黄原胶对酪蛋白酸钠乳状液稳定性的影响

研究了一定pH条件下,黄原胶浓度及剪切稀化效应对酪蛋白酸钠乳状液稳定性的影响。结果表明,在酸性条件下,黄原胶无法抑制酪蛋白的变性沉淀,乳液在制备之初,即产生严重絮凝。在中性和弱碱性条件下,黄原胶在一定浓度范围内,诱发了乳状液的排斥絮凝;体系的pH显著影响了乳状液的稳定性,pH6条件下,较低的黄原胶浓度(0.2wt%)便可赋予乳状液良好的稳定性。均质过程大大降低了黄原胶的粘度,导致乳状液的稳定性下降,与添加未经均质处理的黄原胶相比,添加量增大近一倍,才能获得稳定的乳状液。      

含酒精乳状液的稳定性

介绍了体系的 pH值 ,盐 ,小分子表面活性剂 ,黄原胶 ,蔗糖以及均质压力对含酒精的脂肪乳状液体系稳定性的影响 .通过对各种体系的粘度和分层状态的测定 ,比较了不同酒精浓度下乳浊液对各种因素的稳定性能的变化 .实验结果表明酒精的存在使 pH值、Ca2 、KCl等对酪蛋白稳定的乳状液的破坏作用更明显 ;小分子表面活性剂和较高的均质压力对提高体系的抗分层稳定性均有促进作用 ;在所添加的浓度范围内 ,黄原胶显示了与乳状液体系明显不相容性 ,体系的稳定性明显降低 ;蔗糖对体系的稳定性有一定程度的提高 .     

黄原胶对O/W乳状液稳定性的影响

报道了含有黄原胶的２０Ｏ／Ｗ乳状液贮藏在２７～３０℃的分层动力学的研究。实验运用超声波技术考察了从０．０００５～０．５ｗｔ％的一系列浓度的黄原胶对体系分层特性的影响。在非常低（＜０．００１ｗｔ％）的黄原胶浓度下，实验体系的稳定性变化不大。０．０１～０．０２ｗｔ％的黄原胶可引起样品底部富水层出现，但体系无明显分层。当黄原胶浓度增加到０．０２ｗｔ％以上，乳状液很快分层，且分层的状态取决于黄原胶添加量。只有当添加量超过０．２５ｗｔ％，黄原胶才能起到提高体系稳定性的作用。对非吸附性的黄原胶的这种影响，可以用“排除絮凝”和弱凝胶结构形成的机理进行解释。     

阴离子多糖对大豆蛋白乳状液乳析稳定性的影响

研究了卡拉胶、黄原胶和羧甲基纤维素钠(CMC)3种阴离子多糖对大豆蛋白乳状液乳析稳定性的影响。结果表明:添加0.03%卡拉胶的乳状液乳析稳定性较好,而添加CMC或0.06%以上黄原胶的乳状液乳析稳定性则较差;随着阴离子多糖浓度的增加,添加CMC的乳状液顶部粒径d3,2增大,添加卡拉胶或黄原胶的大豆蛋白乳状液顶部粒径d3,2先减小后增大;添加阴离子多糖的乳状液的顶部粒径d3,2与乳析率呈较好的正相关性。     

黄原胶对罗非鱼蛋白-大豆蛋白混合体系乳浊液稳定性的影响

以罗非鱼和豆粕为原料,采用碱溶-等电点沉淀法制备鱼分离蛋白(fish protein isolates,FPI)和大豆分离蛋白(soybean protein isolats,SPI),固定蛋白浓度0.5%,在pH 4.0和7.0条件下,高压均质(一级压力30 MPa,二级压力4 MPa),实验黄原胶(xanthan gum,XG)的添加对FPI、FPI-SPI(质量比2∶1)、FPI-SPI(质量比1∶1)和SPI乳浊体系粒径分布、微观显微结构和乳析指数的影响。结果表明:随着黄原胶的添加(0~0.09%),乳浊体系平均粒径减小(P0.05);在pH 4.0条件下,乳浊液液滴聚集和絮凝现象明显减少,宏观乳析稳定性提高(P0.05),添加0.06%和0.09%黄原胶的FPI-SPI混合乳浊体系4℃放置10 d都没有明显的分层,而不同比例混合蛋白体系之间的差异不明显(P0.05);在pH 7.0条件下,添加0.06%的黄原胶时,FPI-SPI(质量比2∶1)和FPI-SPI(质量比1∶1)混合乳浊体系微观絮凝现象没有明显改善,宏观乳析稳定性明显提高(P0.05),4℃放置10 d没有明显的分层现象。总体分析,2种蛋白物理混合对乳浊液体系稳定性的改善程度有限,而适量的黄原胶能明显提高酸性条件下体系的乳浊液稳定性。     

NaCl浓度、多糖以及小分子乳化剂对全蛋粉乳化性质的影响

以全蛋粉(WEP)为乳化剂制备水包油型乳状液,以乳化活性(EAI)和乳化稳定性(ESI)为乳化性质的指标,研究盐、多糖以及小分子乳化剂对全蛋粉乳化性质的影响以及不同乳状液在高温下的耐热性。单因素试验表明:全蛋粉乳化性质分别在NaCl、黄原胶以及单甘酯的添加量为0.5 mol/L、0.08%、0.06%时达到最大值。正交试验结果表明:各因素对全蛋粉乳化性质影响的主次关系为,黄原胶>单甘酯>盐浓度。在优化组合条件下全蛋粉的乳化活性和乳化稳定性分别提高了0.49倍和14.43倍;并且添加黄原胶和复合物后的乳状液耐热性显著提高。     

亲水胶体对含酒精O/W(水包油)乳状液稳定性的影响

研究了卡拉胶、刺槐豆胶,及其混和胶作为稳定剂,对以酪蛋白酸钠稳定的含酒精O/W乳状液体系稳定性的影响.结果表明,单独添加一定浓度的卡拉胶可改善体系的分层稳定性,而单独加入刺槐豆胶会加速体系失稳,当m(卡拉胶)∶m(刺槐豆胶)=4∶1加入到体积分数为15%的酒精乳状液中,加入量为0.02%时体系稳定性最好.同时研究了两多糖的加入方式、热处理时间,以及蔗糖存在下对乳状液稳定性及黏度的影响.结果表明,卡拉胶与刺槐豆胶分别加入到乳状液中稳定效果较好,并且卡拉胶和刺槐豆胶分别在90℃保温6min后加入有利于体系的稳定;质量分数为10%的蔗糖存在增强了复合胶存在下体系的稳定性.     

高压均质对二十二碳六烯酸功能因子输送体系稳定性影响

以酪蛋白酸钠-葡萄糖美拉德反应产物（Millard reaction products,MRPs）作为乳化剂,在不同的均质条件下制备O/W型二十二碳六烯酸（docosahexaenoic acid,DHA）藻油乳状液,以相同条件下单独的酪蛋白酸钠作为对比,利用稳定性分析仪分析、贮藏期间的氧化程度分析和激光共聚焦显微镜观察对DHA藻油乳状液的物理稳定性、氧化稳定性和微观结构进行评价。结果显示：利用酪蛋白酸钠-葡萄糖MRPs制备的DHA藻油乳状液的物理稳定性和氧化稳定性远优于同等条件下单独的酪蛋白酸钠,说明酪蛋白酸钠经美拉德反应改性后具有优良的乳化性和抗氧化活性;同时,均质压力和次数对乳状液的稳定性和微观结构具有明显的影响。较优的工艺条件为均质压力95 MPa、均质3 次,此时酪蛋白酸钠-葡萄糖MRPs制备的DHA藻油乳状液的状态较好,Turbiscan稳定性分析仪对其扫描结果显示,乳状液只有轻微的顶部脂肪上浮和底部澄清,稳定性系数为1.55,小于其他各组;室温（25 ℃）贮藏28 d期间的总氧化值处于同期的最低水平;激光共聚焦显微镜下乳状液中油滴的粒径较小,主要分布在0.47～0.59 μm之间,且形态完整、较为均一。     

亲水性胶体对橙汁饮料稳定性的影响

目的以30%橙汁饮料为对象,研究结冷胶、黄原胶、海藻酸钠等亲水性胶体对橙汁稳定性的影响。方法采用U8(88)均匀设计筛选出对橙汁稳定性影响最为显著的因素,再通过L9(34)正交设计进一步验证优化橙汁饮料中的胶体最佳复配方案。结果对橙汁沉淀影响最为显著的胶体是海藻酸钠、结冷胶、果胶、黄原胶,而瓜尔胶、阿拉伯胶和羧甲基纤维素钠(CMC)的影响不显著,其中结冷胶和黄原胶有利于橙汁的混浊稳定性,但是黄原胶和CMC的加入会促进橙汁的絮凝产生。海藻酸钠和结冷胶是影响橙汁稳定性的重要因素,一定用量的海藻酸钠和结冷胶复配能很好抑制产品沉淀,维持体系的混浊稳定性;黄原胶是引起产品絮凝的主要因素,适量的果胶和海藻酸钠可以防止絮凝形成。结论在海藻酸钠、结冷胶和果胶添加量分别为1.2‰、0.32‰和0.8‰时,橙汁具有最佳稳定性,产品的沉淀量最少,混浊稳定性最高,同时可最大程度防止絮凝。经过验证,在最优胶体复配条件下,其沉淀稳定性为98.52%,混浊稳定性达94.89%,产品无明显絮凝。     

黄原胶对蔗糖酯乳浊液流变特性及稳定性的影响

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。     

Influence of xanthan gum on the formation and stability of sodium caseinate oil-in-water emulsions

Studies have been made of the changes in droplet sizes, surface coverage and creaming stability of emulsions formed with 30% (w/w) soya oil, and aqueous solution containing 1 or 3% (w/w) sodium caseinate and varying concentrations of xanthan gum. Addition of xanthan prior to homogenization had no significant effect on average emulsion droplet size and surface protein concentration in all emulsions studied. However, addition of low levels of xanthan (≤0.2 wt%) caused flocculation of droplets that resulted in a large decrease in creaming stability and visual phase separation. At higher xanthan concentrations, the creaming stability improved, apparently due to the formation of network of flocculated droplets. It was found that emulsions formed with 3% sodium caseinate in the absence of xanthan showed extensive flocculation that resulted in very low creaming stability. The presence of xanthan in these emulsions increased the creaming stability, although the emulsion droplets were still flocculated. It appears that creaming stability of emulsions made with mixtures of sodium caseinate and xanthan was more closely related to the structure and rheology of the emulsion itself rather than to the rheology of the aqueous phase.     

Effect of Aqueous Phase Composition on Stability of Sodium Caseinate/Sunflower oil Emulsions

The aim of the present work was to investigate the effect of aqueous phase composition on the stability of emulsions formulated with 10 wt% sunflower oil as fat phase. Aqueous phase was formulated with 0.5, 2, or 5 wt% sodium caseinate, or sodium caseinate with the addition of two different hydrocolloids, xanthan gum or locust bean gum, both at 0.3 or 0.5 wt% level or sodium caseinate or with addition of 20 wt% sucrose. Emulsions were processed by Ultra-Turrax and then further homogenized by ultrasound. Creaming and flocculation kinetics were quantified by analyzing the samples with a Turbiscan MA 2000. Emulsions were also analyzed for particle size distribution, microstructure, viscosity, and dynamic surface properties. The most stable systems of all selected in the present work were the 0.3 or 0.5 wt% XG or 0.5 wt% LBG/0.5 wt% NaCas coarse emulsion and the 20 wt% sucrose/5 wt% NaCas fine emulsion. Surprisingly, coarse emulsions with the lower concentration of NaCas, which had greater D _4,3, were more stable than fine emulsions when the aqueous phase contained XG or LBG. In these conditions, the overall effect was less negative bulk interactions between hydrocolloids and sodium caseinate, which led to stability. Sugar interacted in a positive way, both in bulk and at the interface sites, producing more stable systems for small-droplet high-protein-concentration emulsions. This study shows the relevance of components interactions in microstructure and stability of caseinate emulsions.     

Rheological properties of emulsions containing milk proteins mixed with xanthan gum

Oil in water emulsions (30% w/w) containing mixtures of milk proteins with xanthan gum were rheologically characterized at ambient temperature and the evolution of their properties was measured during a month under cold storage. The milk proteins used were sodium caseinate and whey concentrate at 2% mixed with xanthan gum at 0.3% or 0.5%. Emulsions properties were compared to those of respective aqueous systems and in general showed same rheological behaviour as their respective aqueous system, however, emulsions presented higher consistency index, due to oil droplets concentration. The flow behaviour index showed a small variation, increasing its value slightly. The consistency of emulsions with xanthan was similar, independently of the milk protein used, confirming that xanthan rheology predominates on emulsion rheology.     

Oil-in-water emulsions stabilized by sodium caseinate: Influence of pH,high-pressure homogenization and locust bean gum addition

The effect of pH, addition of a thickening agent (locust bean gum) or high-pressure homogenization on the stability of oil-in-water emulsions added by sodium caseinate (Na-CN) was evaluated. For this purpose, emulsions were characterized by visual analysis, microstructure and rheological measurements. Most of the systems were not stable, showing phase separation a few minutes after emulsion preparation. However, creaming behavior was largely affected by the pH, homogenization pressure or locust bean gum (LBG) concentration. The most stable systems were obtained for emulsions homogenized at high pressure, containing an increased amount of LBG or with pH values close to the isoelectric point (pI) of sodium caseinate, which was attributed to the size reduction of the droplets, the higher viscosity of continuous phase and the emulsion gelation (elastic network formation), respectively. All the studied mechanisms were efficient to decrease the molecular mobility, which slowed down the phase separation of the emulsions. In addition, the use of sodium caseinate was also essential to stabilize the emulsions, since it promoted the electrostatic repulsive interactions between droplets.     

Interfacial composition and stability of emulsions made with mixtures of commercial sodium caseinate and whey protein concentrate

The interfacial composition and the stability of oil-in-water emulsion droplets (30% soya oil, pH 7.0) made with mixtures of sodium caseinate and whey protein concentrate (WPC) (1:1 by protein weight) at various total protein concentrations were examined. The average volume-surface diameter (d₃₂) and the total surface protein concentration of emulsion droplets were similar to those of emulsions made with both sodium caseinate alone and WPC alone. Whey proteins were adsorbed in preference to caseins at low protein concentrations (<3%), whereas caseins were adsorbed in preference to whey proteins at high protein concentrations. The creaming stability of the emulsions decreased markedly as the total protein concentration of the system was increased above 2% (sodium caseinate >1%). This was attributed to depletion flocculation caused by the sodium caseinate in these emulsions. Whey proteins did not retard this instability in the emulsions made with mixtures of sodium caseinate and WPC.     

椰子油纳米乳液制备工艺优化及其稳定性分析

为制备较为稳定的椰子油乳液,将酪蛋白酸钠(Sodium caseinate,SC)和黄原胶(Xanthan gum,XG)复合作为乳化剂,椰子油为油相,采用超声方法制备椰子油乳液。以平均粒径、Zeta-电位、离心稳定性及浊度等为考察指标,通过单因素实验筛选出超声功率、超声时间、油相质量分数和水相pH的合理研究范围。以平均粒径为响应值,用Box-Behnken响应面法对超声功率、超声时间和水相pH做进一步优化实验并对制备的乳液进行稳定性实验。结果表明,最佳制备工艺参数为:超声功率为480 W,超声时间为18 min,水相pH为7,所得椰子油纳米乳液的平均粒径为304.5±13.2 nm。所制备的椰子油纳米乳液在热处理温度40～90℃,pH6～8,离子浓度0～0.5 mol/L条件下具有良好的稳定性,且经3次冻融循环后乳液保持稳定,为构建用于食品加工的高稳定性椰子油乳液提供了理论支持。     

Heat stability of oil-in-water emulsions formed with intact or hydrolysed whey proteins: influence of polysaccharides

The heat stability of emulsions (4 wt% corn oil) formed with whey protein isolate (WPI) or extensively hydrolysed whey protein (WPH) products and containing xanthan gum or guar gum was examined after a retort treatment at 121 °C for 16 min. At neutral pH and low ionic strength, emulsions stabilized with both 0.5 and 4 wt% WPI (intact whey protein) were stable against retorting. The amount of β-lactoglobulin (β-lg) at the droplet surface increased during retorting, especially in the emulsion containing 4 wt% protein, whereas the amount of adsorbed α-lactalbumin (α-la) decreased markedly. Addition of xanthan gum or guar gum caused depletion flocculation of the emulsion droplets, but this flocculation did not lead to their aggregation during heating. In contrast, the droplet size of emulsions formed with WPH increased during heat treatment, indicating that coalescence had occurred. The coalescence during heating was enhanced considerably with increasing concentration of polysaccharide in the emulsions, up to 0.12% and 0.2% for xanthan gum and guar gum, respectively; whey peptides in the WPH emulsions formed weaker and looser, mobile interfacial structures than those formed with intact whey proteins. Consequently, the lack of electrostatic and steric repulsion resulted in the coalescence of flocculated droplets during retort treatment. At higher levels of xanthan gum or guar gum addition, the extent of coalescence decreased gradually, apparently because of the high viscosity of the aqueous phase.     

Rheology,particle-size distribution,and stability of low-fat mayonnaise produced via double emulsions

In this study, the effects of the double emulsification method on the rheological properties, particle size, and stability of low-fat mayonnaise were studied. Different water-phase-to-oil ratios (2:8 and 4:6) of primary emulsions and different stabilizer types (sodium caseinate, xanthan gum, and lecithin-whey protein concentrate) were used to produce double-emulsified mayonnaise. As a control sample, mayonnaise was prepared conventionally. Sodium caseinate was found to be the most efficient stabilizer. In the presence of sodium caseinate, the stability and apparent viscosity of double-emulsified mayonnaise increased but their particle sizes decreased. It was found that flow behavior of double-emulsified and conventionally prepared mayonnaise could be described by the power law model. The double-emulsified mayonnaise samples were not different from the control samples in terms of stability and particle size. In addition, using the double emulsion method, it was possible to reduce the oil content of mayonnaise to 36.6%.     

面筋蛋白粒子-黄原胶Pickering乳液的制备及其表征

制备黄原胶与面筋蛋白纳米粒协同稳的Pickering乳液,表征Pickering乳液的物理化学性能和微观结构。结果显示：通过黄原胶与面筋蛋白纳米粒协同作用,可制备出稳定性较好的Pickering乳液。低质量分数的黄原胶（0.2%）会促进乳析;当黄原胶质量分数不小于0.3%时,乳液于4 ℃贮存30 d仍无乳析现象;当黄原胶质量分数为1%时,贮存30 d乳液出现析油的现象。不同乳化顺序得到乳液的稳定性不同。乳液M-WG-XG（面筋蛋白纳米粒与玉米油乳化得粗乳液,然后加入黄原胶二次分散）的稳定性最好,同时乳液的平均粒径最小（21.4±0.314）μm。黄原胶的加入增大了乳液的净电荷,乳液的稳定性提高。共聚焦显微镜结果表明,乳液M-WG-XG液滴分布均匀,界面层呈现出多层结构。相比于其他方式制备的乳液,乳液M-WG-XG有更好的黏弹性和离子稳定性。     

Influence of pH and biopolymer ratio on sodium caseinate—guar gum interactions in aqueous solutions and in O/W emulsions

Many colloidal food systems contain both proteins and polysaccharides. In the present study, the phase behaviour of mixed sodium caseinate—guar gum aqueous solutions was investigated: segregative phase separation was observed in solutions containing at least 0.04% of guar gum and 1.6% of sodium caseinate, thus indicating the limited compatibility of the polysaccharide and the protein.In addition, the functionality of guar gum as gravitational stabilizer in sodium caseinate stabilized 25% O/W emulsions was checked. At pH conditions significantly larger than the iso-electric point (IEP) of sodium caseinate, addition of small amounts of guar gum (0.1–0.2%) gave raise to fast serum separation, which was thought to be due to depletion flocculation. Increasing the polysaccharide concentration and/or the oil volume fraction limited the degree of phase separation, since depletion flocculation induced a sufficiently strong three-dimensional network to withstand gravity effects.Considering different guar gum concentrations at pH 5.0, 5.5, 6.0 and 6.5, it became obvious that the phase separation behaviour in the absence of guar gum was largely affected by the pH, whereas in the presence of at least 0.1% of guar gum it became mainly affected by the guar gum concentration. Hereby, higher guar gum concentrations introduced a longer delay time before separation could effectively be detected. As laser diffraction particle size analysis results were not significantly affected by guar gum addition, it was concluded that the guar gum-induced flocculation was weak in nature and largely reversible.Combining all results, it was concluded that guar gum could effectively be used to prevent phase separation problems that could occur due to flocculation around the protein's IEP, provided that at least 1.0% of guar gum is added to ensure depletion stabilization by formation of a sufficiently strong three-dimensional network to overcome separation effects. Increasing the ionic strength through addition of salt further reinforces the network in order to prevent its collapse due to gravity.