Abstract
Conventional emulsions are two‐phase emulsion systems widely used for the encapsulation and delivery of active ingredients that consist of lipid or water droplets containing bioactive compound(s). An emulsifier forms an interfacial thin layer surrounding individual droplets that create interactions with hydrophilic and hydrophobic phases. Generally, the mean droplet diameter for this type of emulsion ranges from 0.3^μm to 100^μm. The resultant emulsion is cloudy or opaque in appearance, and is prone to gravitational separation and droplet coalescence. The initial concentration of droplets and size distribution can be controlled to a great extent in this type of emulsion by the nature of the emulsifying agent used to stabilize the droplets. Furthermore, interfacial properties of the emulsion, including dimensions, charge, rheology, and environmental stresses (e.g. temperature, pH, ionic strength, and enzyme activity) response can be controlled by accurate selection of emulsifier type. This chapter discusses the preparation and characterization of conventional emulsions as well as their feasibility to encapsulate bioactive compounds. The stability of this type of emulsion under in vitro and in vivo digestion systems is critically evaluated.