The pace of development of Pickering emulsions stabilized by food-derived particles such as starches and proteins has recently soared to replace conventional emulsions using a large amount of chemical emulsifiers. The protein-stabilized emulsions cannot be transported to small intestine due to its degradation in stomach condition. The starch-stabilized emulsions have a low colloidal stability because of their large size, so they cannot be applied to beverages. In this study, to increase the colloidal stability of starch-stabilized emulsions, starch nanocrystals (SNC) obtained by sulfuric acid hydrolysis were used to stabilize emulsions, and ultrasonic treatment was added to further increase the colloidal stability. An oil-soluble dye (Nile Red) was used to visualize changes in the lipid phase during digestion. Lipid-labeled Pickering emulsions were passed through a simulated gastrointestinal tract consisting of mouth, stomach, and intestinal phases, and changes in lipid location and morphology were monitored using confocal laser scanning microscopy. The lipid droplets were slightly enlarged in the mouth condition, highly flocculated in the gastric condition, and completely digested in the small intestine condition. Our results show that the additional ultrasonication to the SNC-stabilized emulsions resulted in enhanced colloidal stability, and the SNC-stabilized emulsions produced by the above process were stable in the mouth and stomach conditions and completely digested in the small intestine condition. So, the SNC-stabilized emulsions produced through this study could be effectively applied to functional beverages as a chemical emulsifier-free delivery systems.

To enhance the oral bioavailability (BA) of curcumin (CUR), we applied 1 wt% CUR-loaded lipid nanoparticle (LNP) system prepared with tristearin (TS) and short (Brij S10) / long (Brij S100) PEGylated surfactants. All LNPs were colloidally stable under high ion strength and pH 3 conditions regardless of the PEG chain length. However, the long-chained PEGylation prevented LNP surface better than the short-chained PEGylation from the lipase/bile salt adsorption according to ζ potential results after treatment of lipase and bile solutions. Actually, the short-chained LNPs were digested rapider than the long-chained one in the simulated small intestinal condition due to the faster displacement of PEGylated surfactants on LNP surface by bile salts. Furthermore in the rat model pharmacokinetics for oral administration of CUR, the long-chained LNP group had 10.62-fold BA of native CUR group due to the coabsorption of CUR with the mixed micelles made after gastrointestinal digestion, and had 4.57-fold BA of the short-chained LNP group despite the same molarity use (17.058 mM) of both emulsifiers due to the reduced digestion rate by long-chained PEG on LNP surface. In conclusion, since CUR incorporated in LNPs was improved in the bioavailability, the designed LNP system may serve as an encapsulation strategy to enhance the bioavailability of non-bioavailable nutraceuticals in foods.