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This research aimed to investigate the possibility of forming gelled nanoemulsions (NEs) by inducing attractive interactions among the nanodroplets. The effect of salt concentration and changes in pH on the stability and gelation behavior of 2, 4, and 5% sodium caseinate (SC) and whey protein isolate (WPI)-stabilized 40% canola oil-in-water NEs were investigated. For the effect of salt, sodium chloride was added in a concentration of 0.1, 0.5, and 1 M in the continuous phase of the NEs at neutral pH, whereas to study the effect of acidification, the pH of the NEs was adjusted to the isoelectric point (pI) of the proteins. The addition of salt led to attractive gelation in WPI NEs because of a screening of charge. In contrast, the gel strength of SC-stabilized NEs was reduced with salt, which was attributed to the loss of close packing of droplets and their surrounding repulsive barriers because of charge screening and to the steric barrier of interfacial SC preventing droplet aggregation. All the NEs with pH at the pI of proteins transformed into strong attractive gels made of droplet aggregates irrespective of the type or concentration of protein because of the complete charge neutralization. The strength of the acidified NE gels increased with a decrease in droplet size and the type of protein used. Overall, research on the effect of different environmental factors on the stability and gelation behavior of protein-stabilized NEs could be useful for possible applications of these nanoscale materials in various food systems.

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The goals of this research were to develop oil-inwater nanoemulsions (NE) encapsulating curcumin by partially replacing sodium caseinate (SC) with pea protein isolate (1:1) and to investigate the lipid digestibility and bioaccessibility of curcumin using in vitro digestion. Structural changes in oil droplets during digestion were also examined using particle-size measurement and confocal laser-scanning microscopy. Both SC and mixed protein (MP)-stabilized NE were stable for the experimental time frame of eight weeks without significant changes in the droplet size. About 50% active curcumin encapsulated in the NE remained stable over eight weeks where the stability was higher for SC compared to the MP-stabilized NE (MPE). An increase in the droplet sizes and changes in their distribution during in vitro digestion were found to be a combined effect of the presence of digestive enzymes and also the rapid changes in the ionic strength and pH of the system. The lipid digestibility of the MPE was significantly lower than the SCstabilized NE, which was attributed to a stronger viscoelastic oil-droplet interface in the presence of pea proteins. However, the former was found to be as efficient as the latter in successfully releasing about 50% curcumin in the simulated intestine phase. Therefore, pea proteins can be used to partially replace SC as an emulsion stabilizer for the protection and delivery of oil-soluble bioactive compounds.Keywords Curcumin Á Nanoemulsion Á Sodium caseinate Á Pea protein isolate Á In vitro digestion Á Bioaccessibility J Am Oil Chem Soc (2018) 95: 1013-1026.