Interfacial Composition of Sodium Caseinate Emulsions

Oil-in-water emulsions stabilized by sodium caseinate were prepared and diluted with water or solutions of α_sl- or β-casein. The emulsions were aged for 24 hr and the composition of the aqueous phase (and hence of the surface) was determined using Fast Protein Liquid Chromatography. There was no distinct preference for either α_sl- or β-casein at the surface during homogenization, but on aging, β-casein replaced some, but not all, of the surface α_sl-casein. The exchange was stoichiometric, unless the initial surface concentration was low, in which case extra adsorption occurred to achieve a protein load of - 1.2 mg m^-2. Build up of multilayers was not observed.     

酒精对酪蛋白酸钠溶液及O/W乳状液的影响

介绍了酒精对酪蛋白酸钠溶液及酪蛋白稳定的O/W乳状液性质的影响 .试验表明酒精在一定程度上可以降低酪蛋白酸钠的溶解度 .界面张力的测定则表明酒精的存在在很大程度上可以降低油—水界面和油—酪蛋白溶液界面的界面张力 .含酒精的乳状液体系的粘度会由于酒精的存在而提高 ,在酒精体积分数达 3 0 %时 ,乳状液体系的粘度会突然大幅度升高 .通过O/W乳状液的分层稳定性测定可发现 ,低浓度的酒精可以提高酪蛋白稳定的乳状液的分层稳定性 ,但酒精质体积分数超过 3 2 %时 ,乳状液的分层稳定性会受到破坏 .含酒精的O/W乳状液体系中油相含量的提高在一定范围内可以提高乳状液的稳定性 ,但高分散相浓度的含酒精的乳状液体系中由于连续相中酒精浓度的提高使乳状液体系稳定性下降 .     

Sodium Caseinate/Sunflower Oil Emulsion-Based Gels for Structuring Food

Protein gels have attired attention since they allow structuring foods with no trans or saturated fats. The effects of protein concentration and sucrose addition on gelation kinetics and on physical properties of sodium caseinate (NaCas)/sunflower oil emulsion-based gels were studied by two methods: a new application of backscattering of light (BS) using a Turbiscan equipment and by dynamic oscillatory rheology. Structure of gels was also described by confocal laser scanning microscopy (CLSM) and small angle X-ray scattering (SAXS). T _gel values decreased with increasing sucrose or NaCas concentration. BS method sensed early changes in structure, while rheological measurements were less sensitive to those changes. However, tendencies found by rheological measurements were the same as the ones found by BS experiments. CLSM images of gels formed from emulsions containing high sucrose and protein concentrations had big oil droplets that were not present in initial emulsions. Gels with sucrose concentrations between 15 and 30 wt/wt% released oil. SAXS patterns showed that NaCas nanoaggregate sizes in the aqueous phase were smaller with increasing sucrose concentration. Polar groups of protein interacted with sucrose, and therefore, interactions among protein molecules diminished. As a result of weaker protein molecule interactions, nanoaggregates were smaller. However, this effect was beneficial. In the macroscale, rheological properties and visual appearance of gels were improved. The gel formulated with 5 wt/wt% NaCas and 10 wt/wt% sucrose had a smooth surface and was stable to syneresis and oil release. This formulation was a good alternative to trans fat.     

酪蛋白酸钠-葵花籽油协同对乳化肠品质特性的影响

以猪后腿肉为原料肉,酪蛋白酸钠、葵花籽油预乳化液替代猪背膘制备乳化肠,研究不同比例（0、25%、50%、75%、100%）预乳化液替代对乳化肠蒸煮损失率、物理化学组成、色泽、质构、脂肪酸组成及硫代巴比妥酸值的影响。结果显示：随着预乳化液替代比例增加,乳化肠中蛋白质、水分的含量显著增加（P＜0.05）,灰分含量变化差异不显著,脂肪含量显著下降（P＜0.05）,从18.58%降低到10.17%;蒸煮损失率降低;乳化肠的亮度值随预乳化液代替猪背膘比例的增加呈上升趋势,红度值和黄度值呈下降趋势;预乳化液替代组乳化肠的质构特性优于对照组;预乳化液替代猪背膘制备乳化肠还可以改变乳化肠的脂肪酸组成,随替代比例的增大,乳化肠中必需脂肪酸亚油酸在总脂肪酸中所占的比例显著增加（P＜0.05）,多不饱和脂肪酸所占的比例增加,高达55.92%,饱和脂肪酸从39.72%降低到13.52%,满足消费者对低脂多不饱和脂肪酸肉制品的需求;随替代比例的增大,乳化肠的TBARS值逐渐减小,用预乳化液替代猪背膘可增强乳化肠的氧化稳定性。因此,酪蛋白酸钠、葵花籽油预乳化液替代猪背膘可显著改善乳化肠的品质及营养特性。     

酪蛋白钠稳定肉糜机理的研究

通过对添加酪蛋白钠预制乳剂香肠样品与对照样的扫描电镜照片的分析，证明了酪蛋白钠可在脂肪球表面形成１μｍ强韧亲水蛋白膜，稳定了肉糜的脂肪蛋白质水体系     

超声波处理对酪蛋白酸钠-大豆油预乳化液乳化稳定性的影响

为改善预乳化液的乳化稳定性,本研究应用超声波技术制备酪蛋白酸钠-大豆油预乳化液,研究不同时间(0、3、6、9、12 min)超声波处理(20 kHz,450 W)对预乳化液的p H值、电导率、乳液分层指数、液滴粒度分布和平均粒径大小以及黏度的影响。结果表明,不同超声波处理时间对酪蛋白酸钠-大豆油预乳化液p H值和电导率没有显著影响(P0.05)。在0 h时,各超声波处理组和对照组的乳析率差异不显著(P0.05),在贮藏12、24、36 h时,各超声波处理组的乳析率显著低于对照组(P0.05)。超声波时间对预乳化液的粒径分布范围和粒径大小影响显著(P0.05),随着超声波时间的延长,D_(4,3)、D_(3,2)和D_(50)显著变小(P0.05)。在剪切速率0.1 s~(-1)时,超声波时间对酪蛋白酸钠-植物油预乳化液的黏度有显著影响,各组超声波预乳化液的黏度均显著高于对照组(P0.05)。因此,应用超声波处理酪蛋白酸钠-大豆油预乳化液,可以延长贮藏期,减小乳化液粒径,提高黏度,有效改善乳化稳定性。     

Competitive Adsorption Between Sodium Caseinate and Oil-Soluble and Water-Soluble Surfactants in Oil-in-Water Emulsions

Competitive adsorption between sodium caseinate and either a water-soluble surfactant, Tween 60 (polyoxyethylene sorbitan monostearate—PSM) or an oil-soluble surfactant, Span 60 (sorbitan monostearate—SM) was studied in oil-in-water emulsions. Surfactants were present during homogenization. Surface concentration of protein in freshly prepared emulsions decreased as concentration of PSM or SM increased. However, only partial displacement of protein was observed with either surfactant. The reduction in protein surface concentration was greater in the presence of PSM. Interfacial protein composition was independent of surfactant type. In the absence of surfactant, preferential adsorption of β-casein occured in emulsions containing ≤1.0 wt % protein. On addition of surfactant preference for β-casein at the interface was reduced.     

The Effect of Sodium Carboxymethylcellulose on the Stability and Bioaccessibility of Anthocyanin Water-in-Oil-in-Water Emulsions

Water-in-oil-in-water (W₁/O/W₂) emulsions provide protective encapsulation to plant bioactive compounds in food matrix and under gastrointestinal conditions. However, the stability of the emulsions during the storage is crucial for their use in the food industry. Hence, the aim of this study was to enhance the stability and bioaccessibility of W₁/O/W₂ emulsions containing anthocyanins with the use of sodium carboxymethylcellulose (CMCNa). The emulsions were prepared by ultrasound technology, adding polyglycerol polyricinoleate (PGPR) in the inner aqueous phase of emulsions, and lecithin and Tween 20 in the outer aqueous phase. The systems were physicochemical characterized over the time and their behavior under simulated gastrointestinal conditions was investigated. Our results showed high encapsulation efficiencies above 90% and an increase in bioaccessibility with the use of CMCNa. Moreover, the polymer addition slowed down the free fatty acid release and increased the oil digestibility of lecithin-stabilized emulsions. These latter emulsions presented the highest bioaccessibility (31.08?±?1.73%), the more negative values of ζ-potential and no variations on the particle size and the backscattering profile over the time, thus being the most stable emulsions. These results provide useful information for the design of anthocyanin emulsion-based delivery systems to guarantee their functionality in food matrices as well as through the gastrointestinal tract.     

Oil-in-Water Emulsions Stabilized by Sodium Caseinate or Whey Protein Isolate as influenced by Glycerol Monostearate

Competitive adsorption between glycerol monostearate (GMS) and whey protein isolate (WPI) or sodium caseinate was studied in oil-in-water emulsions (20 wt % soya oil, deionized water, pH 7). Addition of GMS resulted in partial displacement of WPI or sodium caseinate from the emulsion interface. SDS-PAGE showed that GMS altered the adsorbed layer composition in sodium caseinate stabilized emulsions containing < 1.0 wt % protein. Predominance of β-casein at the interface in the absence of surfactant was reduced in the presence of GMS. The distribution of α-lactalbumin and β-lactoglobulin between the aqueous bulk phase and the fat surface in emulsions stabilized with WPI was independent of the concentration of added protein or surfactant.     

酪蛋白酸钠功能性的研究

本文研究了酪蛋白酸钠乳化能力EC在不同浓度、温度、盐类、油脂品种及不同乳化剂等条件的影响下的变化及高浓度酪蛋白酸钠溶液的粘度受浓度、温度、pH值的影响情况。结果表明:乳化性随温度的升高、浓度的减小而降低,盐类、油脂品种及其它乳化剂均对其EC不同程度影响;粘度随温度的降低、浓度的升高、pH值的升高而增大,且当pH达11.0时最大。     

Stability of Whey Protein Concentrate/Sunflower Oil Emulsions as Affected by Sucrose and Xanthan Gum

The effect of the addition of sucrose and xanthan gum, protein concentration, and processing method on the stability and destabilization mechanism type of emulsions formulated with two commercial whey protein concentrate powders was described and quantified following system changes with a Turbiscan TMA 2000, a light scattering equipment and a confocal laser scanning microscope. Two different processing methods that gave particle sizes with different orders of magnitude were compared: homogenization by ULTRA-TURRAX (UT) and by ultrasound (US). The addition of sucrose to the aqueous phase of emulsions significantly diminished volume-weighted mean diameter (D _4,3) and improved stability. When the aqueous phase contained xanthan gum, the main destabilization mechanism for UT emulsions changed from creaming to flocculation. For US emulsions, although some aggregation was detected by confocal laser scanning microscopy, it was not great enough to modify the backscattering average (BS_av) in the middle zone of the tube (20–50 mm). At low protein concentrations, the profiles corresponded to destabilization of small aggregates. In those conditions, creaming was markedly enhanced as evident from creaming rate values. Independently of aqueous phase composition, US emulsions stabilized by protein concentrations higher than 5 wt% were stable, indicating that whey proteins were good emulsion stabilizers at pH close to 7. This study shows the relevance of protein type on stability and describes for the first time a behavior for whey proteins different from the one reported for caseins in literature.     

酪蛋白酸钠膜的水分吸附特性

作者以大豆蛋白酪蛋白酸钠(NaCas)膜为对象,从吸附动力学和水分吸附等温线研究了蛋白膜的水分吸附特性.NaCas膜水分达到平衡所需要的时间受到所处相对湿度(RH)条件和增塑剂含量的影响.RH和增塑剂含量越低,达到平衡的时间越短;反之,则越长.TGase改性明显降低了蛋白膜的水分吸附速率及达到平衡的水分含量.NaCas膜水分吸附等温线数据能很好地与GAB模型吻合.     

Creaming Stability of Oil-in-Water Emulsions Formed with Sodium and Calcium Caseinates

Creaming stability of emulsions formed with calcium caseinate, determined after storage of emulsions at 20 °C for 24 h, increased gradually with an increase in protein concentration from 0.5% to 2.0%; further increases in caseinate concentration had much less effect. In contrast, the creaming stability of sodium caseinate emulsions showed a decreased with an increase in protein concentration from 0.5% to 3.0%. Confocal laser micrographs of emulsions formed with >2% sodium caseinate showed extensive flocculation of oil droplets with the appearance of a network structure. However, emulsions formed with calcium caseinate or emulsions formed with low concentrations of sodium caseinate (0.5% and 1.0%) were homogenous with no sign of flocculation.     

盐及酪蛋白酸钠对藜麦面团及面条品质的影响

本文以藜麦面为研究对象,通过添加KCl、NaCl、酪蛋白酸钠以改善藜麦面团的性质,研究了不同处理条件对藜面团质的硬度、咀嚼性、黏度等质构特性以及储能模量、损耗模量、复合粘度等流变学特性的影响。结果表明:当添加的水量为50%藜麦面团成型的光滑程度、弹性较好;当藜麦面中加入1.5%酪蛋白酸钠+1% KCl所制备的藜麦面团粘性适中、硬度和弹性较好;NaCl、KCl、酪蛋白酸钠的加入,均可改善面团的G'、G'、黏度,1.5%酪蛋白酸钠+1% KCl加入,可增大藜麦面团的G'、G'、黏度;NaCl和酪蛋白酸钠都可以明显的改善藜麦面条吸水率,NaCl可降低藜麦面条的干物质损失率,KCl的作用与之相反,而酪蛋白酸钠与1% KCl联合使用,在增加其吸水率的同时减少了干物质损耗率,当同时添加2.0%酪蛋白酸钠和1% KCl条件下达到最适,而且恢复能力达到最佳;酪蛋白酸钠与1% KCl可增加藜麦面条表面片层的致密程度。因此,1.5%酪蛋白酸钠+1% KCl的添加量对藜麦面团的弹性、硬度、咀嚼性均达到最佳,同时添加2.0%酪蛋白酸钠和1% KCl能显著（P<0.05）改善藜麦面条的蒸煮损失及干物质损失率,降低面汤浊度,还可以增加藜麦面条的硬度,从而增加其咀嚼性。     

Rheological Behavior of High-Concentration Sodium Caseinate Dispersions

ABSTRACT: Apparent viscosity and frequency sweep (G′, G″) data for sodium caseinate dispersions with concentrations of approximately 18% to 40% w/w were obtained at 20 °C; colloidal glass behavior was exhibited by dispersions with concentration ≥23% w/w. The high concentrations were obtained by mixing frozen powdered buffer with sodium caseinate in boiling liquid nitrogen, and allowing the mixtures to thaw and hydrate at 4 °C. The low-temperature G′−G″ crossover seen in temperature scans between 60 and 5 °C was thought to indicate gelation. Temperature scans from 5 to 90 °C revealed gradual decrease in G′ followed by plateau values. In contrast, G″ decreased gradually and did not reach plateau values. Increase in hydrophobicity of the sodium caseinate or a decrease in the effective volume fraction of its aggregates may have contributed to these phenomena. The gelation and end of softening temperatures of the dispersions increased with the concentration of sodium caseinate. From an Eldridge–Ferry plot, the enthalpy of softening was estimated to be 29.6 kJ mol⁻¹. Practical Application: The results of this study should be useful for creating new products with high concentrations of sodium caseinate.     

酪朊酸钠酶解液的分级膜分离的研究

利用截留不同分子质量(10ku、5ku、3ku和1ku)的超滤膜将水解度为11 5 %的酪朊酸钠水解液按分子质量大小分为5级,利用SDS -PAGE研究了酪朊酸钠水解液的分子质量分布及分级膜的分离效果。结果表明,分级膜分离方法对酪朊酸钠水解液中的混和肽类能按照分子量大小进行有效的分离。     

高酰基结冷胶/酪蛋白酸钠复合凝胶粘弹行为的研究

本文研究了酪蛋白酸钠浓度、结冷胶浓度、离子和测试条件对高酰基结冷胶/酪蛋白酸钠复合凝胶粘弹性的影响。结果表明:高酰基结冷胶/酪蛋白酸钠共混体系为典型的切力变稀流体,表观粘度随着酪蛋白酸钠浓度的升高而降低,而随着阳离子浓度的增大出现先增大后减小的变化趋势。压缩速度对复合凝胶硬度几乎无影响,而内聚性和弹性则随着压缩速度的增加而增大。内聚性随着压缩应变的增大出现先增大后减小的变化趋势。复合凝胶的硬度和弹性随着酪蛋白酸钠浓度的增加而下降,但复合凝胶的内聚性对酪蛋白酸钠浓度不敏感。高酰基结冷胶浓度越高,复合凝胶的硬度和弹性越大。相对于一价离子而言,二价离子形成的凝胶更强且用量更少。钾离子的添加对复合凝胶保水性影响较弱,而钙离子的添加则可以提高复合凝胶的保水性。     

水相pH和Na+对微晶纤维素与猪油的Pickering乳液稳定性的影响

考察水相pH和Na+浓度对微晶纤维素（MCC）和猪油形成的Pickering乳液稳定性的影响。分别将不同pH和含有1% MCC的不同Na+浓度的水相与等体积的油相混合、制备MCC-猪油Pickering乳液,分析不同水相pH（pH4~9）和不同Na+浓度（0~500 mmol/L）条件下,乳液的外观结构、乳析指数、微观结构、粒径、Zeta电位以及乳液流变特性的变化。结果表明,在pH5~8条件下,MCC-猪油Pickering乳液均未出现明显分层现象,且乳析指数未发生变化,乳滴粒径小于pH4和pH9条件,具有更好的黏度和抗剪切能力,其中,在pH6条件下表现出最好的稳定效果。当Na+浓度在300 mmol/L及以上时,随着静置时间的延长,乳液稳定性下降的越快;Na+浓度为400 mmol/L时,乳液静置3 d会出现分层现象。随着Na+浓度的升高,静电屏蔽作用使得乳液颗粒粒径不断增大,Zeta电位绝对值降低,黏度和抗剪切能力下降。中低pH（pH5~8）水相及低Na+浓度（≤300 mmol/L）水相条件下MCC-猪油Pickering乳液具良好的乳化稳定性,但pH4和pH9及高Na+浓度（>300 mmol/L）水相条件下乳液的稳定性欠佳。探讨不同pH和Na+浓度条件对MCC-猪油Pickering乳液乳化稳定性的影响及其原理,为其在功能性预乳化肉制品的加工与应用提供一定参考。     

pH值对低酯果胶/酪蛋白酸钠复合体系流变及结构特性的影响

为研究pH值对低酯果胶/酪蛋白酸钠复合体系流变及结构特性的影响,分别在不同酸性条件下（pH 3.0、3.5、4.0、4.5、5.0、5.5）对复合体系的静态剪切及动态黏弹流变特性、Zeta电位、粒径、浊度、微观结构进行测定。结果表明：复合体系流变特性呈两段式变化,在pH 3.0～4.0时,随pH值的增大,复合体系流体指数n和tanδ均增大,稠度系数K减少;在pH 4.5～5.5时,体系n和tanδ骤减后继续增加,且增加程度更大,K骤增后继续减少。复合体系Zeta电位值随着pH值的增大而降低。Zeta电位值在pH 3.0～4.0时为正,在pH 4.5～5.5时为负。复合体系粒径和浊度值均随着pH值的增大呈先增大后减小的趋势,在pH 4.5时达到最大。随着pH值的降低,复合体系微观结构由杂乱变得细密。在pH 3.0～4.0时,体系以低酯果胶附着在酪蛋白表面结构为主;在pH 4.5～5.5时,体系中低酯果胶的网状结构更明显。因此,pH值的变化会改变复合体系的流变及结构特性,从而影响体系的稳定性。