There is increasing consumer pressure for commercial products that are more natural, sustainable, and environmentally friendly, including foods, cosmetics, detergents, and personal care products. Industry has responded by trying to identify natural alternatives to synthetic functional ingredients within these products. The focus of this review article is on the replacement of synthetic surfactants with natural emulsifiers, such as amphiphilic proteins, polysaccharides, biosurfactants, phospholipids, and bioparticles. In particular, the physicochemical basis of emulsion formation and stabilization by natural emulsifiers is discussed, and the benefits and limitations of different natural emulsifiers are compared. Surface-active polysaccharides typically have to be used at relatively high levels to produce small droplets, but the droplets formed are highly resistant to environmental changes. Conversely, surface-active proteins are typically utilized at low levels, but the droplets formed are highly sensitive to changes in pH, ionic strength, and temperature. Certain phospholipids are capable of producing small oil droplets during homogenization, but again the droplets formed are highly sensitive to changes in environmental conditions. Biosurfactants (saponins) can be utilized at low levels to form fine oil droplets that remain stable over a range of environmental conditions. Some nature-derived nanoparticles (e.g., cellulose, chitosan, and starch) are effective at stabilizing emulsions containing relatively large oil droplets. Future research is encouraged to identify, isolate, purify, and characterize new types of natural emulsifier, and to test their efficacy in food, cosmetic, detergent, personal care, and other products.

No abstract

No abstract

No abstract

The utilization of lutein as a natural colorant or nutraceutical in many foods, supplements, and 17 other commercial products is currently limited because of its low water-solubility and chemical instability. The purpose of this study was to evaluate the effect of Maillard conjugates on the physical and chemical stability of lutein-enriched emulsions exposed to different temperatures 20 and pH values, as well as on their potential gastrointestinal fate. Oil-in-water emulsions were prepared using either casein or casein-dextran conjugates as emulsifiers. Both types of emulsions showed a slight increase in particle aggregation at temperatures exceeding 37 ˚C, and 23 became more prone to color fading (lutein degradation) as the temperature was increased. 24 Casein-coated oil droplets were highly unstable to flocculation near their isoelectric point (pH 4 25 to 5) due to the reduction in electrostatic repulsion. However, casein-dextran-coated droplets 26 were stable from pH 3 to 7, which was attributed to strong steric repulsion by the dextran moiety. 27 The casein-coated droplets were unstable to aggregation in the gastric phase of the simulated 28 GIT, whereas the casein-dextrin-coated ones were stable, which was again attributed to increased steric repulsion. Emulsifier type did not strongly influence lutein bioaccessibility. This work shows that Maillard conjugates can improve the physical stability of lutein-enriched emulsions without adversely affecting the bioaccessibility of the bioactive agent.