Oxidative Barrier Properties and in vitro Digestion of Particle and Particle-Polymer Stabilized Pickering Emulsions

Encapsulation is widely used in the food industry to protect materials from moisture, heat or other conditions. The oil-in-water (O/W) emulsion encapsulation system is widely used in the delivery of bioactive compounds, antimicrobial compounds, flavor and vitamins in the food, pharmaceutical and biomedical industry. Because many compounds are very sensitive to oxidation and degradation, it is a significant challenge to extend the shelf life of products in the food industry. The barrier properties of an emulsion interfacial layer are essential in reducing oxidation in the oil phase. Chapter 2 focuses on microcapsules stabilized using silica (SiO2) nanoparticles and SiO2-polymer nano-complexes to enhance these barrier properties. In this study, we selected polyethylenimine (PEI), a cationic polymer, coated on SiO2 nanoparticles by electrostatic attraction. The stability of the emulsions was determined by measuring particle size, zeta-potential and by fluorescence imaging. The permeability of the interface to free radicals was measured by using a fluorescence-based method. Retinol was used as a model compound to study bioactive compound stability in the presence of free radicals.;To better control lipid bioavailability, it is important to gain a better understanding of the role interfacial composition plays in the digestion of emulsions. A variety of surface-active substances, such as bile salts, enzymes and phospholipids may alter interfacial composition and the properties of the emulsion. Chapter 3 presents measurements of the effects of such interfacial changes on the kinetics of free fatty acid release, by comparing emulsions stabilized by SiO2 nanoparticles with those stabilized by whey protein isolate (WPI) in a simulated intestinal environment. This study can be useful in the design of food emulsion systems that control the digestion and absorption of lipids in the small intestine.