阿拉伯树胶-肌原纤维蛋白共建乳状液体系的物理稳定性

研究不同质量分数阿拉伯树胶(arabic gum,AG)对肌原纤维蛋白(myofibrillar protein,MP)为乳化剂的乳化体系稳定性的影响。结果显示,乳化活性和乳化稳定性随着AG质量分数的增加呈先增加后降低的变化趋势。AG质量分数为0.3%时,MP-AG共建乳状液体系表现出最高的物理稳定性,显著地增加了ζ-电势,降低了粒径大小,表现出最低的乳析指数(P0.05)。激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)观察结果表明,与单独以MP为乳化剂的样品相比,添加0.3%AG的乳状液样品液滴颗粒最小,这与粒径大小和分布的结果相一致。通过CLSM进一步观察MP在界面上的吸附行为,结果表明,与未添加AG的乳状液样品相比,添加0.3%AG的MP-AG共建乳状液体系所形成的界面膜更加坚固和致密。总之,AG可以促进蛋白质在油水界面上的吸附作用,提高MP乳化的水包油型乳状液的物理稳定性。     

低钠条件下超声处理对鸡肉肌原纤维蛋白乳液稳定性的影响

低钠条件下肌原纤维蛋白（myofibrillar protein,MP）作为乳化剂制备的乳液稳定性差,本实验采用高强度超声波（high intensity ultrasound,HIU）（频率20 kHz、功率450 W）对低钠条件下（0.15 mol/L NaCl）MP进行不同时间（0、3、6、9、12 min）处理,测定处理后MP乳液乳化活性指数（emulsifying activity index,EAI）、乳液稳定性指数（emulsion stability index,ESI）、Turbiscan稳定性指数（turbiscan stability index,TSI）和平均粒径等,并进行微观结构观察和流变性分析等,研究低钠条件下超声处理对鸡肉MP乳化特性及其乳液稳定性和流变性能的影响。结果表明：与对照组相比,随着超声处理时间延长,MP的EAI和ESI显著增加（P＜0.05）,MP制备乳液的TSI和粒径随着超声处理时间的延长明显减小,且乳液液滴分布均匀,乳液Zeta-电位的绝对值显著增加（P＜0.05）。乳液的流变学特性分析结果表明超声波明显提高了MP乳液的黏弹性。MP乳液的油-水界面张力分析结果显示超声处理有效增强了MP的移动性,使界面张力迅速降低,同时超声处理显著增加了MP乳液吸附蛋白相对含量（P＜0.05）,这表明超声处理MP有助于稳定乳液。通过冷场扫描电子显微镜观察进一步证实了超声处理12 min MP制备的乳液液滴体积最小。综上,超声波能够有效提高低钠条件下MP的乳液稳定性,本实验可为超声处理在减盐乳化型肉制品中的应用提供理论参考。     

豌豆分离蛋白-羧甲基纤维素纳静电复合物在乳液中的应用研究

为改善豌豆分离蛋白(PPI)在酸性乳液体系中的应用特性,采用阴离子多糖-羧甲基纤维素钠(CMC)与PPI在酸性条件下形成的静电复合物稳定O/W型乳液。首先研究了3% PPI溶液的溶解度、表面疏水性随CMC浓度(0~0.5%)的变化,在此基础上,分析了PPI-CMC静电复合物对乳液ζ-电位、粒径、粘度、乳析稳定性指数及微观结构的影响。结果表明:在pH4.5条件下,随着CMC浓度由0增加至0.5%,乳状液滴表面负电性不断增强,当CMC浓度≥0.4%时,PPI乳液稳定性明显提高,液滴分散均匀,絮凝程度明显降低,在4 ℃下存放一周,未发现明显分层。因此,通过调控PPI-CMC相互作用可有效改善PPI在酸性乳液体系中的应用特性,研究成果有望为高豌豆蛋白酸性乳品和饮料的开发提供参考。     

高压均质对大豆蛋白乳液性质影响的研究进展

大豆蛋白作为一种高分子蛋白质,具有良好双亲性和表面活性,可通过在油水界面形成粘弹性蛋白层的方式在乳液中起到乳化作用,从而提高乳液体系的稳定性。高压均质技术是一种通过静高压和均质阀产生的综合效应从而改变蛋白质的结构和加工特性的新型非热加工技术,可以制备纳米级的大豆蛋白乳液。本文聚焦大豆蛋白乳液,阐述了高压均质制备大豆蛋白乳液的过程以及均质条件的影响,分析总结了高压均质处理对大豆蛋白乳液结构（粒径、ζ-电位、空间结构）和功能特性（流变特性、乳化性能和凝胶性能）影响的国内外研究进展及作用机理。最后,针对目前研究进展对高压均质在大豆蛋白乳液的加工应用做出展望,以期为大豆蛋白乳液的研究提供一定的帮助。     

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.     

超声处理大豆分离蛋白与壳聚糖复合物对O/W型乳液稳定性的影响

为探究超声处理大豆分离蛋白-壳聚糖（soybean protein isolate-chitosan,SPI-CS）复合物对形成O/W型乳 液性质的影响,主要研究了复合物表面疏水性、乳化活性、乳化稳定性与油-水界面张力、乳液粒径、乳液稳定性 之间的关系。结果表明：未经超声处理的SPI-CS复合物表面疏水性、乳化活性、乳化稳定性和界面吸附性较低,形 成的O/W型乳液粒径相对较大,约100 μm,乳液Zeta电位较低,乳滴有发生聚集的倾向。乳液贮存7 d后乳层析指数 最高。经超声处理后SPI-CS复合物形成的乳状液性质发生明显变化,随着超声功率的增加,形成的O/W型乳液的稳 定性有所增加：超声功率为400 W时SPI-CS复合物形成的乳液最为稳定,乳层析指数最低;当超声功率超过400 W 时,乳液的光学显微镜观察显示其粒径有所增大,同时乳液的Zeta电位、乳化活性和乳化稳定性明显下降,界面张 力降低缓慢。超声处理暴露了蛋白质分子的内部结构,使部分结构展开、柔性增加,促进了其与壳聚糖之间的静电 相互作用,说明超声处理的大豆分离蛋白与壳聚糖形成的复合物影响了O/W型乳液的稳定性及相关性质。     

Effect of chitosan molecular weight on the stability and rheological properties of β-carotene emulsions stabilized by soybean soluble polysaccharides

In this study, β-carotene emulsions were prepared using a two-stage homogenization process and adsorption of chitosan to anionic droplets coated with soybean soluble polysaccharides (SSPS). Effects of the molecular weights of chitosan on the stability and rheological properties of β-carotene emulsions were investigated. Results demonstrated that the ζ-potential, particle size and rheological properties of emulsions were greatly dependent on the chitosan molecular weight. It was found that the particle size of SSPS-stabilized emulsions increased with the rise of chitosan molecular weight at higher chitosan concentrations (>0.2 wt%). Chitosan molecular weight had a significant impact on the heat and light stability of β-carotene in emulsions. SSPS-stabilized emulsion with the adsorption of medium molecular weight-chitosan (MM-chitosan) was more stable than those with the adsorption of low and high molecular weight-chitosan (LM-chitosan and HM-chitosan). Dynamic oscillatory shear tests indicated that the viscoelasticity could be enhanced by the adsorption of higher molecular weight of chitosan onto the SSPS-coated droplet surfaces.     

Physicochemical properties of a dressing-type o/w emulsion as influenced by orange pulp fiber incorporation

A low-in-oil dressing-type o/w emulsion incorporating a rich-in-fiber orange pulp commercial product, either in crude form or following comminution, was prepared and the rheological properties and physicochemical stability of the emulsion were studied. Interactions between the adsorbed at the droplet surfaces yolk proteins and the pulp surface constituents, possibly electrostatic in nature, resulted in extensive droplet aggregation. This was reflected in the dramatic increase of emulsion rheological parameter values, derived by applying the power or the Casson equation to shear stress-rate of shear data. Pulp incorporation resulted in an improvement of emulsion stability against creaming while the stability against droplet coalescence was only marginally affected. In addition, the rheological parameter values of the fortified with pulp emulsion exhibited an appreciable increase with storage, especially in the case of emulsions incorporating the crude pulp. These findings are combined with oil droplet or pulp particle size and ζ-potential data to probe the emulsion structure and explain its behavior during aging.     

Influence of chitosan on stability and lipase digestibility of lecithin-stabilized tuna oil-in-water emulsions

The influence of chitosan concentration (0–0.3 wt%) and molecular weight (120, 250 and 342.5 kDa) on the physical stability and lipase digestibility of lecithin-stabilized tuna oil-in-water emulsions was studied. The ζ-potential, droplet size, creaming stability, free fatty acids and glucosamine released was measured for the emulsions when they were subjected to an in vitro digestion model. The ζ-potential of the oil droplets in lecithin-chitosan stabilized emulsions changed from positive (≈+53 mV) to negative and the emulsions were unstable to droplet aggregation for all chitosan concentrations and molecular weights used after being subjected to the digestion model. The amount of free fatty acid and glucosamine released per unit amount of emulsion was higher when pancreatic lipase was included in the digestion model. These results suggest that lecithin-chitosan coated droplets can be degraded by lipase under simulated gastrointestinal conditions. Consequently, chitosan coated lipid droplets may serve as useful carriers for the delivery of bioactive lipophilic nutraceuticals.     

Effects of protein concentration and oil-phase volume fraction on the stability and rheology of menhaden oil-in-water emulsions stabilized by whey protein isolate with xanthan gum

The influences of protein concentration (0.2, 1, 2 wt%) and oil-phase volume fraction (5%, 20%, 40% v/v) on emulsion stability and rheological properties were investigated in whey protein isolate (WPI)-stabilized oil-in-water emulsions containing 0.2 wt% xanthan gum (XG). The data of droplet size, surface charge, creaming index, oxidative stability, and emulsion rheology were obtained. The results showed that increasing WPI concentration significantly affected droplet size, surface charge, and oxidative stability, but had little effect on creaming stability and emulsion rheology. At 0.2 wt% WPI, increasing oil-phase volume fraction greatly increased droplet size but no significant effect on surface charge. At 1 or 2 wt% WPI, increasing oil-phase volume fraction had less influence on droplet size but led to surface charge more negative. Increasing oil-phase volume fraction facilitated the inhibition of lipid oxidation. Meanwhile, oil-phase volume fraction played a dominant role in creaming stability and emulsion viscosity. The rheological data indicated the emulsions may undergo a behavior transition from an entropic polymer gel to an enthalpic particle gel when oil-phase volume fraction increased from 20% to 40% v/v.     

Effect of chitosan on the stability and properties of modified lecithin stabilized oil-in-water monodisperse emulsion prepared by microchannel emulsification

The effect of chitosan (CHI) on the stability of monodisperse modified lecithin (ML) stabilized soybean oil-in-water (O/W) emulsion was investigated. Monodisperse emulsion droplets with particle size of 24.4 ± 0.7 μm and coefficient of variation below 12% were prepared by microchannel (MC) emulsification using a hydrophilic asymmetric straight-through MC silicon 24 × 24 mm microchip consisting of 23,348 microchannels. The stability of the ML stabilized monodisperse emulsion droplets was investigated as a function of CHI addition at various concentration, pH, ionic strength, thermal treatment and freezing-thawing treatment by means of particle size and ζ-potential measurements as well as microscopic observation. The monodisperse O/W emulsions were diluted with CHI solution at various concentrations to a final droplet concentration of 1 wt% soybean oil, 0.25 wt% ML and 0–0.5 wt% CHI at pH 3. Pronounced droplet aggregation was observed when CHI was present at a concentration range of between 0.01 and 0.04 wt%. Above this concentration range, flocculations were less extensive, indicating some restabilization. ML stabilized emulsions were stable at a wide range of NaCl concentrations (0–1000 mM) and pH (3–8). On the contrary, in the presence of CHI, aggregation of the emulsion droplets was observed when NaCl concentration was above 200 mM and when the pH started to approach the pKa of CHI (i.e. ∼6.2–7.0). Emulsions containing CHI were found to have better stability at high temperature (>70 °C) in comparison to the emulsion stabilized only by ML. With sucrose/sorbitol as cryoprotectant aids, emulsions with the addition of CHI were found to be more resistant to droplet coalescence as compared to those without CHI after freezing at −20 °C for 22 h and thawing at 30 °C for 2 h. The use of CHI may potentially destabilize ML-stabilized O/W emulsions but its stability can be enhanced by selectively choosing the appropriate CHI concentrations and conditions of preparation.     

Improved oxidative barrier properties of emulsions stabilized by silica–polymer microparticles for enhanced stability of encapsulants

The materials encapsulated within oil-in-water emulsions are prone to oxidation due to the permeation of oxidative species across the oil–water interface and into the lipid phase. Thus, the oxidative barrier properties of the interfacial layer are pivotal in reducing oxidation within emulsified oils. To enhance these barrier properties, we explored an approach of stabilizing emulsions using ‘silica–polymer microparticles’. We hypothesize that these microparticles will enhance the barrier properties of emulsion interfaces by mechanisms such as higher interfacial thickness and quenching of oxidative species before they permeate into the emulsions. Silica–ε-polylysine (Si–EPL) microparticles were synthesized by electrostatic aggregation of anionic silica nanoparticles and cationic ε-polylysine in the aqueous phase. Formation of Si–EPL microparticles was validated using particle size, ζ-potential and scanning electron microscopy measurements. These microparticles were subsequently used for emulsion stabilization. Emulsions stabilized by silica nanoparticles alone were used as control. Oxidative barrier properties were determined by measuring the rate of permeation of peroxyl radicals from the aqueous to the oil phase of the emulsion using fluorescence based methods. The rate of permeation of peroxyl radicals was significantly lower in emulsions stabilized by Si–EPL microparticles compared to that stabilized by silica nanoparticles. One of the mechanisms responsible for the observed effect was enhanced quenching of peroxyl radical by Si–EPL microparticles before they can permeate inside the oil phase. To further validate the results, stability of a model bioactive compound, retinol, encapsulated in these emulsions was compared. Consistent with peroxyl radical permeation measurements, emulsion stabilized by Si–EPL microparticles significantly improved the oxidative stability of retinol compared to that stabilized by silica nanoparticles alone. Thus, by engineering the physical properties of the interfacial layers, the oxidation of the encapsulants in emulsions can be controlled.     

不同NaCl浓度条件下亚麻籽胶对肌原纤维蛋白凝胶作用力及乳化特性的影响

为改善低盐肉制品凝胶乳化品质的降低,明确亚麻籽胶（flaxseed gum,FG）添加对肉制品品质的影响,以肌原纤维蛋白（myofibrillar protein,MP）为研究对象,通过测定乳析指数、电位值、粒径、显微观察研究不同NaCl浓度条件下FG对MP乳液乳化稳定性的影响,而化学键的测定显示FG对MP凝胶化学作用力的影响。结果表明,形成MP凝胶及FG-MP凝胶体系的关键是二硫键和非二硫共价键的贡献;不同NaCl浓度对FG-MP乳液的乳析指数、ζ-电位、粒径的影响均不显著（P＞0.05）,而MP乳液随着NaCl浓度的提高,乳化稳定性、ζ-电位、粒径均显著变化（P＜0.05）。特别是在低浓度NaCl条件下,FG的加入可以显著提高MP乳液的稳定性（P＜0.05）。显微观察发现加入FG可以改善MP乳液液滴聚集的现象。因此,说明在低浓度NaCl条件下加入FG可以显著提高肌原纤维蛋白乳液的乳化稳定性,提高其抗盐能力,促进亚麻籽在肉制品中的应用。     

不同热处理温度对生物解离提油后大豆乳状液稳定性的影响

以生物解离技术提取的大豆乳状液为研究对象,探究不同热处理温度（55、65、75、85、95?℃）对乳状液的稳定性及相关机理的影响。通过ζ-电位、粒径分布、显微镜观察、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、傅里叶变换红外光谱和荧光光谱等的测定发现：随着温度的升高,乳状液ζ-电位和粒径明显增大;乳状液黏度下降速率逐渐加快;热处理温度低时,乳状液蛋白的亚基分布几乎没有差别,当热处理温度升高到85?℃时亚基分子质量增大,在温度为95?℃时亚基分子质量增大更明显。乳状液经热处理后其蛋白质α-螺旋含量降低,无规卷曲含量增加,且这种变化趋势随着热处理温度的升高而更加明显。随着热处理温度的升高,蛋白的荧光强度降低,发生了荧光猝灭现象。     

花青素共价交联大豆蛋白对其表面疏水性及功能性的影响

为了研究在不同共价交联条件(生物酶法和化学碱法)下,花青素对大豆分离蛋白(soy protein isolate,SPI)的表面疏水性与功能特性的影响。采用荧光探针表征SPI交联花青素后表面疏水性的变化,采用起泡性、乳化性、粒径分析及ζ-电位分析等指标研究花青素对SPI功能性质的影响。结果表明,SPI与花青素共价交联后其表面疏水性显著下降(p<0.05),且添加的花青素浓度与SPI的表面疏水性成反比。尤其是花青素浓度为0.05%时,相较于SPI,酶法和碱法交联的花青素-SPI共价复合物(LC3和AC3)表面疏水性分别减少了87.71%和82.71%;花青素的添加使SPI的起泡性能和乳化性能得以改善,当添加相同浓度的花青素时,生物酶法比化学碱法的改善效果更明显;SPI与花青素交联后提高了ζ-电位的绝对值,使溶液液滴粒径分布更加均匀,溶液的稳定性更强,尤其LC3的ζ-电位绝对值比SPI和AC3分别高了64.35%和10.98%。     

大豆分离蛋白与卵磷脂间相互作用对O/W型乳状液稳定性的影响

研究大豆分离蛋白与卵磷脂的复合比例及相互作用对乳化体系稳定性及功能性质的影响。结果显示:乳状液的乳化活性和粒径分布等性质受大豆分离蛋白与卵磷脂比例分配的影响较大。当大豆分离蛋白与卵磷脂间的质量比为10∶1时,复合体系的乳化活性较高(98.1 m~2/g),同时乳液的体积平均直径D_(4,3)最小(13.34μm),乳液双峰分布程度较低。乳化稳定性和ζ-电位测试结果显示,复合体系中大豆分离蛋白与卵磷脂比例为1∶1或100∶1都不利于体系稳定,此时激光共聚焦显微镜观测乳液出现相分离和不规则非球形液滴。这说明大豆分离蛋白与卵磷脂作为复合乳化剂具有最适配比,在该比例下大豆分离蛋白与卵磷脂间的相互作用对食品级水包油(oil-in-water,O/W)乳状液的稳定性是有利的。     

大豆可溶性多糖与Fe2+对O/W乳状液物理稳定性及流变特性的影响

研究大豆可溶性多糖(soybean soluble polysaccharides,SSPS)及不同浓度的Fe2+对大豆分离蛋白(soy isolated protein,SPI)稳定的O/W乳状液的物理稳定性和流变特性的影响。通过测定14 d内添加SSPS和不同浓度的Fe2+的乳状液的稳定动力学指数(turbiscan stability index,TSI)、稳态流变、粒径大小及分布和Zeta-电位,确定其物理稳定性。结果表明,与SPI乳状液相比,添加SSPS后,SSPS-SPI乳状液的TSI显著降低(p<0.05),液滴的表面积平均直径(d_3,2)和体积平均直径(d_4,3)增加,粘度系数增加,Zeta-电位绝对值降低,表明SSPS增加了SPI乳状液的粘度,提高了乳状液的物理稳定性;添加0.1 mmol/L Fe2+后,乳状液的TSI最低,液滴的d_3,2和d_4,3分别为0.686、2.136 μm,为最小粒径,粘度增加,稳定性较好;随着Fe2+浓度的增加,乳状液的TSI显著增加(p<0.05),粒径增大,分布范围变宽,表明0.2~0.5 mmol/L的Fe2+降低了乳状液的物理稳定性。总之,SSPS和0.1 mmol/L Fe2+的添加,提高了SPI稳定的O/W乳状液的物理稳定性。     

高压均质协同高酰基结冷胶对青椒蛋蔬液流变特性及稳定性的影响

研究高压均质（high pressure homogenization,HPH）协同高酰基结冷胶（high acyl gellan gum,HA）处理对青椒蛋蔬液（liquid egg with green pepper juice,LEGP）稳定系数、持水力、流变特性、粒径及电位的影响,进而探讨HPH协同HA对LEGP流变特性及稳定性的影响。结果表明：HPH处理可以明显提高LEGP的稳定系数、持水力、屈服应力、表观黏度和ζ-电位绝对值,并减小体系粒径,说明HPH处理可以有效提高LEGP体系稳定性。与HPH相比,HPH协同HA处理可以进一步提高LEGP的稳定系数、持水力、屈服应力、表观黏度和ζ-电位绝对值,使体系粒径进一步减小且分布更均匀,表明HPH协同HA处理可以更好地提高LEGP体系稳定性;其中,均质压力为150 MPa时,LEGP的稳定系数和持水力达到最大。流变实验结果表明HPH处理或HPH协同HA处理样品的流变模型均符合Herschel-Buckley模型,且其流体为带屈服值的假塑性流体,其中,HPH协同HA处理均质压力为150 MPa时,LEGP的屈服应力、表观黏度和弹性模量最高,流体的假塑性最强,体系粒径最小,ζ-电位绝对值最大,LEGP表现出最高的稳定性。     

疏水改性木薯淀粉的制备及其对肌原纤维蛋白乳化特性的影响

为了提高木薯淀粉的疏水性,使其作为颗粒乳化剂改善肌原纤维蛋白(myofibrillar protein,MP)的乳化特性,实验利用辛烯基琥珀酸酐(octenyl succinate anhydride,OSA)对原料木薯淀粉(native tapioca starch,NTS)进行疏水改性处理,得到不同改性水平和取代度(DS值)的疏水改性木薯淀粉(octenyl succinate tapioca starch,OSTS),并利用OSTS与MP制备复合乳化液。通过XRD、FT-IR、SEM和PLM分析了OSTS的结构变化,并测定了乳化液的乳液指数(EI值)、乳化活性(emulsifying activity index,EAI)、乳化稳定性(emulsion stability index,ESI)、Zeta-电位、粒径分布、巯基含量和界面蛋白含量。结果显示,在木薯淀粉分子中成功引入了疏水基团,疏水改性处理对木薯淀粉颗粒的晶体结构基本无影响;随淀粉改性水平和DS值的增加OSTS-MP复合乳化液的EAI和ESI呈显著增加趋势(P<0.05),3.0%OSTS-MP复合乳化液稳定性最...     

Production and stabilization of a flaxseed oil multi-layer emulsion containing sodium caseinate and pectin

The purpose of this research is the evaluation of a flaxseed oil-in-water emulsion, stabilized by a multi-layer structure consisting of sodium caseinate (Na-caseinate) and pectin to provide a basis for the combination of these materials for future studies. In the first step, the o/w emulsion (10 g oil, 90 g aqueous phase, and a pH 6.8) with varying concentration of Na-caseinate was investigated. Second, the pectin solution (0.05–1.5 g/100 g solution) was added to the primary emulsions and the pH was adjusted to 3.0. The emulsions were characterized by mean particle size (dynamic light scattering and static light scattering techniques), ζ-potential, turbidity value, creaming index, and the visualization of the microstructure. A clear separation of the oil phase at low protein contents and destabilizing by depletion flocculation at high protein content were observed. Extensive droplet flocculation and coalescence were determined until the pectin concentration reached 0.5 g/100 g solution for the secondary emulsion. After 7 days of storage, a 1.5 g/100 g solution pectin content had good stability with a relatively small size distribution, high turbidity value, and no cream phase separation.