吐温/短链醇/丁酸乙酯/水微乳体系相行为及微观结构

通过绘制拟三元相图研究吐温/短链醇/丁酸乙酯/水微乳体系(MEs)的相行为,比较不同吐温表面活性剂、助表面活性剂短链醇及表面活性剂与短链醇的质量比(K_m)对单相微乳区面积及全稀释通道数的影响,并基于NMR方法对吐温80/乙醇/丁酸乙酯/水单相微乳区全稀释线上(混合表面活性剂和油相的质量比9∶1,逐渐增大水相分数)的微观结构变化、分子运动性及分子间相互作用进行表征。揭示单相微乳区稀释线上可能存在油包水→有序双连续结构→水包油→肿胀胶束的微观结构变化;根据NMR-1D NOESY选择性激发试验结果推测双连续结构中各组分间的相互作用为：丁酸乙酯分子包裹在双层结构内部,与水分子较少接触;乙醇分子同时存在于液滴界面及水相中,与水相有直接作用;吐温80的亲水基团在界面外层与水相接触,疏水基团在界面内层伸向油滴内部,与水相无相互作用。     

食品级肉豆蔻酸异丙酯微乳的制备研究

本文以肉豆蔻酸异丙酯为原料,筛选出肉豆蔻酸异丙酯空白微乳的最佳配方。首先采用伪三元相图法,以微乳区面积为指标,筛选出表面活性剂和助表面活性剂;探究表面活性剂与助表面活性剂质量之比Km值与亲水亲油平衡值(HLB值)对微乳形成的影响,然后以离心和染色实验来判断微乳的稳定性和构型。结果表明:当以肉豆蔻酸异丙酯作为油相,吐温80复配司盘80作为复合表面活性剂,无水乙醇为助表面活性剂(表面活性剂∶助表面活性剂∶IPM=4∶2∶4),且Km=2∶1,HLB=7.5时,形成的微乳液稳定性最好。此条件下,油包水型微乳的最大载水量为15.3%。因此可以说明伪三元相图法制备肉豆蔻酸异丙酯方法方便可行。      

全稀释食品级单辛酸甘油酯微乳体系的构建

以单辛酸甘油酯为油相,通过拟三元相图方法,研究了吐温20、60、80以及单硬脂酸甘油酯、尼泊金乙酯等表面活性剂,乙醇、丙二醇、正丁醇等助表面活性剂对于微乳体系增溶能力的影响。结果表明,添加醇有助于形成微乳体系,油相中醇的比例越高,微乳相越大,但表面活性剂相中醇的含量不易过多;微乳体系的水相全稀释性主要取决于油与表面活性剂的质量比Wo/Ws,在单辛酸甘油酯/吐温80/乙醇/水和单辛酸甘油酯/吐温80/丙二醇/水体系中,当Wo/Ws>1时,即使添加足量的醇也无法形成全稀释微乳。而且,表面活性剂的复配不一定具有增效作用。最后,确定微乳配方为油相∶单辛酸甘油酯与丙二醇质量比2∶1;表面活性剂相:吐温80与乙醇质量比为2∶1;水相∶双蒸水。该食品级单辛酸甘油酯微乳单相区面积为73.81%,具有3条可无限稀释通道。盐离子浓度和pH的稳定性研究表明,该微乳体系在NaCl浓度0.1～0.6mol/L范围内稳定性较好,且受pH影响较小。      

棕榈仁油/甘油/吐温/水体系中的微乳化作用研究

分别以吐温-20、吐温-40、吐温-60、吐温-80和吐温-85为表面活性剂,甘油为助表面活性剂,在相同的条件下,制作了棕榈仁油/甘油/吐温/水四组分体系的拟三元相图.讨论了助表面活性剂(醇)与表面活性剂的质量比(Km)及不同表面活性剂对混合体系微乳化作用的影响.结果表明,所研究的各体系中,以吐温-60所形成的微乳状液区最大.     

南极磷虾油W/O型微乳液制备及稳定性研究

目的:制备一种南极磷虾油微乳包埋方法并研究其稳定性。方法:以肉豆蔻酸异丙酯(IPM)为油相,Tween 80和Span 80复配表面活性剂相,乙醇为助表面活性剂,制备南极磷虾油油包水(W/O)型微乳液,并利用拟三元相图法考察各组分对微乳的影响。通过动态光散射法测定微乳液在离心试验、高温试验、盐度试验、贮藏试验中微乳液粒径大小变化,考察微乳液的稳定性。结果:在复配表面活性剂中,Tween 80和Span 80的质量比为6∶4,乙醇作为助表面活性剂且与表面活性剂质量比K_m=1.0时,得到稳定性良好的微乳液体系。结论 :该南极磷虾油微乳液制备简便,稳定性良好,是一种新型南极磷虾油的包埋方法。     

甘油解猪油微乳液的制备及其氧化稳定性研究

采用滴加水法制备甘油解猪油微乳液,考察不同表面活性剂、助表面活性剂、制备温度及制备方式等因素对微乳液形成过程中最大增容水量的影响,并鉴别该微乳液的类型及测定其氧化稳定性.结果表明,以吐温80为表面活性剂,无水乙醇为助表面活性剂,以甘油解猪油为油相,在60℃的条件下通过磁力搅拌的方式制得的微乳液增溶效果最好,该微乳液呈油...     

板栗花精油微乳的制备工艺

本文采用转相乳化法制备板栗花精油微乳,并通过伪三元相图考察表面活性剂、助表面活性剂、表面活性剂与助表面活性剂的比值(Km值)和油相对微乳形成的影响,以确定板栗花精油微乳的最优制备工艺参数。结果表明:板栗花精油微乳的最佳工艺为:聚乙二醇硬脂酸酯-15(HS-15)为表面活性剂,甘油为助表面活性剂,Km为2,油酸乙酯(EO)与精油等比例混合为油相,所制备的板栗花精油微乳为O/W型。以最佳微乳配方中混合表面活性剂与油相比例7∶3为试样,微乳的特性参数电导率、黏度和p H分别为180.2μs/cm,44.7 m Pa·s和6.66。此研究为板栗花精油微乳的制备及应用提供技术支持。     

橄榄油微乳体系的相行为及影响因素研究

本文以大豆卵磷脂和司盘80(Span80)复配为表面活性剂,乙醇为助表面活性剂,构建橄榄油微乳体系。采用拟三元相图法,考察亲水亲油平衡值(HLB值)、表面活性剂与助表面活性剂的比值(Km值)、盐浓度等因素对微乳体系相行为的影响,并通过电导率、负染透射电镜等方法研究微乳体系的结构,以优化体系配方、考察微乳液的形成规律。结果表明:大豆卵磷脂与Span80以质量比为3:1复配为混合表面活性剂,并与助表面活性剂无水乙醇按质量比(Km值)为2:1混合,所形成的大豆卵磷脂/Span80/乙醇/橄榄油/水微乳区域面积最大;甘油或少量盐离子的加入,可以在一定程度上增大微乳单相区的面积,但当盐浓度(C_NaCl)大于4 mol/L时,微乳区域面积明显减小;在大豆卵磷脂/Span80/橄榄油/乙醇/甘油/水微乳体系中,当水相(w_水/w_甘油=1:1)含量大于22 wt%时,体系逐渐由W/O型转变为双连续型结构。当水相含量超过30 wt%,体系则发生相分离。此研究为橄榄油微乳液的制备及应用提供理论和技术支持。     

全稀释食品级单辛酸甘油酯微乳的稳定性研究

以单辛酸甘油酯(GMC)为油相,吐温80为表面活性剂,丙二醇和乙醇为助剂,与水制备出具有高稀释性的食品级微乳.通过粒径分析,浑浊度对比,离心及贮藏试验,考察盐离子浓度、pH、温度、稀释对表面活性剂相与油相质量比分别为7∶3、8∶2的T73、T82稀释线上微乳贮藏稳定性的影响.结果表明,稀释会导致T73上微乳粒径增大,pH、盐离子、温度对水分含量高达99％的T73-100(用100倍表面活性剂相与油相质量比为7∶3的混合物质量的水相稀释)微乳稳定性影响较大;T82具有较好的稀释稳定性,且T82-100微乳分别在NaCl浓度0.1～0.6 mol/L,pH 3～8,温度0～40℃之间贮藏30 d后,平均粒径均小于35 nm.     

表没食子儿茶素没食子酸酯(EGCG)抗氧化微乳液的制备与表征

以肉豆蔻酸异丙酯为油相,吐温80-司盘80复配表面活性剂（HLB为6）为表面活性剂,乙醇为助表面活性剂（Km值为4∶1）制备了油包水型的表没食子儿茶素没食子酸酯（EGCG）抗氧化微乳液,并对其稳定性和抗氧化活性进行考察。通过测定电导率鉴别微乳液类型,纳米粒度仪测定微乳液的粒径,考察25℃条件下贮藏时间对微乳粒径的影响,评价微乳液的稳定性。同时,采用氧化稳定仪测定EGCG微乳液在花生油和亚麻籽油中的抗氧化活性。结果表明,微乳液外观澄清透明,在25℃贮藏条件下的稳定性好,放置50 d后微乳液的粒径变化小,放置期间未出现分层、破乳现象,并且在植物油中表现出较好的抗氧化活性。      

Incorporation of soybean oil improves the dilutability of essential oil microemulsions

Plant essential oils (EOs) have strong antimicrobial and antioxidant activities. However, their water insolubility and volatility limit their practical application. Microemulsions are thermodynamically stable delivery systems for hydrophobic bioactive compounds but can be destabilized after dilution by the polar phase. In the present study, soybean oil (SBO) was studied for the impacts on formation and dilutability of EO microemulsions comprised of polysorbate 80 (Tween™ 80) as a surfactant and equal mass of water and propylene glycol as the polar phase. The oil phase contained EO (cinnamon bark oil, eugenol, or thymol) and SBO at 1:0, 2:1 or 4:1 mass ratios. Pseudo-ternary phase diagrams were constructed after titrating the polar phase into Tween™ 80–oil mixture at 1:1 to 9:1 mass ratios. Blending SBO with EO expanded the regimes of microemulsions and reduced the droplet dimensions that were stable over 90 days. Viscosity and electrical conductivity data indicated the transition from W/O to O/W microemulsions as the content of polar phase increased from 10% to 90% w/w. The enhanced dilutability of microemulsions after blending with SBO can broaden the application of EOs.     

食品级水包油型月见草油微乳的稳定性研究

以月见草油为油相,吐温80、月桂酸为表面活性剂制备水包油型的食品级微乳并对其稳定性进行考察。通过透射电镜观察微乳形态,动态光散射仪测定微乳的粒径,紫外分光光度法测定苏丹Ⅱ含量,考察pH、贮藏温度、贮藏时间对稳定性的影响。结果表明,微乳液外观澄清透明,透射电镜观察为均匀球状液滴。微乳液在pH5~7时稳定性较好。在4℃和20℃贮藏条件下的稳定性较好,放置30d微乳液的粒径变化较小,微乳的包封率可达92.21%、91.89%,放置期间未出现分层、破乳现象。而在60℃下放置30d后微乳出现浑浊,包封率下降较大。      

丁香油的微乳液研究

研究了盐(NaCl)对于香油微乳液体系相态的影响,结果表明,随NaCl浓度的增加,体系由2相态(O/W型微乳液-丁香油)经3相态、4相态、3相态再转变成2相态(W/O型微乳液-水)。电导实验结果表明用正丁醇做助表面活性剂时,体系发生电导渗透(6.0ml水),在含水量为18.0ml时完全相反转(即由W/O型转变为O/W型),并可以获得较为稳定的O/W型丁香油微乳液。     

Solubilisation of soybean oil in microemulsions using various surfactants

Microemulsions are transparent, isotropic solutions of oil, water and surfactant (and possibly cosurfactant) which are thermodynamically stable, and have been much studied in terms of pharmaceutical and cosmetic applications. However, the application of microemulsions in foods has been limited both due to toxic or irritant nature of ionic surfactants and the difficulty of solubilising large triglycerides. Three surfactants, food-grade ethoxylated mono- and diglycerides (EMD) and phospholipids, and non-food-grade polyoxyethylene oleyl ether (POE) were examined for their ability to form microemulsions using soybean oil, and their areas of formation expressed on phase diagrams. Microemulsions prepared with EMD and phospholipids required the presence of a short-chain alcohol for formation. Both oil/water (o/w) and water/oil (w/o) microemulsions could be formed using EMD, and the microemulsion area of the phase diagram increased on addition of sucrose and increase in temperature. Depending on sucrose and ethanol concentrations, microemulsions formed with EMD were found to retain their integrity at temperatures below which they formed. Microemulsions could be formed using phospholipids, but only at high surfactant concentration and in the presence of a short-chain alcohol. O/w microemulsions containing 10% oil (w/w) were prepared with POE at surfactant concentrations of >20% (w/w). Dynamic light scattering of microemulsion samples diluted with water indicated particle radii of 6.5 nm. Freeze-fracture SEM showed the structures to be of a droplet type, however, this was more evident at higher surfactant/oil concentrations. The results indicated that it is possible to formulate microemulsions at low EMD and POE surfactant concentration. These microemulsions systems may potentially be used for encapsulation of oil-soluble bioactives, e.g. α-tocopherol, in food systems.     

Formulation of food-grade microemulsions with glycerol monolaurate: effects of short-chain alcohols,polyols, salts and nonionic surfactants

The formulation of food-grade microemulsions with glycerol monolaurate (GML) for antimicrobial applications has been studied. The compositions included water, GML, short-chain alcohols (such as ethanol), polyols (propylene glycol and glycerol), salts (organic, such as sodium benzoate, sodium lactate and sodium propionate, and inorganic, such as NaCl) and several nonionic surfactants [such as ethoxylated sorbitan esters, sucrose esters (SEs)]. The phase behavior of these systems is discussed with respect to the influence of composition on the degree of oil solubilization in the aqueous phase. The oil solubilization was dramatically improved in the presence of the short-chain alcohols and polyols, organic salts contributed to the improvement of oil solubilization as hydrotropes. Tween 20 being the most hydrophilic surfactant in Tweens solubilized the maximum oil, but in the presence of SEs it is hard to form oil-in-water microemulsions. Viscosity measurements along selected dilution lines indicate that at a certain composition the system inverts from a water-in-oil to an oil-in-water microemulsion.     

Formulation of a cosurfactant-free O/W microemulsion using nonionic surfactant mixtures

ABSTRACT:  A cosurfactant-free O/W microemulsion composed of oil, a mixture of hydrophilic and hydrophobic surfactants, and water has been developed using food-grade components as a nutrient delivery system. We started our investigation to monitor the phase behavior of this system based on a hydrophilic surfactant (Tween 80). From a phase diagram, the weight ratio of 5.4:33.8:60.8 = oil:surfactant:water was selected as a combination ratio for the O/W microemulsion system. We also investigated the combination effect of different hydrophobic surfactants to Tween 80 on microemulsion formation. Use of hydrophobic surfactants with Tween 80 produced smaller droplets than Tween 80 alone. Rheological studies showed that all microemulsions followed shear-thinning behavior. The turbidity of microemulsions did not change after accelerated stability tests, indicating that this microemulsion system was stable under the given harsh conditions. When docosahexaenoic acid (DHA) oil was applied to this microemulsion system, the particle size and the turbidity were not significantly changed. Dilution with a different aqueous medium, either water or acidic fluid, did not significantly change the microemulsion turbidity. DHA oil incorporated in microemulsion showed higher oxidation stability than free DHA oil.     

Microemulsions: a potential delivery system for bioactives in food

Microemulsions are thermodynamically stable, transparent, low viscosity, and isotropic dispersions consisting of oil and water stabilized by an interfacial film of surfactant molecules, typically in conjunction with a cosurfactant. Microemulsions (so-called due to their small particle size; 5-100 nm) have found application in a wide variety of systems, such as pharmaceutical and oil recovery, but their application in food systems has been hindered by the types of surfactant permissible for use in food. The objective of this review is to provide an overview of the structures and phase behavior of microemulsions, methods of microemulsion formation, and techniques which may be used for characterization. A comprehensive review of previous work on both food-grade microemulsion systems, and non-food-grade systems of specific food interest is included. The application of microemulsions as reaction media, their ability to solubilize proteins and hence their use as a separation technique is also documented. In addition, attention is focused on the application of microemulsions as delivery systems for delivery of bioactive compounds, and the links between microemulsions and increased bioavailability. Future research, both applied and fundamental, should focus on surfactants which are not restricted for use in foods.     

In vitro release of propranolol from oil/water microemuisions

Oil/water (o/w) microemulsions containing propranolol were studied. Isopropylmyristate was used as the oil, Tween 60 as a surfactant, butanol as a co-surfactant and a buffer of pH 6.5 for the continuous phase. The lipophilicity of propranolol was enhanced by formation of lipophilic ion-pairs to obtain a disperse phase that could act as a reservoir; octanoic acid was used as counter-ion. The diffusion rates of propranolol from microemulsions through a hydrophilic membrane decreased as the concentration of octanoic acid increased. The apparent permeability constant, determined at the beginning of the experiment, was 2.9 × 10⁻⁹ cm s⁻¹ for propranolol alone and diminished until 3.5 × 10⁻¹⁰ cm s⁻¹ in the presence of octanoic acid, at a concentration of 16.4 times that of propranolol.     

Lemon oil solubilization in mixed surfactant solutions: Rationalizing microemulsion & nanoemulsion formation

Lipophilic functional ingredients are usually incorporated into aqueous-based foods and beverages in the form of colloidal dispersions. In this study, we investigated the rate and extent of solubilization of emulsified lemon oil in mixed non-ionic surfactant solutions (buffer: propylene glycol = 2:1): sucrose monopalmitate (SMP) and/or Tween 80 (T80). The influence of surfactant concentration, type, and mixing ratio on lemon oil solubilization was investigated, with the aim of identifying suitable conditions for preparing stable microemulsions and nanoemulsions. Solubilization was monitored by measuring changes in light scattering by lemon oil droplets after they were dispersed in surfactant solutions (pH 7). The solubilization process was rapid (<few minutes), with the rate increasing with increasing surfactant concentration. For a particular surfactant type and concentration, lemon oil was transferred from nanoemulsion droplets into microemulsion droplets until a critical lemon oil concentration (C_sat) was reached, after which it remained as nanoemulsion droplets. The value of C_sat increased with increasing surfactant concentration and was higher for SMP than Tween 80. The impact of storage at pH 3.5 on the physical stability of microemulsions and nanoemulsions was examined. Acid stable colloidal dispersions could not be formed using SMP alone. However, relatively stable nanoemulsions and microemulsions could be formed when ≥75 or 50 wt% Tween 80 was incorporated into the surfactant phase, respectively. This study provides important information for the rational design of food-grade colloidal delivery systems for encapsulating and delivering functional lipids for food and beverage applications.     

Linker-based bio-compatible microemulsions

In this work we have studied the formulation of biocompatible microemulsions using lecithin as the main surfactant and bio-compatible linker molecules (hexyl polyglucoside asthe hydrophilic linker and sorbitan monoleate as the lipophilic linker). These bio-compatible systems are discussed as potential substitutes for chlorinated solvents in dry-cleaning applications and as solvent delivery systems for pharmaceutical applications. Formulation parameters and conditions were evaluated using isopropyl myristate (IPM) as the model oil. It was found that the proposed linker-based formulations were able to form alcohol-free microemulsions while achieving higher solubilization capacity than similar systems reported in the literature. In addition, these lecithin/linker formulations were able to form microemulsions with a wide range of oils, from polar chlorinated hydrocarbons to hydrophobic oils such as squalene. These microemulsions were achieved under isotonic conditions (0.9% NaCl) by only varying the relative proportions of the linkers. The "solvency" power of these bio-compatible formulations was tested for the removal of hexadecane (used as model oil) from cotton fabrics and compared to the solvency power of a typical dry cleaning solvent tetrachloroethylene (PCE). While PCE and the linker-based lecithin formulation removed the same amount of hexadecane at low loading ratios (less than 1% oil volume fraction), at higher loading ratios the linker-based lecithin formulation retained its oil removal capacity while the efficiency of the PCE system declined rapidly. These initial results thus demonstrate the remarkable oil solubilization capacity of these bio-compatible linker-based lecithin formulations and illustrate their potential as environmentally friendly replacements for organic solvents.