# Microencapsulation of Anthocyanins--Critical Review of Techniques and Wall Materials
## 2 Microencapsulation Techniques
### Physical Methods
#### 2.1.3 Electrospraying/Electrospinning  
Electohydrodynamic processes are composed of two sister technologies, including electrospraying and electrospinning, and apply high-voltage electrostatic forces to fabricate electrically charged jets from a polymer solution. There are only minor differences between the two methods. Electrospraying is referred to as the formation of solid particles once the solution has a low concentration and viscosity. However, a transition from electrospray to electrospinning occurs by using higher concentrations and viscose solution, which cause entanglements and cohesion of the molecular chain, resulting in nano- or microscale ultrathin continuous fibers. These processes can be divided into uniaxial and coaxial. In the former, core and wall materials are pumped into the electric field via the same tip. Still, in the latter, the wall material solution and bioactive ingredients are simultaneously ejected through two various concentric nozzles. Finally, the inner liquid is encapsulated by an outer polymeric solution [60; 61]. These methods provide a broad range of benefits. They are innovative, cost-effective, and one-step methods that offer a promising approach for the fabrication of encapsulated bioactive ingredients. Moreover, they are performed at atmospheric pressure and room temperature, which are suitable conditions for the encapsulation of heat-sensitive components and protecting them from thermal degradation [62]. Importantly, they result in a high surface-to-volume ratio, enhanced EE, tailored release of bioactive molecules, and improved functionality and physical properties of the composites. Additionally, they do not utilize chemical crosslinkers and do not require postprocessing treatments, hence taking priority over the aforementioned methods [17]. The EE, morphology, and physical properties of particles or fibers are mainly influenced by operational parameters, ambient conditions, and intrinsic properties of the solutions. Processing conditions consist of the flow rate, electrical potential applied, and distance between the tip of the syringe nozzle and the collector. Ambient conditions are modified in terms of the humidity and temperature. Intrinsic properties also include the surface tension, viscosity, concentration, molecular weight of polymer, and electrical conductivity. [PERSON] et al. [63] employed an electrohydrodynamic process for the encapsulation of acai fruit extract into zein electrosprayed particles. The formation of ultrathin fibers was reported while applying zein (20% _w/o_). However, the electric charge broke the chains while using zein (16% _w/o_), resulting in dispersed droplets. They effectively performed encapsulation with an efficiency of around 72%. Furthermore, the phenolic loss of the encapsulated samples was two and eight times lower than commercial dehydrated acai fruit after baking (180 \({}^{\circ}\)C) and sterilization (121 \({}^{\circ}\)C), respectively. Moreover, these authors reported that as the injection flow increased, the solvent could not entirely evaporate, causing aggregation and producing particles that were larger in diameter. In another study, [PERSON] et al. [64] incorporated black carrot anthocyanins into a blend of gelatin and chitosan through the electrospraying technique. They emphasized the total solid content and rheological properties of the solution in capsule formation, according to which, an increased concentration led to a higher viscosity that hindered the proper evaporation of the solvent. At the same time, a decreased concentration caused insufficient chain entanglements. It was reported that capsule development only occurred when the range of solid content was between 6.4 and 6.8%. In the study by [PERSON] et al., anthocyanins from sour cherry were encapsulated in gelatin and gelatin-lactalbumin using coaxial and uniaxial electrospray. According to spectrophotometric results, the EEs varied between 70.2 and 79.2%.