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Francisco Jiménez-colmenero - One of the best experts on this subject based on the ideXlab platform.
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Preparation and impact of multiple (water-in-oil-in-water) emulsions in meat systems.
Food chemistry, 2013Co-Authors: Susana Cofrades, I. Antoniou, Maria Teresa Solas, Ana M. Herrero, Francisco Jiménez-colmeneroAbstract:The aim of this paper was to prepare and characterise multiple emulsions and assess their utility as pork backfat replacers in meat gel/emulsion model systems. In order to improve the fat content (in quantitative and qualitative terms) pork backfat was replaced by a water-in-oil-in-water emulsion (W1/O/W2) prepared with olive oil (as lipid phase), Polyglycerol Ester of polyricinoleic acid (PGPR) as a lipophilic emulsifier, and sodium caseinate (SC) and whey protein concentrate (WP) as hydrophilic emulsifiers. The emulsion properties (particle size and distribution, stability, microstructure) and meat model system characteristics (composition, texture, fat and water binding properties, and colour) of the W1/O/W2, as affected by reformulation, were evaluated. Multiple emulsions showed a well-defined monomodal distribution. Freshly prepared multiple emulsions showed good thermal stability (better using SC) with no creaming. The meat systems had good water and fat binding properties irrespective of formulation. The effect on texture by replacement of pork backfat by W1/O/W2 emulsions generally depends on the type of double emulsion (associated with the hydrophilic emulsifier used in its formulation) and the fat level in the meat system.
Hans Jörg Limbach - One of the best experts on this subject based on the ideXlab platform.
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Foams stabilized by multilamellar Polyglycerol Ester self-assemblies.
Langmuir : the ACS journal of surfaces and colloids, 2012Co-Authors: Corina Curschellas, Peter Fischer, Erich J. Windhab, Joachim Kohlbrecher, Thomas Geue, Bertrand Schmitt, Martine Rouvet, Hans Jörg LimbachAbstract:The importance of surfactant self-assemblies in foam stabilization is well-known. The aim of the current study was to investigate the self-assemblies of the nonionic surfactant Polyglycerol Ester (PGE) in bulk solutions, at the interface and within foams, using a combined approach of small-angle neutron scattering, neutron reflectivity, and electron microscopy. PGE bulk solutions contain vesicles as well as open lamellar structures. Upon heating of the solutions the lamellar spacing increases, with significant differences in the presence of NaCl or CaCl2 as compared to the standard solution. The adsorption of the multilamellar structures present in the bulk solutions lead to a multilayered film at the air–water interface. The ordering within this film was increased as a result of a 20% area compression mimicking a coalescence event. Finally, PGE foams were shown to be stabilized not only by strong interfacial films but also by agglomerated self-assemblies within the interstitial areas of the foams.
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Characteristics of Polyglycerol Ester and its different fractions
Journal of colloid and interface science, 2012Co-Authors: Corina Curschellas, Erich J. Windhab, Kornél Nagy, Hans Jörg LimbachAbstract:Abstract Polyglycerol Esters obtained from edible oils are commonly used surfactants in the food industry. Despite their widespread application, the composition and properties of these surfactants are still not well characterized. This study reveals the presence of so far unknown tetra-, penta-antennary constituents in Polyglycerol Esters, which exhibit very strong sodium affinity. The implications of these new insights on surfactant activity were investigated. Liquid–liquid extraction was used to fractionate a Polyglycerol Ester ingredient in order to link physicochemical behavior to the polarity of the fractions. The most polar fraction showed faster adsorption kinetics and higher elastic moduli than the full mixture, whereas the least polar fraction showed slower adsorption kinetics and lower elastic moduli as compared to the complex mixture. The addition of Na + was shown to accelerate the agglomeration of surfactant self-assemblies in bulk solutions and also to increase the elastic modulus at the air–water interface. These observations suggest that the composition of natural Polyglycerol Esters is more diverse than so far assumed and the overall behavior of these mixtures is determined not only by the amphyphilic interactions between mono- and penta-antennary forms, but also by the endogenous salt content of the ingredient.
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Scanning force microscopy as a tool to investigate the properties of Polyglycerol Ester foams
Journal of colloid and interface science, 2012Co-Authors: Corina Curschellas, Rabea Keller, Rüdiger Berger, Uwe Rietzler, Daniela Fell, Hans-jürgen Butt, Hans Jörg LimbachAbstract:Abstract Foamed products are a popular class of food products. The mechanism of stabilization of the air bubbles is often only partially understood. The current study aims at better understanding the stabilization of air–water interfaces through the low molecular weight surfactant Polyglycerol Ester (PGE). We chose PGE films as an exemplary case for a non-equilibrium situation at an air–water interface – a situation that requires the development of new experimental techniques. Several different film preparation and transfer methods onto solid substrates have been tested. The films were then investigated by scanning force microscopy, and structural artifacts associated to the sample preparation were identified and discussed. In addition to the study of Langmuir monolayers and Gibbs adsorption layers, we have proposed a new approach to investigate the skins of foam bubbles. We thereby were able to determine that PGE indeed covers bubbles by a multilayer structure and that the pH plays a role in the structuring of the films. We show that a combination of different film preparation methods allows us to get an insight into the aggregation behavior of PGE at the air–water interface and thereby better understand the stabilization mechanism of this particular surfactant.
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Interfacial aspects of the stability of Polyglycerol Ester covered bubbles against coalescence
Soft Matter, 2012Co-Authors: Corina Curschellas, Deniz Zeynel Gunes, Hélène Deyber, Brigitte Watzke, Erich J. Windhab, Hans Jörg LimbachAbstract:Most liquid foams are not stable, with one destabilization process being coalescence. The current study aims at better understanding the coalescence of bubbles covered by the non-ionic surfactant Polyglycerol Ester (PGE) in dilute solutions. Large deformations of bubble surfaces are of importance in understanding coalescence as they can induce coalescence events. Furthermore, during coalescence and the subsequent shape relaxation large deformations are imposed on the surfaces. These large deformation experiments were carried out using interfacial shear and dilatational rheology. Furthermore isolated coalescence events of bubbles were observed. The largest fraction of the interfacial shear modulus was recovered within 1 minute of halting the large deformations, with the overall recovery happening on a timescale of hours. When mimicking coalescence by reducing the surface area, a short-term increase in the elastic modulus was observed in dilatational rheology. The remarkably slow, two-mode exponential shape relaxation recorded for sufficiently covered bubbles following their coalescence hints at important interfacial structuring phenomena. As a result of the low solubility of PGE, coalescence appears to help in achieving a certain stability level at short timescales via an increase in surface coverage and the growth of multi-layer domains. Finally, coalescence patterns in two-dimensional foams were investigated, which suggested that in the absence of prior coalescence, very long adsorption times (>12 hours) are required to reach significant stability. These experiments also revealed a remarkable stability of Polyglycerol Ester foams against Ostwald ripening.
Erich J. Windhab - One of the best experts on this subject based on the ideXlab platform.
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Foams stabilized by multilamellar Polyglycerol Ester self-assemblies.
Langmuir : the ACS journal of surfaces and colloids, 2012Co-Authors: Corina Curschellas, Peter Fischer, Erich J. Windhab, Joachim Kohlbrecher, Thomas Geue, Bertrand Schmitt, Martine Rouvet, Hans Jörg LimbachAbstract:The importance of surfactant self-assemblies in foam stabilization is well-known. The aim of the current study was to investigate the self-assemblies of the nonionic surfactant Polyglycerol Ester (PGE) in bulk solutions, at the interface and within foams, using a combined approach of small-angle neutron scattering, neutron reflectivity, and electron microscopy. PGE bulk solutions contain vesicles as well as open lamellar structures. Upon heating of the solutions the lamellar spacing increases, with significant differences in the presence of NaCl or CaCl2 as compared to the standard solution. The adsorption of the multilamellar structures present in the bulk solutions lead to a multilayered film at the air–water interface. The ordering within this film was increased as a result of a 20% area compression mimicking a coalescence event. Finally, PGE foams were shown to be stabilized not only by strong interfacial films but also by agglomerated self-assemblies within the interstitial areas of the foams.
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Characteristics of Polyglycerol Ester and its different fractions
Journal of colloid and interface science, 2012Co-Authors: Corina Curschellas, Erich J. Windhab, Kornél Nagy, Hans Jörg LimbachAbstract:Abstract Polyglycerol Esters obtained from edible oils are commonly used surfactants in the food industry. Despite their widespread application, the composition and properties of these surfactants are still not well characterized. This study reveals the presence of so far unknown tetra-, penta-antennary constituents in Polyglycerol Esters, which exhibit very strong sodium affinity. The implications of these new insights on surfactant activity were investigated. Liquid–liquid extraction was used to fractionate a Polyglycerol Ester ingredient in order to link physicochemical behavior to the polarity of the fractions. The most polar fraction showed faster adsorption kinetics and higher elastic moduli than the full mixture, whereas the least polar fraction showed slower adsorption kinetics and lower elastic moduli as compared to the complex mixture. The addition of Na + was shown to accelerate the agglomeration of surfactant self-assemblies in bulk solutions and also to increase the elastic modulus at the air–water interface. These observations suggest that the composition of natural Polyglycerol Esters is more diverse than so far assumed and the overall behavior of these mixtures is determined not only by the amphyphilic interactions between mono- and penta-antennary forms, but also by the endogenous salt content of the ingredient.
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Interfacial aspects of the stability of Polyglycerol Ester covered bubbles against coalescence
Soft Matter, 2012Co-Authors: Corina Curschellas, Deniz Zeynel Gunes, Hélène Deyber, Brigitte Watzke, Erich J. Windhab, Hans Jörg LimbachAbstract:Most liquid foams are not stable, with one destabilization process being coalescence. The current study aims at better understanding the coalescence of bubbles covered by the non-ionic surfactant Polyglycerol Ester (PGE) in dilute solutions. Large deformations of bubble surfaces are of importance in understanding coalescence as they can induce coalescence events. Furthermore, during coalescence and the subsequent shape relaxation large deformations are imposed on the surfaces. These large deformation experiments were carried out using interfacial shear and dilatational rheology. Furthermore isolated coalescence events of bubbles were observed. The largest fraction of the interfacial shear modulus was recovered within 1 minute of halting the large deformations, with the overall recovery happening on a timescale of hours. When mimicking coalescence by reducing the surface area, a short-term increase in the elastic modulus was observed in dilatational rheology. The remarkably slow, two-mode exponential shape relaxation recorded for sufficiently covered bubbles following their coalescence hints at important interfacial structuring phenomena. As a result of the low solubility of PGE, coalescence appears to help in achieving a certain stability level at short timescales via an increase in surface coverage and the growth of multi-layer domains. Finally, coalescence patterns in two-dimensional foams were investigated, which suggested that in the absence of prior coalescence, very long adsorption times (>12 hours) are required to reach significant stability. These experiments also revealed a remarkable stability of Polyglycerol Ester foams against Ostwald ripening.
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Structure and mechanical properties of a Polyglycerol Ester at the air-water surface.
Langmuir : the ACS journal of surfaces and colloids, 2008Co-Authors: Natalie Duerr-auster, Rok Gunde, Erich J. WindhabAbstract:We studied the structure and mechanical properties of surface films resulting from the adsorption of a dispersed Lβ phase at the air−water interface. This Lβ phase corresponds to multilamellar vesicles and is formed by a commercial Polyglycerol fatty acid Ester (PGE) in aqueous solution at temperatures below the main chain-melting temperature (Tm = 58 °C). We measured the adsorption kinetics using the pendant drop technique and mechanical properties of PGE films using oscillatory surface shear and dilatational rheometric methods. Though the adsorption kinetics are very slow, we show that the Lβ phase of PGE is surface-active and forms viscoelastic films at the air−water surface after sufficiently long adsorption times. The rheological response functions to shear and dilatational deformation are reminiscent of those of temporary networks, indicating an intermolecular connectivity at the surface. This temporary network is probably created by hydrophobic interactions of alkyl chains. We obtained more detaile...
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microstructure and stability of a lamellar liquid crystalline and gel phase formed by a Polyglycerol Ester mixture in dilute aqueous solution
Langmuir, 2007Co-Authors: N Duerrauster, Peter Fischer, Rok Gunde, J Kohlbrecher, T Zuercher, Erich J. WindhabAbstract:The self-assembly behavior of a commercial mixture of Polyglycerol fatty acid Esters (PGE) and water is investigated as a function of temperature and surfactant content. The phase diagram of this pseudo-binary mixture was characterized using a combination of cross-polarized light and freeze−fracture electron microscopy (cryo-SEM), X-ray diffraction (XRD), small-angle neutron scattering (SANS), and differential scanning calorimetry (DSC). Our experiments show that the morphology of the supramolecular aggregates is lamellar and present in the form of a continuous or dispersed phase (multilamellar vesicles) depending on the water content of the system. Under the effect of temperature, the short- and long-range order of the bimolecular layers successively changes from a biphasic surfactant dispersion to a lamellar liquid-crystalline (Lα) and a stable lamellar gel phase (Lβ) upon cooling; this transition is found to be irreversible. Formation of the lamellar aggregates can be related to the average molecular s...
Hajime Toguchi - One of the best experts on this subject based on the ideXlab platform.
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In Vitro and in Vivo Evaluation of Mucoadhesive Microspheres Prepared for the Gastrointestinal Tract Using Polyglycerol Esters of Fatty Acids and a Poly(acrylic acid) Derivative
Pharmaceutical Research, 1995Co-Authors: Yohko Akiyama, Naoki Nagahara, Toshio Kashihara, Shinichiro Hirai, Hajime ToguchiAbstract:Two types of Polyglycerol Ester of fatty acid (PGEF)-based microspheres were prepared: Carbopol 934P (CP)-coated microspheres (CPC-microspheres) and CP-dispersion microspheres (CPD-microspheres). Comparative studies on mucoadhesion were done with these microspheres and PGEF-based microspheres without CP (PGEF-microspheres). In an in vitro adhesion test, the CPD-microspheres adhered strongly to mucosa prepared from rat stomach and small intestine because each CP particle in the CPD-microsphere was hydrated and swelled with part of it remaining within the microsphere and part extending to the surface serving to anchor the microsphere to the mucus layer. The gastrointestinal transit patterns after administration of the CPD-microspheres and PGEF-microspheres to fasted rats were fitted to a model in which the microspheres are emptied from the stomach monoexponentially with a lag time and then transit through the small intestine at zero-order. Parameters obtained by curve fitting confirmed that the gastrointestinal transit time of the CPD-microspheres was prolonged compared with that of the PGEF-microspheres. MRT in the gastrointestinal tract was also prolonged after administration of the CPD-microspheres compared with that following the administration of the PGEF-microspheres.
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pH‐Independent Controlled‐Release Microspheres Using Polyglycerol Esters of Fatty Acids
Journal of pharmaceutical sciences, 1994Co-Authors: Yohko Akiyama, Shinichiro Hirai, Minoru Yoshioka, Hidetoshi Horibe, Nobuyuki Kitamori, Hajime ToguchiAbstract:Abstract The release of a drug having low solubility in a certain pH range from controlled‐release microspheres using tetraglycerol pentastearate and tetraglycerol monostearate in combination as the matrix base showed pH dependence. Trepibutone, an acidic drug having lower solubility in an acidic medium, was released pH‐independently from the microspheres which incorporated magnesium oxide, a solid base. It might have resulted from the pH inside the matrix being kept in an optimum range for drug release due to the incorporation of a solid base. On the other hand, the addition of water soluble acidic or basic excipients was ineffective to achieve pH‐independent release. For papaverine, a basic drug, pH‐independent drug‐release characteristics could be achieved by adding Eudragit L100‐55, an enteric polymer. It is thought that the enteric polymer increased the pores for drug release by dissolving in a higher pH range, where the solubility of papaverine is low, and thereby made the release pH‐independent. Further, selecting a Polyglycerol Ester of a fatty acid with an appropriate hydrophile–lipophile balance as the matrix could yield a drug with the desired release rate at any pH.
Susana Cofrades - One of the best experts on this subject based on the ideXlab platform.
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Preparation and impact of multiple (water-in-oil-in-water) emulsions in meat systems.
Food chemistry, 2013Co-Authors: Susana Cofrades, I. Antoniou, Maria Teresa Solas, Ana M. Herrero, Francisco Jiménez-colmeneroAbstract:The aim of this paper was to prepare and characterise multiple emulsions and assess their utility as pork backfat replacers in meat gel/emulsion model systems. In order to improve the fat content (in quantitative and qualitative terms) pork backfat was replaced by a water-in-oil-in-water emulsion (W1/O/W2) prepared with olive oil (as lipid phase), Polyglycerol Ester of polyricinoleic acid (PGPR) as a lipophilic emulsifier, and sodium caseinate (SC) and whey protein concentrate (WP) as hydrophilic emulsifiers. The emulsion properties (particle size and distribution, stability, microstructure) and meat model system characteristics (composition, texture, fat and water binding properties, and colour) of the W1/O/W2, as affected by reformulation, were evaluated. Multiple emulsions showed a well-defined monomodal distribution. Freshly prepared multiple emulsions showed good thermal stability (better using SC) with no creaming. The meat systems had good water and fat binding properties irrespective of formulation. The effect on texture by replacement of pork backfat by W1/O/W2 emulsions generally depends on the type of double emulsion (associated with the hydrophilic emulsifier used in its formulation) and the fat level in the meat system.