基于OSA变性淀粉为乳化剂的番茄红素纳米乳的体外消化特性研究

以2种不同的辛烯基琥珀酸酯变性淀粉(OSA1、OSA2变性淀粉)作为乳化剂,构建番茄红素稳定的纳米乳液体系,通过体外模拟消化,研究其消化特性。结果表明:2种纳米乳液的粒径在口腔、胃消化阶段并无明显变化,在肠消化阶段明显增加;结合激光共聚焦显微镜观察可知,2种OSA变性淀粉为乳化剂的纳米乳都在模拟口腔和胃阶段变化较小,在模拟肠消化阶段中会发生大量水解。2种纳米乳液中游离脂肪酸释放总量OSA2 OSA1,且2种纳米乳液的番茄红素生物可给率也均远高于对照组,番茄红素纳米乳液的生物可给率OSA2 OSA1。     

OSA变性淀粉的乳化特性及其对纳米乳液构建影响的研究

研究生物大分子辛烯基琥珀酸淀粉(OSA)的乳化特性,并以其为乳化剂构建负载番茄红素的稳定纳米乳液体系。研究结果表明:溶解温度70℃,淀粉浓度为30%(w/w)时,OSA变性淀粉的乳化性能最佳。以其为乳化剂,当油相(中链甘油三酯,MCT)中番茄红素的质量浓度为0.1%(w/w),油水比1∶9时,通过高压均质得到的纳米乳液粒径120 nm,番茄红素负载率63%,经过一个月的储藏后,乳液粒径增加到160 nm,增长幅度小于34%,性状稳定,没有油相析出,表明OSA变性淀粉适合作为构建安全稳定纳米乳液的乳化剂。     

基于OSA变性淀粉为乳化剂对番茄红素纳米运输体系构建影响研究

尝试以2种不同的辛烯基琥珀酸酯化淀粉(OSA1、OSA2)作为乳化剂,研究其乳化特性,在不同条件下构建番茄红素稳定的纳米乳液体系。结果表明最佳的制备条件:乳化剂浓度30%,采用高压微射流均质机,均质压力为100 MPa,循环5次,2种乳液粒径分别为(107±1.32) nm、(101±0.81) nm,保留率分别为85.67%±0.63%和86.78%±0.36%。在常温下储藏4周,乳液粒径分别增至(158.84±3.51)nm和(129.18±4.22)nm。与未被包埋的番茄红素相比,2种纳米乳液包埋的番茄红素的降解速度明显降低,说明基于OSA变性淀粉为乳化剂构建纳米乳液能有效抑制番茄红素的降解。综合2种纳米乳液在储藏过程中粒径的变化与番茄红素保留率,其稳定性表现为OSA2 OSA1,此结果与2种淀粉的乳化活性和乳化稳定性呈正相关性。     

番茄红素纳米乳液体系的稳定性能研究

针对以食品级生物大分子辛烯基琥珀酸酯化淀粉（OSA变性淀粉）为乳化剂构建的负载番茄红素纳米乳液体系,采用Turbiscan AGS稳定性分析仪监测24 h内纳米乳液的稳定性变化趋势,探索体系失稳的主要原因;对负载番茄红素纳米乳液在不同储存和应用条件下的稳定性能进行系统研究。研究结果表明：奥氏熟化可能是导致番茄红素纳米乳液失稳的主要原因。不同储存条件对体系粒径和番茄红素保留率的研究结果表明：储存条件对体系稳定性影响显著,其中对乳液粒径增长的影响程度依次为温度＞光照＞氧气,对番茄红素保留率的影响依次为氧气＞温度＞光照。纳米乳液在4 ℃避光充氮气条件下储存28 d,乳液粒径仅从138 nm增到157 nm,番茄红素的保留率为41%,体现了良好的稳定性。对番茄红素纳米乳液在不同pH、离子浓度和蔗糖浓度的模拟食品体系中的稳定性研究表明,乳液的耐酸性较强,盐离子和蔗糖分子不会对纳米乳液的稳定性造成太大的影响。     

柚皮苷纳米乳液递送体系的消化特性

通过体外模拟消化研究以乳清分离蛋白(whey protein isolate,WPI)、ι-卡拉胶(ι-carrageenan,ι-Car)和阿拉伯胶(gum arabic,GA)作为乳化剂稳定的单层以及双层柚皮苷(naringin,NA)纳米乳液的消化规律。对NA单层纳米乳液(NA/WPI-e)和NA双层纳米乳液(NA/WPI/ι-Car-e和NA/WPI/GA-e)进行液滴粒径、Zeta电位和微观结构检测,考察其在胃肠消化阶段的水解程度。结果表明:在胃模拟消化中,单层及双层纳米乳液的液滴聚集,乳液平均粒径显著增大(P0.05),Zeta电位绝对值基本上高于原始乳液;在小肠模拟消化过程中,NA纳米乳液均发生解絮凝现象。经胃肠消化后NA/WPI-e的游离脂肪酸(free fatty acids,FFAs)释放率最高为97.3%,NA生物利用率为10.06%。NA/WPI/ι-Car-e的FFAs释放率和NA生物利用率均低于NA/WPI-e,而GA质量浓度为1 mg/mL的NA/WPI/GA-e则表现出比NA/WPI-e更高的生物利用率,达到12.13%。NA/WPI-e、NA/WPI/ι-Car-e、NA/WPI/GA-e的FFAs释放率均显著高于对照组(34%),表明纳米乳液递送体系能有效提高NA的生物利用率。     

pH驱动法制备姜黄素乳液

目的：采用pH驱动法将姜黄素包埋在O/W乳液中,分别探究3种乳化剂：乳清分离蛋白（WPI）、酪蛋白酸钠和辛烯基琥珀酸酐（OSA）变性淀粉对姜黄素乳液的影响。方法：以山茶油为油相,采用动态高压微射流制备空白乳液,利用pH驱动法制得姜黄素乳液。考察3种姜黄素乳液的粒子特性和包封率;测定不同pH值条件下姜黄素乳液粒子特性和外观变化,并通过体外消化试验考察姜黄素的生物可接受率及胃、肠道稳定性。结果：OSA变性淀粉稳定乳液具有较大的平均粒径[（327.8 ± 9.2） nm]和包封率[（81.7 ± 1.5）%],在pH 4~7范围具有良好的pH值稳定性。3种姜黄素乳液的胃、肠道稳定性无显著差异,其中OSA变性淀粉和WPI稳定乳液生物可接受率较高,分别为（43.4 ± 1.4）%,（47.1 ± 4.7）%。结论：3种乳化剂均能达到稳定乳液的效果,采用pH驱动法可将姜黄素包埋在乳液中,为设计生物活性物质载体提供新思路。     

自由基接枝改性对乳清分离蛋白乳化稳定性的影响

为研究蛋白的共价接枝改性对其乳化稳定性的影响,本文以乳清分离蛋白（whey protein isolate,WPI）和表没食子儿茶素没食子酸酯（epigallocatechingallate,EGCG）为原料,通过自由基接枝法制备WPI-EGCG复合物。利用扫描电镜（SEM）对其微观结构进行观测,通过测定界面蛋白吸附量、界面流变学特性来探究共价接枝对界面特性的影响;进而以WPI-EGCG接枝物为乳化剂构建番茄红素纳米乳液,并对其物理化学稳定性及储藏稳定性进行研究。结果表明,EGCG的自由基接枝改变了WPI的结构,使之具有更高的黏度和界面稳定性,使以接枝物为乳化剂的番茄红素纳米乳液体系具有更高的物化稳定性。WPI-EGCGE接枝物稳定的番茄红素纳米乳液在37 ℃下储藏30 d后粒径和ζ-电位绝对值分别增加了268.3 nm和17.6 mV,乳液中番茄红素的保留率仍有66.23%,呈现出更佳的番茄红素保护效果。本研究为功能活性物质纳米乳液载运体系的构建提供了参考。     

超声均质法制备以乳清蛋白-OSA变性淀粉为乳化剂的纳米乳液

乳清蛋白乳液易在乳清蛋白等电点(pI≈4. 5)发生液滴聚集,限制了其在食品工业中的广泛使用。为探索乳清蛋白和辛烯基琥珀酸酯变性淀粉(octenyl succinic anhydride modified starch,OSA变性淀粉)组合改善纳米乳液物理稳定性的可行性,以超声波均质法分别制备乳清蛋白和乳清蛋白-OSA变性淀粉(质量比为7∶3)稳定的纳米乳液,研究pH、离子强度和热处理对纳米乳液稳定性的影响。当pH=4时,乳清蛋白纳米乳液的粒径显著增大至2 100 nm,而乳清蛋白-OSA变性淀粉纳米乳液粒径仅为280 nm,说明添加OSA变性淀粉能有效减弱乳清蛋白纳米乳液的液滴聚集。乳清蛋白-OSA变性淀粉纳米乳液的粒径在Na~+浓度0. 6 mol/L和40～80℃下无显著变化。研究表明添加OSA变性淀粉有望扩大乳清蛋白纳米乳液在酸性食品中的应用。     

负载姜黄素/花色苷的木薯淀粉基W1/O/W2型Pickering双重乳液的制备及性质

以木薯纳米淀粉、木薯醋酸酯变性淀粉为颗粒乳化剂制备食品级W₁/O/W₂型Pickering双重乳液,分别于内层水相、油相对姜黄素与花色苷进行负载。考察不同木薯醋酸酯变性淀粉质量分数对双重乳液显微形态、粒径、Zeta电位、负载率及贮藏稳定性的影响,并分析其在体外消化过程的控释性能。结果表明,木薯醋酸酯变性淀粉质量分数为6%时,乳液综合性能最好。此时,乳滴分布均匀,呈“三相两膜”结构,粒径为3.65μm,Zeta电位为-14.50mV,姜黄素、花色苷的负载率达到95.23%、93.00%,4、25、40℃时贮藏20d均未出现明显分层;经模拟消化后乳液中姜黄素、花色苷保留率为41.59%、76.29%,与游离姜黄素、花色苷相比,二者生物利用率分别提高了约4倍、3倍。证实了木薯淀粉基双重乳液能实现在模拟消化系统中对活性物质的保护,并能有效提升其生物利用率。研究结果旨在为食品工业中淀粉基功能性乳液运载体系的构建及新型食品级Pickering双重乳液的开发提供理论参考。     

番茄红素微乳液的制备及表征

为提高番茄红素的稳定性和水溶性,采用低能乳化法制备番茄红素微乳液,利用伪三元相图优化番茄红素微乳液配方。探讨油相、乳化剂、助乳化剂、乳化剂与助乳化剂质量比(Km值)对微乳液形成的影响,通过计算并比较伪三元相图微乳液区域面积确定各因素的最佳值,并对微乳液的类型、形态、粒径、多分散指数(PDI)和Zeta电位进行测定。结果表明,番茄红素微乳液最佳配方为油相为亚麻籽油、乳化剂为吐温80、助乳化剂为无水乙醇、Km值为2∶1,采用最佳配方得到的番茄红素微乳液为O/W型,微乳液液滴呈规则球形,粒径为(167.70±0.45)nm, PDI为0.179±0.006,Zeta电位为(-7.71±0.53) mV。采用该方法制备的番茄红素微乳液均一稳定。     

In vitro bioaccessibility of ergocalciferol in nanoemulsion‐based delivery system: the influence of food‐grade emulsifiers with different stabilising mechanisms

The effect of emulsifier type on the in vitro bioaccessibility of ergocalciferol‐loaded nanoemulsions was examined (mouth, stomach and small intestinal phases). Oil‐in‐water nanoemulsions were prepared using emulsifiers with different stabilising mechanisms: decaglycerol monooleate (MO7S; steric), modified lecithin (ML; electrostatic), sodium caseinate (SC; electrosteric) and ML‐MO7S (combined electrostatic and steric). The droplet size, size distribution, ζ‐potential and microstructure of nanoemulsions during digestion depended on the emulsifier type. The fate of lipid in the small intestinal phase also relied on the emulsifier type, with the free fatty acids release rate decreasing in the following order: MO7S > ML‐MO7S > ML > SC. The ergocalciferol bioaccessibilities in nanoemulsions prepared using MO7S (62%), ML (64%) and ML‐MO7S (65%) were similar and significantly higher than that stabilised by SC (12%). No significant loss of ergocalciferol was observed in all nanoemulsions after full digestion; they were chemically stable against digestion conditions, regardless of the emulsifier type.     

EFFECT OF EMULSION DROPLETS ON THE RHEOLOGY OF WHEY PROTEIN ISOLATE GELS

The effects of droplet size and emulsifier type on the rheology of whey protein isolate (WPI) gels containing emulsion droplets was studied. Gels were prepared by dispersing droplets of corn oil (20 wt%, d₃₂= 0.7 – 4 μm) in a 10 wt% WPI solution (pH 7.0, 50 mM NaCl), and heating at 90C for 15 min. Gel strength was determined by measuring the stress of gels at 20% compression using an Instron Universal Testing Machine. Droplets stabilized by WPI increased the gel strength, those stabilized by non-ionic surfactants (Tween 20 and Triton X-100) decreased it slightly, and those stabilized by SDS decreased it drastically. Gel strength increased as the droplet size decreased for droplets stabilized by WPI, but was relatively insensitive to the size of droplets stabilized by the small molecule surfactants. These observations may be explained in terms of the interactions between the emulsifiers and the protein network. Droplets coated with emulsifiers which can be incorporated into the protein network reinforce the structure and so increase gel strength, whereas droplets coated with emulsifiers which cannot be incorporated into the protein network disrupt the three dimensional structure of the gel and decrease its strength.     

In vitro study of intestinal lipolysis using pH-stat and gas chromatography

Developing healthy products requires in-depth knowledge of digestion. This study focuses on lipid digestion in relation to emulsion properties typically followed by pH-stat. Although this is a fast and easy method to follow the overall digestion, it provides no details on lipid digestion products. Thus, the aims of the present study were to use gas chromatography (GC) to determine all products present during lipolysis, i.e. monoglycerides (MG), diglycerides (DG) and triglycerides (TG), and to compare this method with the pH-stat method for free fatty acids (FFA). Fine, medium and coarse emulsions stabilized with two different emulsifiers (whey protein isolate (WPI) or gum arabic) were digested under in vitro intestinal conditions. Although the amount of FFA increased for both methods for WPI stabilized emulsions, the amount of FFA was 2-3 times higher when determined by GC compared with pH-stat. GC analysis showed decreasing amounts of MG and DG with increasing droplet size for both emulsions. Molar ratios of FFA/DG and MG/DG were twofold higher for WPI than for gum arabic stabilized emulsions. This indicates that the total production of lipolytic products (i.e. FFA + MG + DG) depends on the droplet size and the emulsifier but their proportions only depend on the emulsifier. Although pH-stat provides a fast measure of FFA release, it is influenced by the emulsifier type at the oil-water interface and therefore care should be taken when interpreting pH-stat results. We suggest combining this method with GC for accurate FFA determination and further evaluation of all lipolytic products.     

Influence of biopolymer emulsifier type on formation and stability of rice bran oil-in-water emulsions: whey protein, gum arabic, and modified starch

Rice bran oil (RBO) is used in foods, cosmetics, and pharmaceuticals due to its desirable health, flavor, and functional attributes. We investigated the effects of biopolymer emulsifier type and environmental stresses on the stability of RBO emulsions. Oil-in-water emulsions (5% RBO, 10 mM citrate buffer) stabilized by whey protein isolate (WPI), gum arabic (GA), or modified starch (MS) were prepared using high-pressure homogenization. The new MS used had a higher number of octenyl succinic anhydride (OSA) groups per starch molecule than conventional MS. The droplet diameters produced by WPI and MS were considerably smaller (d < 300 nm) than those produced by GA (d > 1000 nm). The influence of pH (3 to 8), ionic strength (0 to 500 mM NaCl), and thermal treatment (30 to 90 °C) on the physical stability of the emulsions was examined. Extensive droplet aggregation occurred in WPI-stabilized emulsions around their isoelectric point (4 < pH < 6), at high salt (> 200 mM, pH 7), and at high temperatures (>70 °C, pH 7, 150 mM NaCl), which was attributed to changes in electrostatic and hydrophobic interactions between droplets. There was little effect of pH, ionic strength, and temperature on emulsions stabilized by GA or MS, which was attributed to strong steric stabilization. In summary: WPI produced small droplets at low concentrations, but they had poor stability to environmental stress; GA produced large droplets and needed high concentrations, but they had good stability to stress; new MS produced small droplets at low concentrations, with good stability to stress. Practical Application: This study showed that stable rice bran oil-in-water emulsions can be formed using biopolymer emulsifiers. These emulsions could be used to incorporate RBO into a wide range of food products. We compared the relative performance of whey protein, GA, and a new MS at forming and stabilizing the emulsions. The new OSA MS was capable of forming small stable droplets at relatively low concentrations.     

聚甘油脂肪酸酯结构对姜黄素纳米乳液稳定性及其功能特性的影响

使用聚甘油脂肪酸酯(polyglycerol fatty acid esters,PGFEs)制备姜黄素纳米乳液,并探究PGFEs的脂肪链长(C10～C18)对姜黄素纳米乳液的乳液特性、贮存稳定性、抗氧化活性及抗菌活性的影响.结果表明:PGFEs脂肪链长的增加会使乳液粒径增大、Zeta电位变低,但不影响姜黄素的包封效率...     

Comparison of Gum Arabic, Modified Starch, and Whey Protein Isolate as Emulsifiers: Influence of pH, CaCl2 and Temperature

ABSTRACT: The particle size and zeta potential of model beverage emulsions (0.01 wt% soybean oil-in-water emulsions, d ≅ 1 mm) stabilized by gum arabic, modified starch, or whey protein isolate (WPI) were studied with varying pH (3 to 9), CaCl₂ concentration (0 to 25 mM), and temperature (30 °C to 90 °C). Temperature, pH, CaCl₂ strongly influenced emulsions stabilized by WPI because its stabilizing mechanism was mainly electrostatic repulsion, but not those stabilized by gum arabic or modified starch because their stabilizing modes of action were mainly steric repulsion. This study may have important implications for the application of WPI as an emulsifier in beverage emulsions.     

Beverage emulsions: Comparison among nanoparticle stabilized emulsion with starch and surfactant stabilized emulsions

Emulsions are widely used in beverages to impart desired appearance and flavor to the products. Ring formation in beverages with emulsions during thermal processing and storage is one of the key challenges. This study was aimed at comparing the relative effectiveness of silica nanoparticle based emulsifiers with surfactant and biopolymer based emulsifier (modified starch) in influencing physical stability of emulsions in a model juice. The stability of emulsions was measured by characterizing changes in emulsion droplet size, zeta potential, UV–vis absorbance and visual evaluation of phase separation or ring formation in both primary emulsions and beverage emulsions as a function of storage time. The influence of thermal processing on stability of emulsions both immediately after processing and upon storage was evaluated. The thermal processing conditions simulated both high temperature short time and low temperature long time pasteurization conditions. The results demonstrate that the mean droplet diameter of primary emulsions stabilized by selected emulsifiers was stable during storage for 21 days with and without pasteurization. Based on measurements of mean droplet diameter and visible ring formation, polyoxyethylene sorbitan monolaurate (tween-20) stabilized emulsion was not stable in a model juice and the stability of this emulsion was further reduced with thermal processing. In contrast, starch and silica stabilized emulsions in a model juice did not show significant changes in particle diameter or visible ring formation during storage with and without prior thermal processing, although starch stabilized emulsion did show a decrease in absorbance during storage. Zeta potential measurements in a model juice indicate that the surface properties of emulsions were significantly distinct from those of primary emulsion, indicating interaction of juice components with the emulsion interface influencing the surface charge at the interface. These changes in zeta potential of emulsion droplets did not correlate with reduced stability of the emulsions. Overall, the results demonstrate that nanoparticle stabilized emulsions can improve stability of emulsion in beverages as compared to surfactant and biopolymer stabilized emulsions and provides a comprehensive matrix to evaluate stability of emulsions in beverages.     

高压微射流制备橙皮精油纳米乳液影响因素研究

本文探讨了乳化剂类型、浓度和均质条件(压力和均质次数)对橙皮精油纳米乳液平均粒径(mean droplet diameter,MDD)、浊度以及贮藏稳定性的影响。采用四种乳化剂(皂树苷,QS;变性淀粉,MS;乳清分离蛋白,WPI;十二烷基硫酸钠,SDS),经高压微射流经不同均质压力和均质次数制备橙皮精油纳米乳液。结果表明,在一定范围,随着乳化剂浓度增加,MDD会逐渐减小,而SDS、QS、WPI和MS合适的浓度分别为2%、4%、4%和8%(w/w)。随着均质压力和均质次数增加,纳米乳液MDD和浊度都呈现较相似的减小趋势,在压力和次数分别增加到22000 psi和4次时,四种纳米乳液粒径可小于150 nm。研究发现,均质压力与MDD近似指数关系,乳液的相黏度比也会影响其MDD。贮藏实验表明,经25 ℃贮藏21 d,四种纳米乳液MDD基本稳定。     

Effect of salt ions on an ultrasonically modified soybean lipophilic protein nanoemulsion

Soybean lipophilic proteins (LP) are promising emulsifiers for nanoemulsion delivery systems. We analysed the effect of common salt ions on the stability of nanoemulsion delivery systems that contained ultrasonically modified soybean LP. Moreover, explored the mechanism of influence. The LP nanoemulsions presented large absolute zeta (ζ) potentials at low salt ion concentrations, and their particle size distribution was relatively uniform. The emulsification, encapsulation efficiency and oxidation stability were superior to those of other nanoemulsions. The ultrasonically modified samples presented higher absolute ζ potentials and smaller droplet sizes than the pristine ones and formed uniform protein films at different salt ion concentrations. Therefore, ultrasonication improved the emulsification, encapsulation efficiency and oxidation stability of the emulsions, effectively improve the stability of nano-delivery systems in different salt ion environments and maximise delivery efficiency at low salt ion concentrations. These results are helpful for the development of LP nanoemulsion systems that are stable at different salt ion concentrations.     

Physical Stability of Octenyl Succinate–Modified Polysaccharides and Whey Proteins for Potential Use as Bioactive Carriers in Food Systems

The high cost and potential toxicity of biodegradable polymers like poly(lactic‐co‐glycolic)acid (PLGA) has increased the interest in natural and modified biopolymers as bioactive carriers. This study characterized the physical stability (water sorption and state transition behavior) of selected starch and proteins: octenyl succinate–modified depolymerized waxy corn starch (DWxCn), waxy rice starch (DWxRc), phytoglycogen, whey protein concentrate (80%, WPC), whey protein isolate (WPI), and α‐lactalbumin (α‐L) to determine their potential as carriers of bioactive compounds under different environmental conditions. After enzyme modification and particle size characterization, glass transition temperature and moisture isotherms were used to characterize the systems. DWxCn and DWxRc had increased water sorption compared to native starch. The level of octenyl succinate anhydrate (OSA) modification (3% and 7%) did not reduce the water sorption of the DWxCn and phytoglycogen samples. The Guggenheim–Andersen–de Boer model indicated that native waxy corn had significantly (P < 0.05) higher water monolayer capacity followed by 3%‐OSA‐modified DWxCn, WPI, 3%‐OSA‐modified DWxRc, α‐L, and native phytoglycogen. WPC had significantly lower water monolayer capacity. All Tg values matched with the solid‐like appearance of the biopolymers. Native polysaccharides and whey proteins had higher glass transition temperature (Tg) values. On the other hand, depolymerized waxy starches at 7%‐OSA modification had a “melted” appearance when exposed to environments with high relative humidity (above 70%) after 10 days at 23 °C. The use of depolymerized and OSA‐modified polysaccharides blended with proteins created more stable blends of biopolymers. Hence, this biopolymer would be suitable for materials exposed to high humidity environments in food applications.