Academic literature on the topic 'Multi-layer emulsions'

The enzymatic hydrolysis of triglycerides with lipases (EC 3.1.1.3.) involves substrates from both water and oil phases, with the enzyme molecules adsorbed at the water-oil (w/o) interface. The reaction rate depends on lipase concentration at the interface and the available interfacial area in the emulsion. In emulsions with large drops, the reaction rate is limited by the surface area. This effect must be taken into account while modelling the reaction. However, determination of the interfacial saturation is not a trivial matter, as enzyme molecules have the tendency to unfold on the interface, and form multi-layer, rendering many enzyme molecules unavailable for the reaction. A multi-scale approach is needed to determine the saturation concentration with specific interfacial area so that it can be extrapolated to droplet swarms. This work explicitly highlights the correlation between interfacial adsorption and reaction kinetics, by integration of the adsorption kinetics into the enzymatic reaction. The rate constants were fitted globally against data from both single droplet and drop swarm experiments. The amount of adsorbed enzymes on the interface was measured in a single drop with a certain surface area, and the enzyme interfacial loading was estimated by Langmuir adsorption isotherm.

The tear film at the ocular surface is covered by a thin layer of lipids. This oily phase stabilizes the film by decreasing its surface tension and improving its viscoelastic properties. Clinically, destabilization and rupture of the tear film are related to dry eye disease and are accompanied by changes in the quality and quantity of tear film lipids. In dry eye, eye drops containing oil-in-water emulsions are used for the supplementation of lipids and surface-active components to the tear film. We explore in detail the biophysical aspects of interactions of specific surface-active compounds, cetalkonium chloride and poloxamer 188, which are present in oil-in-water emulsions, with tear lipids. The aim is to better understand the macroscopically observed eye drops–tear film interactions by rationalizing them at the molecular level. To this end, we employ a multi-scale approach combining experiments on human meibomian lipid extracts, measurements using synthetic lipid films, and in silico molecular dynamics simulations. By combining these methods, we demonstrate that the studied compounds specifically interact with the tear lipid film enhancing its structure, surfactant properties, and elasticity. The observed effects are cooperative and can be further modulated by material packing at the tear–air interface.

ABSTRACT This paper summarizes a multi-year research program to address the decanting of water from oil spill fluids recovered by skimmers. The first series of tests, with two weir-type skimmers at Ohmsett, was conducted to study the rate and amount of free water separation that can be expected in temporary storage containers. The goal of this study was to predict the best time to decant water back into the boomed area and optimize the available onsite storage space. The results indicated that “primary break” (the initial separation of the recovered liquids) occurred within a few minutes to one hour, depending on the physical characteristics of the oil. Rapidly decanting this free water layer may offer immediate increases of 200 to 300% in available temporary storage volume. Initial oil concentrations in the decanted water also depended on the physical properties of the oil; they ranged from 100 to 3000 mg/L These declined by a factor of approximately 3 after one hour of settling, and by a factor of approximately 5 after one day. The second series of tests was undertaken to develop a more complete understanding of the use of emulsion breakers injected into an oil spill recovery system at both lab-scale (at SL Ross) and mid-scale (at Ohmsett). The experiments were designed to assess the injection/mixing/settling regimes required for optimum water-removal from a meso-stable water-in-oil emulsion with an oil spill demulsifier. The use of a demulsifier injected into a recovery system, combined with decanting, did substantially reduce the volume of water in temporary storage tanks and the water content of emulsions for disposal/recycling.

The work is devoted to optimization modeling of an influence of pasteurization with oxygen absorbers on spoilage processes of lipids of boiled sausage products. According to the results, the influence on changes of peroxide and acid numbers of lipids of small sausages, pasteurized at presence of an oxygen absorber, has been mathematically prognosticated. At mathematical modeling, mathematic packages MathCad and «Data analysis» (ЕТ) MSExcel were used. The experiment was planned according to the plan of full factorial experiment. The dependence as to the influence of the recipe composition of sausage products at their storage on peroxide and acid number values has been revealed. The conducted modeling allows to state the adequacy of obtained regressive equations. The obtained empirical dependencies allow to prognosticate a storage term of boiled sausages products, pasteurized with elements of active package at using protecting barrier multi-layer polymeric materials. The optimization modeling was conducted by structuring a mathematical model as an analytic expression that reflects the connection of factor signs with a parametric index. The obtained response functions are adequate and have a high correspondence to real experimental data. Storage terms were substantiated for small sausages, which recipe included beef, pork, poultry meat and also food emulsions, based on animal proteins. The process of repeated pasteurization was conducted at temperature 85–90 °С during 15–20 minutes

Acquisition of a healthy lifestyle through diet has driven the food manufacturing industry to produce new food products with high nutritional quality. In this sense, consumption of bioactive compounds has been associated with a decreased risk of suffering chronic diseases. Nonetheless, due to their low solubility in aqueous matrices, high instability in food products during processing and preparation as well as poor bioavailability, the use of such compounds is sometimes limited. Recent advancements in encapsulation and protection of bioactive compounds has opened new possibilities for the development of novel food products. In this direction, the present review is attempting to describe encapsulation achievements, with special attention to nanostructured lipid-based delivery systems, i.e., nanoemulsions, multi-layer emulsions and liposomes. Functionality of bioactive compounds is directly associated with their bioavailability, which in turn is governed by several complex processes, including the passage through the gastrointestinal tract and transport to epithelial cells. Therefore, an overview of recent research on the properties of these nanostructured lipid-based delivery systems with a strong impact on the functionality of bioactive compounds will be also provided. Nanostructured lipid-based delivery systems might be used as a potential option to enhance the solubility, stability, absorption and, ultimately, functionality of bioactive compounds. Several studies have been performed in this line, modifying the composition of the nanostructures, such as the lipid-type or surfactants. Overall, influencing factors and strategies to improve the efficacy of encapsulated bioactive compounds within nanostructures have been successfully identified. This knowledge can be used to design effective targeted nanostructured lipid-based delivery systems for bioactive compounds. However, there is still a lack of information on food interactions, toxicity and long-term consumption of such nanostructures.

Els extractes comercials de polifenols són molt utilitzats para formular aliments. La seva efectivitat, però, depèn de la seva capacitat per mantenir l’estabilitat i biodisponibilitat dels ingredients actius. L’encapsulació és una estratègia que permet aconseguir-ho. S’han investigat dos sistemes per encapsular un extracte ric en procianidines: emulsions aigua-en-oli-en-aigua (W1/O/W2) i microcàpsules sòlides (obtingudes per atomizació d’emulsions W1/O/W2). Per produir les emulsions s’utilitzà emulsificació amb membranes (ME) premix i, en particular, l’estudi es centrà en com la capa interfacial (O–W2) afecta l’estabilitat de les emulsions i l’alliberament de procianidines. Mitjançant ME premix es produïren emulsions O/W i W1/O/W2 estabilitzades amb un fracció proteica de sèrum de llet (WPI) i amb complexos WPI-carboximetil cel•lulosa (WPI–CMC), WPI-goma aràbiga (WPI–GA) i WPI–Quitosà (WPI–Chi). Mesures d’absorció mostraren que els complexos WPI–polisacàrid formen interfases de major gruix però menor densitat que les formades únicament per WPI. Les emulsions W1/O/W2 enriquides amb procianidines i estabilitzades amb complexos WPI–CMC, WPI–GA, o WPI–Chi retingueren al menys el 70% de las procianidines inicials en acabar el procés de ME premix. L’estabilitat de l’emulsió va dependre del tipus d’interfase i del pH de la fase W2. La velocitat d’alliberament de procianidines es va correlacionar amb el gruix de la interfase formada per WPI–polisacàrid: les interfases de major gruix disminueixen la velocitat d’alliberament. Totes les emulsions W1/O/W2 varen permetre produir microcàpsules de procianidines després d’una etapa d’atomització i recuperar l’estructura pròpia d’una emulsió doble en rehidratar-se. La composició de la interfase determinà la mida de partícula de les emulsions W1/O/W2 després de la rehidratació. En particular, el complex WPI–CMC fou capaç d’estabilitzar les gotes d’oli durant les distintes etapes de la producció de microcàpsules, malgrat que va retenir moderadament la migració de procianidines a través de la interfase O–W2. .<br>Los extractos comerciales de polifenoles son muy utilizados para formular alimentos. Su efectividad, sin embargo, depende de su capacidad para mantener la estabilidad y biodisponibilidad de los ingredientes activos. La encapsulación es una estrategia que permite conseguirlo. Se han investigado dos sistemas para encapsular un extracto rico en procianidinas: emulsiones agua-en-aceite-en-agua (W1/O/W2) y microcápsulas sólidas (obtenidas por atomización de emulsiones W1/O/W2). Para producir las emulsiones se empleó emulsificación por membranas (ME) premix y, en particular, el estudio se centró en cómo la capa interfacial (O–W2) afectó la estabilidad de las emulsiones y la liberación de procianidinas. Con ME premix se produjeron emulsiones O/W y W1/O/W2 estabilizadas con un fracción proteica de suero de leche (WPI) y con complejos WPI-carboximetil celulosa (WPI–CMC), WPI–goma arábiga (WPI–GA) y WPI–Quitosano (WPI–Chi). Medidas de adsorción mostraron que los complejos WPI–polisacáridos forman interfases de mayor espesor pero menor densidad que las formadas únicamente por WPI. Las emulsiones W1/O/W2 enriquecidas en procianidinas y estabilizadas con complejos WPI–CMC, WPI–GA, o WPI–Chi retuvieron al menos el 70% de las procianidinas iniciales tras el proceso de ME premix. La estabilidad de la emulsión dependió del tipo de interfase y del pH de la fase W2. La velocidad de liberación de procianidinas se correlacionó con el espesor de la interfase formada por WPI–polisacáridos: las interfases de mayor espesor disminuyen la velocidad de liberación. Todas las emulsiones W1/O/W2 permitieron producir microcápsulas de procianidinas después de una etapa de atomización y recuperar la estructura propia de una emulsión doble tras la rehidratación. La composición de la interfase determinó el tamaño de partícula de las emulsiones W1/O/W2 después de la rehidratación. En particular, el complejo WPI–CMC fue capaz de estabilizar las gotas de aceite durante las distintas etapas de la producción de microcápsulas pese a que retuvo, moderadamente, la migración de procianidinas a través de la interfase O–W2.<br>Commercial extracts rich in polyphenols are extensively used to formulate foods. Nevertheless, their effectiveness depends on preserving the stability and bioavailability of the active ingredients. Encapsulation is a strategy to meet these requirements. We have investigated two encapsulation systems to entrap a procyanidin-rich extract: water-in-oil-in-water (W1/O/W2) emulsions and solid microcapsules (spray dried W1/O/W2 emulsions). While premix membrane emulsification (ME) was used to produce these emulsions, we focused on how the interfacial layer (O–W2) affected emulsion stability and procyanidin release. Premix ME enabled to produce single and double emulsions stabilized with whey protein isolate (WPI), and WPI–Carboxymethyl cellulose (WPI–CMC), WPI–Gum Arabic (WPI–GA) and WPI–Chitosan (WPI–Chi) complexes. Adsorption measurements showed that WPI–polysaccharides interfaces form thicker but less dense layers than only WPI. In O/W emulsions, different interfacial structures made of WPI and CMC led to large differences in lipid oxidation. The negatively charged droplets of the emulsions stabilized with WPI–MC would attract positively charged transition metals, promoting lipid oxidation. Procyanidin-loaded W1/O/W2 emulsions stabilized by WPI–CMC, WPI–GA, or WPI–Chi complexes retained at least 70% of the initial procyanidins at the end of premix ME. Emulsion stability depended on the interfacial layer and the pH of the W2 phase. The release rate of procyanidins was correlated to the interfacial thickness of the WPI–polysaccharide layer: thicker layers lowered the release rate. All the W1/O/W2 emulsions were able to produce procyanidin-loaded microcapsules after spray drying and could all recover their W1/O/W2 emulsion structure upon rehydration. The interfacial composition affected particle size of W1/O/W2 emulsions after microcapsule rehydration. Particularly, WPI–CMC complex was able to truly stabilize the W1/O droplets during the different stages of microcapsule production although it moderately retained the migration of procyanidins through the O–W2 interface. For each type of encapsulation system, a tailor-made hydrophilic emulsifier is required to comply with the type of protection needed, the addenda used and the delivery conditions.

Abstract Measurement of sand build-up in the production separators has been a challenge for field personnel due to the limitations of current technologies. Nucleonic-type level profiler has been previously implemented in a few offshore locations but limited due to special handling and permit/license requirements of radioactive material involved. Therefore, this paper aims to present the acceleration of new non-nucleonic tomographic technology testing and qualification to measure accumulating sand in separators as well as multi-disciplinary approvals for fast-track field application. The general idea in tomography is to expose the target of interest to electrical signals and measure the response of the target. With the aid of mathematical models, it is possible to infer the distribution of different materials within the target from the responses. Results of tomographic measurements are displayed on a computer as a vertical profile. The tested tomographic solution was based on a tomographic technology called Electrical Tomography. The key idea in Electrical Tomographic image construction is to find a permittivity and conductivity distribution for which the observations predicted by the model are in good agreement with actual ET measurement data and hence profiling is to be created. The test was performed at the laboratory with a full tomographic profiler setup including a test probe sensor for profiling, electronics, and a computer unit. In addition to the tomographic instrumentation, a transparent plastic vessel was used for visual observations of the accumulated sand layers. Visual observations were made simultaneously with tomographic imaging. In the test setup, we had sand, water, emulsion, and oil. The samples were placed into a transparent vessel. It was visually observed that the probe sensor was able to distinguish "wet sand-water" interface and "water-oil interface" in all the tested conditions. At the end of the test, the sand layer was flattened and packed more tightly and the change in the layer thickness was seen in the tomographic image. We concluded that the resolution of the detection of the sand layer was in the range of 1-2 cm. The technology is novel as it is a non-nucleonic profiler and a field-safe technology to be used. The profiler is intrinsically safe and certified to the most demanding IECEx class to be used in Zone 0 hazardous atmospheres. Detailed engineering of the technology to be installed at one of the production separators has proceeded. Finite Element Analysis has shown that the system can withstand turbulent conditions within the multi-phase production separator.