•Adsorption of β-casein/β-lactoglobulin mixtures was studied at the O/W interface.•Transient interfacial tests and harmonic drop oscillations were performed.•Small amplitude oscillations evidenced a ...prevalent solid-like behaviour.•β-Casein mainly affects the adsorption and rheological properties of mixed layers.
This paper investigates the adsorption behaviour of two milk proteins, β-casein and β-lactoglobulin, both alone and in binary mixtures, at the sunflower oil-water interface (O/W) in order to better understand the emulsifying functionality of protein mixtures commonly used in the manufacture of milk protein-stabilised emulsions.
A commercial non-purified oil was used, to analyse the behaviour of interfaces close to real systems. A constant protein concentration (1g/l) and different β-lactoglobulin:β-casein ratios (1:3; 1:1; 3:1) were used during the tests and interfacial protein interactions were studied with a pendant drop tensiometer.
Experimental results evidenced that the adsorption and the interfacial rheological properties of β-casein/β-lactoglobulin adsorbed layers are mainly affected by the presence of β-casein molecules, which is probably the most abundant protein at interface, as also suggested by the application of two rheological models, commonly adopted for the description of bulk properties of mixed systems. Dynamic data evidenced a solid-like behaviour for the interfacial layer similar to 3D weakly-structured systems.
Emulsion gels are structured emulsions suitable for different uses for their specific behaviour, which is strongly dependent on the characteristics of the gelled dispersing phase. Therefore, it is ...important to adopt the specific gelling agent to tune the final emulsion rheological behaviour properly. Pectin is extremely interesting among potential hydrophilic gelling agents owing to its specific characteristics. In the present work, four different low-methoxyl pectins were adopted to prepare gels to be used as the dispersing phase in cosmetic or pharmaceutical emulsion gels. The rheological characterisation of pectin gels, prepared at room temperature to avoid the damage to potential thermolabile components, was carried out with small amplitude oscillations. The obtained gels were used, together with a common non-ionic surfactant (Tween 60), to prepare olive oil emulsion gels suitable to design new cosmetic products. A simple empirical model, proposed to relate the emulsion complex modulus to the oil fraction and properties of the dispersing phase, has shown itself to be a potentially useful tool to design formulations with desired properties.
The essential oils of
Origanum ehrenbergii and
O. syriacum collected in Lebanon were analysed by GC and GC–MS and evaluated for their anticholinesterase, NO production inhibitory activities, and ...antioxidant properties.
O.
ehrenbergi essential oil was characterised by the presence of 37 components, representing 94.9% of the total oil of which thymol (19%) and
p-cymene (16.1%) were the main abundant compounds. Thirty-six compounds characterised the
O.
syriacum essential oil, representing 90.6% of the total oil. The most abundant components were thymol (24.7%) and carvacrol (17.6%).
O. ehrenbergii demonstrated interesting scavenging effects on DPPH with an IC
50 value of 0.99
μg/ml. In addition, both
O. ehrenbergii and
O. syriacum oils inhibited oxidation of linoleic acid after 30
min of incubation, as well as after 60
min of incubation with IC
50 values of 42.1 and 33.6
μg/ml, and 46.9 and 58.9
μg/ml, respectively. Interestingly,
O. ehrenbergii oil inhibited NO production in the murine monocytic macrophage cell line RAW 264.7 with an IC
50 value of 66.4
μg/ml. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition was assessed by modifications of the Ellman’s method.
O. ehrenbergii exhibited a strong activity against both cholinesterases with IC
50 values of 0.3
μg/ml. The data suggest that
O. ehrenbergii and
O. syriacum oils could be used as a valuable new flavour with functional properties for food or nutriceutical products with particular relevance to supplements for the elderly.
In this work the effects of ι-carrageenan and κ-carrageenan on macroscopic properties of commercial sunflower oil/water systems, stabilised by whey proteins, were investigated by measuring the ...interfacial and bulk rheological properties, the particle size distribution and the creaming stability. The main aim was to investigate the relationship between interfacial characteristics and emulsion stability, evidencing the conditions to be used to improve the emulsion properties.
Transient interfacial tension and dilatational dynamic moduli were measured with a “pendant drop” tensiometer; experimental results have shown that, in the investigated range, the carrageenan increases the interfacial tension and yields a more resistant layer surrounding the oil drops, mostly in the presence of ι-type.
Bulk rheological tests carried out on emulsions, manufactured by using the same components and sunflower oil, have evidenced that the addition of the carrageenan to the protein system causes an increase of the emulsion viscosity and, as a consequence, a reduction of droplet movement and aggregation.
The analysis of Drop Size Distribution (DSD), adopted to investigate the coalescence stability, evidenced that polysaccharide addition yields larger droplets but reduces significantly the change of polydispersity with time (within the tested range), suggesting greater emulsion stability. This result was also confirmed by an analysis of the “creaming index”, carried out measuring the separated cream layer of samples stored up to 24 h: low values were obtained when carrageenan was used. Moreover, it was observed that stability improves significantly by adding ι-carrageenan rather than κ-carrageenan.
Finally, experimental results have shown that DSD seems more affected by interfacial tension values, whereas stability is dependent on the viscoelasticity of the interfacial layer.
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•A new technique for the simultaneous inner coating of hollow fibers is presented.•CO2/CH4 separation using Pebax®/PAN composite hollow fiber membranes is performed.•Effect of Pebax® ...solution viscosity on gas transport of composite membranes is studied.
Poly(ether-b-amide) (Pebax®1657)/polyacrylonitrile (PAN) composite hollow fiber membranes for a potential use in CO2/CH4 separation were prepared by a new continuous coating method, referred to as cross-flow filtration. This technique allows to obtain the simultaneous coating of a large number of fibers, facilitating the scale-up. The dense layer was deposited in the lumen of the fibers allowing the coating of all the fibers in a single step. The coating on the inner surface of the fibers avoids the negative effects such as sticking or accidental mechanical damages occurring in the case of external coating. The membrane preparation was optimized by modulating different parameters. The optimal range of viscosity and concentration of the polymer solution to obtain a selective homogeneous Pebax® layer was identified. The presence of the Pebax®1657 dense layer was confirmed by IR spectroscopy and the morphology of the composite membranes was observed by SEM analysis. The gas separation performance of the membrane modules was determined by single gas permeation measurements. A preliminary optimization yielded membranes with PCO2=5×10−3 (m3m−2h−1bar−1), αCO2/CH4=18 equal to that of the neat dense polymer. The PEBAX®/PAN hollow fibers modules are potentially useful for application in the purification of biogas.
The objective of this research was to study the effect of diclofenac sodium compartmentalization on the physico-chemical properties (such as size, drug entrapment efficiency and percutaneous ...permeation across rabbit skin) of niosomal vesicles used as carriers. Niosomes were prepared starting from nonionic commercial surfactants belonging to the class of Polysorbates and Pluronics: mixtures of Span 60/F127 and Tween 60/F127 at different ratios were used to obtain vesicles and all formulations were compared in terms of dimensions, morphology, polydispersity index and entrapment efficiency. Moreover, the enhancing effect of niosomes on the
ex vivo
percutaneous penetration of diclofenac sodium was investigated using Franz-type diffusion chambers and compared to that obtained by using the corresponding drug solution. Results demonstrated that niosomes were spherical and homogeneous in shape. Their size was found to be dependent on the hydrophile-lipophile balance of the surfactant mixture: increasing hydrophobicity resulted in smaller vesicles. Drug incorporation led to a significant variation in vesicle size dependently from the compartment in which the drug was located. The permeation of diclofenac from free solution used as control was found to be lower respect to that obtained for all niosomal formulations, that can be considered as percutaneous permeation enhancers. In particular, the results indicated that the highest cumulative amounts of diclofenac permeated across rabbit skin after 24 h were obtained by formulations in which the drug was located in the aqueous core.
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The microstructure of organogels based on monoglycerides of fatty acids (MAGs) and policosanol and on different edible oils was investigated by using different techniques ...(calorimetry, nuclear magnetic resonance, infrared spectroscopy, rheology, polarized light microscopy) towards a better understanding and control of the oil gelation phenomena. Dynamic moduli were related via a fractal model to microstructural information such as solid content and fractal dimension. Infrared spectroscopy evidenced that network structure in MAGs gel is mainly due to hydrogen bonding, whereas in policosanol system is mainly given by van der Waals interactions. Because of the different relative contribution of molecular interactions, the investigated organogelators exhibit a distinguished macroscopic behavior. MAGs are sensitive to the utilized oil and structuration occurs quickly, even though at a temperature lower than policosanol. Policosanol organogels exhibit a behavior independent of the used oil and a slower gelation rate, as a result of the weaker van der Waals interactions. Nevertheless, at lower concentration a stronger final gel is obtained, probably due to of the large number of interactions arising among the long alkyl chains of the fatty alcohols. Obtained results evidenced that policosanol is very effective in gelation of different oils and seems promising for potential commercial uses.
The aim of this work is to investigate the simultaneous adsorption of a globular protein, ovalbumin, and two different types of food emulsifiers, non-ionic Tween 60 and anionic Admul DATEM, at the ...air–water and sunflower oil–water interfaces. A commercial non-purified oil was used, aiming at investigating the behaviour of interfaces close to real systems. A pendant drop tensiometer was used to carry out transient interfacial tension measurements and small amplitude oscillations. A constant protein concentration (0.1 g/l) and different emulsifier/protein ratios (ranging between 0 and 0.6) were used during the tests.
Experimental results evidenced that the non-ionic emulsifier replaces the protein on the interface (only a partial replacement was observed in the tested conditions) whereas the anionic molecule interacts with the protein forming complexes which can be almost completely replaced by the single emulsifier.
The interfacial layers are characterised by a prevalent solid-like behaviour, which proved to be similar to 3D weakly structured systems. The rheological properties are strongly dependent on the nature of both the emulsifier and the interface, nevertheless it was observed that ovalbumin yields a more structured and stronger layer than Admul and Tween. In mixed systems, increasing the emulsifier concentration, the extension of this 2D network decreases whereas the strength seems to be less dependent and evidences only a slight reduction for Admul addition at the A/W interface.
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► Simultaneous adsorption of emulsifiers and protein was investigated at air/water and oil/water interfaces. ► Dilatational interfacial tension and dynamic moduli were measured by a pendant drop system. ► Non-ionic emulsifier (Tween 60) replaces the protein on the interface. ► Anionic emulsifier (Admul DATEM) interacts with the protein forming complexes. ► Interfacial layers behave like 3D weakly structured systems with a prevalent solid-like behaviour.
A moderate red wine consumption and a colored fruit-rich diet protect the cardiovascular system, thanks to the presence of several polyphenols. Malvidin-3-0-glucoside (malvidin), an anthocyanidine ...belonging to polyphenols, is highly present in red grape skin and red wine. Its biological activity is poorly characterized, although a role in tumor cell inhibition has been found. To analyze whether and to which extent, like other food-derived polyphenols, malvidin affects the cardiovascular function, in this study, we have performed a quantitative analysis by high-performance liquid chromatography of polyphenolic content of red grape skins extract, showing that it contains a high malvidin amount (63.93±12.50 mg/g of fresh grape skin). By using the isolated and Langendorff perfused rat heart, we found that the increasing doses (1–1000 ng/ml) of the extract induced positive inotropic and negative lusitropic effects associated with coronary dilation. On the same cardiac preparations, we observed that malvidin (10⁻¹⁰–10⁻⁶ mol/L) elicited negative inotropism and lusitropism and coronary dilation. Analysis of mechanism of action revealed that malvidin-dependent cardiac effects require the activation of the phosphatidylinositol 3-kinase (PI3K)/nitric oxide (NO)/cGMP/PKG pathway and are associated with increased intracellular cGMP and the phosphorylation of endothelial NO synthase (eNOS), PI3K–AKT, ERK1/2, and GSK-3β. AKT and eNOS phosphorylation was confirmed in human umbilical vein endothelial cell. We also found that malvidin act as a postconditioning agent, being able to elicit cardioprotection against ischemia/reperfusion damages. Our results show the cardioactivity of polyphenols-rich red grape extracts and indicate malvidin as a new cardioprotective principle. This is of relevance not only for a better clarification of the beneficial cardiovascular effects of food-derived polyphenols but also for nutraceutical research.
The aim of the present work was the rheological and microstructural analysis of olive oil/mono- and diglycerides/cocoa butter organogels as a potential oil phase of structured food emulsions. Step ...temperature ramp tests at different shear rates and controlled cooling conditions (5 °C/min) were adopted to evaluate the onset of crystallisation temperature (
T
co
) and viscosity of different samples. In order to study the crystallisation phenomena potentially occurring in adopted raw materials, a preliminary characterisation was carried out on pure and blended fats (olive oil and/or cocoa butter), evidencing a relevant effect of adopted shear rate on
T
co
. Afterwards, the influence of mono- and diglycerides on organogelation of either pure or blended fats was investigated, increasing the organogelator from 0.5% (
w
/
w
) up to 60% (
w
/
w
) and observing the increase of
T
co
with its concentration from 17.7 ± 2.7 °C up to 64.5 ± 1.0 °C. Experimental results showed that
T
co
is only determined by the organogelator concentration, and it does not depend on the shear rate and fat source. On the other hand, sample viscosity depends on both the amount of organogelator and the oil phase composition, increasing with saturated fat concentration. Finally, the obtained results allow the fat to be designed with the desired properties: its crystallisation point and rheology can be predicted on the basis of the amounts of the organogelator and the saturated fats, respectively.
