Formation of biopolymer particles by thermal treatment of β-lactoglobulin–pectin complexes

The purpose of this study was to prepare and characterize biopolymer particles based on thermal treatment of protein–polysaccharide electrostatic complexes formed from a globular protein (β-lactoglobulin) and an anionic polysaccharide (beet pectin). Initially, the optimum pH and pectin concentration for forming protein–polysaccharide complexes were established by mixing 0.5 wt% β-lactoglobulin solutions with beet pectin (0–0.5 wt%) at different pH values (3–7). Biopolymer complexes in the sub-micron size range (d = 100–300 nm) were formed at pH 5.0 and 0.1 wt% pectin. These particles were then subjected to a thermal treatment (30–90 °C at 0.8 °C min⁻¹). The presence of pectin increased the thermal aggregation temperature of the protein, although aggregate formation was still observed when the protein–polysaccharide systems were heated above about 70 °C. The impact of pH (3–7) on the properties of heat-treated biopolymer particles (83 °C, 15 min, pH 5) was then established. The biopolymer particles were stable to aggregation over a range of pH values, which increased as the amount of pectin was increased. The biopolymer particles prepared in this study may be useful for encapsulation and delivery of bioactive food components, or as substitutes for lipid droplets.     

Impact of surface deposition of lactoferrin on physical and chemical stability of omega-3 rich lipid droplets stabilised by caseinate

There is considerable interest in developing delivery systems to encapsulate and protect chemically labile lipophilic food components, such as omega-3 rich oils. In this study, multilayer emulsion-based delivery systems were prepared consisting of omega-3 rich oil droplets coated by either caseinate (Cas) or lactoferrin–caseinate (LF–Cas). Surface deposition of LF onto Cas-coated oil droplets was confirmed by ζ-potential measurements. Emulsions containing lactoferrin and caseinate had better physical stability to pH changes and salt addition (pH 3–7, 0–50 mM CaCl₂ at pH 7) than those containing only caseinate (pH 5–7, 0–2 mM CaCl₂ at pH 7). The addition of LF also retarded the formation of lipid oxidation markers (hydroperoxides and thiobarbituric acid reactive substances) in the emulsions. The ability of LF to enhance both the physical and chemical stability of protein-stabilised emulsions is useful for the fabrication of delivery systems designed for utilisation within the drug and food industries.     

Influence of the overall charge and local charge density of pectin on the complex formation between pectin and β-lactoglobulin

The complex formation between β-lactoglobulin (β-lg) and pectin is studied using pectins with different physicochemical characteristics. Pectin allows for the control of both the overall charge by degree of methyl-esterification as well as local charge density by the degree of blockiness. Varying local charge density, at equal overall charge is a parameter that is not available for synthetic polymers and is of key importance in the complex formation between oppositely charged (bio)polymers. LMP is a pectin with a high overall charge and high local charge density; HMP_B and HMP_R are pectins with a low overall charge, but a high and low local charge density, respectively. Dynamic light scattering (DLS) titrations identified pH_c, the pH where soluble complexes of β-lg and pectin are formed and pH_?, the pH of phase separation, both as a function of ionic strength. pH_c decreased with increasing ionic strength for all pectins and was used in a theoretical model that showed local charge density of the pectin to control the onset of complex formation. pH_? passed through a maximum with increasing ionic strength for LMP because of shielding of repulsive interactions between β-lg molecules bound to LMP, while attractive interactions were repressed at higher ionic strength. Potentiometric titrations of homo-molecular solutions and mixtures of β-lg and pectin showed charge regulation in β-lg–pectin complexes. Around pH 5.5–5.0 the pK_as of β-lg ionic groups are increased to induce positive charge on the β-lg molecule; around pH 4.5–3.5 the pK_a values of the pectin ionic groups are lowered to retain negative charge on the pectin. Since pectins with high local charge density form complexes with β-lg at higher ionic strength than pectins with low local charge density, pectin with a high local charge density is preferred in food systems where complex formation between protein and pectin is desired.     

Stabilization of acidic soy protein-based dispersions and emulsions by soy soluble polysaccharides

Soy soluble polysaccharides (SSPS) are shown to prevent destabilization of soy protein isolate (SPI) dispersions and SPI-based oil-in-water (O/W) emulsions under acidic conditions. Addition of SSPS above a critical concentration (0.25 wt%) increased the stability of 0.50 wt% SPI dispersions against aggregation and phase separation under conditions where SPI would normally precipitate (near its isoelectric point). Though SSPS neutralized SPI surface charge via electrostatic interaction, there was increased stability against aggregation due to steric repulsion. At acidic pH, addition of 1 wt% NaCl electrostatically screened protein–polysaccharide complexation which led to SPI precipitation and sedimentation. However, the order of salt addition had a significant impact on charge screening, with salt added before pH adjustment reducing SPI–SSPS complexation whereas it had less effect when added afterwards. Salt penetration efficacy diminished with decreasing pH. O/W emulsions (5 wt% oil) prepared with 0.50 wt% SPI destabilized at pH 4–5 due to protein aggregation, but addition of ≥0.25 wt% SSPS improved emulsion stability by inhibiting protein–protein interactions thus limiting increases in oil droplet diameter over time. Overall, both dispersion and emulsion stability greatly depended on pH, ionic strength and SSPS concentration. These results demonstrated that SSPS could effectively stabilize acidic SPI dispersions and that SPI–SSPS interactions may be used as a tool to improve the kinetic stability of SPI-based O/W emulsions.     

Complex coacervation of chitosan and soy globulins in aqueous solution: a electrophoretic mobility and light scattering study

The effect of pHs and heating on the protein–polysaccharide complexation between the 0.5 wt% soy globulin (7S or 11S) and 0.1 wt% chitosan was studied. Electrophoretic and light scattering techniques were used to examine the electrical charge and aggregation of the individual biopolymers and complexes. At pH 3.0–6.5, 7S (or 11S) globulin in the presence of chitosan had significantly higher ζ‐potentials and lower particles size than 7S (or 11S) globulin alone did (e.g. 600–6000 nm at pH 5.5), indicating the formation of complexes. After heating 7S (or 11S)–chitosan mixtures had higher positive value of ζ‐potential. 7S (or 11S)–chitosan mixtures exhibited a significant increase in positive value of ζ‐potential and stability after heating at lower pH values (pH 3.3 instead of pH 4.5). Compared with other mixtures, at pH 2.5–6.0, the most remarkable decrease in aggregation was obtained for 11S–chitosan mixtures after heating at pH 3.3.     

Formation and microstructural characterization of whey protein isolate/beet pectin coacervations by laccase catalyzed cross-linking

The purpose of this study was to characterize the properties of stable and reinforced protein–polysaccharides complex coacervations firstly formed by electrostatic interaction between WPI and beet pectin, and followed by laccase cross-linking through ferulic acid present in beet pectin. The interaction of whey protein isolate (WPI, 6 g/100 ml) with beet pectin (0–0.16 g/100 ml) in aqueous solutions was studied at different pH (3–7). ζ-potential and light-scattering techniques were used to provide information about the electrical charge and aggregation of individual biopolymers and complex coacervations. Stable WPI/beet pectin complex coacervations were formed when system consisted of 6 g/100 ml WPI and 1 g/100 ml beet pectin at pH 3.5. The microstructure and viscoelastic properties of WPI and beet pectin complex coacervations in the presence of laccase (0, 100, 300 U) was also studied using FT-IR, rheology, and confocal laser scanning microscopy (CLSM) techniques. The results obtained clearly showed that laccase catalyzed cross-linking of ferulic acid present in beet pectin had a remarkable influence on the physical properties of WPI–beet pectin complex coacervations microstructure. The reinforced complex coacervations formed fine networking structures which may provide convenient means for food industry to incorporate bioactive components into food products.     

Physicochemical properties of lactoferrin stabilized oil-in-water emulsions: Effects of pH,salt and heating

Lactoferrin is a globular protein from bovine milk with an unusually high isoelectric point (pI > 8), which may lead to novel functional properties in foods and other products because it is cationic across a wide pH range. In this study, we investigated the influence of pH (2–9), NaCl addition (0–200 mM), CaCl₂ addition (0–200 mM), and thermal processing (30–90 °C, 20 min) on the stability of lactoferrin (LF) stabilized oil-in-water emulsions. At ambient temperature, the emulsions were stable to droplet aggregation at low pH (pH ≤ 6), but exhibited some aggregation at pH ≈ pI (pH 7–9). The thermal stability of the emulsions depended on pH, holding temperature, and thermal history. When LF-coated droplets were heated in distilled water, and then their pH was adjusted in the range 2–9, they were highly unstable to aggregation at pH 7 and 8. On the other hand, when the pH was altered in the range 2–9 first, and then they were heated, the LF-coated droplets were highly unstable to aggregation at pH ≥ 5 when heated above 50 °C. The stability of the emulsions to salt addition depended on pH and salt type, which was attributed to counter-ion binding and electrostatic screening effects. For NaCl, emulsions were stable from 0 to 200 mM at pH 3 and 9, but aggregated at ≥100 mM at pH 6. For CaCl₂, emulsions were stable from 0 to 200 mM at pH 3, but aggregated with ≥150 mM CaCl₂ at pH 6 and 9. These results have important implications for the formulation and production of emulsion-based products using lactoferrin as an emulsifier.     

Modulation of physicochemical properties of lipid droplets using β-lactoglobulin and/or lactoferrin interfacial coatings

There is considerable interest in the development of food-grade delivery systems to encapsulate, protect and release bioactive lipids. In this study, emulsion-based delivery systems were prepared consisting of lipid droplets covered by β-lactoglobulin (BLG) and/or lactoferrin (LF) coatings. BLG and LF are globular proteins with relatively low (pI ∼ 5) and high (pI ∼ 8) isoelectric points, respectively. Mixed systems were prepared by adding LF to BLG-stabilized corn oil-in-water emulsions (BLG/LF-coated droplets) or by adding BLG to LF-stabilized corn oil-in-water emulsions (LF/BLG-coated droplets) at pH 7, where there is an electrostatic attraction between the proteins. The influence of pH (3–7), ionic strength (0–60 mM CaCl₂ or 0–200 mM NaCl, pH 7), and thermal treatment (21–90 °C, pH 7, 20 min) on the physical stability of the resulting emulsions was examined. Emulsions with good stability to pH, salt, and thermal processing could be created using mixed interfacial coatings. In addition, we found that the lipids in these emulsions could still be digested using an in vitro digestion model to simulate small intestine conditions. This work may lead to the formation of emulsion-based delivery systems with improved physicochemical and functional performance.     

Influence of environmental stresses on the physicochemical stability of orange oil bilayer emulsions coated by lactoferrin–soybean soluble polysaccharides and lactoferrin–beet pectin

Based on layer-by-layer electrostatic deposition, orange oil bilayer emulsions stabilized with lactoferrin (LF)–soybean soluble polysaccharides (SSPS) and lactoferrin (LF)–beet pectin (BP) were prepared. The effect of environmental stresses (ionic strength, pH, freeze–thaw and light) on the physicochemical stability of primary and secondary emulsions was investigated. In the absence of anionic polysaccharides, orange oil emulsion was highly unstable and aggregated at pH 7–9 and NaCl of 0.1–0.5 M. The droplets in LF–SSPS coated emulsion were stable against aggregation at pH range of 3–10 and NaCl concentration less than 0.3 M, while the droplets in LF–BP coated emulsion were stable against aggregation at pH 4–9 and NaCl concentrations of 0–0.5 M. All the primary and secondary emulsions showed the instability after the freeze–thaw treatment and the stability could be improved in the presence of maltodextrin. During the light exposure (0.35 W/m², 45 °C) for 8 h, the bilayer emulsions could protect key volatile compounds (decanal, octanal and geranial) from the oxidation compared with the primary emulsions. These results suggested that the layer-by-layer electrostatic deposition could improve the stability of LF-coated emulsion to environmental stresses.     

Microstructure & rheology of mixed colloidal dispersions: Influence of pH-induced droplet aggregation on starch granule–fat droplet mixtures

The creation of high quality reduced-fat food products is challenging because the removal of fat adversely affects quality attributes, such as appearance, texture, and flavor. This study investigated the impact of pH-induced droplet aggregation on the properties of model food systems consisting of fat droplets and starch granules. Oil-in-water emulsions (2 wt.% oil) containing whey-protein coated lipid droplets aggregated extensively when heated (90 °C, 5 min) at pH values around their isoelectric point (pH 5) but not at lower (pH 3.5) or higher (pH 7) values, which was attributed to changes in electrostatic repulsion. The physicochemical properties of mixed lipid droplet–starch dispersions (2 wt.% oil, 4 wt.% starch) prepared under similar conditions (pH 3.5, 5, and 7; 90 °C for 5 min) were also measured. At pH 5, extensive lipid droplet aggregation was observed in mixed systems, which led to a large increase in their yield stress and apparent viscosity when compared to mixed systems at pH 3.5 and 7. These results show that the rheological properties of mixed fat droplet–starch granule suspensions can be modulated by controlling the electrostatic interactions between the fat droplets so as to change their flocculation state. This study has important implications for fabricating high quality reduced-fat products with desirable sensory attributes.     

Colloidal stability and interactions of milk-protein-stabilized emulsions in an artificial saliva

Oil-in-water emulsions (20 wt% soy oil) with lactoferrin or β-lactoglobulin (β-lg) as the interfacial layer were prepared using a two-stage valve homogenizer. At pH 6.8, lactoferrin produces a stable cationic emulsion whereas β-lg forms an anionic emulsion. These emulsions were mixed with an artificial saliva that contained a range of mucin concentrations and salts. Negatively charged mucin was shown to interact readily with the positively charged lactoferrin-stabilized emulsion droplets to provide a mucin coverage of approximately 1 mg/m². As expected, the negatively charged β-lg-stabilized emulsion droplets had lower mucin coverage (0.6 mg/m² surface load) under the same conditions. The β-lg-stabilized emulsions were stable but showed depletion flocculation at higher mucin levels (≥1.0 wt%). In contrast, lactoferrin-stabilized emulsion droplets showed considerable aggregation in the presence of salts but in the absence of mucin. This salt-induced aggregation was reduced in the presence of mucin, possibly because of its binding to the positively charged lactoferrin-stabilized emulsion droplets and thus a reduction in the positive charge at the lactoferrin-coated droplet surface. However, at higher mucin concentration (≥2.0 wt%), lactoferrin-stabilized emulsions also showed droplet aggregation.     

Thermal analysis of β-lactoglobulin complexes with pectins or carrageenan for production of stable biopolymer particles

Biopolymer nanoparticles can be formed by thermal treatment of electrostatic complexes of globular proteins and anionic polysaccharides. The purpose of this study was to provide insights into the physicochemical origin of biopolymer particle formation using differential scanning calorimetry (DSC) and temperature-scanning turbidity measurements. DSC measurements indicated that high methoxyl pectin (HMP), low methoxyl pectin (LMP) and carrageenan (C) had little impact on the thermal denaturation temperature of β-lactoglobulin (T_m ～ 78 °C) at pH 4.75, where electrostatic complexes are formed. Temperature scanning turbidity measurements indicated that extensive biopolymer aggregation occurred above T_m for β-lactoglobulin-pectin systems, but not for β-lactoglobulin-carrageenan systems. This difference was attributed to the greater strength of the attractive electrostatic interactions between the protein and carrageenan molecules, compared to the protein and pectin molecules. The biopolymer particles formed by heating β-lactoglobulin-pectin complexes were relatively stable to association/dissociation from pH 3 to 7 for HMP and from pH 4 to 7 for LMP, whereas the β-lactoglobulin-C complexes were highly unstable to pH changes. The β-lactoglobulin-pectin nanoparticles (d = 200–300 nm) may therefore be useful as natural delivery systems or fat replacers in the food, pharmaceutical, cosmetic and other industries.     

Stabilization of multilayered emulsions by sodium caseinate and κ-carrageenan

The influence of the κ-carrageenan concentration and pH on the properties of oil-in-water multilayered emulsions was studied. Multilayered emulsions were prepared by the mixture of a primary emulsion stabilized by 0.5% (w/v) sodium caseinate (Na-CN) with κ-carrageenan solutions with different concentrations (0.05–1% w/v). The emulsions were evaluated at pH 7 and 3.5. At pH 7, there was little adsorption of κ-carrageenan onto the droplet surface and a depletion flocculation was observed when the polysaccharide concentration exceeded 0.5% (w/v). At pH 3.5, a mixed κ-carrageenan–Na-CN second layer was formed around the protein-covered droplets and the emulsions showed bridging flocculation at lower polysaccharide concentrations (0.05–0.25% w/v). Stable emulsions could be formed with the highest κ-carrageenan concentration (1% w/v) at both pH values (7.0 and 3.5). Thus, stable emulsions were successfully produced using protein–polysaccharide interfacial complexes, and the oil droplet diameter, zeta potential and rheological properties of these emulsions were not affected by changes in the pH.     

Formation of protein nanoparticles by controlled heat treatment of lactoferrin: Factors affecting particle characteristics

Lactoferrin is a globular protein from milk that has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. In this study, we examined the possibility of preparing food-grade bovine lactoferrin (bLf) nanoparticles using a simple thermal processing method. Differential Scanning Calorimetry (DSC), light scattering, and ζ-potential techniques were used to provide information about the conformational changes, aggregation, and electrical charge of bLf in aqueous solutions. DSC studies indicated that the protein had two thermal denaturation temperatures (61 and 93 °C), which were associated with two different lobes of the protein. Protein denaturation was found to be irreversible, which was attributed to the formation of protein nanoparticles, whose size depended on the temperature and duration of the thermal treatment. Higher holding temperatures produced faster protein aggregation and larger protein nanoparticles: 85 > 80 > 75 > 70 °C. The protein nanoparticles produced by thermal treatment were resistant to subsequent changes in pH (from 3 to 11) and to salt addition (0–200 mM NaCl). The lactoferrin nanoparticles produced in this study may be useful as function ingredients in commercial products.     

In situ study of flocculation of whey protein-stabilized emulsions caused by addition of high methoxyl pectin

The effect of pectin addition to a 10% oil-in-water emulsion stabilized with whey protein isolate was measured in situ using Ultrasound (US) and Diffusing Wave Spectroscopy (DWS). At pH 7 changes in velocity of sound and in 1/l* were measured while adding pectin to the emulsion, indicating a change in the spatial organization of the droplets perhaps caused by a change in the hydration layer. At pH 3.5, sequential additions of pectin showed four different stages in the interactions between droplets. At very low concentration of pectin (<0.02%) no changes were observed, while at 0.02–0.04% pectin 1/l* decreased, perhaps indicating the occurrence of long-range interactions. Between 0.045 and 0.06% pectin, a dramatic change in velocity, attenuation and 1/l* occurred because of the change in hydration layer and surface charge distribution of the oil droplets. Finally, at high concentration of pectin (above 0.06%) bridging flocculation occurred leading to changes in droplet size and size distribution.     

Fabrication of viscous and paste-like materials by controlled heteroaggregation of oppositely charged lipid droplets

This study describes the formation of materials with novel textural characteristics by controlled heteroaggregation of oppositely charged protein-coated lipid droplets. Heteroaggregation was induced by mixing a suspension of β-lactoglobulin (β-Lg)-coated lipid droplets (ζ = −51 mV, d₄₃ ∼ 0.35 μm, 20 wt.%) with a suspension of lactoferrin (LF)-coated lipid droplets (ζ = +32 mV, d₄₃ ∼ 0.35 μm, 20 wt.%) under conditions where the two proteins had opposite charges (pH 7). The mean particle size, flow behaviour, and shear modulus of the materials depended on positive-to-negative particle ratio (0–100%), pH (3–9), ionic strength (0–400 mM), and temperature (30–90 °C). The largest particle sizes, highest viscosities, and largest gel strengths were observed at intermediate particle ratios (40% LF:60% β-Lg), which was attributed to a strong electrostatic attraction between oppositely charged droplets (0 mM NaCl, pH 7, 25 °C). A reduction in particle aggregation, viscosity, and gel strength occurred at intermediate ionic strengths due to screening of the electrostatic attraction between oppositely charged droplets. However, increased aggregation, thickening, and gelation occurred at higher ionic strengths due to screening in electrostatic repulsion between similarly charged droplets. Thermal treatment of the samples (90 °C) promoted a substantial increase in gel strength due to protein denaturation and increased droplet attraction. This study has important implications for the utilisation of controlled particle aggregation to create novel structures in foods, cosmetics, personal care, and other products.     

Fabrication and characterization of filled hydrogel particles based on sequential segregative and aggregative biopolymer phase separation

In this study, filled hydrogel particles were created based on the ability of proteins and ionic polysaccharides to phase separate through both aggregative (complexation) and segregative (incompatibility) mechanisms. At pH 7, a mixture of 3% (w/w) high-methoxy pectin and 3% (w/w) sodium caseinate phase separated through a segregative mechanism. Following centrifugation, the phase separated system consisted of an upper pectin-rich phase and a lower casein-rich phase. Casein-coated lipid droplets added to the phase separated pectin/caseinate system partitioning into the lower casein-rich phase. This was attributed to a reduction in the unfavorable osmotic stress in this phase associated with biopolymer depletion. When shear was applied this system formed an oil-in-water-in-water (O/W₁/W₂) emulsion consisting of oil droplets (O) contained within a casein-rich watery dispersed phase (W₁) suspended in a pectin-rich watery continuous phase (W₂). Acidification of the O/W₁/W₂ system from pH 7–5 promoted adsorption of pectin around the casein-rich W₁ droplets, resulting in the formation of filled hydrogel particles (d = 3–4 μm) that remained stable to aggregation or dissociation when stored for 24 h at ambient temperature. These particles may be useful as encapsulation and delivery systems for lipophilic components in the food, cosmetics and pharmaceutical industries.     

动态高压微射流处理顺序对果胶-乳铁蛋白复合物结构及性质的影响

采用动态高压微射流（dynamic high pressure microfluidization,DHPM）分别以不同的处理顺序：DHPM预处理乳铁蛋白（lactoferrin,LF）后与果胶（pectin,P）混合（MLFP）、DHPM预处理果胶后与乳铁蛋白混合（MPLF）以及乳铁蛋白与果胶混合后再经DHPM处理（MLFP）,制备3 种乳铁蛋白-果胶复合物,探究DHPM的处理顺序对复合物结构及性质的影响。结果表明：DHPM处理使复合物的分散性增大,乳化性减小。且经DHPM处理后的3 种复合物中,MLFP的分散性和乳化性最强,而MLFP的分散性和乳化性最低,这与界面张力测定结果一致。经DHPM处理后复合物粒径也显著减小（P＜0.05）,且MPLF＜MLFP ＜MLFP＜空白对照组复合物。ζ-电位和荧光光谱结果表明,果胶和LF复合物主要通过两者间静电作用结合,且DHPM处理促进果胶与LF的相互作用。本研究为探讨食品组分在食品加工过程中的结构和性质变化提供一定的理论依据。     

Impact of dietary fiber coatings on behavior of protein-stabilized lipid droplets under simulated gastrointestinal conditions

Multilayer emulsions containing lipid droplets coated by lactoferrin (LF) - anionic polysaccharide layers have improved resistance to environmental stresses (such as pH, salt, and temperature), but their behavior within the gastrointestinal tract (GIT) is currently unknown. The objective of this research was therefore to monitor changes in the physicochemical properties and digestibility of these systems under simulated GIT conditions. Primary emulsions (5% corn oil, 0.5% LF) were prepared using a high-pressure homogenizer. Secondary emulsions (5% corn oil, 0.5% LF, 0.5% polysaccharide) were prepared by incorporating alginate, low methoxyl pectin (LMP) or high methoxyl pectin (HMP) into primary emulsions. Emulsions were then subjected to simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) conditions in sequence. LF, LF-LMP and LF-HMP emulsions were stable to droplet aggregation in the stomach but aggregated in the small intestine, whereas LF-alginate emulsions aggregated in both the stomach and small intestine. The presence of a dietary fiber coating around the initial lipid droplets had little influence on the total extent of lipid digestion in SIF, but LF-alginate emulsions had a slower initial digestion rate than the other emulsions. These results suggest that the dietary fiber coatings may become detached in the small intestine, or that they were permeable to digestive enzymes. Pepsin was found to have little influence on the physical stability or digestibility of the emulsions. The knowledge obtained from this study is important for the design of delivery systems for encapsulation and release of lipophilic bioactive ingredients.     

Influence of non-ionic surfactant on electrostatic complexation of protein-coated oil droplets and ionic biopolymers (alginate and chitosan)

The purpose of this study was to examine the influence of a non-ionic cosurfactant (Tween 20) on the formation and properties of electrostatic complexes consisting of charged oil droplets and charged biopolymers. The mean droplet diameters in oil-in-water emulsions prepared using a membrane homogenizer were considerably larger when β-lactoglobulin (BLG) was used alone (≈8 μm), than when it was used in combination with Tween 20 (≈2 μm). The cationic oil droplets formed by membrane homogenization (4.0 μm pore size) were mixed with either alginate (anionic) solution (1% oil: 0–0.5% alginate: pH 3.5) or with alginate (anionic) and then chitosan (cationic) solutions (0.4% oil: 0.1% alginate; 0–0.2% chitosan: pH 4.5). The electrical characteristics, microstructure, and physical stability of the electrostatic complexes formed were determined. Under certain conditions multilayer emulsions consisting of oil droplets coated by alginate or alginate/chitosan layers were formed, whereas under other conditions microclusters consisting of aggregated oil droplets embedded within alginate or alginate/chitosan complexes were formed. The presence of the cosurfactant had a major impact on the electrical charge and dimensions of the electrostatic complexes formed. This study shows that various kinds of electrostatic complexes can be formed from charged oil droplets and charged biopolymers, and that their functional characteristics can be controlled using non-ionic cosurfactants.