Emulsifying properties of sweet potato protein: Effect of protein concentration and oil volume fraction

The effect of protein concentrations (0.1, 0.25, 0.5, 1.0, 1.5 and 2.0% w/v) and oil volume fractions (5, 15, 25, 35 and 45% v/v) on properties of stabilized emulsions of sweet potato proteins (SPPs) were investigated by use of the emulsifying activity index (EAI), emulsifying stability index (ESI), droplet size, rheological properties, interfacial properties and optical microscopy measurements at neutral pH. The protein concentration or oil volume fraction significantly affected droplet size, interfacial protein concentration, emulsion apparent viscosity, EAI and ESI. Increasing of protein concentration greatly decreased droplet size, EAI and apparent viscosity of SPP emulsions; however, there was a pronounced increase in ESI and interfacial protein concentration (P < 0.05). In contrast, increasing of oil volume fraction greatly increased droplet size, EAI and emulsion apparent viscosity of SPP emulsions, but decreased ESI and interfacial protein concentration significantly (P < 0.05). The rheological curve suggested that SPP emulsions were shear-thinning non-Newtonian fluids. Optical microscopy clearly demonstrated that droplet aggregates were formed at a lower protein concentration of <0.5% (w/v) due to low interfacial protein concentration, while at higher oil volume fractions of >25% (v/v) there was obvious coalescence. In addition, the main components of adsorbed SPP at the oil–water interface were Sporamin A, Sporamin B and some high-molecular-weight aggregates formed by disulfide linkage.     

不同黏度多糖阿拉伯胶和瓜尔胶对肌原纤维蛋白乳化性质的影响

选取两种分子质量相近、黏度相差较大的天然高分子多糖阿拉伯胶（arabic gum,AG）和瓜尔胶（guar gum,GG）分别与肌原纤维蛋白（myofibrillarprotein,MP）进行复合,研究不同多糖添加量（0.1%～0.5%）对MP-多糖复合物乳液性质的影响规律。结果表明,AG和GG均可以显著改善MP的乳化性质,其中AG对乳化活性的改善效果较好,而GG更有利于乳液的稳定性。随着多糖质量分数增加,乳化活性指数和稳定性指数均呈先升高后降低趋势,AG和GG添加量分别为0.3%和0.2%时,乳化活性指数和稳定性指数达到最大值。界面蛋白含量测定结果显示,AG和GG均会导致界面蛋白含量下降,尤其是GG的作用更明显。随着AG和GG添加量增加,乳液粒径逐渐减小,且尺寸分布更加均一,添加量超过0.3%后,GG组乳液出现少量絮凝现象。同一添加量下,GG组乳液粒径明显小于AG组。流变学分析证实,所有乳液均为假塑性流体,表现出弱凝胶性质。AG添加量较少（≤0.3%）时会降低乳液黏度,并明显提高乳液的储能模量,而GG的添加使乳液表观黏度和储能模量均显著提高,与AG相比,高黏度GG制备的乳液拥有更高的...     

The effect of chitosan on the properties of emulsions stabilized by whey proteins

The influence of the cationic amino polysaccharide chitosan content (0–0.5%) on particle size distribution, creaming stability, apparent viscosity, and microstructure of oil-in-water emulsions (40% of rapeseed oil) containing whey protein isolate (WPI) (4%) at pH 3 was investigated. The emulsifying properties, apparent viscosity and phase separation behaviour of aqueous WPI/chitosan mixture at pH 3 were also studied. The interface tension data showed that WPI/chitosan mixture had a slightly higher emulsifying activity than had whey protein alone. An increase in chitosan content resulted in a decreased average particle size, higher viscosity and increased creaming stability of emulsions. The microstructure analysis indicated that increasing concentration of chitosan resulted in the formation of a flocculated droplet network. This behaviour of acidic model emulsions containing WPI and chitosan was explained by a flocculation phenomenon.     

pH-dependent emulsifying properties of pea [Pisum sativum (L.)] proteins

Emulsifying properties of two partially purified legumin and vicilin (PL and PV) and protein isolate (PPI) from dry pea seeds at various pH values (3.0, 5.0, 7.0 and 9.0) were investigated. The tested emulsion characteristics included droplet size, flocculation and coalescence indices (FI and CI), creaming index, as well as interfacial protein adsorption. Some physicochemical properties of these proteins, e.g., free sulfhydryl and disulfide bond contents, protein solubility (PS), surface hydrophobicity (H_o) and thermal stability (and denaturation), were also characterized. The results indicated that emulsifying ability and emulsion stability of various pea proteins considerably varied with the preparation process, protein composition and pH. Overall, all the pea proteins exhibited least emulsifying ability at pH 5.0 (around isoelectric point), and concomitantly, the resultant emulsions were most unstable against coalescence and creaming. The emulsifying ability of these proteins at pH 3.0 was generally better than that at neutral or alkali pH values, and among all the three proteins, PL exhibited highest emulsifying ability at this pH. The flocculated state and size of droplets in fresh emulsions did not directly affect stability of these emulsions against flocculation and coalescence (upon 24 h of storage), and even creaming (up to 7 days). Interestingly, the PL and PV exhibited much better creaming stability than PPI, at pH deviating from the pI. The emulsifying properties of these proteins were not only related to their PS and H_o, but also associated with the protein adsorption and nature (e.g., viscoelasticity) of interfacial protein films. These results can greatly extend the knowledge for understanding the emulsifying properties of pea proteins, especially the pH dependence of emulsion characteristics.     

Utilisation of pectin coating to enhance spray-dry stability of pea protein-stabilised oil-in-water emulsions

In this study, development of pea (Pisum sativum) protein stabilised dry and reconstituted emulsions is presented. Dry emulsions were prepared by spray-drying liquid emulsions in a laboratory spray-dryer. The effect of drying on the physical stability of oil-in-water emulsions containing pea protein-coated and pea protein/pectin-coated oil droplets has been studied. Oil-in-water emulsions (5 wt.% Miglyol 812 N, 0.25 wt.% pea protein, 11% maltodextrin, pH 2.4) were prepared that contained 0 (primary emulsion) or 0.2 wt.% pectin (secondary emulsion). The emulsions were then subjected to spray-drying and reconstitution (pH 2.4). The stability of the emulsions to dry processing was then analysed using oil droplet size, microstructure, Zeta potential, and creaming measurements. Obtained results showed that the secondary emulsions had better stability to droplet aggregation after drying than primary emulsions. To interpret these results, we propound that pectin, an anionic polysaccharide, formed a less charged protective layer around the protein interfacial film surrounding the oil droplets that improved their stability to spray-drying mainly by increasing steric effects.     

Emulsifying characterization of hens egg yolk proteins in oil-in-water emulsions

Emulsifying properties of egg yolk as a function of pH and oil volume were studied. Egg yolk proteins formed larger emulsion particles at pH 3 and the mean droplet size of the emulsions was decreased with increasing pH. A linear relationship between turbidity and mean droplet size of egg yolk emulsions could not be obtained. This may be due to the floculation of the emulsions. Egg yolk proteins formed thicker multilayers at low oil volume, however total protein adsorption ratio against original proteins was 55–65%, independent to protein and oil concentration. Electrophoretic analysis of the egg yolk emulsion revealed that the main components to adsorb at the interface was glanular lipovitellins, even though its emulsifying property was lower than that of plasma because of poor solubility at low ionic strength (0.1 M NaCl) at pH 7. These results indicate that the main contributor for egg yolk emulsion is granules and it can affect the emulsifying properties of egg yolk at different pH values.     

紫苏油乳液的制备及其稳定性影响因素研究

本研究针对紫苏油不饱和脂肪酸含量高,在储存过程中易氧化等特点,采用高压均质法制备紫苏油乳液,通过激光粒度仪分析乳液粒径大小与分布,通过TURBISCAN浓缩体系稳定性分析仪监测乳液稳定性的变化趋势,探究乳化剂用量、油水比例、高压均质的压力和循环次数及HLB值对紫苏油乳液稳定性的影响,以提供一种紫苏油缓释方法,拓宽紫苏油在食品中的应用范围。试验结果表明,紫苏油乳液粒径主要分布在300~670nm;乳化剂浓度由0.2%增加至1.2%,乳液粒径下降,稳定性提高;浓度为1.2%时,乳液平均粒径(d=513nm)最小。随着油水比增加,紫苏油乳液稳定性下降;高压均质过程对乳液的稳定性有显著影响,压力越大,循环次数越高,乳液越稳定。与单一乳化剂(HLB=15)相比,复配乳化剂(HLB=8~14)可制得更为稳定的乳液,且当HLB值为11时,紫苏油乳液的平均粒径(d=374nm)最小,乳液稳定性最佳。     

高强度超声辅助乳化对金鲳鱼蛋白-茶皂苷复合乳液性质的影响

为提升金鲳鱼蛋白乳液的稳定性,改善金鲳鱼蛋白的功能特性,以金鲳鱼蛋白-茶皂苷复合物为乳化剂、大豆油为油相,采用高强度超声(HIUS)辅助乳化制备金鲳鱼蛋白-茶皂苷复合乳液,测定超声处理前后不同乳化剂与油相比例的金鲳鱼蛋白-茶皂苷复合乳液的乳化性、粒径分布、Zeta-电位、流变性、微观形态及贮藏稳定性。结果表明：与未超声处理金鲳鱼蛋白-茶皂苷复合乳液相比,超声处理后乳液的乳化活性指数和乳化稳定性指数总体增高,粒径减小,Zeta-电位的绝对值增加,流动指数升高,黏度系数降低,乳液液滴分布更均匀,乳液液滴更小,贮藏稳定性较好。综上,HIUS处理有助于改善金鲳鱼蛋白-茶皂苷的乳化性能。     

再生纤维素凝胶对乳清分离蛋白预乳化液稳定性的影响

利用再生纤维素（regenerated cellulose,RC）凝胶改善蛋白质预乳化液的乳化稳定性。考察添加量分别为0%、0.4%、0.8%、1.2%、1.6%的RC对乳清分离蛋白（whey protein isolate,WPI）-橄榄油预乳化液乳化稳定性、乳化活性、粒度大小、微观结构、流变特性的影响。结果表明,添加RC可以显著提高WPI预乳化液的乳化稳定性及乳化活性（P＜0.05）,RC添加量为0.8%时可以有效抑制乳化液的分层现象;随着RC添加量的增加,乳化液粒度大小及絮凝程度显著降低（P＜0.05）;乳化液流变学特性显示RC具有很好的增稠作用和凝胶性能。结果表明RC的添加对于WPI-预乳化液稳定性有很大影响,预乳化液中添加1.2% RC,可以有效增加乳化液黏度,获得较强的凝胶网络结构,显著降低粒度,改善乳化液稳定性。     

Cross-linking proteins by laccase: Effects on the droplet size and rheology of emulsions stabilized by sodium caseinate

The aim of this work was to evaluate the influence of laccase and ferulic acid on the characteristics of oil-in-water emulsions stabilized by sodium caseinate at different pH (3, 5 and 7). Emulsions were prepared by high pressure homogenization of soybean oil with sodium caseinate solution containing varied concentrations of laccase (0, 1 and 5 mg/mL) and ferulic acid (5 and 10 mM). Laccase treatment and pH exerted a strong influence on the properties with a consequent effect on stability, structure and rheology of emulsions stabilized by Na-caseinate. At pH 7, O/W emulsions were kinetically stable due to the negative protein charge which enabled electrostatic repulsion between oil droplets resulting in an emulsion with small droplet size, low viscosity, pseudoplasticity and viscoelastic properties. The laccase treatment led to emulsions showing shear-thinning behavior as a result of a more structured system. O/W emulsions at pH 5 and 3 showed phase separation due to the proximity to protein pI, but the laccase treatment improved their stability of emulsions especially at pH 3. At pH 3, the addition of ferulic acid and laccase produced emulsions with larger droplet size but with narrower droplet size distribution, increased viscosity, pseudoplasticity and viscoelastic properties (gel-like behavior). Comparing laccase treatments, the combined addition of laccase and ferulic acid generally produced emulsions with lower stability (pH 5), larger droplet size (pH 3, 5 and 7) and higher pseudoplasticity (pH 5 and 7) than emulsion with only ferulic acid. The results suggested that the cross-linking of proteins by laccase and ferulic acid improved protein emulsifying properties by changing functional mechanisms of the protein on emulsion structure and rheology, showing that sodium caseinate can be successfully used in acid products when treated with laccase.     

酪蛋白酸钠-大豆油乳化体系的影响因素

为探究非均相液态体系条件对乳化效果的影响,改善油脂的乳化效果,以酪蛋白酸钠为乳化剂,研究不同的体系条件(蛋白添加量、脂水体积比、p H、Na Cl浓度)对大豆油乳化液相关特性的影响。结果表明,在蛋白添加量为0. 1%~0. 5%(质量分数)时,蛋白添加量的增加使乳液黏度及界面蛋白吸附量均显著提高;液滴平均粒径由60μm下降至7. 28μm,粒径分布范围变窄。在脂水比1∶2~2∶1范围内,随着脂水比增加,乳液黏度增大;脂水比> 1∶1时,黏度较其他组高出5倍左右,通过微观结构图发现这与乳滴紧密堆积有关;除了脂水比2∶3和1∶1变化不显著外,乳液的界面蛋白吸附量呈上升趋势;脂水比<1∶1时乳滴平均粒径和分布范围差别不大,随后粒径先减小又有所增加。乳液p H在3~11范围内,p H为3和5时乳滴聚集严重,平均粒径及分布范围较其他组高。Na Cl的加入可以显著提高乳液黏度和界面蛋白吸附量,Na Cl浓度≤0. 6 mol/L时,乳液粒径均小于对照组,其中浓度为0. 12 mol/L时达到最小值,但Na Cl浓度为0. 84 mol/L时乳滴中出现较大粒径乳滴,使其平均粒径超过对照组,Na Cl浓度≥0. 36 mol/L时乳液zeta-电位绝对值较对照组小。综上,乳化的适宜条件为:酪蛋白添加量为0. 5%,脂水比为3∶2,p H为7~9,Na Cl浓度≤0. 6 mol/L。     

Emulsifying properties of proteins extracted from Australian canola meal

Canola protein albumin fraction, globulin fraction, and canola protein isolate (CPI) were compared to commercial soy protein isolate (SPI) in terms of their emulsifying properties at various pH values. The globulin fraction had higher emulsifying capacity (EC), higher emulsifying activity index (EAI), and the droplet size of emulsions it stabilized was consistently smaller irrespective of pH compared to albumin fraction or CPI. In comparison to SPI, globulin fractions also had higher EC at all pH values tested, higher EAI at acidic pH, and smaller or comparable average emulsion droplet size at both pH 4 and 7. The stability of canola protein based emulsions were comparable to those of SPI based emulsions at most pH values (except the emulsion stabilized by the CPI at pH 4), with no significant (p > 0.05) changes in droplet size during storage for up to 7 days at room temperature. These emulsions, however, experienced separation into the emulsion and serum phases after 24 h storage at room temperature with the exception of CPI- and SPI-stabilized emulsions at pH 9. This study demonstrates the comparable emulsifying properties (forming or stabilizing) of some canola proteins to commercially available SPI, suggesting the potential use of canola proteins in food applications.     

The characterization of the semi-solid W/O/W emulsions with low concentrations of the primary polymeric emulsifier

Semi-solid multiple W/O/W emulsions with low concentrations (0.8, 1.6 and 2.4% w/w) of lipophilic polymeric primary emulsifier PEG-30-dipolyhydroxystearate (PDHS) have been formulated. Both emulsions, primary and multiple, were prepared with high content of inner phase (Phi1 = Phi2 = 0.8). All the formulations differ only in the lipophilic emulsifier concentration. Evaluating several parameters such as macroscopic and microscopic aspect, droplet size, accelerated stability under centrifugation and flow and oscillatory rheological behaviour, assessed the multiple systems. It is possible to formulate the semi-solid W/O/W multiple emulsions with low concentrations of PDHS as the primary emulsifier. It appeared that the highest long-term stable multiple emulsion with the lowest droplet size, the highest apparent viscosity and highest elastic characteristic, was the sample with the highest concentration (2.4% w/w) of the primary emulsifier.     

Emulsifying properties of gum kondagogu (Cochlospermum gossypium), a natural biopolymer

BACKGROUND: Natural polymers are widely used as emulsifying agents in the food and pharmaceutical industries because of their low cost, biocompatibility and non‐toxic nature. In the present study, emulsifying properties of the novel natural biopolymer gum kondagogu (GKG) were investigated. GKG solutions of different concentrations (0.1–0.6% w/v) were prepared in water and emulsified with liquid paraffin oil (40% v/v) in a high‐speed homogeniser. Flow properties of the emulsions were measured using a rheometer. Emulsion stability and droplet size distribution were determined by visual observation, photomicrography and laser‐scattering particle size distribution analysis. RESULTS: The emulsions prepared with GKG showed pseudoplastic behaviour. The size of oil droplets and the viscosity of emulsions at concentrations of 0.4–0.6% w/v showed little change over time (up to 30 days), indicating that the emulsions were stable. Measurements of the zeta potential of emulsions adjusted to different pH, with and without added electrolyte, showed that the stabilisation of emulsions with GKG was due to mutual repulsion between electrical double layers of particles and adsorption of macromolecules on oil droplets. CONCLUSION: The results of this experimental investigation show that GKG is a good emulsifying agent even at low concentrations, with many potential applications in the food and pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

Characterisation of emulsion properties and of interface composition in O/W emulsions prepared with hen egg yolk, plasma and granules

Comprehension of hen egg yolk emulsifying properties remains incomplete because competition between its various emulsifiers (proteins and lipoproteins containing phospholipids) has not been clearly elucidated and colloidal interactions between yolk-stabilised oil droplets have not been documented. Recent studies emphasised the interest of the fractionation of yolk into plasma and granules to improve this comprehension. In the present study, we characterised, concurrently, emulsion properties (oil droplet size and stability against creaming) and interface attributes (interfacial concentrations of proteins and phospholipids, SDS-PAGE profiles of adsorbed proteins and zeta potential) in oil-in-water (O/W) emulsions prepared with yolk, plasma and granules. We observed these features at four physicochemical conditions (pH 3.0 or 7.0 and at 0.15 or 0.55 M NaCl). Emulsion properties in emulsions made with yolk or plasma varied similarly as a function of pH and NaCl concentration whereas granules emulsions exhibited distinct properties. Therefore the main contributors to yolk emulsifying properties are to be sought for among plasma constituents (proteinaceous or phospholipids). Since, in plasma emulsions, variations of emulsion stability against creaming correlated exclusively to variations of protein interfacial concentration, a driving contribution of the proteinaceous part of plasma, namely apo-LDL, was hypothesised. In the pH and ionic strength ranges studied, zeta potentials of the interfaces were low, excluding extended electrostatic repulsion between oil droplets. We deduced that steric repulsion is the main interaction opposing to droplet aggregation in food emulsions made with yolk.     

Effect of modified Acacia gum (SUPER GUM™) on the stabilization of coconut o/w emulsions

Two modified Acacia gums, the already tested SUPER GUM? EM2 and the new EM10, were used as combined emulsifiers and stabilizers in coconut oil model emulsions. The properties of gum solutions as well as those of the emulsions were examined. The gum solutions were completely mechanically stable during high-pressure homogenization; therefore, the gum could be added to the emulsion prior to high-pressure treatment. The emulsions were prepared by a small-scale rotor-stator process and by high-pressure homogenization, respectively. Droplet size, stability and rheological properties of the emulsions were examined. As expected, the high-pressure process was very effective. The emulsions made with both modified gums had a droplet size below 1 μm and were completely stable for at least 7 weeks at up to 30 °C. The new SUPER GUM? EM10 was more efficient as an emulsifier than EM2; the droplet size distribution was more homogenous. All emulsions proved to be low-viscous and nearly Newtonian liquids. It can be concluded that the emulsion stability was mainly a result of the excellent emulsifying properties and not of an additional thickening effect of the gums. The modified Acacia gums can be recommended as an emulsifier and stabilizer for application in different food products, preferably in low-viscous emulsions such as coconut milk drinks or other beverages.     

Effect of salt content on the rheological properties of salad dressing-type emulsions stabilized by emulsifier blends

The effects that salt content and composition of emulsifier blends exert on the rheological properties of salad dressing-type emulsions were studied. Binary blends of egg yolk and different types of amphiphilic molecules (Tween 20, sucrose laurate and pea protein), in several proportions, were used to stabilize emulsions. Salt concentration was ranged from 0 to 2.3% w/w. Steady-state flow tests and small-amplitude oscillatory shear measurements within the linear viscoelastic region were carried out. Rheological tests were complemented with droplet size distribution measurements. Rheological properties and physical stability of the emulsions studied were significantly influenced by salt content and the nature of binary emulsifier blends. In general, the values of rheological parameters studied increased with salt content. However, salt affects in much higher extent the properties of emulsions stabilized by high proportions of egg yolk or pea protein in the emulsifier blend, rather than those mainly stabilized by non-ionic low-molecular-weight surfactants, which are less sensitive to changes in the ionic strength. In this sense, the increase observed in the values of viscosity and linear viscoelastic functions of emulsions is more important when a protein is predominant in the emulsifier blend. This effect was explained on the basis of a more apparent increasing interdroplet interactions and viscosity of the continuous medium, both of them induced by salt addition, which lead to the consecution of an extensively flocculated state and improved creaming stability. On the contrary, different blends of pea protein and egg yolk showed a quite similar evolution of the rheological parameters with salt concentration.     

Pea (<Emphasis Type="Italic">Pisum sativum,L.</Emphasis>) Protein Isolate Stabilized Emulsions: A Novel System for Microencapsulation of Lipophilic Ingredients by Spray Drying

Oil-in-water emulsions can be considered as an important delivery system for lipophilic food molecules. In this study, pea protein isolate (PPI) was studied for its emulsifying capacity at various pH values and pH 7 was selected to prepare emulsions for the production of dry microcapsules. Emulsions stabilized by PPI just enough to cover oil droplets were mixed with solutions of starch hydrolysates of various dextrose equivalent (DE) and subsequently spray dried to yield powders with 30 wt% oil. Effects of DE (6, 12, 19, and 28) on feed emulsion properties and on the characteristics of the spray-dried powders were examined. Reconstituted emulsion oil droplet size and stability were affected by DE in all cases. Microencapsulation efficiency of dried emulsions increased significantly with increasing DE. The scanning electron microscope results showed that lower maltodextrins DE microcapsules are shallow and presented rough surfaces or invaginations. However, higher carbohydrates DE microcapsules were circular and uniform showing minimum cracks and dents on the surface confirming these DE to be efficient encapsulating materials. The formation of the drying matrix seems control the destabilization of pea protein-coated oil droplets during spray drying. In systems where the matrix is formed in a uniform manner, the interfacial protein film is less affected by the drying process. Thus the functionalities of pea protein can be protected during drying by using high DE carbohydrates.     

低钠条件下超声处理对鸡肉肌原纤维蛋白乳液稳定性的影响

低钠条件下肌原纤维蛋白（myofibrillar protein,MP）作为乳化剂制备的乳液稳定性差,本实验采用高强度超声波（high intensity ultrasound,HIU）（频率20 kHz、功率450 W）对低钠条件下（0.15 mol/L NaCl）MP进行不同时间（0、3、6、9、12 min）处理,测定处理后MP乳液乳化活性指数（emulsifying activity index,EAI）、乳液稳定性指数（emulsion stability index,ESI）、Turbiscan稳定性指数（turbiscan stability index,TSI）和平均粒径等,并进行微观结构观察和流变性分析等,研究低钠条件下超声处理对鸡肉MP乳化特性及其乳液稳定性和流变性能的影响。结果表明：与对照组相比,随着超声处理时间延长,MP的EAI和ESI显著增加（P＜0.05）,MP制备乳液的TSI和粒径随着超声处理时间的延长明显减小,且乳液液滴分布均匀,乳液Zeta-电位的绝对值显著增加（P＜0.05）。乳液的流变学特性分析结果表明超声波明显提高了MP乳液的黏弹性。MP乳液的油-水界面张力分析结果显示超声处理有效增强了MP的移动性,使界面张力迅速降低,同时超声处理显著增加了MP乳液吸附蛋白相对含量（P＜0.05）,这表明超声处理MP有助于稳定乳液。通过冷场扫描电子显微镜观察进一步证实了超声处理12 min MP制备的乳液液滴体积最小。综上,超声波能够有效提高低钠条件下MP的乳液稳定性,本实验可为超声处理在减盐乳化型肉制品中的应用提供理论参考。     

Emulsifying properties of canola and flaxseed protein isolates produced by isoelectric precipitation and salt extraction

The emulsifying (emulsion capacity, EC; emulsion activity/stability indices, EAI–ESI and creaming stability, CS) and physicochemical properties (surface charge/hydrophobicity, protein solubility, interfacial tension, and droplet size) of chickpea (ChPI), faba bean (FbPI), lentil (LPI), and pea (PPI) protein isolates produced by isoelectric precipitation and salt extraction were investigated relative to each other and a soy protein isolate (SPI). Both the legume source and method of isolate production showed significant effects on the emulsifying and physicochemical properties of the proteins tested. All legume proteins carried a net negative charge at neutral pH, and had surface hydrophobicity values ranging between 53.0 and 84.8 (H₀-ANS), with PPI showing the highest value. Isoelectric precipitation resulted in isolates with higher surface charge and solubility compared to those produced via salt extraction. The EC values ranged between 476 and 542 g oil/g protein with LPI showing the highest capacity. Isoelectric-precipitated ChPI and LPI had relatively high surface charges (~−22.3 mV) and formed emulsions with smaller droplet sizes (~ 1.6 μm), they also displayed high EAI (~ 46.2 m²/g), ESI (~ 84.9 min) and CS (98.6%) results, which were comparable to the SPI.