不同乳化剂制备乳状液对大豆蛋白凝胶强度影响

通过静置分层实验和离心分层实验考察了不同乳化剂(卵磷脂、Tween20、大豆蛋白、卵清蛋白和酪蛋白)、p H(3、4、5、6、7、8)、氯化钠浓度(10、50、100、150、200 mmol/L)以及热处理(90℃、30 min)对机械乳化法和超声乳化法制备乳状液稳定性的影响;并考察p H 7及不同盐浓度(0 mmol/L和200 mmol/L)条件下不同乳状液对热诱导大豆蛋白凝胶15%(w/v),90℃加热30 min)凝胶强度的影响。结果表明,小分子乳化剂(卵磷脂和Tween20)制备的乳状液的稳定性优于大分子乳化剂(大豆蛋白、卵清蛋白以及酪蛋白)制备的乳状液;超声法制备的乳状液的稳定性高于机械法制备的乳状液;以超声乳化得到的卵清蛋白乳状液为溶剂制备的大豆蛋白凝胶强度最好;氯化钠的加入可以有效提高凝胶的强度。     

乳清蛋白水解物结合吐温对O/W型乳状液稳定性的影响

探讨乳清蛋白水解物(whey protein hydrolysate,WPH)对Tween 20制备的大豆油水包油型乳状液(10%,p H7.0)稳定性的影响。利用中性蛋白酶对乳清蛋白进行限制性水解(60 min)具有最高的乳化活性和乳化稳定性(P0.05),不同浓度的WPH与Tween 20共同制备乳状液的WPH乳化稳定性能够明显增加(P0.05)。其中,5 mg/m L的WPH与Tween 20形成了最稳定的乳状液,具有最高的浊度和ζ-电势(P0.05),并具有最小的体积平均粒径(P0.05)。这主要是较高浓度的WPH会与Tween 20在界面上形成竞争吸附。因此,我们的研究结果表明,经过限制性水解得到的WPH可作为助乳化剂应用在食品乳状液中来提高其稳定性。     

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。     

大豆油乳状液体系氧化稳定性影响因素的研究

研究了乳状液体系中不饱和脂肪酸的氧化机制，重点探讨了乳化剂种类、用量、pH和EDTA对大豆油乳化体系（O／W）氧化稳定性的影响。结果显示：乳化剂种类和pH对于乳状液体系的氧化稳定性有显著影响，对于阴离子乳化剂SDS稳定的乳状液，pH4．0的氧化速率比pH7．0和9．0快得多；对于非离子乳化剂Tween20稳定的乳状液，pH的影响不显著；对于阳离子乳化剂CTAB稳定的乳状液，随着pH的升高，氧化速率变快；同时在pH4．0条件下，氧化速率SDS〉CTAB〉Tween20，而在pH7．0和9．0条件下，氧化速率CTAB〉SDS≌Tween20。乳状液体系中自带的微量金属离子对于体系也有相当大的影响，随着金属离子螯合剂EDTA浓度的增加，其乳状液氧化速率显著降低。乳化剂用量也会影响体系的氧化稳定性，随着乳化剂用量的增加，乳状液的氧化稳定性变差，这种稳定性的弱化是由于粒径变小、油滴表面积增大引起的。     

紫苏籽油乳状液的制备及其稳定性评价

将富含α-亚麻酸的紫苏籽油制备成水包油型(O/W)乳状液后,其稳定性、水溶性得到改善,并可作为ω-3多不饱和脂肪酸的传递系统,应用于功能食品的开发。分别采用阿拉伯胶、HI-CAP 100、纯胶2 000、可溶性大豆多糖、酪蛋白酸钠和大豆分离蛋白制备紫苏籽油乳状液,研究乳化剂对乳状液粒径、黏度及物理稳定性的影响。结果显示:4%阿拉伯胶制备的乳状液粒径最小(0.678μm),粒径主要分布在0.1~10μm之间,随着乳化剂浓度的增大,乳状液的黏度不断升高,且不稳定性指数和Slope值逐渐降低,其中,除HI-CAP 100和酪蛋白酸钠外,乳化剂质量分数≥4%时,乳状液稳定性良好。     

不同乳化剂对油酸和亚油酸乳状液稳定性的影响

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。     

界面组成对乳化颗粒填充乳清蛋白凝胶强度及持水性的影响

考察了p H(3、7)、氯化钠浓度(50、200mmol/L)以及热处理(90℃、30min)对不同乳化剂(乳清分离蛋白、Tween20、Tween20+马铃薯蛋白水解物)制备O/W乳状液分层稳定性的影响。并以凝胶持水性和凝胶强度为指标,考察了p H和氯化钠浓度对上述不同界面组成的乳化颗粒填充乳清蛋白热诱导凝胶性质的影响。结果表明,以乳状液为溶剂制备的凝胶持水性与凝胶强度高于以水为溶剂制备的凝胶。加入一定量的氯化钠有助于乳状液凝胶持水性与凝胶强度的增加。研究表明,p H和盐浓度对乳状液填充凝胶强度均有影响,乳状液性质对乳状液填充凝胶强度和持水性有一定影响。     

乳化体系中花生油氧化稳定性的研究

主要探讨花生油乳化体系中乳化剂类型、用量、pH值、EDTA、温度等对花生油氧化稳定性的影响,结果显示:乳化剂种类和pH对于乳状液体系的氧化稳定性有显著影响,阴离子乳化剂SDS稳定的乳化液,pH4.0的氧化速率最快;非离子乳化剂Tween20稳定的乳化液,pH的影响不是很显著;阳离子乳化剂CTAB稳定的乳化液,随着pH的升高,氧化速率变快。乳化液体系中微量金属离子对于体系也有相当大的影响,随着金属离子螯合剂EDTA浓度的增加,其乳化体系中花生油的氧化速率显著降低。乳化剂用量也会影响体系的氧化稳定性,随着乳化剂用量的增加,乳化乳化体系中花生油的氧化稳定性降低。     

葵花籽蛋白水解物对水包油型乳状液物理和氧化稳定性的影响

利用碱性蛋白酶对葵花籽蛋白进行适度水解后,将葵花籽蛋白水解物(SSH)添加到以单甘酯作为乳化剂制备的乳状液中,通过测定乳状液的乳化活性、乳化稳定性、粒径、絮凝指数、凝结指数以及乳状液贮藏14 d过氧化值和丙二醛含量的变化,评价SSH对乳状液物理和氧化稳定性的影响。结果表明:添加SSH可显著提高乳状液的乳化活性、乳化稳定性、絮凝和凝结稳定性,显著降低乳状液的粒径;SSH添加量为1.0%时,乳状液具有较好的物理稳定性,同时又具有较好的氧化稳定性。     

乳化剂类型、浓度及水相pH对水包核桃油乳状液物理稳定性的影响

为了了解在水包核桃油乳状液中乳化剂类型、浓度及水相p H对其物理稳定性的影响,考察四种乳化剂即乳清分离蛋白(WPI)、十二烷基磺酸钠(SDS)、十二烷基三甲基溴化铵(DTAB)以及失水山梨醇聚氧乙烯酯(Tween20)在p H3.0和p H7.0条件下形成稳定的水包核桃油乳状液所需要的最低浓度。结果表明,p H对阳离子表面活性剂DTAB、非离子表面活性剂Tween20乳化效果影响较大,在p H3.0和7.0条件下形成稳定乳状液所需DTAB最低浓度分别为0.8%、2.0%,而Tween20最低浓度分别为0.6%、0.3%;p H(等电点除外)对两性大分子表面活性剂WPI和阴离子表面活性剂SDS的乳化效果影响较小。研究结果表明不同类型乳化剂在不同p H条件下对水包核桃油乳状液的物理稳定性影响差异较大。     

苹果提取物对花生蛋白水解物水包油乳状液氧化稳定性的影响

将苹果提取物(apple extract,AE)添加到花生蛋白水解物(peanut protein hydrolysate,PPH)制备的乳状液中,通过测定絮凝稳定性、凝结稳定性、氧化稳定性、色氨酸荧光损失及蛋白分布等指标,探讨PPH与AE对乳状液脂质氧化的联合抑制作用以及乳状液的氧化稳定性。研究结果表明,蛋白质与多酚化合物能够形成共价结合,提高乳状液的稳定性。还能增加PPH在界面上的吸附量,有效的降低PPH制备的乳状液在贮藏期间的过氧化物和丙二醛的生成量。界面膜上的AE和PPH协同作用提供改进的物理屏障,促进乳状液在储存期间的氧化稳定性。添加AE浓度为100μg/mL时,乳状液在储藏期间最为稳定,但是AE的添加量超过100μg/mL会与PPH形成竞争吸附,影响PPH在界面上的分布,导致稳定性下降。     

Antioxidant and emulsifying properties of potato protein hydrolysate in soybean oil-in-water emulsions

The efficacy of a previously developed antioxidative potato protein hydrolysate (PPH) for the stabilisation of oil droplets and inhibition of lipid oxidation in soybean oil-in-water (O/W) emulsions was investigated. Emulsions (10% lipid, pH 7.0) with PPH-coated oil droplets were less stable than those produced with Tween 20 (P < 0.05). However, the presence of PPH, whether added before or after homogenisation with Tween 20, retarded emulsion oxidation, showing reduced formation of peroxides up to 53.4% and malonaldehyde-equivalent substances up to 70.8% after 7-d storage at 37 °C (P < 0.05), when compared with PPH-free emulsions. In the emulsions stabilised by PPH + Tween 20, 8–15% of PPH was distributed at the interface. Adjustment of the pH from 3 to 7 markedly increased ζ-potential of such emulsions (P < 0.05). Inhibition of lipid oxidation by PPH in soybean O/W emulsions can be attributed to both chemical and physical (shielding) actions.     

Iron-Catalyzed Oxidation of Menhaden Oil as Affected by Emulsifiers

The ability of Tween 20 and whey protein isolate (WPI) to influence lipid oxidation was investigated by evaluating the effects of emulsifier concentration and physical location on iron-catalyzed oxidation of emulsified Menhaden oil. Addition of Tween 20 or WPI to the aqueous phase of a 0.5 wt% Tween 20 stabilized emulsion increased lipid oxidation as determined by both thiobarbituric acid reactive substances (TBARS) and lipid peroxides. Tween 20 (2.0 wt%) and WPI (0.05–1.0 wt%) combinations inhibited TBARS formation 23–60%. Oxidation of a WPI-stabilized emulsion decreased with decreasing pH (3–7) but in a Tween 20 stabilized emulsion oxidation increased with decreasing pH. The low oxidation rate for the WPI-stabilized emulsion at pH 3 was increased when Tween 20 displaced WPI from the droplet interface. Results indicate that the oxidative stability of emulsifed Menhaden oil could be increased by controlling emulsifier type, location and concentration.     

Effects of water-soluble soybean polysaccharide on rheological properties,stability and lipid digestibility of oil-in-water emulsion during in vitro gastrointestinal digestion

Water-soluble soybean polysaccharide (SSPS) is a naturally occurring emulsifier. SSPS was used as the sole emulsifier to stabilize an oil-in-water (O/W) emulsion. The effects were investigated of different SSPS concentrations (3–20% (w/w)) on the lipid digestibility, rheological properties and stability of O/W emulsions during in vitro digestion model. The droplet size of the emulsions tended to increase during the oral phase because the emulsions were unstable and droplets coalesced, except with a SSPS concentration of 20% (w/w). The presence of SSPS markedly reduced the free fatty acid (FFA) content after its stabilized O/W emulsion passed through in vitro gastrointestinal digestion. The amount of FFA significantly decreased as the concentration of SSPS increased due to SSPS stabilization film on oil droplet surface and high viscous system. SSPS may be an attractive alternative ingredient to control the lipid digestibility of emulsions for various food products.     

过氧化氢酶固体脂质纳米粒的制备

通过W/O/W两步乳化技术和乳化-溶剂挥发法制备装载亲水性大分子的固体脂质纳米粒。结果表明:聚乳酸-羟基乙酸共聚物(PLGA)是一种有效的乳化剂,其浓度对粒子的大小、电位有一定影响。乳化工艺为第一步乳化超声20 s和第二步乳化超声30 s,选用二氯甲烷-丙酮作为有机溶剂,乳化剂PLGA的添加量为15%,此时包封率达到58.75%,得到的粒子形态均一、分布均匀;体外释放试验表明:释药性能符合长效制剂特征,且释放后的酶结构并未遭到严重破坏。     

Preparation and impact of multiple (water-in-oil-in-water) emulsions in meat systems

The aim of this paper was to prepare and characterise multiple emulsions and assess their utility as pork backfat replacers in meat gel/emulsion model systems. In order to improve the fat content (in quantitative and qualitative terms) pork backfat was replaced by a water-in-oil-in-water emulsion (W₁/O/W₂) prepared with olive oil (as lipid phase), polyglycerol ester of polyricinoleic acid (PGPR) as a lipophilic emulsifier, and sodium caseinate (SC) and whey protein concentrate (WP) as hydrophilic emulsifiers. The emulsion properties (particle size and distribution, stability, microstructure) and meat model system characteristics (composition, texture, fat and water binding properties, and colour) of the W₁/O/W₂, as affected by reformulation, were evaluated. Multiple emulsions showed a well-defined monomodal distribution. Freshly prepared multiple emulsions showed good thermal stability (better using SC) with no creaming. The meat systems had good water and fat binding properties irrespective of formulation. The effect on texture by replacement of pork backfat by W₁/O/W₂ emulsions generally depends on the type of double emulsion (associated with the hydrophilic emulsifier used in its formulation) and the fat level in the meat system.     

Effect of α-lactalbumin and β-lactoglobulin on the oxidative stability of 10% fish oil-in-water emulsions depends on pH

The objective of this study was to investigate the influence of pH on lipid oxidation and protein partitioning in 10% fish oil-in-water emulsions prepared with different whey protein isolates with varying ratios of α-lactalbumin and β-lactoglobulin. Results showed that an increase in pH increased lipid oxidation irrespective of the emulsifier used. At pH 4, lipid oxidation was not affected by the type of whey protein emulsifier used or the partitioning of proteins between the interface and the water phase. However, at pH 7 the emulsifier with the highest concentration of β-lactoglobulin protected more effectively against oxidation during emulsion production, whereas the emulsions with the highest concentration of α-lactalbumin were most stable to oxidation during storage. These differences were explained by differences in the pressure and adsorption induced unfolding of the individual protein components.     

OPTIMIZATION OF EMULSIFICATION AND MICROENCAPSULATION OF EVENING PRIMROSE OIL AND ITS OXIDATIVE STABILITY DURING STORAGE BY RESPONSE SURFACE METHODOLOGY

ABSTRACT

Microencapsulation is a technique by which small droplets of liquid or solid particles are coated with a thin film of wall materials to protect susceptible ingredients in food products to assure their quality or effectiveness. Microencapsulation of liquid lipid into powdery matrixes of wall materials includes two unit operations: emulsification of the lipid with an aqueous solution of wall material and drying of the emulsion. The effects of hydrophile–lipophile balance (HLB) value, emulsifier content and oil content on the evening primrose oil‐in‐water emulsion stability were studied by response surface methodology (RSM). The HLB value, emulsifier content and oil content all had significant effects on the emulsion stability (P < 0.05). Of them, the HLB value and emulsifier content contributed more effects than the oil content. The optimized HLB value, emulsifier content and oil content were used to mix with wall materials: gum arabic (GA), maltodextrin (MD) and/or sodium caseinate (NaC). The oil was encapsulated with these materials individually or in combination by spray‐drying, and their oxidative stability during storage was compared. The microcapsules with a single wall material were relatively susceptible to oxidation than those with multiple wall materials. The most desirable composition of the mixture of GA, MD and NaC by RSM was 17.2, 75 and 7.8%, respectively.

PRACTICAL APPLICATIONS

Response surface methodology (RSM) provided a valuable means to help us understand the relative or interactive effects of three important parameters: HLB value, emulsifier content and oil content on the emulsion stability of the oil‐in‐water (o/w) system. The information obtained would be useful for the preparation of similar o/w emulsion system as needed in some product development for foods. In addition, the effects of gum arabic, maltodextrin and sodium caseinate on the oxidative stability of microencapsulated oil were also studied by RSM. The results revealed the relative or interactive effects of these materials and gave the optimal conditions in minimizing the oxidative instability in this study. Since these wall materials are readily available and widely used in a variety of products, the information provided by this study would be useful for product‐developing professionals to use these materials more efficiently in terms of obtaining optimal microencapsulated products against lipid oxidation and cost effectiveness.     

W/O/W型复乳的制备优化及包埋矢车菊素-3-葡萄糖苷效果分析

研究制备方法和乳化剂对W/O/W型复乳稳定性的影响,优化工艺参数,并研究体系包埋矢车菊素-3-葡萄糖苷（cyanidin-3-glucoside,C-3-G）的效果。得到优化条件：初乳搅拌速率15 500 r/min、复乳搅拌速率7 000 r/min、油相乳化剂聚甘油蓖麻醇酯添加量16%、亲水性乳化剂的亲水亲油平衡值10、亲水性乳化剂添加量10%,优化后离心保留率达到80.25%。利用优化得到的复乳体系包裹C-3-G,发现复乳对C-3-G有良好的包裹能力,复乳对C-3-G的载药量为1 500 mg/L,包封率为98.08%,且C-3-G的包埋提高内水相渗透压和复乳稳定性。