天然大豆分离蛋白稳定高内相乳液的制备及表征

本研究以天然大豆分离蛋白(SPI)为原料,探究了其稳定高内相乳液(HIPEs)的基本性质。对SPI的SDS-PAGE电泳、平均粒径,ζ电位进行表征与测定,探讨了蛋白浓度对稳定HIPEs显微结构、油滴粒径及流变性质的影响。结果表明:实验室制备SPI颗粒性质优良,为天然低变性率SPI。新鲜制备的HIPEs呈凝胶状,将其放置在室温下储藏6个月后仍保持稳定,稳定性优于牛血清白蛋白(BSA)及酪蛋白酸钠(SC)稳定的HIPEs。显微结构图表明其内部存在紧密堆积的网络结构。蛋白浓度为1.0 wt%时,SPI稳定HIPEs的最高油相体积分数为0.87。油相体积分数为0.8时,SPI稳定HIPEs的最低蛋白浓度为0.6 wt%。流变性质表明HIPEs内部存在以弹性为主的凝胶网络结构,随着蛋白浓度的增大,油滴粒径逐渐减小且呈均匀分布,粘弹性能逐渐增大。本研究对于开发新型高脂健康食品提供了新思路。     

南瓜籽分离蛋白颗粒稳定的高内相皮克林乳液的 制备及应用研究

为了得到一种性能优异的天然来源的颗粒稳定剂,以南瓜籽为原料,采用碱溶酸沉法制备了南瓜籽分离蛋白（PSPI）,利用反溶剂法制备了南瓜籽分离蛋白颗粒（PSPI Ps),并以PSPI Ps为稳定剂制备了高内相皮克林乳液（HIPPEs）。考察了水相PSPI Ps质量分数、油相体积分数和水相pH对HIPPEs微观结构、粒径和流变性能的影响,并通过扫描电子显微镜以及激光共聚焦扫描显微镜对HIPPEs的界面结构进行了表征。另外,探究了HIPPEs的耐酸碱能力、常温储存稳定性、热稳定性和光稳定性。结果表明：制备的HIPPEs为O/W型微米级乳液;水相PSPI Ps质量分数在0.2%～2.0%范围时,随着PSPI Ps质量分数的增加,乳液液滴粒径显著减小,凝胶强度显著增加;油相体积分数在50%～84%范围时,随着油相体积分数的增加,乳液液滴粒径增加,而凝胶强度减小;水相pH在3～9范围时,随着水相pH的增加,乳液液滴粒径先增大后减小,凝胶强度先减小后增加;所制备的HIPPEs具有良好的耐酸碱能力、常温储存稳定性、热稳定性以及光照稳定性。综上,PSPI Ps是一种性能优异的高内向乳液稳定剂。     

油酸乙氧基化物与硬脂酸乙氧基化物的合成与性能

以油酸和硬脂酸为原料,与环氧乙烷(EO)反应得到平均EO加合数为15的油酸乙氧基化物(OAE-15)和硬脂酸乙氧基化物(SAE-15)。通过FT-IR以及化学方法确定了生成物的结构。对OAE-15和SAE-15的物化性能和应用性能进行了测试并进行了对比,结果表明:SAE-15的去污性能优于OAE-15,降低表面张力的能力和效率都高于OAE-15,二者泡沫性能相当;OAE-15的润湿性能和乳化性能都优于SAE-15。     

高内相Pickering乳液替代脂肪对肉糜制品特性的影响

将β-乳球蛋白纳米颗粒(β-lactoglobulin nanoparticles,β-LGNPs)稳定的高内相Pickering乳液(high internal phase Pickering emulsion,HIPEs)应用于肉糜制品中替代动物脂肪,以改善产品品质并减少饱和脂肪酸摄入.结果表明,随着乳液替代比例的...     

脱脂芝麻粕稳定高内相乳液的制备及特性

分别以去皮和带皮脱脂芝麻粕为稳定剂制备了高内相乳液(HIPEs),研究了该乳液的基本性质,探讨了脱脂芝麻粕添加量、油相体积分数、体系pH以及离子浓度对HIPEs微观结构、粒径及流变性质的影响。结果表明:油相体积分数为0. 75时,去皮和带皮脱脂芝麻粕稳定HIPEs的最低添加量分别为5. 0%和3. 0%;去皮和带皮脱脂芝麻粕添加量为5. 0%时,其稳定HIPEs的最高油相体积分数分别为0. 75和0. 85;脱脂芝麻粕在中性pH以及添加适量NaCl下,制备的HIPEs更稳定。流变性质研究表明,HIPEs内部存在以弹性为主的凝胶网络结构,随着脱脂芝麻粕添加量的增大,HIPEs粒径逐渐减小且呈均匀分布,黏弹性能逐渐增大。     

两步乳化法改善蛋白基高内相乳液稳定性

本研究以天然牛血清白蛋白（BSA）为蛋白模型,针对其制备的蛋白基高内相乳液（HIPEs）稳定性差的问题,在对蛋白不改性的基础上,改变乳化方式即采用两步乳化法能产生显著的改善效果。先用高能均质方式（高速均质30000 r/min、超声、微射流）制备出油相（?）为0.2,体积平均粒径（d4,3）在17.60~0.425 μm范围内的初始乳液,即微乳滴;再用低能均质方式（高速均质13500 r/min）,以微乳滴为类Pickering稳定剂制备?为0.8的HIPEs。通过改变蛋白浓度和制备初始乳液的均质能量,制备了不同特性的HIPEs,并对初始乳液的界面蛋白吸附率（AP%）、粒径进行了表征,同时对HIPEs室温存储20 d前后的外观、微观结构和流变特征进行了观测。最后对初始乳液进行了去除游离蛋白的对比实验和HIPEs的热稳定性测试。结果显示蛋白浓度在1 wt%最合适,但即使低至0.1 wt%依然可以制备出倒置不流动的HIPEs。当微乳滴的d4,3在2.16 μm及以下时可以有效提升HIPEs的稳定性。研究表明,正是由于微乳滴的存在显著改善了HIPEs的储藏稳定性和热稳定性。     

大豆乳清蛋白/大豆种皮多糖聚合物对高内相乳液稳定性的影响

通过向黄浆水中添加多糖，使大豆乳清蛋白(WSP)与大豆种皮多糖(SHP)发生静电相互作用形成聚合物，用于制备稳定的高内相乳液(HIPEs)。结果表明:随着多糖添加量的增加，聚合物中多糖含量增加，蛋白质含量降低，聚合物微观结构更加致密，热稳定性提高。通过傅里叶变换红外光谱、扫描电子显微镜、差示扫描量热仪测定WSP和SHP之间存在静电相互作用。此外，研究证实SHP/WSP聚合物可以稳定75%油相的HIPEs，且随着SHP/WSP聚合物中多糖含量增加，HIPEs表观黏度增加，G''和G''增加。通过测定热处理或冻融前、后HIPEs的流变及多重光散射，证实SHP/WSP聚合物稳定HIPEs具有良好的热稳定性，且冻融后重新剪切可再次形成稳定的HIPEs。本研究结果为黄浆水的利用提供了新思路，也为蛋白多糖聚合物稳定乳液方面的研究提供理论参考。     

高内相乳液的制备及在食品中的应用

高内相乳液为分散相体积分数在74.05%以上的乳液,在食品、化妆品、制药、材料和石油工业上被广泛应用。近年来,以生物大分子和固体颗粒代替小分子表面活性剂来稳定高内相乳液的方法引起研究人员的注意。其中,探索生物来源的固体颗粒是该领域的研究热点之一。此外,高内相乳液作为功能因子的传递体系表现出独特的优势,可有效提高功能因子的稳定性和生物利用度。本文在以往研究的基础上,综述稳定高内相乳液的乳化剂种类,制备方法及在食品领域的应用情况,并展望其发展前景。     

乳滴粒径和皂皮皂苷浓度对高内相乳液凝胶及其模板油凝胶构建的影响

以天然皂皮皂苷为乳化剂,采用激光散射技术、动态流变学以及激光共聚焦显微技术探究了乳滴粒径皂皮皂苷质量分数对高内相乳液凝胶（HIPE-gels）及其模板制备的油凝胶流变特性和微结构的影响。结果表明： HIPE-gels和油凝胶均表现出剪切稀化特性,油滴间形成非共价物理交联的弹性凝胶结构;随粒径减小,乳滴堆积紧密,赋予HIPE-gels和油凝胶更强的凝胶网络结构和黏弹性;皂皮皂苷质量分数较低（≤1.5%）时,乳滴间的静电排斥作用对HIPE-gels的黏弹性和强度起主导作用,当皂皮皂苷质量分数较高（>1.5%）时,游离皂皮皂苷分子提高了HIPE-gels的凝胶强度,而油凝胶强度随乳滴粒径减小和皂皮皂苷质量分数的增加得到强化。     

脂肪酸甲酯乙氧基化物磺酸钠的性能

制备了脂肪酸甲酯乙氧基化物磺酸钠(C₁₆₁₈FMEE-7SO),研究其基本物化性能,并与脂肪酸甲酯磺酸钠(C₁₆₁₈MES)进行比较。结果表明,C₁₆₁₈FMEE-7SO的表面活性低于C₁₆₁₈MES,耐钙、耐碱性高于C₁₆₁₈MES,起泡能力低于C₁₆₁₈MES,润湿时间长于C₁₆₁₈MES;C₁₆₁₈FMEE-7SO与液体石蜡形成的乳液稳定性高于C₁₆₁₈MES,与大豆油形成的乳液稳定性低于C₁₆₁₈MES;30℃时,C₁₆₁₈FMEE-7SO的去污力低于C₁₆₁₈MES,低温(11℃)时,C₁₆₁₈FMEE-7SO的去污力(JB-02、JB-03污布)高于C₁₆₁₈MES。     

Rheological properties of corn oil emulsions stabilized by commercial micellar casein and high pressure homogenization

The rheological behavior of corn oil emulsions prepared by high pressure homogenization (HPH) was investigated. Coarse emulsions of corn oil (10-30 g oil/100 g emulsion) in casein dispersions containing 0.5-3.5 g micellar casein/100 g casein dispersion in an oil-free basis were homogenized at 0-300 MPa. Flow behavior under continuous increasing (0-150 s⁻¹) or decreasing (150-0 s⁻¹) shear rate was tested. Emulsions that showed macroscopic change in consistency were tested for viscoelasticity (G′). Homogenization of emulsions with low oil concentration (10 g/100 g) resulted in Newtonian behavior for all treatment pressures. The rheological behavior of emulsions with higher oil concentration (30 g/100 g) was dependent on casein concentration in the aqueous phase and varied from Newtonian to shear thinning. Homogenization pressures between 20 and 100 MPa induced the formation of a gel-like structure possibly through pressure-induced interactions between caseins surrounding adjacent droplets.     

Construction of plant-based adipose tissue using high internal phase emulsions and emulsion gels

There is growing consumer demand for plant-based meat and seafood analogs due to ethical, environmental, and health concerns associated with the production of real meat and seafood. Meat and seafood analogs should mimic the desirable appearance, texture, and flavor of the real versions. In this study, we investigated the possibility of using advanced emulsion technologies to create plant-based adipose tissue. High internal phase emulsions (HIPEs) were formulated that consisted of concentrated dispersions of soybean protein-coated soybean oil droplets. The HIPEs contained 75% soybean oil and 0.25 to 3% soybean protein. At higher protein contents, the HIPEs mimicked the appearance of beef adipose tissue but were too soft at ambient temperature and did not melt upon heating. These problems could be partly overcome by using emulsion gels that consisted of soybean protein-coated soybean oil droplets dispersed in an agar hydrogel. The final composition of these emulsion gels was 60% soybean oil, 2% soybean protein, and 0.25 to 2% agar. The incorporation of the agar increased the hardness of the emulsion gels at ambient temperature and led to melting behavior. Nevertheless, the emulsion gels were still somewhat softer that real beef adipose tissue at ambient temperature and they melted at a higher temperature. These results show that concentrated emulsion gels containing cold-setting polysaccharides may be useful for mimicking the desirable physicochemical attributes of animal adipose tissue but further research is required to more accurately simulate their properties.     

Properties of oil/water emulsions stabilized by casein-acid polysaccharide mixtures

Properties of oil/water emulsions stabilized with the soluble casein-acid polysaccharide mixtures were investigated. Compared to initial protein solutions, higher emulsifying properties of the mixtures are demonstrated. A study is made on the influence of the properties of the mixtures for obtaining thermostable emulsions of hard consistency which could be applied in production of a great variety of foodstuffs. The role of the formation of protein-acid polysaccharide complexes is discussed.     

Rheology and stability of whey protein stabilized emulsions with high CaCl2 concentrations

The influence of pH and CaC1₂ on the rheology and physical stability of emulsions stabilized by whey protein isolate (WPI) has been studied. The particle size, creaming index and shear viscosity of 10 wt% soy bean oil-in-water emulsions (d=0.55 μm) were measured with varying pH (3, 5 and 7) and CaC1₂ concentration (0–150 mM). In the absence of CaCl₂ extensive droplet aggregation occurred around the isoelectic point of the whey proteins (4<pH<6) because of their low electrical charge. In the presence of CaC1₂, extensive droplet aggregation, viscosity enhancement and creaming instability occurred at pH 7 for CaC1₂>3 mM. These effects were much less pronounced in emulsions at pH 3 even at 150 mM CaC1₂. Droplet aggregation, creaming and viscosity of emulsions at pH 5 were fairly independent of CaC1₂ concentration. Droplet aggregation was induced by CaC1₂ probably because of the reduction in electrostatic repulsion between droplets. Re-stabilization of oil-in-water emulsions at high CaC1₂ concentrations was not observed in this study.     

Influence of interfacial composition on oxidative stability of oil-in-water emulsions stabilized by biopolymer emulsifiers

The objective of this research was to evaluate the influence of storage pH (3 and 7) and biopolymer emulsifier type (Whey protein isolate (WPI), Modified starch (MS) and Gum arabic (GA)) on the physical and oxidative stability of rice bran oil-in-water emulsions. All three emulsifiers formed small emulsion droplets (d₃₂ < 0.5 μm) when used at sufficiently high levels: 0.45%, 1% and 10% for WPI, MS and GA, respectively. The droplets were relatively stable to droplet growth throughout storage (d₃₂ < 0.6 μm after 20 days), although there was some evidence of droplet aggregation particularly in the MS-stabilized emulsions. The electrical charge on the biopolymer-coated lipid droplets depended on pH and biopolymer type: −13 and −27 mV at pH 3 and 7 for GA; −2 and −3 mV at pH 3 and 7 for MS; +37 and −38 mV at pH 3 and 7 for WPI. The oxidative stability of the emulsions was monitored by measuring peroxide (primary products) and hexanal (secondary products) formation during storage at 37 °C, for up to 20 days, in the presence of a pro-oxidant (iron/EDTA). Rice bran oil emulsions containing MS- and WPI-coated lipid droplets were relatively stable to lipid oxidation, but those containing GA-coated droplets were highly unstable to oxidation at both pH 3 and 7. The results are interpreted in terms of the impact of the electrical characteristics of the biopolymers on the ability of cationic iron ions to interact with emulsified lipids. These results have important implications for utilizing rice bran oil, and other oxidatively unstable oils, in commercial food and beverage products.     

Influence of pH and CaCl2 on the stability of dilute whey protein stabilized emulsions

The influence of pH and CaCl₂ on the physical stability of dilute oil-in-water emulsions stabilized by whey protein isolate has been studied. The particle size, zeta potential and creaming stability of 0.05 wt% soy bean oil-in-water emulsions (d ≈ 0.53 μm) were measured with varying pH (3 to 7) and CaCl₂ concentration (0 to 20 μM). In the absence of CaCl₂ extensive droplet aggregation occurred around the isoelectric point of the whey proteins (4 < pH < 6) because of their low electrical charge, which led to creaming instability. Droplet aggregation occurred at higher pH when CaCl₂ was added to the emulsions. The minimum concentration of CaCl₂ required to promote aggregation increased as the pH increased. Aggregation was induced in the presence of CaCl₂ probably because of the reduction in electrostatic repulsion between droplets, caused by binding of counter ions to droplet surfaces and electrostatic screening effects.     

米糠制油生产中酸值升高影响因素的研究

通过对米糠压榨制油、米糠浸出制油工艺中物料酸值的变化及影响因素的试验分析,找出了生产工艺中的酸值升高点,并讨论了引起酸值变化的主导因素———解脂酶的活性及其作用。米糠挤压膨化预处理浸出工艺是米糠制油工艺的最佳选择,也是解决米糠浸出制油过程中毛米糠油酸值升高,提高油脂加工得率的行之有效的方法。     

W/O/W emulsions with high internal droplet volume fraction

We prepared water-in-oil-in-water (W/O/W) double emulsions with high internal aqueous droplet fraction using food-based ingredients. These compartmentalised materials were comprised of oil globules dispersed in an external aqueous phase, with the globules themselves containing densely packed inner aqueous droplets. We were able to obtain double emulsions with large globule fractions (up to 45 vol.%) using only 5 vol.% oil (relative to the overall composition). In the final state, the inner droplet fraction within the globules could exceed 90 vol.%. The method was based on two successive emulsification steps, followed by osmotic swelling (transport of water from the external phase to the inner droplets through the oil phase). During the final step, the swelling was controlled by the osmotic pressure mismatch between the external and internal aqueous phases using solutes dissolved at different concentrations. The osmotic swelling model of Mezzenga et al. (Langmuir, 2004, 20, 3574-3582) was re-adapted in the limit of small Laplace pressures to predict the final composition resulting from osmotic equilibration. The internal droplet fraction was lower than that predicted by the model as a consequence of coalescence phenomena occurring during the swelling process. The proposed approach constitutes a valuable guide within the prospect of formulating emulsions with enhanced encapsulation capacity and reduced fat content.