitats linking Cádiz and the Ebro Delta. Although the species has a high tolerance to salinity and temperature, ecological niche modelling indicates that benthic habitat constraints prevent along-shore colonisation suggesting that such expansions would need to be aided by human release

Bianchi type II models in the presence of perfect fluid and anisotropic dark energy

Spatially homogeneous but totally anisotropic and non-flat Bianchi type II cosmological model has been studied in general relativity in the presence of two minimally interacting fluids; a perfect fluid as the matter fluid and a hypothetical anisotropic fluid as the dark energy fluid. The Einstein's field equations have been solved by applying two kinematical ans\"{a}tze: we have assumed the variation law for the mean Hubble parameter that yields a constant value of deceleration parameter, and one of the components of the shear tensor has been considered proportional to the mean Hubble parameter. We have particularly dwelled on the accelerating models with non-divergent expansion anisotropy as the Universe evolves. Yielding anisotropic pressure, the fluid we consider in the context of dark energy, can produce results that can be produced in the presence of isotropic fluid in accordance with the \Lambda CDM cosmology. However, the derived model gives additional opportunities by being able to allow kinematics that cannot be produced in the presence of fluids that yield only isotropic pressure. We have obtained well behaving cases where the anisotropy of the expansion and the anisotropy of the fluid converge to finite values (include zero) in the late Universe. We have also showed that although the metric we consider is totally anisotropic, the anisotropy of the dark energy is constrained to be axially symmetric, as long as the overall energy momentum tensor possesses zero shear stress.Comment: 15 pages; 5 figures; matches the version published in The European Physical Journal Plu

Dermatophylosis in Santa Inês sheep from Distrito Federal

Relataram-se quatro casos de dermatofilose em ovinos da raça Santa Inês, no período de um ano. Microscopicamente observaram-se filamentos na forma de "trilho de bonde" e zoósporos nos quatro casos. A tentativa do isolamento do microrganismo foi realizada por meio do método de Haalstra e em apenas um caso obteve-se sucesso, observando-se colônias de aparência lisa, formato circular, cor amarelada e hemolítica em ágar sangue. O exame direto com coloração de Gram mostrou-se um método bastante eficiente na confirmação da presença do microrganismo afetando a epiderme em razão da morfologia típica do agente.Four cases of dermatophylosis were reported in Santa Inês sheep in a study period of one year. Microscopically, septate filaments and coccoid forms zoospores were observed. Attempts to isolate the microorganisms were accomplished using Haastra's method and it was successful in only one case. Dermatophilus congolensis samples have grown on blood agar, colonies where hemolytic, small, round and pigmentation vary from yellow to orange. The gram staining method was efficient to confirm the presence of the microorganism affecting the epidermis due to typical morphology of the agent