# Microencapsulation of Natural Food Antimicrobials: Methods and Applications
## 2 Encapsulation Methods
### Emulsification  
One of the most promising methods for the encapsulation of various hydrophobic and hydrophilic as well as heat-labile compounds is the emulsion method. At least two immiscible liquids, including an oily phase and aqueous phase, produce an emulsion in which one liquid is dispersed with small droplets in the other one. The continuous phase isthe aqueous dispersion of the wall material, and active agents to be encapsulated are in the dispersed phase. Emulsifiers are used in emulsions for coalescence prevention with different concentrations depending on the wall material along with the aqueous/lipophilic ratio. Formation of interfacial forces between two phases can decrease degradation and deterioration processes of active agents [59]. Double emulsions such as W\({}_{1}\)/O/W\({}_{2}\) are the most popular type of multiple emulsions for the encapsulation of active agents. However, contrary to common coacervation methods, hydrophilic/aqueous cores can be encapsulated directly in the aqueous suspension by application of this method [60]. The emulsion method is used for oil encapsulation in pharmaceutics in particular due to its high encapsulation efficiency, high reproducibility, ability to be easy scaled up and possibility of controlling particle size. Linseed oil has been encapsulated into alginate-lupin protein beads by the emulsification method for decreasing oxidation of highly unsaturated fat acids [11]. Physical and light oxidative properties of eugenol encapsulated through molecular inclusion and emulsion diffusion methods have been studied [26]. According to the obtained thermogravimetric analysis results, applying the emulsion method with polycaprolactone (PCL) as a wall material showed more efficient results for the encapsulation of EG than molecular inclusion due to high EE, storage stability and protection of EG from light oxidation damage [26]. Nisin was encapsulated in hydrophobic poly lactic acid (PLA) particles by a single emulsion method [25]. High EE was obtained for increased nisin concentration from 1.5 to 3.0 mg/mL without any changes in particle morphology. Application of more emulsification steps improved nisin encapsulation due to the increased electrostatic interactions between nisin and PLA at the interface. Manipulation of the final emulsification step temperature has contributed to the formation of hollow-structured microspheres at high temperatures, whereas solid nanospheres have been produced at room temperature below the glass transition temperature of PLA (52.5 \({}^{\circ}\)C) [25].  
The effects of different additives and polymers on the sustained release of encapsulated lysozyme from PLGA (poly (lactic-co-glycolic acid)) microspheres produced by the solid-oil-water emulsion evaporation-extraction method have been investigated. In fact, the adsorption of protein on the surface of hydrophobic PLGA microspheres is the main reason for the incomplete release. Addition of different additives, such as poly ethylene glycol (PEG), poloxamer 188 and bovine serum albumin (BSA), could inhibit the adsorption of lysozyme onto the PLGA surface [27].