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.     

Preparation of Monodisperse Food-Grade Oleuropein-Loaded W/O/W Emulsions Using Microchannel Emulsification and Evaluation of Their Storage Stability

W/O/W emulsion is an emerging system in developing new functional and low-calorie food products. The aim of this study is to produce food-grade monodisperse water-in-oil-in-water (W/O/W) emulsions loaded with a hydrophilic bioactive oleuropein. W/O/W emulsions were prepared via high-pressure homogenization and subsequent microchannel (MC) emulsification. The internal aqueous phase was a 5-mM sodium phosphate buffer containing d(+)-glucose (5 wt.%) and oleuropein (0.1–0.7 wt.%). The oil phase consisted of soybean oil and tetraglycerin monolaurate condensed ricinoleic acid esters (TGCR; 3–8 wt.%). The external aqueous phase was a 5-mM sodium phosphate buffer containing d(+)-glucose (5 wt.%) and decaglycerol monolaurate (1 wt.%). Oleuropein-loaded submicron W/O emulsions with average droplet diameters as small as 0.15 μm and monomodal droplet size distributions were prepared by high-pressure homogenization when applying high TGCR concentrations of 5–8 wt.% and low oleuropein concentrations of 0.1–0.3 wt.%. Monodisperse oleuropein-loaded W/O/W emulsions with average W/O droplet diameters of around 27 μm and coefficients of variation of below 5 % were successfully prepared when using a silicon MC array plate with wide channels of 5-μm depth and 18-μm width. The monodisperse W/O/W emulsions prepared at high TGCR concentrations and low oleuropein concentrations were the most stable during 40 days of storage. The adsorption behavior of oleuropein at the internal aqueous–oil interface was relevant to W/O/W emulsions microstructure and stability. The results are believed to provide useful information for successfully preparing stable monodisperse W/O/W emulsions loaded with hydrophilic functional compounds. The surface activity of the loaded material seems to be a key parameter in optimizing the formulation of W/O/W food emulsion.     

Preparation and Characterization of Water/Oil/Water Emulsions Stabilized by Polyglycerol Polyricinoleate and Whey Protein Isolate

ABSTRACT: In this study we tried to prepare stable water-in-oil-in-water (W/O/W) emulsions using polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier and whey protein isolate (WPI) as a hydrophilic emulsifier. At first, water-in-oil (W/O) emulsions was prepared, and then 40 wt% of this W/O emulsion was homogenized with 60 wt% aqueous solution of different WPI contents (2, 4, and 6 wt% WPI) using a high-pressure homogenizer (14 and 22 MPa) to produce W/O/W emulsions. The mean size of final W/O/W droplets ranged from 3.3 to 9.9 μm in diameter depending on the concentrations of PGPR and WPI. It was shown that most of the W/O/W droplets were small (<5 μm) in size but a small population of large oil droplets (d > 20 μm) was also occasionally observed. W/O/W emulsions prepared at the homogenization pressure of 22 MPa had a larger mean droplet size than that prepared at 14 MPa, and showed a microstructure consisting of mainly approximately 6 to 7-μm droplets. When a water-soluble dye PTSA as a model ingredient was loaded in the inner water phase, all W/O/W emulsions showed a high encapsulation efficiency of the dye (>90%) in the inner water phase. Even after 2 wk of storage, >90% of the encapsulated dye still remained in the inner water phase; however, severe droplet aggregation was observed at relatively high PGPR and WPI concentrations.     

Synergistic effects of polyglycerol ester of polyricinoleic acid and sodium caseinate on the stabilisation of water–oil–water emulsions

The inherent thermodynamic instability of water–oil–water (W/O/W) emulsions has restrictions for their application in food systems. The objective of this study was to develop a food grade W/O/W emulsions with high yield and stability using minimal concentrations of surfactants. Emulsions were prepared using soybean oil, polyglycerol ester of polyricinoleic acid (PGPR) alone or in combination with sodium caseinate (NaCN) as emulsifier(s) for primary water-in-oil (W/O) emulsions and NaCN as the sole emulsifier for secondary W/O/W emulsions. Increasing the concentration of PGPR (0.5–8%w/v) had no effect on the droplet sizes of the resulting W/O/W emulsions. However, significant increases in droplet sizes of W/O/W emulsions were observed when the concentration of NaCN in external phase was reduced from 0.5 to 0.03% (w/v) (p<0.05). Percentage yields of emulsions (using a water-soluble dye) improved when PGPR concentration in the inner phase was increased from 0.5 to 8% (w/v). A stable W/O/W emulsion with a yield >90% could be prepared with 4% (w/v) PGPR alone as primary hydrophobic emulsifier and 0.5% (w/v) NaCN as external hydrophilic emulsifier. The concentration of PGPR in the inner phase could be reduced to 2% (w/v) without affecting the yield and stability of the W/O/W emulsion by partially replacing PGPR with 0.5% (w/v) NaCN, which was added to the aqueous phase of the primary W/O emulsion. The results indicate that a possible synergistic effect may exist between PGPR and NaCN, thus allowing formulation of double emulsions with reduced surfactant concentration.     

A Novel Approach to Improving the Quality of Bittern-Solidified Tofu by W/O Controlled-Release Coagulant. 1: Preparation of W/O Bittern Coagulant and Its Controlled-Release Property

To explore the controlled-release capacity and potential application of water in oil (W/O) emulsions, W/O emulsions with bittern solution as the aqueous phase were prepared with polyglycerol polyricinoleate (PGPR) as the emulsifier. Several factors that influenced the preparation of W/O bittern coagulants were investigated. Optimized conditions were applied as follows: bittern solution/oil phase at 4:6 or 5:5 (w/w), processing temperature at 65 °C, emulsifier concentration higher than 0.6 wt% and high-pressure homogenization at 60 MPa; W/O emulsions that had a good particle size distribution, good rheological properties, good embedding ratio and high stability were prepared. The optimized W/O emulsions also exhibited the expected controlled-release ability, affected by the bath temperature, shear speed and emulsion characteristics. The preliminary results also showed that the application of W/O emulsions has the potential to improve tofu quality by delaying the solidification of soybean protein and creating a much smoother and finer gel structure.     

Production of reduced-fat whipped toppings by solid fat-based W/O/W double emulsions: proof of concept

Water-in-oil-in-water (W/O/W) double emulsions present a reduced-fat alternative to conventional O/W food emulsions, as part of the dispersed oil phase is replaced with water. In this study, the concept of a reduced-fat whipped topping produced by W/O/W technology was proven. Whipping of a W/O/W emulsion, containing only 20% oil phase and a solid fat content of 78%, produced a superior whipped topping, in terms of firmness and overrun, compared to its whipped O/W emulsion counterparts. The presence of PGPR in the oil phase increased structure formation during whipping, while the additional dispersed-phase volume resulted in a better air inclusion. Two commercial monoacylglycerols (saturated and unsaturated) were investigated to improve the whipping properties of the produced W/O/W double emulsion. Both increased the susceptibility towards partial coalescence, thereby reducing whipping time and overrun, while increasing firmness of the produced whipped topping. Furthermore, the effect was stronger for the unsaturated than for the saturated monoacylglycerol.     

一种水包油包胶型乳液的制备及其在乳化肠中的应用

以结冷胶和无水氯化钙为内水相凝固剂,酪蛋白酸钠为外水相乳化剂,制备一种水包油包胶（S/O/W）型 乳液。以多重乳液粒径和分布为指标,研究酪蛋白酸钠添加量对S/O/W型多重乳液加工适应性的影响。结果表明： 正交试验得到S/O型单重乳液最佳制备条件为：内水相中结冷胶添加量0.2%、无水氯化钙添加量0.5%;内水相乳化 剂聚甘油蓖麻醇酯添加量2.5%;油相为精炼猪油,油水体积比3∶2;剪切速率17 500 r/min,剪切时间1.5 min。将制 得的S/O型单重乳液与不同添加量酪蛋白酸钠混合制得S/O/W型多重乳液。当酪蛋白酸钠添加量0.1%时,S/O/W型 多重乳液粒径符合加工要求,且贮藏、热处理、剪切稳定性较好。以多重乳液替代猪脂肪制备的低脂乳化肠与高脂 （精炼猪油含量20%）乳化肠外观不存在明显差异;微观结构观察结果表明,多重乳液在乳化肠中包裹良好、分布 均匀。     

Occlusive power evaluation of O/W/O multiple emulsions on gelatin support cells

The water content of the stratum corneum plays an important role in providing skin suppleness and smoothness. The diffusion of water through the skin is limited primarily by the stratum corneum and the noncornified part of the epidermis has negligible water barrier properties. Multiple emulsions are vesicular systems utilized for the prolonged liberation of active ingredients. The O/W/O multiple emulsion type is employed in cosmetics because its high oil content is able to maintain an occlusive film (barrier) on the skin surface. The objective of this study was to determine the occlusive power of O/W/O multiple emulsions on gelatin support cells. The results showed that occlusive products form a uniform layer on the surface of gelatin after the test, whereas nonocclusive products form two layers: an aqueous phase on the gelatin, and an oil phase above the aqueous phase. Thus, the different occlusive powers are due to the homogeneity of this layer and to its ability to prevent water evaporation.     

Release rate profiles of magnesium from multiple W/O/W emulsions

Water-in-oil-in-water (W/O/W) emulsions were formulated based on rapeseed oil, olive oil, olein and miglyol. Polyglycerol polyricinoleate and sodium caseinate were used as lipophilic and hydrophilic emulsifiers, respectively. Magnesium was encapsulated in the inner aqueous droplets. Emulsion stability was assayed through particle sizing and magnesium release at two storage temperatures (4 and 25 °C) over 1 month. Irrespective of the oil nature, both the primary W/O and W/O/W emulsions were quite stable regarding the size parameters, with 10-μm fat globules and 1-μm internal water droplets. Magnesium leakage from W/O/W emulsions was influenced by the oil type used in the formulation: the higher leakage values were obtained for the oils characterized by the lower viscosity and the higher proportion of saturated fatty acids. Magnesium release was not due to droplet–globule coalescence but rather to diffusion and/or permeation mechanisms with a characteristic rate that varied over time. In addition, W/O/W emulsions were resistant to various thermal treatments that mimicked that used in pasteurization processes. Finally, when W/O/W emulsions were placed in the presence of pancreatic lipase, the emulsion triglycerides were hydrolysed by the enzyme. These results indicated a possible use of W/O/W emulsions loaded with magnesium ions in food applications.     

Evaluation of Folic Acid Nano-encapsulation by Double Emulsions

In this study, optimization of spray drying for double emulsions containing pectin-whey protein concentrate (WPC) was investigated for nano-encapsulation of folic acid. Five independent variables including pectin and WPC content, dispersed phase content, pH, surfactant type of Span, and polyglycerol polyricinoleate (PGPR) were considered along with encapsulation efficiency (EE) as the main response. The experiment design was performed by a Taguchi approach. Final double emulsions were formulations containing an internal nano/micro-emulsion composed of a water in oil (W/O) system with folic acid present in the water phase, re-emulsified within an aqueous phase of pectin-WPC complexes. The average of folic acid EE was approximately 88.3 % in a range of 82.3 to 95.0 %. The main effect analysis with a Taguchi technique revealed that the dispersed phase content of double emulsions was the most important factor affecting EE (36 %) and surfactant had the minimum influence (5 %). Also, it was revealed that the most important interaction between independent variables in terms of EE was between WPC and dispersed phase content while pectin-pH had the lowest interaction. Finally, optimum conditions were determined as 1.0 % pectin, 4.0 % WPC, and 15 % dispersed phase, pH = 6, with a PGPR nano-emulsion which resulted in 99.0 % EE of folic acid.     

Stability and release properties of double-emulsions stabilised by caseinate–dextran conjugates

The subject of the present paper was to investigate the possibility of stabilising water-in-oil-in-water emulsions (W/O/W) by using sodium caseinate (SC)–dextran (Dex) conjugates in order to influence the release of vitamin B₁₂ from the inner water phase (W₁) to the outer aqueous phase (W₂).To prepare the conjugate the SC was combined with Dex (M_r 250,000 or 500,000 g/mol) and incubated at 60 °C and a humidity of 79% for 8 h.The double emulsions, with encapsulated vitamin B₁₂, were prepared using a two-step emulsification technique. Whereas different amounts of polyglycerin polyricinoleate (PGPR, E476) were the hydrophobic emulsifier, the conjugate and the SC alone were used as the hydrophilic emulsifiers. The investigations comprised the determination of the particle size distribution of the W/O/W emulsion and measurement of the amount of vitamin B₁₂ migration from W₁- to the W₂-phase during the second stage of emulsion preparation and after heating or pH changing of emulsion.The water-containing oil droplets of the W/O/W emulsions were smaller and distributed more narrowly using SC–Dex conjugate as emulsifier instead of pure protein. Under acidic conditions, the conjugate-containing emulsions were more coalescence stable than the emulsions with SC, and the vitamin B₁₂ release from the inner W₁-phase was significantly decreased.     

Effects of enzymatically modified starch on the encapsulation efficiency and stability of water-in-oil-in-water emulsions

The present study was performed to investigate the possibility of using 4-α-glucanotransferase (4αGTase)-treated starch in W/O/W emulsions to increase their encapsulation efficiency (EE) and stability. Emulsions were prepared using soybean oil, polyglycerol polyricinoleate (PGPR), 4αGTase-treated starch and Tween 20. The mean diameter of W/O/W droplets ranged from 4 to 10 μm depending on the sonication time. When the dye was loaded in the internal water phase, the emulsion prepared by sonication for 1 and 2 min showed a high EE of the dye (>90%). The W/O/W emulsion prepared by sonication for 3 min showed an EE of <90%, but this EE was improved by adding 4αGTase-treated starch to the internal water phase. 4αGTase-treated starch was added to the internal water phase of W/O/W emulsions prepared with a low concentration of PGPR, and the PGPR concentration required to maintain an EE >90% was reduced. W/O/W emulsions containing 4αGTase-treated starch also showed better stability against heating and shearing stresses. These results indicated that 4αGTase-treated starch could be used in the preparation of W/O/W emulsions, which would allow the formulation of W/O/W emulsions with a reduced surfactant concentration.     

Double emulsion (W/O/W) gel stabilised by polyglycerol polyricinoleate and calcium caseinate as mangiferin carrier: insights on formulation and stability properties

Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W₁/O/W₂ emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL⁻¹. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W₁/O/W₂ emulsions. Subsequently, the MGF-loaded W₁/O/W₂ emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W₁/O/W₂ emulsions were investigated. The MGF-loaded W₁/O/W₂ emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W₁/O/W₂ emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W₁/O/W₂ emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin.     

基于三种多糖与酪蛋白复配制备W/O/W型乳液及其包封红景天苷效果的研究

为提高红景天苷稳定性及口服吸收效果,本研究以红景天苷为内水相,含聚甘油蓖麻醇酯的菜籽油为油相,分别采用葡聚糖、壳聚糖和大豆多糖混合酪蛋白作为外水相,制备W/O/W型多重乳液。研究了不同浓度的三种多糖对多重乳液的微观结构、粒径、电位、贮藏稳定性、乳化性、包埋率、载药量和体外消化过程的影响。结果显示,相比于酪蛋白对照组、壳聚糖-酪蛋白组和大豆多糖-酪蛋白组,葡聚糖-酪蛋白W/O/W型多重乳液稳定性最好。高浓度的葡聚糖能够明显提升葡聚糖-酪蛋白多重乳液的贮藏稳定性,当葡聚糖添加量为1.2%时,多重乳液平均粒径最小,可达623.03±5.21 nm（P<0.05）;电位绝对值最高（P<0.05）,平均电位为?37.3±0.46 mV;对酪蛋白乳化性质提升最大（P<0.05）;对红景天苷的包埋率最高（P<0.05）,可达92.8%,载药量为162.89±4.21 μg/g。模拟消化研究发现葡聚糖-酪蛋白多重乳液不仅能有效地保护红景天苷,还能够靶向地在模拟肠道内传递和释放,葡聚糖添加量为1.2%的葡聚糖-酪蛋白负载体系的稳定性和控释效果最佳。该研究结果可为红景天苷在食品和医药中的应用提供理论支撑。     

On the Effect of Tastant Excluded Fillers on Sweetness and Saltiness of a Model Food

ABSTRACT: In this study, the effect on taste due to the addition of air bubbles to a water-based gel was investigated. The gel phase contained either sucrose to give a sweet taste or sodium chloride to give a salty taste. For the sweet gels, taste intensities were evaluated for samples with different volume fractions of the air bubbles (up to 40%, v/v) and different concentrations of the sucrose. For the salty gels, samples were evaluated at 40% volume fraction of air bubbles. It was found that a reduction of the sodium chloride or sucrose by the same weight percentage as the volume fraction of the air bubbles in the samples gave equal taste perception as the nontastant-reduced samples. Moreover, saltiness and sweetness perception were clearly enhanced at 40% volume fractions of air bubbles if the sodium chloride or sucrose was not reduced. Thus, the overall tastes of the samples appeared to depend mainly on the concentration levels of the salt or the sucrose in the aqueous phase irrespective of the volume fraction of the air bubbles. However, the air bubbles were found to change the texture and appearance of the samples. It has been demonstrated that the inclusion of air bubbles offers scope for the reduction of sodium chloride or sucrose in food products.     

碱热改性米渣谷蛋白对W/O/W型双重乳液稳定性的影响

目的：实现米渣谷蛋白在乳浊体系中的应用。方法：选取碱热改性米渣谷蛋白和span80,采用一步乳化法制备W/O/W型双重乳液,并考察蛋白浓度对双重乳液稳定性的影响。结果：当蛋白质量分数从0.5%升高至2.5%时,乳液大粒径峰消失,显微结构中液滴的双重结构增强,表观黏度及黏弹性提高,离心稳定性和贮藏稳定性增强。当蛋白质量分数为2.5%时,离心后乳清析出指数从37.21%降至10.56%,分层时间从6 h延长至96 h。蛋白质与span80形成复合膜共同稳定油水界面,形成中间态液滴,当界面蛋白足以形成刚性界面膜时,液滴从中间态转为稳定的双重结构;当蛋白质量分数为3.0%时,双重乳液发生絮凝使大粒径峰重新出现,稳定性下降,离心后乳清析出指数为16.48%,制备后96 h左右分层,过剩的蛋白质一部分参与内相液滴的构建,另一部分单独形成O/W型液滴吸附于大体积液滴外侧。结论：一步乳化法下,蛋白质量分数为2.5%时,可制得稳定双重乳液。     

Stability of Anthocyanin‐Rich W/O/W‐Emulsions Designed for Intestinal Release in Gastrointestinal Environment

Abstract: Anthocyanins belong to the most important hydrophilic plant pigments. Outside their natural environment, these molecules are extremely unstable. Encapsulating them in submicron‐sized containers is one possibility to stabilize them for the use in bioactivity studies or functional foods. The containers have to be designed for a target release in the human gastrointestinal system. In this contribution, an anthocyanin‐rich bilberry extract was encapsulated in the inner aqueous phase of water‐in‐oil‐in‐water‐double emulsions. The physical stability as well as the release of free fatty acids and encapsulated, bioactive substances from the emulsions during an in vitro gastrointestinal passage were investigated. The focus was on the influence of emulsion microstructural parameters (for example, inner and outer droplet size, disperse phase content) and required additives (emulsifier systems), respectively. It could be shown that it is possible to stabilize anthocyanins in the inner phase of double emulsions. The release rate of free fatty acids during incubation was independent of the emulsifier used. However, the exterior (O/W)‐emulsifier has an impact on the stability of multiple emulsions in gastrointestinal environment and, thus, the location of release. Long‐chained emulsifiers like whey proteins are most suitable to transport a maximum amount of bioactive substances to the effective location, being the small intestine for anthocyanins. In addition, it was shown that the dominating release mechanism for entrapped matter was coalescence of the interior W₁‐droplets with the surrounding W₂‐phase. Practical Application: Microencapsulation of phytochemicals and bioactives is in the focus of functional food development. Here, the influence of matrix material, formulation, and structural parameters on stabilization and release of the molecules encapsulated has to be known for target product and process design. As the results are representative for hydrophilic active ingredients encapsulated in double emulsion systems a cross‐sectoral use in the pharmaceutical sector is possible.     

Physical and Oxidative Stabilities of O/W Emulsions Formed with Rice Dreg Protein Hydrolysate: Effect of Xanthan Gum Rheology

The shortening of shelf-life of food emulsions is frequently due to poor creaming and lipid oxidation stability. The lipid oxidation of O/W emulsions can be inhibited by rice dreg protein hydrolysate (RDPH); however, emulsions were stabilized by Tween-20. Polysaccharides can control the rheology and network structure of the aqueous continuous phase by increasing viscosity and yield stress, hence retarding phase separation and gravity-induced creaming, especially for xanthan gum. The objective of this research was to evaluate whether emulsions formed with 2 wt% RDPH and stabilized by xanthan gum (0–0.5 wt%) could produce 20 % (v/v) soybean oil-in-water emulsions that had good physical and oxidative stability. The degree of flocculation of droplets as a function of xanthan gum concentration was assessed by the microstructure, rheology, and the creaming index of emulsions. Addition of xanthan gum prior to homogenization had no significant effect on the mean droplet diameter in all emulsions studied. Increase in xanthan gum concentration led to the increase in creaming stability of emulsions, due to an increase in viscosity of the continuous phase and/or the formation of a droplet network with a yield stress, as well as the enhanced steric and electrostatic repulsion between the droplets. Lipid oxidation of the emulsions was significantly inhibited at xanthan gum concentrations of 0.12 wt% or above with RDPH, which could due to the fact that xanthan gum increases the viscosity of the aqueous phase and hindered the diffusion of oxidants to the oil droplet surface area, synergistic effect between RDPH and xanthan gum to suppress oil peroxidation, and metal ion chelation capability of xanthan gum. Thus, stable protein hydrolyzates-type emulsions could be obtained with increasing concentration of xanthan gum.     

米糠蛋白O/W及W/O/W乳液制备及界面稳定性

为对比不同米糠蛋白质量浓度下O/W及W/O/W乳液的稳定性,以米糠蛋白作为基料,采用双乳化法制备O/W及W/O/W乳液,考察不同米糠蛋白质量浓度下乳液的微观形态和稳定性并探究其界面稳定机理。结果表明：W/O/W乳液的贮存稳定性显著优于O/W乳液;与相同蛋白含量的O/W乳液相比,W/O/W乳液的黏度显著提高;当米糠蛋白质量浓度为0.4 g/100 mL时,W/O/W乳液的稳定性较O/W乳液提高了1 倍以上;乳液内部包裹更多的W/O液滴,W/O/W乳液的粒径较大;而此时静电斥力也较大,起到稳定乳液的目的。同时,米糠蛋白质量浓度不小于0.4 g/100 mL时,O/W及W/O/W乳液中蛋白质的吸附率较高,达到78%以上。本研究为天然米糠蛋白质在食品级乳液中的开发提供参考,为粮食副产物的综合利用提供了新思路。     

Taste perception and purchase intent of oil‐in‐water spreads: effects of oil types and salt (NaCl or KCl) concentrations

Associations of sodium intake with heart‐related problems are creating awareness towards reducing sodium. Potassium chloride (KCl), a substitute for sodium chloride (NaCl), has the disadvantage of imparting bitterness at high concentrations. We evaluated physical characteristics, taste perception and purchase intent of KCl and NaCl in oil‐in‐water spreads/emulsions composed by olive, rice bran and soya bean oils. Consumers (N = 300) evaluated saltiness/bitterness of emulsions prepared with 65% oil, and NaCl (0.5% and 1.0%) or KCl (0.75% and 1.5%). Olive oil spreads (104.07–107.43 Pa s) had higher viscosity compared to other spreads (59.16–74.96 Pa s). Type of oil had significant effects on bitterness, overall taste liking and viscosity. Taste liking decreased due to bitterness of olive oil spreads (mean drop=1.72–2.43). Purchase intent was positively associated with saltiness and pH and increased with oil claims (increase = 1.3%–22.1%) compared to sodium claims (increase = 0.0%–12.9%). These findings are useful for understanding taste perception of emulsions.