# Encapsulated Probiotics: Potential Techniques and Coating Materials for Non-Dairy Food Applications
## 3 Probiotic Encapsulation Techniques
### Coacervation  
Coacervation (phase separation, which produces capsules with sizes of 1 um to 1 mm) is a process whereby an initial solution is separated into a polymer-rich phase (coacervate) and a polymer-poor phase (coacervation medium). Coacervation techniques can be further categorized into simple and complex coacervations. Simple coacervation involves only a single polymer. In simple coaervation, phase separation can be induced when a strongly hydrophilic substance, water-miscible non-solvent, or inorganic salt (desolvation of the polymer) is added into a colloid solution. On the other hand, complex coaervation refers to the ionic interactions between two or more polymers (usually a protein and a polysaccharide) of opposite charges. During complex coaervation, when the charge is neutralized, the polymers separate, deposit on the droplet, and form coaervates [41; 53]. Therefore, complex coaervation is preferable in probiotics encapsulation and the food industry [43].  
Complex coaervation is known to produce capsules with high loading capacity that can incorporate a high number of probiotics. This technique provides high encapsulation efficiency, even at a very high (99%) payload. Complex coaervation is a simple process that does not involve high temperatures and hence, is safe for probiotics. [PERSON] et al. [54] showed that probiotic _L. plantarum_ and phytosterols, co-entrapped by heteroprotein complex coaervation utilizing whey protein isolate and gum Arabic, resulted in increased probiotic viability in Iranian white cheese. [PERSON] et al. [46] demonstrated improved resistance to simulated gastrointestinal tract conditions of the microcapsules of probiotic _L. acidophilus_ encapsulated by complex coaervation followed by transflutaminase crosslinking (up to 9.07 log CFU/g survival) and maintained probiotic viability (up to 9.59 log CFU/g) for 60 days at freezing (\(-18\)\({}^{\circ}\)C) temperature.  
The complex coaervation technique also produces microcapsules with water immiscibility which leads to optimal controlled-release properties. Complex coaervation can produce microcapsules with sizes ranging from 1 to 100 \(\upmu\)m. However, complex coaervation is hard to scale up, as the solute used to form coaervates must be in liquid form. The range of polymers employed in this technique is also limited as coaervates are only stable within a range of pH, ionic strength, and temperature. Gelatin is the most common polymer employed in complex coaervation. However, the use of animal-based protein is limited in certain situations [55]. [PERSON] et al. [56] demonstrated that in comparison with the protein/polysaccharide complex coaervation, the encapsulated probiotic in water/water emulsion via type-A gelatin/sodium caseinate coaervation had a better survival rate after heating, ambient storage, and simulated digestion. The authors indicated that the increased protection of the type-A gelatin/sodium caseinate matrix was associated with lower hygroscopicity, solubilization, and wettability and could also be caused by the significantly higher hydrophobicity. Complex coaervation is also regarded as a costly technique because an additional hardening process is required.  
Complex coaervation is suitable for non-dairy probiotic foods. In the study by [PERSON] et al. [22], probiotic orange and apple juices were produced with the aid of complex coaervation associated with enzymatic crosslinking. As indicated by the results, encapsulated _L. acidophilus_ LA-02 incorporated in fruit juices can survive throughout a storage period of 63 days (4 \({}^{\circ}\)C). In addition, complex coaervation was also used by [PERSON] et al. [14] to encapsulate _B. animalis_ subsp. _lactis_ in the development of probiotic sugar cane juice. The viability of _B. animalis_ during storage and delivery was enhanced through complex coaervation.