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Natural emulsifiers have become of increasing interest within the food and beverage industry. Oat bran is a natural side-stream product produced during oat refinement that may be used to obtain amphiphilic extracts. Our hypothesis was that the oat bran extract is rich in surface-active and amphiphilic oat saponins and proteins that can form and stabilize emulsions. For this, we examined the surface activity of oat bran extract at oil-water and air-water interfaces, its ability to form oil-in-water emulsions and their stability against various stress tests. The highly surface-active oat bran extract acted as an ionic emulsifier, forming highly negatively charged submicron-sized emulsion droplets. These emulsions were stable over a wide range of pH (4–9), heat treatment (≤50 °C), and during storage at ≤25 °C up to 42 days. However, the emulsions showed instability at pH 2–3, at high ionic strengths, and during freeze-thawing. The formation and stability of the emulsions is related to interfaces containing oat saponins or oat saponin-protein complexes rather than a protein layer. These findings show that oat bran extract is a highly promising natural emulsifier, providing the food and beverage industry with a viable substitute to traditional emulsifiers. [ABSTRACT FROM AUTHOR]

Casein and soy soluble polysaccharide formed compacted complex aggregates in pH 3–4.5 aqueous solutions by electrostatic and hydrophobic interactions. The diameters of the complex aggregates were about 133 nm. The oil in water emulsion produced from the complex at pH 4 was stable after 500 days of storage in pH 2–6.8 media at 4 °C due to the compacted complex interfacial film. The curcumin loading efficiency of the emulsion was 99.9% and diameter of the droplets was about 324 nm. Only 3% of the loaded curcumin degraded when the emulsion was stored at 4 °C for 40 days. About 73% of the curcumin was released after 2 h digestion of the emulsion in simulated gastric fluid followed by 2 h digestion in simulated intestinal fluid. The curcumin pharmacokinetics in mice was analyzed after oral administration. The curcumin absorption of the emulsion treatment group was more rapid and effective than the absorption of curcumin/Tween 20 suspension treatment group. The curcumin oral bioavailability of the emulsion group was 11-fold higher than the bioavailability of curcumin/Tween 20 suspension group. This study demonstrated that casein and soy polysaccharide complex emulsion is an applicable system for oral delivery of lipophilic nutrients and drugs. [ABSTRACT FROM AUTHOR]

Proteins as natural amphiphilic biopolymers can stabilize emulsions and are attracting intensive interest due to their abundant resource, good emulsifying properties, biocompatibility, biodegradability, nutritional benefits, and high acceptance as food ingredients. Relying on the rational design of protein-polysaccharide interactions and their differences in physicochemical properties, the interfacial structure and properties of protein-based emulsions can be effectively improved. This review summarizes the influence of various types of cellulose (i.e., nanocellulose, microcrystalline cellulose (MCC), cellulose derivatives and regenerated cellulose (RC)) on the stabilization and interaction mechanism of protein-based emulsions. The key role of cellulose in protein-based emulsions can be summarized as the following points, namely strengthening network stabilization, improving emulsifying property, adjusting emulsion structure, enhancing environmental stability and regulating lipid digestion. The application potential of protein-based emulsions focusing on fat replacer, 3D printed food, delivery vehicle, and material design can also be improved by introducing various types of cellulose. [Display omitted] • Introducing cellulose improves structure and properties of protein-based emulsions. • Rational combination of protein and cellulose allows designing tailor-made emulsions. • Various types of cellulose have varied effects on protein-based emulsions. • Key role of cellulose on protein emulsions and their applications are summarized. [ABSTRACT FROM AUTHOR]

In this study, BSA-dextran conjugate, produced by Maillard reaction, was used as emulsifier and stabilizer to produce curcumin-loaded oil in water emulsions. At fixed pH and BSA-dextran concentration in aqueous phase, the increases of curcumin concentration in oil phase from 12 to 15 mg/mL and oil volume fraction from 20% to 40% did not influence curcumin loading efficiency, but the oil-water interfacial films became imperfect, which were observed by transmission electron microscopy. The emulsion with integrated and cross-linked interfacial film formed on a heat treatment was long-term stable at various temperature and pH conditions, including physical stability of the emulsion and chemical stability of the loaded curcumin. Ex vivo fluorescence images of mice by means of hydrophobic fluorescence probe-loaded BSA-dextran emulsion revealed that the emulsion and/or released probe were mainly in gastrointestinal tract after oral administration and almost disappeared at 24 h post-administration. The pharmacokinetics analysis demonstrated that curcumin-loaded BSA-dextran emulsion could increase curcumin oral bioavailability in mice by 4.8-fold compared with curcumin/Tween 20 suspension. This study verifies that the emulsion can protect loaded curcumin from decomposition and also can promote curcumin absorption in gastrointestinal tract, indicating that protein-polysaccharide emulsions are good oral delivery systems for hydrophobic drugs and nutrients. [ABSTRACT FROM AUTHOR]

One of the current trends prominent in the food and pharmaceutical industries is the use of colloidal structures to stabilize emulsions. Complexes formed by bio-compounds, such as protein (ptn), polysaccharides (poly), and phenolic compounds (phe) have the potential to offer physical stability, besides other functional properties to emulsions, such as preservation against oxidation and thermal stability. This review focuses on recent insights regarding the contribution of ptn-poly, ptn-phe and ptn-poly-phe complexes on liquid interfaces designing innovative colloidal arrangements. Topics on the formation of non-covalent or covalent binary and ternary complexes, processes involved in the modification of molecules or complexes formation, and the different strategies of colloidal structures at the water-oil interface are addressed. Herein the information may contribute to the rational design of novel complexes with specific physicochemical and functional attributes, as well as encourage further research on this topic. [Display omitted] • Biopolymers and phenolic compounds were used to form complex. • Binary and ternary complexes can be applied to produce stable emulsions. • Complex type influences interfacial properties. • Complexation between biopolymers is affected by process conditions. [ABSTRACT FROM AUTHOR]

Abstract: Composition of soybean proteins is briefly described. Gels and gelling processes of soybean proteins and other functionalities such as colloidal properties and emulsifying properties are described. The effects of temperature, pH, ionic strength, processing conditions such as high pressure, ultrasonic treatment, utilisation of enzyme, chemical modification are also described since they have been found useful to improve the processing and final product. [Copyright &y& Elsevier]

Abstract: The emulsifying properties and emulsion stability of medium chain triglyceride (MCT) oil in water emulsions stabilized by plant proteins (potato, soy, and pea) as well as those extracted from milk (sodium caseinate and whey) have been investigated at two different pH values (7 and 10). The effect of protein type, concentration, pH and temperature has been studied using droplet size distribution, interfacial tension, and interfacial elasticity measurements. The interfacial tension is measured as a function of concentration ranging from 0.01% to 2.5% using the pendant drop method. The interfacial elasticity is also measured using the oscillating drop technique. The stability of the resulted emulsions is assessed using a stress test whereby the emulsions are placed at 60 or 40 °C for 24 h by measuring the droplet size distribution before and after the stress test. The interfacial tension decreases with increase of the pH and increase of the protein concentration pH value. A higher elasticity at the oil/water interface is obtained at pH = 10 when compared to that at pH = 7 for both Na-caseinate and pea proteins. Fine and stable emulsions are obtained at pH = 10, showing good correlation between interfacial tension and emulsion formation as well as between interfacial elasticity and emulsion stability for milk and plant proteins. [Copyright &y& Elsevier]

Abstract: In oil-in-water (O/W) emulsions, the droplets covered by native proteins are more prone to oxidation than droplets covered by surfactants. We attempted in this work to improve the barrier properties of protein-stabilized interfacial layers by controlled modifications of their composition and structure. Native bovine β-lactoglobulin (BLG) or β-casein (BCN), partially aggregated BLG and mixtures of the proteins with dilauroyl phosphatidylcholine (DLPC) were used to prepare emulsions and reconstituted Langmuir–Blodgett films. Lipid oxidation in the emulsions, as evaluated from oxygen uptake and formation of conjugated dienes, propanal and hexanal was roughly unmodified with aggregated BLG and DLPC–BLG mixtures and even favored with DLPC–BCN mixtures. The reconstituted phospholipid/protein interfacial layers presented interfacial heterogeneity evidenced by atomic force microscopy (AFM). This indicates that the structural homogeneity of the interface could be a key factor in controlling lipid oxidation. [Copyright &y& Elsevier]

Pectins extracted from sugar beet pulp are promising additives for the food and beverage industry due to their good emulsifying properties. However, the relationship between molecular structure and emulsifying properties is still not fully understood; thus, systematic optimization of pectin extraction for a better emulsifying activity is not possible. In this study, we assess the underlying relationship between molecular structure and emulsifying properties by linking relevant structural parameters of 43 acid-extracted sugar beet pectins to their emulsifying properties. Sugar beet pectins with distinct structural characteristics were produced by acid extraction using varying conditions. The extracted polysaccharides were used as emulsifying agents in oil-in-water emulsions. Resulting droplet sizes were measured to correlate molecular characteristics with emulsifying properties. Analyses of protein content, degree of methylation, degree of acetylation, mean molecular weights, and trans -ferulic acid contents showed that these parameters affect the emulsifying properties to some degree, but cannot fully explain the differences observed among all pectins. However, a linear correlation between the proportion of neutral sugar side chains and droplet sizes was observed. The influence of galactose (18–30 mol%) was negligible, but increasing amounts of branched arabinans (up to 57 mol% arabinose) positively affected the emulsification result. Based on these results, it can be concluded that particularly branched arabinan side chains play an important role in the sugar beet pectin-based stabilization of emulsions. Thus, the arabinose content appears to be a suitable indicator to estimate the emulsifying properties of acid-extracted sugar beet pectins. [Display omitted] • 43 sugar beet pectins with different molecular structures were extracted. • Structures and emulsifying properties of all pectins were analyzed. • Pectins with higher protein contents did not lead to smaller oil droplets. • Ferulic acid, molecular weight, DM, and DAc had neglectable to moderate impact. • Higher portions of arabinan side chains clearly resulted in smaller droplets. [ABSTRACT FROM AUTHOR]

Abstract: The microstructural and large deformation rheological properties of model food gels were studied by performing notch propagation tensile testing on the gels using a tensile stage and observing changes in the microstructure of the gels during tensile testing using confocal laser scanning microscopy (CLSM). Heat-set whey protein (WP) gels containing either added sodium caseinate (NaCN) or sunflower oil droplets emulsified with WP or NaCN as the emulsifier protein were prepared in 0 or 50mM NaCl. The WP gel structure strengthened in the presence of added NaCl and NaCN. The rheological properties of WP gels containing sunflower oil droplets emulsified with WP or NaCN were influenced by the NaCl concentration, oil concentration and extent of oil droplet aggregation in the gel or by the type of emulsifier protein used. During tensile testing, the notch length in all gels increased above a certain critical stress, leading to fracture of the gels through the notch. Also, the microstructural changes in the oil phase of emulsion filled gels subjected to tensile testing were influenced by the structural properties of the WP gel matrix and the proximity of the oil droplet to the fracture path. [ABSTRACT FROM AUTHOR]

Abstract: Food and pharmaceutical industries all over the world are witnessing an increasing demand for collagen and gelatin. Mammalian gelatins (porcine and bovine), being the most popular and widely used, are subject to major constraints and skepticism among consumers due to socio-cultural and health-related concerns. Fish gelatin (especially from warm-water fish) reportedly possesses similar characteristics to porcine gelatin and may thus be considered as an alternative to mammalian gelatin for use in food products. Production and utilization of fish gelatin not only satisfies the needs of consumers, but also serves as a means to utilize some of the byproducts of the fishing industry. This review focuses on the unique features, advantages, constraints, and challenges involved in the production and utilization of fish gelatin in order to provide a comprehensive look and deeper insight on this important food ingredient, as well as prospects for its future commercial exploitation and directions for future studies. [Copyright &y& Elsevier]

Abstract: The foaming and emulsifying characteristics of proteins are important attributes during the production stage, storage, transport, and consumer perception of quality (appearance) of food dispersions (emulsions and foams). In this contribution, we are concerned with the analysis of interfacial, foaming, and emulsifying characteristics of a typical milk protein (sodium caseinate) as a function of protein concentration in aqueous solution (C, % w/w). We have observed that there exists close relationships between foaming (power of foaming, foam capacity, foam density, and foam conductivity) and the rate of diffusion (slope of π vs. t1/2) of caseinate to the air–water interface. The foam stability (quantified by the relaxation time (t) due to drainage and disproportionation/collapse) correlates linearly with the equilibrium surface pressure (πe) of aqueous solutions of caseinate. At surface pressures lower than that of monolayer saturation (at C<1×10-3%, w/w) the foaming is zero. The emulsifying capacity (quantified by the droplet size and the specific surface area) was correlated with the protein concentration in solution (surface pressure at equilibrium). Coalescence was observed only at the lower caseinate concentration in solution (C<0.1%, w/w). As a coherent protein layer (multilayer) saturates the interface, at higher protein concentrations, the emulsion instability is due to flocculation and/or creaming. The coalescence and creaming rates correlate well with the protein concentration in solution (thus with the surface pressure and/or surface dilatational modulus). [Copyright &y& Elsevier]

The effect of protein/phospholipid ratio on the physicochemical and interfacial properties of biomimetic milk fat globules (BMFGs) was investigated. Butter milk phospholipid (BMP) vesicles prepared with ultrasonication were mixed with whey protein isolate (WPI) at different protein/phospholipid ratios (w/w). After emulsification, the Turbiscan stability index (TSI) was used to quantify the initial stability of BMFGs. At different pH values, visual observation and CLSM were performed to obtain the macro stability and microstructure of BMFGs. In addition, large amplitude oscillatory surface rheology was applied and analysed with Lissajous curves, to explore the oil/water interfacial properties of BMFGs in the nonlinear viscoelastic regime. The TSI indicated a faster creaming rate of BMP stabilized droplets compared to those stabilized by WPI. The macro stability of WPI/BMP co-stabilized BMFGs at different pH was dominated by WPI and BMFGs prepared at the WPI/BMP ratio of 20:80 phase separated from pH 3.0 to 5.0. At acidic pH, the WPI/BMP ratios strongly affected the coalescence and flocculation of BMFGs at the micro level. The surface elasticity indicated that WPI dominated the rheological properties of WPI/BMP co-stabilized oil/water interfaces. Besides, the significant dependence of surface elasticity on deformation amplitudes within the nonlinear regime of WPI stabilized oil/water interfaces indicated a clearly different structure from BMP stabilized interfaces. Conclusively, results of this study showed that the physicochemical and interfacial properties of BMFGs were significantly influenced by the protein/phospholipid ratio in the bulk, which needs to be considered in the design and application of biomimetic milk fat globules. Image 106 • Stability of WPI/BMP co-stabilized droplets at acidic conditions was dominated by WPI. • WPI/BMP ratios strongly affected the microstructure of model emulsion at different pH. • WPI dominated the rheological response of WPI/BMP co-stabilized oil/water interfaces. • The surface elasticity of BMP showed no strain dependence under nonlinear oscillation. [ABSTRACT FROM AUTHOR]