# Microencapsulation of Anthocyanins--Critical Review of Techniques and Wall Materials
## 2 Microencapsulation Techniques
### Physicochemical Methods
#### 2.3.3 Ionic Gelation  
Ionic gelation is a critical technique among the many methods that are used for encapsulating active compounds because it can be technically regarded as low cost and does not require advanced equipment, high temperatures, or organic solvents. Ionic gelation is a type of microencapsulation that can be achieved using processes of atomization, dripping (coextrusion, extrusion), or electrostatic spraying. This process has the benefit of using mild conditions because high temperatures, intense stirring, or organic solvents are not employed to allow for the encapsulation of substances that, under several conditions, would decay. A downside is that the encapsulation of hydrophilic or low-molecular-weight materials demonstrated issues of easy diffusion and rapid release, irrespective of the pH, via the ionic gel matrix [19]. Some techniques (i.e., emulsion method, coating material) need to be applied to maintain the hydrophilic active compounds because only hydrophobic or low-solubility active compounds are directly applicable to ionic gelation. Several authors have successfully employed the ionic gelation strategy for anthocyanin encapsulation. The larger size and low consistency of particles were noted by the authors as being unfavorable points when using this approach (mainly for hydrophilic active compounds). The low polydispersity and strong encapsulation quality are the desirable aspects. In various independent studies with different preparation methods and core materials, macro- and microparticles have been examined. Therefore, in a single sample, the examination of macro and microparticles with coherent conditions will more clearly show the particles' characteristics. It is easier to treat encapsulated bioactive compounds and provides increased stability. Ionic gelation is a fascinating encapsulation process that benefits from ease of use and practicality, while avoiding high temperatures and organic solvents. Particulate types of gel have many usages, including structuring, strengthening, and texturizing agents in food matrices and the potential to enhance visual product acceptability. They can also change shape and scale, allowing for the controlled release of active ingredients in agricultural, pharmaceutical, and food products. There are various studies involving the application of ionic gelation for the microencapsulation of anthocyanins. [PERSON] et al. [91] conducted a recent study on the encapsulation of anthocyanin extract from hibiscus calves with the double emulsion and two ionic gelation techniques (dripping-extrusion and atomization) and evaluated the stability of the resulting microcapsules at various storage temperatures. The authors concluded that encapsulation using the dripping-extrusion technique achieved the most negligible anthocyanin degradation under refrigerated storage conditions, with the encapsulation efficiencies ranging from 67.9 to 93.9%. Another study used the ionic gelation process with dripping-extrusion and atomization to create microparticles comprising anthocyanin extract from Hibiscus sabdariffa L. (HE). A crosslinked solution (CaCl\({}_{2}\)) and a double emulsion (HE/rapeseed oil/pectin) were used. The goal of the research was to see how anthocyanins were released under simulated gastrointestinal environments and how microparticles were used in pectin candy [19]. The authors concluded that the microencapsulation of hibiscus anthocyanin enhanced the bioactive compound's enteric defense, primarily in microparticles formed using dripping-extrusion. Anthocyanin encapsulation by the extract was characterized in another study using an adsorption technique with blank alginate beads. Ionic gelation was combined with a complexation process involving chitosan, whey protein concentrate, or gelatin in this study. The use of cationic polymers in the complexation process was effective in preserving these pigments during refrigerated storage.