W/O/W多重乳状液的实验研究

研究了W/O/W多重乳状液的制备方法及影响其稳定性的因素。通过正交试验选出较佳的工艺参数,获得了较稳定的W/O/W多重乳状液。     

Release rate profiles of magnesium from multiple W/O/W emulsions

Water-in-oil-in-water (W/O/W) emulsions were formulated based on rapeseed oil, olive oil, olein and miglyol. Polyglycerol polyricinoleate and sodium caseinate were used as lipophilic and hydrophilic emulsifiers, respectively. Magnesium was encapsulated in the inner aqueous droplets. Emulsion stability was assayed through particle sizing and magnesium release at two storage temperatures (4 and 25 °C) over 1 month. Irrespective of the oil nature, both the primary W/O and W/O/W emulsions were quite stable regarding the size parameters, with 10-μm fat globules and 1-μm internal water droplets. Magnesium leakage from W/O/W emulsions was influenced by the oil type used in the formulation: the higher leakage values were obtained for the oils characterized by the lower viscosity and the higher proportion of saturated fatty acids. Magnesium release was not due to droplet–globule coalescence but rather to diffusion and/or permeation mechanisms with a characteristic rate that varied over time. In addition, W/O/W emulsions were resistant to various thermal treatments that mimicked that used in pasteurization processes. Finally, when W/O/W emulsions were placed in the presence of pancreatic lipase, the emulsion triglycerides were hydrolysed by the enzyme. These results indicated a possible use of W/O/W emulsions loaded with magnesium ions in food applications.     

Evolutions of rheology,microstructure and starch hydrolysis of pumpkin-enriched bread during simulated gastrointestinal digestion

In this study, the influences of pumpkin flour additions to breadmaking on evolutions of microstructure, rheology and starch hydrolysis during simulated gastrointestinal digestion were investigated. Compared to white bread (PB₀), the bread supplemented with 20% pumpkin flour (PB₂₀) showed more continuous and fibrous gel network structure with most starch granules encapsulated in the network throughout the in vitro digestion. Due to the dilution of digestive fluids and enzymatic hydrolysis, the digesta moduli and viscosity remarkably decreased as time progressed, but PB₂₀ presented significantly higher rheology compared to PB₀ in each digestion phase. At the end of intestinal phase, the in vitro starch digestibility was 69.9% for PB₀, significantly higher than that for PB₂₀ (55.4%). This is presumably attributed to the abundant dietary fibre in pumpkin flour, contributing to the increased digesta viscosity and the formation of more compact and stable gel networks that would hinder the contact of starch granules with α-amylase. In addition, the pumpkin-added breads gave satisfactory results in terms of sensory acceptability. This study has suggested promising potential of incorporating pumpkin flour in the production of functional bakery products with reduced starch digestibility while maintaining good sensory characteristics.     

Occlusive power evaluation of O/W/O multiple emulsions on gelatin support cells

The water content of the stratum corneum plays an important role in providing skin suppleness and smoothness. The diffusion of water through the skin is limited primarily by the stratum corneum and the noncornified part of the epidermis has negligible water barrier properties. Multiple emulsions are vesicular systems utilized for the prolonged liberation of active ingredients. The O/W/O multiple emulsion type is employed in cosmetics because its high oil content is able to maintain an occlusive film (barrier) on the skin surface. The objective of this study was to determine the occlusive power of O/W/O multiple emulsions on gelatin support cells. The results showed that occlusive products form a uniform layer on the surface of gelatin after the test, whereas nonocclusive products form two layers: an aqueous phase on the gelatin, and an oil phase above the aqueous phase. Thus, the different occlusive powers are due to the homogeneity of this layer and to its ability to prevent water evaporation.     

W/O emulsions: solvent phase separation for pH determination

The aim of this investigation was to find a measure for the phase separation by substances capable of rapidly demulsifying emulsions, which is necessary for the correct determination of the pH in cosmetic W/O emulsions. Results are reported for pH determination in the separated water phase of W/O emulsions containing metal soaps, micropigments and thermally unstable active agents. Of the substances investigated – solvents of different polarity and electrolytes – the best were mixtures of the polar butanol, which has a surfactant-like molecular structure and limited oil and water solubility, and the low polar trichloromethane which in particular has strong fat- and wax-dissolving properties. The combination achieved within 10 to 20 min at room temperature complete phase separations. Stable preparations, based on a polymer emulsifier (cetyl dimethicone copolyol), were demulsified as well as metal soap stabilized creams which characteristically contain a high amount of stabilizing waxes. The so-called solvent phase separation method was confirmed by using model preparations of known pH. During the investigation of model emulsions matching those used in practice, it was found, for example, that magnesium and aluminium stearate as well as various types of micronized zinc oxide which are dissolved or dispersed in the oil phase can shift the pH of the aqueous phase during manufacture from an initial acidic value through neutral to pH 8–10. Time-related and temperature-related changes in pH in formulations containing thermally unstable additives such as dihydroxyacetone or urea can be easily monitored.     

The characterization of the semi-solid W/O/W emulsions with low concentrations of the primary polymeric emulsifier

Semi-solid multiple W/O/W emulsions with low concentrations (0.8, 1.6 and 2.4% w/w) of lipophilic polymeric primary emulsifier PEG-30-dipolyhydroxystearate (PDHS) have been formulated. Both emulsions, primary and multiple, were prepared with high content of inner phase (Phi1 = Phi2 = 0.8). All the formulations differ only in the lipophilic emulsifier concentration. Evaluating several parameters such as macroscopic and microscopic aspect, droplet size, accelerated stability under centrifugation and flow and oscillatory rheological behaviour, assessed the multiple systems. It is possible to formulate the semi-solid W/O/W multiple emulsions with low concentrations of PDHS as the primary emulsifier. It appeared that the highest long-term stable multiple emulsion with the lowest droplet size, the highest apparent viscosity and highest elastic characteristic, was the sample with the highest concentration (2.4% w/w) of the primary emulsifier.     

提高W/O/W多重乳状液的稳定性研究

研究了W／O／W多重乳状液稳定性的影响因素。实验表明，W／O／W多重乳状液制备的较佳工艺操作条件为乳化温度40℃，pH值2．5，W／O／W搅拌时间25min，第一相体积比0．48，第二相体积比0．66。     

各相体积比对W/O/W复合乳状液性质的影响

目的：研究用两步乳化法制备W／O／W型复合乳状液时，第一相体积比（内水相与油相的体积比）、第二相体积比（初乳与外水相的体积比）对W／O／W型复合乳状液性质的影响；方法：采用两步乳化法制备W／O／W型复合乳状液，固定制备工艺条件，改变第一相体积比和第二相体积比的数值制备初乳和复乳，用离心分层稳定性评价复乳的稳定性，初乳的离心稳定性、黏度和复乳的粒度分布被测定；结果：随着第一相体积分数增大，初乳黏度增大，初乳和复乳的离心稳定性都提高，但是内水相的体积分数达到65％时，初乳表现出凝胶的外观，所制备的复乳的稳定性反而降低，当内水相的体积分数增加到70％的时候，初乳转相形成O／W型乳状液，不能进一步制备复乳；随着第二相体积分数的增大，复乳黏度线性增大，复乳滴的体积平均粒径减小，复乳的离心稳定性提高。初乳中内水相与油相的适宜的体积比及复乳中初乳和外水相的适宜体积比皆为1：1左右。     

Electrical impedance changes and water content in O/W emulsions during evaporation

A method for measuring the variation of electrical impedance (Z) of thin layers (0.1 mm) of O/W emulsions during evaporation in a controlled environment is presented. The evaporation of an emulsion base (A) either as such and containing 1% glycerin (B) or 1% sodium pyrrolidonecarboxylate (C) was investigated for 120 min at constant air temperature (25°C) and relative humidity (55%). The measured impedance of the emulsion layers increased by three orders of magnitude during the evaporation cycles. The relationship between impedance and water content of the evaporating emulsion layers was investigated. Each emulsion showed a complex linear relationship between log Z and water content, the relationship being represented by two (three, for emulsion A) linear portions in the graph. Plots of water content vs. time, temperature vs. time and rate of water loss vs. water content of the emulsion layers are presented. The data appear to indicate that evaporation proceeds via distinct stages, whose correspondence to different mechanisms of water evaporation is discussed. The potentiality of the present method for water analysis, and for investigating structural changes in emulsions during evaporation, is also discussed.
Les variations d'impédance électrique et la teneur en eau d'émulsions huile dans eau en cours d'évaporation     

米糠蛋白O/W及W/O/W乳液制备及界面稳定性

为对比不同米糠蛋白质量浓度下O/W及W/O/W乳液的稳定性,以米糠蛋白作为基料,采用双乳化法制备O/W及W/O/W乳液,考察不同米糠蛋白质量浓度下乳液的微观形态和稳定性并探究其界面稳定机理。结果表明：W/O/W乳液的贮存稳定性显著优于O/W乳液;与相同蛋白含量的O/W乳液相比,W/O/W乳液的黏度显著提高;当米糠蛋白质量浓度为0.4 g/100 mL时,W/O/W乳液的稳定性较O/W乳液提高了1 倍以上;乳液内部包裹更多的W/O液滴,W/O/W乳液的粒径较大;而此时静电斥力也较大,起到稳定乳液的目的。同时,米糠蛋白质量浓度不小于0.4 g/100 mL时,O/W及W/O/W乳液中蛋白质的吸附率较高,达到78%以上。本研究为天然米糠蛋白质在食品级乳液中的开发提供参考,为粮食副产物的综合利用提供了新思路。     

The effect of the type and the concentration of the lipophilic surfactant on the stability and release kinetics of the W/O/W multiple emulsions

Stable multiple emulsions that contain different lipophilic surfactants in the internal aqueous phase have been formulated. The multiple systems were assessed by evaluating several parameters such as macroscopic aspect, droplet size, percent release and accelerated stability under centrifugation or elevated temperature. The effect of polymeric and monomeric surfactants on the release mechanism and stability was examined. An excess of monomeric surfactant in the oil phase enhances the release rate and decreases stability. The release rate can be decreased by an increase of the lipophilic surfactant concentration. It appears that the more the oil globule swells, the less hydrosoluble drug is released. As a result a high swelling capacity is associated with better stability.     

Production of reduced-fat whipped toppings by solid fat-based W/O/W double emulsions: proof of concept

Water-in-oil-in-water (W/O/W) double emulsions present a reduced-fat alternative to conventional O/W food emulsions, as part of the dispersed oil phase is replaced with water. In this study, the concept of a reduced-fat whipped topping produced by W/O/W technology was proven. Whipping of a W/O/W emulsion, containing only 20% oil phase and a solid fat content of 78%, produced a superior whipped topping, in terms of firmness and overrun, compared to its whipped O/W emulsion counterparts. The presence of PGPR in the oil phase increased structure formation during whipping, while the additional dispersed-phase volume resulted in a better air inclusion. Two commercial monoacylglycerols (saturated and unsaturated) were investigated to improve the whipping properties of the produced W/O/W double emulsion. Both increased the susceptibility towards partial coalescence, thereby reducing whipping time and overrun, while increasing firmness of the produced whipped topping. Furthermore, the effect was stronger for the unsaturated than for the saturated monoacylglycerol.     

不同极性抗氧化剂对油包水乳液氧化稳定性的影响

以富含多不饱和脂肪酸(UPFA)的核桃油为油相,采用超高压微射流均质机制备油包水(W/O)乳液,分别添加非极性抗氧化剂α-生育酚及其极性对应物—6-羟基-2,5,7,8-四甲基色烷-2-羧酸(Trolox)于乳液中,45℃避光保存,检测乳液初级氧化产物—脂质氢过氧化物与次级氧化产物-顶空己醛含量,探究抗氧化剂极性对W/O乳液稳定性影响。结果表明,10~1000μM,α-生育酚与Trolox对W/O乳液脂质氢过氧化物和己醛的形成都具有抑制作用,其中Trolox抗氧化性随浓度的增大而提升,而较高浓度的α-生育酚(500~1000μM)反而降低其对脂质氢过氧化物的抑制作用;α-生育酚分布于乳液油水界面浓度小于极性抗氧化剂Trolox,导致非极性抗氧化剂α-生育酚活性低于极性抗氧化剂Trolox;乳液水相pH 3.0时,Trolox抗氧化性高于水相pH 7.0,水相pH通过影响Trolox在W/O乳液各相分布,从而影响其抗氧化性。     

Formulation and characterisation of O/W emulsions stabilised with modified seaweed polysaccharides

In this study, seaweed polysaccharides (alginate and carrageenan) were modified with dodecenylsuccinic anhydride (DSA), and their stabilising properties in oil-in-water (O/W) emulsion system were evaluated. The physicochemical characteristics were determined by droplet size, interfacial tension and ζ-potential and structurally verified by Fourier transform infrared spectroscopy (FTIR). Both CRG-DSA and ALG-DSA applied in O/W emulsion system exhibited smaller droplet sizes over the increasing concentration and were more stable during storage than native ones. The ζ-potential of DSA-modified seaweed polysaccharides has more negative charge compared with their native forms, owing to the additional carboxyl groups from modification reaction. In addition, DSA-modified seaweed polysaccharides decreased the interfacial tension at soybean oil–water interface from 23.1 and 23.9 mN m⁻¹ to 14.2 and 13.6 mN m⁻¹, respectively. The successful modification reaction was confirmed by FTIR analysis. This study demonstrated that DSA-modified seaweed polysaccharides may serve as prospective emulsifiers in food, pharmaceutical and other industrial fields.     

Double emulsions (W/O/W): physical characteristics and perceived intensity of salty taste

This study addressed the correlation between physical characteristics of double emulsions and sensory perception, as the microstructure of these systems may provide the mechanism to understanding the initial cause of the altered salty taste. Thus, double emulsions (W/O/W) were prepared using different volumes of the internal aqueous phase while maintaining the same fat and sodium contents in the evaluated systems. Polyglycerol polyricinoleate (PGPR) and tween 80 were used as hydrophobic and hydrophilic emulsifiers, respectively. After preparation, the samples were stored at 25 °C for 4 days and submitted to analysis of optical microscopy, distribution and polydispersity of the oil droplets size, electrical conductivity, rheological behaviour and sensorial analysis. It was found that the use of different emulsifier concentrations (PGPR) did not influence the physical characteristics of the emulsions with the same formulation, but emulsions with different internal aqueous phase concentrations presented different results. These distinct characteristics may have influenced sensorial perception, as the emulsion with higher internal phase concentration was considered saltier. Thus, it can be concluded that structural differences of the double emulsions can be used to decrease the sodium contents without perceivable changes in salty taste.     

酪蛋白酸钠-明胶制备S/O/W乳状液的稳定性

碳酸钙是一种常用的强化钙,然而,其悬浮稳定性差,易产生沉淀,严重限制了碳酸钙在食品加工中的应用.以固/油/水(S/O/W)乳状液形式负载碳酸钙,构建具有特定结构分布的钙-脂质微球,有望改善其溶解性和稳定性.本文以食品级碳酸钙为S相,大豆油为O相,酪蛋白酸钠-明胶为W相,构建S/O/W钙-脂质微球,研究不同质量分数明胶和...     

基于熊果酸的W/O/W型Pickering乳液制备方法

目的:提高熊果酸的应用范围和生物利用率。方法:以熊果酸为乳化剂,果胶为外水相,采用两步法制备W/O/W型Pickering乳液。通过单因素试验优化W/O乳液制备条件,研究果胶质量浓度对W/O/W型Pickering乳液理化性质、微观结构、流变学特性及长期稳定性的影响。结果:W/O乳液的最佳制备工艺为熊果酸质量浓度4 g/100 mL、水油质量比2∶3、均质转速9 000 r/min、均质时间5 min;以果胶为外水相制备的双层乳液粒径均在30～40μm,果胶质量浓度的增加使乳液的zeta电位绝对值、流变性能以及4℃贮藏稳定性有着显著性的提高。结论:果胶质量浓度为0.3,0.4,0.5 g/100 mL时能够制备稳定的Pickering双层乳液。     

O/W emulsion and W/O/W multiple emulsion: physical characterization and skin pharmacokinetic comparison in the delivery process of caffeine

The aim of this study was to compare the characteristics of an O/W emulsion and a W/O/W emulsion, formulated with similar ingredients. The physical properties of these two types of vehicles were characterized first. Using three types of in vitro models, human skin biopsies, nitrate acetate cellulose membranes and human reconstituted epidermis, the delivery potential of each vehicle for one hydrophilic drug, caffeine, was compared. The assessment of physical parameters, such as particle size, conductivity and rheological behavior enabled the nature of the test emulsions to be clearly identified. Clear differences were observed in the ability of each type of emulsion to deliver caffeine. Whatever the nature of the membrane used for the pharmacokinetic study, the absorption of caffeine was roughly two-fold lower (2.6 for human skin) when the W/O/W multiple emulsion was used as the vehicle. The concomitant determination of physical and kinetic properties of these two test emulsions allowed the W/O/W multiple emulsion and a simple O/W emulsion to be clearly differentiated.     

Enhancing anti-inflammation activity of curcumin through O/W nanoemulsions

High-speed and high-pressure homogenized O/W emulsions using medium chain triacylglycerols (MCT) as oil and Tween 20 as emulsifier, with mean droplet sizes ranging from 618.6 nm to 79.5 nm, have been successfully prepared. The enhanced anti-inflammation activity of curcumin encapsulated in O/W emulsions is evidenced by the mouse ear inflammation model. There is a 43% or 85% inhibition effect of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced edema of mouse ear for 618.6 nm and 79.5 nm 1% curcumin O/W emulsions, respectively, but a negligible effect is found for 1% curcumin in 10% Tween 20 water solution.