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.     

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.     

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.     

酪蛋白酸钠在咖啡伴侣中的应用

研究了酪蛋白酸钠在咖啡伴侣中的应用特性。将其作为乳化稳定剂和优良蛋白源,配合以海藻酸钠和单甘酯,可使制品冲调后24h无油层析出。     

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。     

混合蛋白酶水解酪朊酸钠工艺的研究

以酪软酸钠为原料,采用混合蛋白酶水解,本文对酶水解工艺参数,小分子肽得率变化进行了系统的研究。本文得出结论:碱性蛋白酶和中性蛋白酶混合使用酶解酪朊酸钠的最适宜条件为:温度为45,pH为6.5,酶解时间为24小时,底物浓度为10%,酶用量为1.55?04u/g.     

酪蛋白酸钠溶液粘度变化的数学模型

研究了浓度为１２－２０％酪蛋白酸钠溶液在６６－９０℃的粘度变化。在ＰＨ值为６．８－７．５的范围内，ＰＨ值对酪蛋白酸钠的粘度没有显著的影响。酪蛋白酸钠溶液粘度的和与溶液的浓度和温度都叶线性关系（Ｒ＾２〉９５％）。酪蛋白酸钠溶液的粘度浓度方程的斜率和截距都与温度呈二次方程的关系（Ｒ＾２＝９４．９１％，Ｒ＾２＝９３．５９％），并由此推导出关于浓度和温度对酪蛋白酸钠溶液粘度相互 半对数方程（Ｒ＾２＝９４．     

Calcium-Induced Destabilization of Oil-in-Water Emulsions Stabilized by Caseinate or by β-Lactoglobulin

The stability to aggregation of 20% soya oil-in-water emulsions stabilized by 0.3 to 2% sodium caseinate or β-lactoglobulin in the presence of calcium chloride solutions was studied using light scattering and electron microscopy. Stability increased with the amount of protein in the emulsion, and decreased with the concentration of added calcium. Growth of particle size with concentration of Ca²⁺ was more in emulsions containing lower concentrations of protein. Sodium chloride at 50 and 100 mM stabilized both systems to the presence of calcium ions. Microstructure and light scattering showed caseinate emulsions formed clusters even at low concentrations of Ca²⁺ while β-lactoglobulin emulsions formed extensive strands.     

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     

微生物转谷氨酰胺酶催化聚合酪蛋白酸钠研究

研究了不同条件下微生物转谷氨酰胺酶 (MTGase)催化酪蛋白酸钠聚合。结果显示 ,MTGase较易催化α 以及β 酪蛋白 ,而不易催化κ 酪蛋白 ,随着酪蛋白量的不断下降 ,而形成的生物聚合物量不断增多。MTGase催化酪蛋白酸钠聚合的较佳条件如下 :酶量 /酪蛋白酸钠比例为 10～ 2 0U/g ,pH 6 0～ 8 0 ,最适催化温度为 37～ 5 0℃。     

Effects of Sodium Caseinate on the Rheological Properties of Starch Pastes

Effects of sodium caseinate on the rheological properties of starch-water pastes have been measured under steady shear conditions. In all cases a power law equation was found to describe the variation of viscosity with shear rate. The sodium caseinate increased the viscosity of the starch pastes and a starch-sodium caseinate synergistic effect occurred. Sodium caseinate caused the swollen starch particles in pastes to increase in volume. It is suggested that this is one of the factors responsible for the observed effects of sodium caseinate on rheological behavior.     

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.     

酪朊酸钠磷酸化结果验证方法研究

酪朊酸钠是一种天然乳化剂，具有良好的乳化，发泡，粘着等功能症，但由于其蛋白质的疏水性度高，影响了其乳化功能性，在总结前人经验的基础上，对其进行了三聚磷酸钠改性。通过对磷酸酪朊 酸钠的差热分析曲线和等电点的测定结果的分析讨论，证明了酪朊酸钠在ＰＨ７－９之间三聚磷酸钠进行改性是成功的，通过三聚磷酸钠改性，发迹了酪朊酸的蛋白质酸结构，酪朊钠分子中加入磷酸酪键是有可能的。     

Functional Properties and Bitterness of Sodium Caseinate Hydrolysates Prepared with a Bacillus Proteinase

The functional and physicochemical characteristics, and bitterness were evaluated on sodium caseinate hydrolysates generated with a commercial Bacillus proteinase complex. At low degrees of hydrolysis (0.5 and 1.0% DH) the hydrolysates compared to the unhydrolyzed substrate had increased emulsion activity at pH 2 and 4. However, higher DH resulted in lower emulsion activities. At pH 8 and 10, the low DH hydrolysates displayed increased foam expansion and decreased foam drainage compared to the starting substrate. The Bacillus proteinase hydrolysates at higher DH had similar bitterness values to tryptic hydrolysates at equivalent DH. However, the Bacillus hydrolysate at 0.5% DH was less bitter (p<0.05) than the tryptic hydrolysate at the same DH.     

Sodium Caseinate and Skim Milk Gels Formed by Incubation with Microbial Transglutaminase

Several suspensions and emulsions containing commercial sodium caseinate or skim milk were gelatinized by Ca²⁺-independent microbial transglutaminase treatment. The characteristics of the gels were largely affected by the enzyme concentrations employed. For caseinate gels generally the higher enzyme concentration gave steep decreases in breaking strength, strain and cohesiveness of the gels. The creep tests on emulsified gels prepared to two different enzyme concentrations showed that the gel made with a higher enzyme concentration was the more viscoelastic. For skim milk gels, the enzyme treatment in higher concentration caused substantial increase of the breaking and hardness while the strain and cohesiveness had little or no changes.     

Moisture Isotherms for Uncooked Meat Emulsions of Different Composition

The equilibrium moisture content of meat emulsions was obtained at different temperatures and fat-protein ratios. Various models were modified after considering the model constants as functions of product temperature and fat-protein ratio. These models were then fitted to predict the major portion of the isotherms. All models except one provided an adequate fit to the experimental data. The heat of de-sorption/sorption decreases with increase in moisture content and approaches a constant value.     

Properties of Laminated Films from Whey Powder and Sodium Caseinate Mixtures and Zein Layers

Corn zein-stearic acid films were laminated to whey powder (WP) and sodium caseinate (SC) mixture (WSM) films. WSM films were prepared at three mass ratios of WP and SC (50:50, 60:40, and 70:30 in w/w) by casting method. WSM films with poor mechanical and barrier properties were produced as the whey powder ratio of WSM increased from 50:50 to 70:30. Corn-zein lamination improved the mechanical and water barrier properties of WSM films by increasing tensile strength (TS) from 4.7-14.5 to 14.0-26.8 MPa and by decreasing water vapor permeabilities (WVP) from 0.432-0.490 to 0.386-0.422 ng m/m² s Pa. However, elongations of corn-zein laminated films were reduced from 64.5-128.0 to 2.6-4.5%. Mechanical and water barrier properties of corn-zein laminated WSM films were affected by the mass ratio of whey powder to sodium caseinate in WSM films. Addition of stearic acid up to 10 g/100 g of corn zein decreased TS and WVP of laminated films to approximately 12 MPa and 0.36 ng m/m² s Pa regardless of mass ratio in WSM film. However, no significant differences in TS and WVP were found with further addition of stearic acids.     

Sodium Caseinate from Skim Milk Powder by Extrusion Processing: Physicochemical and Functional Properties

Sodium caseinate produced on a pilot-plant-scale directly from skim milk powder (SMP) with two-step extrusion process was compared to a commercial product and a sodium caseinate prepared from commercial acid casein by extrusion-processing. The products were compared in terms of physicochemical properties and functional properties, as well as microbiological quality. Although differences existed between the caseinates, overall, those produced from SMP by extrusion appeared comparable to commercial caseinate. Results indicate that a good-quality sodium caseinate with the requisite properties normally associated with commercial sodium caseinate could be produced directly from SMP by extrusion-processing.     

Physical Properties and Oxidative Status of Concentrated-from-Fish Oils Microencapsulated in Trehalose/Sodium Caseinate Matrix

Foods supplemented with omega-3 fatty acids have attracted much attention in the past decade. However, it is difficult to protect polyunsaturated fatty acids from oxidation. Microencapsulation is a technological process used with the aim to protect oils against oxidation or chemical deterioration, to mask unpleasant flavors or retain aromas, and/or to powder polyunsaturated fatty acids for food fortification purposes. The objective of this study was to analyze physical properties and oxidation status of microencapsulated concentrated-from-fish oils. Powders were prepared from emulsions formulated with 10 wt.% of concentrated-from-fish oils as fat phase and 20 or 30 wt.% trehalose solution that also contained 0.5, 2.0, or 5.0 wt.% sodium caseinate as aqueous phase. Encapsulation efficiency was higher for powders coming from 20 wt.% trehalose emulsions, and the percentage of retention of core material increased with increasing sodium caseinate concentration. The powder prepared from 20 wt.% trehalose and 5 wt.% sodium caseinate showed the highest retention of core material. This powder had lower water content and an amorphous matrix. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry method, used for this new application, allowed proving that trehalose/sodium caseinate matrix was efficient for microencapsulation of polyunsaturated oils and that concentrated-from-fish oils was protected from oxidation in powder form. Spectra were very similar to the original oil without any treatments. Most likely, the oxidation products found when core material was extracted were formed during extraction steps.