Non-Invasive Rheo-MRI Study of Egg Yolk-Stabilized Emulsions: Yield Stress Decay and Protein Release.

A comprehensive understanding of the time-dependent flow behavior of concentrated oil-in-water emulsions is of considerable industrial importance. Along with conventional rheology measurements, localized flow and structural information are key to gaining insight into the underlying mechanisms causing time variations upon constant shear. In this work, we study the time-dependent flow behavior of concentrated egg-yolk emulsions with (MEY) or without (EY) enzymatic modification and unravel the effects caused by viscous friction during shear.

Origin of the extremely high elasticity of bulk emulsions, stabilized by Yucca Schidigera saponins.

We found experimentally that the elasticity of sunflower oil-in-water emulsions (SFO-in-W) stabilized by Yucca Schidigera Roezl saponin extract, is by >50 times higher as compared to the elasticity of common emulsions. We revealed that strong specific interactions between the phytosterols from the non-purified oil and the saponins from the Yucca extract lead to the formation of nanostructured adsorption layers which are responsible for the very high elasticity of the oil-water interface and of the respective bulk emulsions. Remarkably, this extra high emulsion elasticity inhibits the emulsion syneresis even at 65 vol% of the oil drops - these emulsions remain homogeneous and stable even after 30 days of shelf-storage.

Gravity-driven syneresis in model low-fat mayonnaise.

Low-fat food products often contain natural, edible polymers to retain the desired mouth feel and elasticity of their full-fat counterparts. This type of product, however, can suffer from syneresis: densification due to the expulsion of fluid. Gaining insight into the physical principles governing syneresis in such soft hybrid dispersions remains a challenge from a theoretical perspective, as experimental data are needed to establish a basis.

Rheology of particle/water/oil three-phase dispersions: Electrostatic vs. capillary bridge forces.

Hypothesis: Particle/water/oil three-phase capillary suspensions possess the remarkable property to solidify upon the addition of minimal amount of the second (dispersed) liquid. The hardening of these suspensions is due to capillary bridges, which interconnect the particles (pendular state). Electrostatic repulsion across the oily phase, where Debye screening by electrolyte is missing, could also influence the hardness of these suspensions.

A Scalable Platform for Functional Nanomaterials via Bubble-Bursting.

A continuous and scalable bubbling system to generate functional nanodroplets dispersed in a continuous phase is proposed. Scaling up of this system can be achieved by simply tuning the bubbling parameters. This new and versatile system is capable of encapsulating various functional nanomaterials to form functional nanoemulsions and nanoparticles in one step.

Sustained satiety induced by food foams is independent of energy content, in healthy adults.

Our previous research demonstrated high, sustained satiety effects of stabilized food foams relative to their non-aerated compositions. Here we test if the energy and macronutrients in a stabilized food foam are critical for its previously demonstrated satiating effects. In a randomized, crossover design, 72 healthy subjects consumed 400 mL of each of four foams, one per week over four weeks, 150 min after a standardized breakfast.

Cyclodextrin-Based Solid-Gas Clathrates.

"Cyclodextrin-gas" clathrates were obtained by crystallization from water solution of α-, β-, and γ-cyclodextrins (CDs) under pressure of the gas to be entrapped into the CD molecules. When the pressure is released, these clathrates are stable at ambient conditions and dissociate at elevated temperature, which makes them interesting for various applications as foam boosters in food and other industries. It was found that under these conditions α-CD forms clathrates with all of the gases used in this study (N2, N2O, CO2, Ar), whereas β- and γ-CDs can form clathrates only with N2.

Aerated drinks increase gastric volume and reduce appetite as assessed by MRI: a randomized, balanced, crossover trial.

Background: Compared with nonaerated, isocaloric controls, aerated foods can reduce appetite throughout an entire dieting day. Increased gastric volumes and delayed emptying are possible but unexplored mechanisms.

Objective: We tested the hypothesis that aerated drinks (foams) of differing gastric stability would increase gastric distension and reduce appetite compared with a control drink.

Sustained hunger suppression from stable liquid food foams.

Objective: Simple aeration of food matrices with gas has previously been shown to generate immediate suppression of appetite, though duration of effects has not been shown. This research tested whether liquids aerated with nitrous oxide (N2 O) to achieve high in-body stability could produce enhanced and sustained effects on eating motivations.

Methods: In two randomized cross-over studies, appetite ratings were collected for 240 min.

Sonication-microfluidics for fabrication of nanoparticle-stabilized microbubbles.

An approach based upon sonication-microfluidics is presented to fabricate nanoparticle-coated microbubbles. The gas-in-liquid slug flow formed in a microchannel is subjected to ultrasound, leading to cavitation at the gas-liquid interface. Therefore, microbubbles are formed and then stabilized by the nanoparticles contained in the liquid.

Colloids in Flatland: a perspective on 2D phase-separated systems, characterisation methods, and lineactant design.

In 1861 Thomas Graham gave birth to a new field of science, today known as colloid science. Nowadays, the notion "colloid" is often used referring to systems consisting of two immiscible phases, one of which is finely dispersed into the other. Research on colloids deals mostly with sols (solids dispersed in a liquid), emulsions (liquids dispersed in liquid), and foams (gas dispersed in a liquid).

Interfacial layers from the protein HFBII hydrophobin: dynamic surface tension, dilatational elasticity and relaxation times.

The pendant-drop method (with drop-shape analysis) and Langmuir trough are applied to investigate the characteristic relaxation times and elasticity of interfacial layers from the protein HFBII hydrophobin. Such layers undergo a transition from fluid to elastic solid films. The transition is detected as an increase in the error of the fit of the pendant-drop profile by means of the Laplace equation of capillarity.

Polymer compatibility in two dimensions. Modeling of phase behavior of mixed polymethacrylate Langmuir films.

We analyze the possibility of polymer blends undergoing phase separation in two dimensions. To this end, we investigate a model system consisting of water-supported Langmuir monolayers, obtained from binary polyalkyl-methacrylate mixtures (PXMA, where X stands for any of the type of ester side groups used: M, methyl-; E, ethyl-; B, butyl-; H, hexyl-; O, octyl-; L, lauryl-methacrylate), by means of self consistent field (SCF) calculations. In particular, we address the conditions which determine demixing and phase separation in the two-dimensional system, showing that a sufficient chain length mismatch in the ester side group moieties is able to drive the polymer demixing.

Surface shear rheology of adsorption layers from the protein HFBII hydrophobin: effect of added β-casein.

The surface shear rheology of hydrophobin HFBII adsorption layers is studied in angle-ramp/relaxation regime by means of a rotational rheometer. The behavior of the system is investigated at different shear rates and concentrations of added β-casein. In angle-ramp regime, the experimental data comply with the Maxwell model of viscoelastic behavior.

PMMA highlights the layering transition of PDMS in Langmuir films.

We report a system consisting of a mixed Langmuir monolayer, made of water-insoluble, spreadable, fluid-like polymers polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA) with a minority P(DMS-b-MMA) copolymer. We have performed both Langmuir trough pressure/area isotherm measurements and Brewster angle microscopy (BAM) observations and complement the experiments with molecularly detailed self-consistent field (SCF) calculations. PDMS undergoes a layering transition that is difficult to detect by BAM.

Polymers at the water/air interface, surface pressure isotherms, and molecularly detailed modeling.

Surface pressure isotherms at the air/water interface are reproduced for four different polymers, poly-L-lactic acid (PLLA), poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), and poly(isobutylene) (PiB). The polymers have the common property that they do not dissolve in water. The four isotherms differ strongly.

Measuring the three-phase contact angle of nanoparticles at fluid interfaces.

We report a generic technique to image and study the wettability of spherical nanoparticles adsorbed at liquid surfaces and demonstrate that nanoparticle monolayers can be imprinted at air-water and oil-water interfaces and their three-phase contact angle at the original liquid interface can be determined by an atomic force microscopy scan on a replica of the interface; the technique is tested using four different types of nanoparticles, the smallest one having a radius of 37 nm.

Theoretical modeling of the kinetics of fibrilar aggregation of bovine beta-lactoglobulin at pH 2.

The authors propose a kinetic model for the heat-induced fibrilar aggregation of bovine beta-lactoglobulin at pH 2.0. The model involves a nucleation step and a simple addition reaction for the growth of the fibrils, as well as a side reaction leading to the irreversible denaturation and inactivation of a part of the protein molecules.

Strong impact of ionic strength on the kinetics of fibrilar aggregation of bovine beta-lactoglobulin.

We investigate the effect of ionic strength on the kinetics of heat-induced fibrilar aggregation of bovine beta-lactoglobulin at pH 2.0. Using in situ light scattering we find an apparent critical protein concentration below which there is no significant fibril formation for all ionic strengths studied.

Time-resolved small-angle neutron scattering during heat-induced fibril formation from bovine beta-lactoglobulin.

We study in situ the kinetics of heat-induced fibrilar aggregation of bovine beta-lactoglobulin at pH 2.0 and 80 degrees C for the first time by time-resolved small-angle neutron scattering. A simple model for the scattering from a mixture of monodisperse charged spheres (monomeric beta-lactoglobulin) interacting via a screened electrostatic repulsion and noninteracting long cylinders (protein fibrils) is used to describe the data.

Thermally induced fibrillar aggregation of hen egg white lysozyme.

We study the effect of pH and temperature on fibril formation from hen egg white lysozyme. Fibril formation is promoted by low pH and temperatures close to the midpoint temperature for protein unfolding (detected using far-ultraviolet circular dichroism). At the optimal conditions for fibril formation (pH 2.

Multiple steps during the formation of beta-lactoglobulin fibrils.

In this study, the heat induced fibrilar aggregation of the whey protein beta-lactoglobulin is investigated at low pH and at low ionic strength. Under these circumstances, tapping mode atomic force microscopy results indicate that the fibrils formed have a periodic structure with a period of about 25 nm and a thickness of one or two protein monomers. Fibril formation is followed in situ using light scattering and proton NMR techniques.

Adsorption Kinetics of Some Polyethylene Glycol Octylphenyl Ethers Studied by the Fast Formed Drop Technique.

The adsorption kinetics of Triton X-100 and Triton X-405 at solution/air and solution/hexane interfaces is studied by the recently developed fast formed drop technique. The dynamic interfacial tension of Triton X-100 and Triton X-405 solutions against hexane has been measured without preequilibration of the water and oil phases. It is found that the dynamic interfacial tension of Triton X-100 solutions passes through a minimum.

A Novel Fast Technique for Measuring Dynamic Surface and Interfacial Tension of Surfactant Solutions at Constant Interfacial Area.

A novel, fast formed drop technique is developed for measuring dynamic surface and interfacial tension of surfactant solutions. It employs the basis of the capillary pressure methods. A new way of formation of a fresh interface is the key point in the proposed technique.

[Epizootiological research on salmonellosis in swine].

The epizootiology of Salmonella infections in swine was studied in 1970-1980 in 7 districts of this country on a number of farms and industrial complexes in order to elucidate some aspects of the epizootiologic process. A total of 26,957 samples taken from swine and the environment were studied bacteriologically. An industrial complex in each district served as a test one to investigate samples from various groups of swine in the technologic process.