Health-conscious consumers are looking for liquid beverages formulated with healthy ingredients to satisfy their daily nutritional needs. Such beverages are ideal transport system for many beneficial bioactive compounds as they can be dissolved, suspended, encapsulated or emulsified.
Most of the healthy ingredients are hydrophobic in nature and their incorporation into aqueous/stable colloidal dispersion is a challenging process.
Industrially processed beverages are formulated with a variety of processing ingredients/aids in order to provide desirable texture, flavor, and shelf-life.
During the manufacture of formulated beverages, numerous unit operations are involved including dissolving, mixing, emulsification,homogenization and thermal treatment.
Emulsification is one of the key processing steps in which fat droplets are finely dispersed into an immiscible continuous phase.
Emulsion formation is aimed to prepare stable dispersions of hydrophobic compounds (oil, oil soluble vitamins, and bioactive compounds) that otherwise would separate from the aqueous medium. Emulsification is a dynamic phenomenon that involves deformation and break-up of liquid fat droplets, forming smaller droplets of narrow size range.
Concomitantly, the newly produced droplets are rapidly adsorbed by surfactant as proteins and emulsifiers, creating a colloidal dispersion. Such a fine dispersion is kinetically active due to colloidal and hydrodynamic interactions leading to inter-droplet collisions which may results in the formation of larger droplets.
This is known as coalescence and it is avoided by the addition of water-soluble polymers, called stabilizers.
Adsorption and coalescence occur within short time scales and the final droplet size range of the colloidal dispersion and its stability is governed by the input of mechanical energy, type and concentration of stabilizer, and emulsifier to stabilizer ratio.