共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
ABSTRACT: The creaming velocity, apparent viscosity, and ultrasonic attenuation spectra (1 to 50 MHz) of 5 wt% n hexadecane oil-in-water emulsions containing different droplet radii (r = 0.15 - 0.7 μm), biopolymer types (gum arabic or modified starch), and biopolymer concentrations (0 to 2.5 wt%) were measured. Depletion flocculation was observed in the emulsions when the nonabsorbed biopolymer concentration exceeded a critical concentration (CFC). The CFC increased with decreasing droplet radius for both biopolymers because the magnitude of the depletion attraction increases with droplet size. The CFC was lower for gum arabic than modified starch because it has a higher effective volume in solution. Depletion flocculation led to an increase in creaming instability and apparent viscosity of the emulsions. Flocculation could be nondestructively monitored by measuring the decrease in ultrasonic attenuation of the emulsions. These results show that depletion flocculation by gum arabic and modified starch can have an adverse effect on the stability of beverage emulsions. 相似文献
3.
本文以粒径、稳定性和流变为考察指标,利用激光粒度仪、食品稳定性分析仪、流变仪等研究不同种类和添加量的食品乳化剂(阿拉伯胶、酪蛋白酸钠、吐温20)对不饱和脂肪酸(油酸和亚油酸)乳状液的制备及其稳定性的影响。结果表明,三种乳化剂均可制备出稳定性较好的乳状液,不同乳化剂的质量分数不同得到乳状液的稳定性不同。较高质量分数的阿拉伯胶(4%,w/v)乳状液,具有最低的澄清指数并且具有最大粘度(0.30~0.40 Pa·s)。当酪蛋白酸钠的质量分数为2%时,制备出的乳状液较稳定,但粒径较大,贮藏稳定性较差。较低质量分数的吐温20(1%,w/v)的乳状液具有最小粒径(0.20~0.21 μm),经过贮藏后变化程度也最小。本文研究了不同食品乳化剂制备的不饱和脂肪酸乳状液及其稳定性,可为不饱和脂肪酸乳状液的制备和应用提供参考。 相似文献
4.
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. 相似文献
5.
将小麦淀粉分别与黄原胶和瓜尔豆胶以一定的比例复配,利用析水率实验、DSC方法和SEM微观结构观察等方法,研究亲水胶体黄原胶和瓜尔豆胶在5次冻融循环过程中对小麦淀粉稳定性的影响。研究结果表明:小麦淀粉的析水率随着循环次数的增加而增加,黄原胶和瓜尔豆胶能够明显降低冻融过程中小麦淀粉的析水率,从而抑制小麦淀粉冻融过程中的老化,且随着亲水胶体浓度的增加,对冻融稳定性的改善作用越强;小麦淀粉经过5次冻融循环后,淀粉胶基形成了大量的孔洞,并产生不连续丝状的,类似纤维的结构,且基质较薄,添加亲水胶体后显著改变了小麦淀粉的表观形态,孔洞明显减少,且淀粉基质增厚,形成了类似片状的网络结构。因此,黄原胶和瓜尔豆胶均能在一定程度上改善小麦淀粉的冻融稳定性,且与添加浓度有关。 相似文献
6.
7.
8.
9.
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。 相似文献
10.
The effects of pectin and guar gum on rheology, microstructure and creaming stability of 1% (w/v) egg yolk granule stabilized emulsions were investigated. While the addition of low amount of pectin (0.1% (w/v)) had no effect on the emulsion viscosity, the addition of 0.5% (w/v) pectin greatly increased the viscosity. Granule-stabilized emulsion without hydrocolloids reflects the pseudoplastic behavior (shear-thinning behavior with flow behavior index, n < 1.0). Hydrocolloids, especially at high concentrations, affected the viscoelastic behavior of the emulsions and both storage (G′) and loss modulus (G′′) were regarded as frequency dependent. Emulsions behaved like a liquid with G′′ > G′ at lower frequencies, and like an elastic solid with G′ > G′′ at higher frequencies. Emulsion microstructure indicated that the presence of hydrocolloids induced flocculation. Creaming stability of emulsions was enhanced by the presence of hydrocolloids and increasing hydrocolloid concentration decreased the creaming by restricting the movement of oil droplets. 相似文献
11.
Fat Particle Structure and Stability of Food Emulsions 总被引:1,自引:0,他引:1
WEN XU ALEX NIKOLOV DARSH T. WASAN ALEX GONSALVES RAJENDRA P. BORWANKAR 《Journal of food science》1998,63(2):183-188
We used a nondestructive Kossel diffraction technique based on the principle of backlight scattering to characterize the structure formation in concentrated model food emulsions. We also measured the effects of temperature, shear, casein micelles and gum on the fat particle packing structure in such systems. Through this technique, we demonstrated the effects of casein micelles on the pair potential of fat particle interactions and shelf life of such systems. We carried out theoretical calculations using a statistical mechanics approach by numerically solving the Ornstein-Zernike equation with Percus-Yevick closure for a bidisperse system consisting of fat particles and micelles, and showed that the experimental results were consistent with theoretical simulations. 相似文献
12.
13.
采用正交实验确定在复配体系中黄原胶与木薯羟丙基二淀粉磷酸酯b淀粉(变性淀粉)质量浓度分别为0.2%和2.0%时,稠度适宜,具有较好流动性。通过对比复配体系与对照组的析水率、稠度、透明度、热稳定性、老化程度、微观结构等结果研究黄原胶对变性淀粉冻融稳定性的影响。结果表明,随冻融次数增加,添加黄原胶的复配体系较变性淀粉糊的理化性质出现显著差异。变性淀粉在6次冻融前后稠度差值为120.68 g·s,添加黄原胶后,其稠度差值为4.14 g·s。添加黄原胶的变性淀粉在冻融循环后透明度从1.17%提高至1.53%、析水率由8.34%降低至6.75%且微观孔洞减少、结构更加紧密。因此,添加黄原胶有效地改善了变性淀粉的冻融稳定性。 相似文献
14.
本文研究了黄原胶浓度对蔗糖酯溶液水力学直径DH、ζ-电势及乳浊液粒径、ζ-电势、显微结构、粘度、模量和乳析分层等指标的影响,在此基础上探讨了黄原胶对蔗糖酯乳浊液流变特性及稳定性的影响。结果表明:随着黄原胶浓度升高,蔗糖酯-黄原胶复合溶液的DH值逐渐增大,ζ-电势逐渐降低。乳浊液的粒径先增大后减小,ζ-电势没有显著的变化(p0.05),乳浊液的粘度和模量逐渐增大。低黄原胶浓度(0~0.01 wt%)条件下,乳浊液仅出现油析分层现象;黄原胶浓度为0.05 wt%时,由于排斥絮凝作用增强,导致乳浊液的水析及油析分层最严重;随着黄原胶浓度进一步升高,由于弱凝胶网络结构的形成,一定程度提高了乳浊液的稳定性;且黄原胶浓度高于0.15 wt%时,乳浊液仅出现水析分层现象。 相似文献
15.
16.
瓜尔胶和黄原胶对马铃薯淀粉及其变性淀粉糊化和流变性质的影响 总被引:2,自引:0,他引:2
研究瓜尔胶和黄原胶对马铃薯淀粉、马铃薯磷酸酯淀粉和马铃薯阳离子淀粉糊化和流变性质的影响。糊化性质实验表明瓜尔胶增加了3种淀粉的峰值黏度和成糊温度,降低了淀粉糊的热稳定性。黄原胶降低了马铃薯淀粉和马铃薯磷酸酯淀粉的峰值黏度并提高了糊的热稳定性和成糊温度,但对马铃薯阳离子淀粉起相反作用。动态流变实验表明加入黄原胶显著提高了3种淀粉的GO`、GO`O`值,降低了损耗角正切值tanδ,黄原胶对马铃薯阳离子淀粉动态流变学性质的影响最大,瓜尔胶对3种淀粉的动态流变学性质的影响不显著。静态流变实验表明加入瓜尔胶和黄原胶后的淀粉糊仍为假塑性流体,滞后环面积减少,稳定性提高,两种胶对马铃薯淀粉和马铃薯磷酸酯淀粉的作用比对马铃薯阳离子淀粉作用明显,并且黄原胶比瓜尔胶对淀粉作用更为显著。研究发现胶体与淀粉之间的电荷相互作用对复配体系的糊化性质和流变学性质起重要的作用。 相似文献
17.
Formation and Coalescence Stability of Emulsions Stabilized by Different Milk Proteins 总被引:1,自引:0,他引:1
The volume fraction of oil emulsified, surface area, droplet diameter, and coalescence rates of emulsions stabilized by different milk proteins were studied at protein concentrations of 0.25, 0.5, 1.0, and 2.0% (w/w); pH 4, 5, and 7; and ionic strengths 0.1 and 0.2. The emulsion activity index (EAI) and coalescence stability generally increased with increasing protein solubility and hydrophobicity. The volume fraction of oil emulsified decreased with increasing ionic strength. Coalescence stability correlated with droplet diameter for emulsions stabilized by α-lactalbumin, β-lactoglobulin, and sodium caseinate (r2=0.96). With the exception of β-lactoglobulin-stabilized emulsions, coalescence stability was largely unaffected by pH. 相似文献
18.
19.
以乳清蛋白为乳化剂,采用高压均质制备水包油乳液,分别在天然乳清蛋白组和热变性乳清蛋白组中添加 不同质量浓度(0.00、0.05、0.10、0.20、0.40 mg/mL)的木犀草素,探究天然和热变性乳清蛋白与木犀草素之间的 相互作用以及形成的乳清蛋白-木犀草素复合物与乳液稳定性的关系。通过测定荧光光谱、动态激光散射、界面物 质含量以及脂质氧化产物含量,研究热变性乳清蛋白与木犀草素复合物形成乳液的稳定性、界面吸附特性和抗氧化 性。结果表明:荧光光谱显示蛋白质和木犀草素相互作用发生荧光猝灭,二者之间形成了蛋白质-木犀草素基态复 合物;该复合物能显著抑制乳液脂质的氢过氧化物和丙二醛的形成(P<0.05),可增强乳液的氧化稳定性,但是 对乳液的物理稳定性无显著影响(P>0.05)。热处理不利于蛋白质在界面的吸附,但可以提高木犀草素在乳液界 面的吸附;而木犀草素的质量浓度对界面蛋白质的吸附没有显著影响(P>0.05)。 相似文献