The main component of microcapsules – the substance to be encapsulated – can be in any aggregate state – liquid, solid, gaseous. The existing methods provide the possibility of microencapsulation of both lyophilic and lyophobic substances. The contents of microcapsules may include an inert filler, which is the medium in which the substance was dispersed in the process of microencapsulation, or is necessary for the subsequent functioning of the active substance. The content of the encapsulated substance in the microcapsules is typically 50-95% of the weight of the capsules. This value may vary depending on the technology and conditions of production, the required ratio of shell material and encapsulated substance, as well as on other process parameters: temperature, degree of dispersion, viscosity of the medium, presence of surfactants, etc. The term “microcapsules” or “nanocapsules” can refer to many different structures. One can use molecules within which the active ingredient is trapped, as well as complexes of complex molecules from which nanocapsules or nanospheres are formed. Nanoencapsulation is said to occur when the size of the molecules is less than a few micrometers. When the size of the molecules is less than one millimeter, we speak of microencapsulation. Different classes of substances can be used as shell material or encapsulating matrix: Waxes and lipids: beeswax, candelilla and carnuba waxes, wax emulsions, glycerol distearate, natural and modified fats. Proteins: gelatin, wheat proteins, soy proteins, zein, gluten, etc. Both proteins themselves and their modifications are used. Carbohydrates: starches, maltodextrins, chitosan, sucrose, glucose, ethyl cellulose, acetate cellulose, alginates, etc.

Degradable polymers: polypropylene, polyvinyl acetate, polystyrene, polybutadiene, etc. The choice of material of shells or encapsulating matrix depends on the purpose, properties and method of release of the encapsulating agent, as well as on the chosen method of microencapsulation. The contents of microcapsules can be released by mechanical destruction of the shells under pressure, by friction, ultrasonic action, melting, by rupture from the inside by vapors or gaseous substances released under changing external conditions, by interaction of the shell substance with the medium when dissolved in it, as well as by diffusion of the contents when the capsule walls swell in the surrounding liquid. Existing methods of microencapsulation can be divided into three main groups: Physical methods of microencapsulation are based on methods of forming shells by mechanical techniques. This group of methods includes fluidized bed coating, extrusion using centrifuges or through tube-in-tube forming devices, vapor condensation (vacuum spraying). Chemical methods are based on chemical transformations leading to film-forming material, namely – formation of a new phase by cross-linking of polymers, poly condensation and polymerization. Both high molecular weight substances (oligomers or polymers) and low molecular weight substances can be subjected to chemical transformations. Physicochemical methods include coacervation, precipitation of film-forming polymer from aqueous medium by adding a component that reduces its solubility, formation of a new phase by temperature change, evaporation of a volatile solvent, solidification of melts in liquid media, extraction substitution, spray drying, and physical adsorption. When selecting a microencapsulation method, several major factors must be considered.