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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]

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]

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]