## 2 Characteristics of Plant-Based Food Matrices as Carriers of Probiotics
### Survival of Probiotics in Plant-Food Products
2% salt concentration to achieve the osmotic effect that allows the release of liquid from cabbage tissue. Maintenance of adequate temperature, salinity, and anaerobic conditions ensures the viability and growth of autochthonous LAB and inhibits spoilage microorganisms ([PERSON] et al., 2014). In the manufacturing of pickled cucumbers, the concentration of salt is higher, reaching 5-7%, which, along with low pH, inhibits the growth of less salt-tolerant microorganisms, promoting fermentative strains such as _P. pentosacus_ and _L. plantarum_([PERSON] et al., 2014). Due to the requirement of functional food for delivering an adequate number of viable cells, some challenges arise in the development of novel plant probiotic products. Preservation methods, such as air drying, freeze-drying, and ultrasound-assisted air-drying, were successfully applied to fruits and vegetables. In the study of [PERSON] et al. (2018), dried apple snacks impregnated with _Lactobacillus casei_ NRRL B-442 were produced. Authors showed the dependence of the probiotic cell viability on temperature and ultrasound application during drying. The higher viability of _Lactobacillus casei_ (\(>\)10\({}^{6}\) CFU/g) in apple snacks was observed at drying at a temperature of 60 \({}^{\circ}\)C with ultrasound-assisted air in comparison to samples of conventional drying at 10 \({}^{\circ}\)C and 40 \({}^{\circ}\)C (\(<\)10\({}^{6}\) CFU/g) ([PERSON] et al., 2014). Different methods of plant-food preservation should be tailored according to the selected plant matrix, probiotic microorganism added, and type of designed food product. [PERSON] et al. (2015) compared three methods: spray drying, freeze drying, and convective hot air drying on the survival of _Lactobacillus plantarum_ 299v and vitamin C content in orange powder. Spray drying and freeze drying were the techniques that resulted in lower losses in viable probiotic cells and better retention of vitamin C ([PERSON] et al., 2014). One of the technologies that protects probiotics against the adverse effects of environmental factors is microencapsulation ([PERSON] et al., 2014). The four techniques of microencapsulation are extrusion, emulsification, freeze drying, and spray drying. Probiotics can be made more resilient to the severe conditions of manufacturing and the human body. However, there are several drawbacks to these techniques, such as the fact that high temperatures and acidity can eventually impact the viability, stability, and size of microcapsule microstructures ([PERSON] et al., 2014). By shielding probiotic bacterial strains from harmful physicochemical elements like high temperatures, oxygen, osmotic pressure, relative humidity, digestive tract enzymes, and, lastly, the stomach's low pH, microencapsulation helps to improve resistance, stability, and survival. Protein and polysaccharide hydrocolloid are the two protective coats that are applied to the bacterium using microencapsulation technology. Plant-derived prebiotic polysaccharides (starch, inulin), since they are resistant to digestive enzymes, can provide an effective protection of probiotic microorganisms throughout the GI passage ([PERSON] et al., 2014). In this regard, prebiotics are an appropriate candidate for encapsulation of probiotics, ensuring their survival in the food matrix during processing and storage as well as in the harsh environment of the digestive tract ([PERSON] et al., 2014). The combination of prebioticmicrocapsules and probiotic core creates a beneficial functional capsule [72]. [PERSON] et al. used a co-encapsulated technique of double-layered microcapsules consisting of alginate and chitosan (electro-hydrodynamic atomization) with inulin and/or resistant starch to protect _Lactobacillus plantarum_ and _Bifidobacterium lactis_. The authors reported successful survival of studied probiotics in gastrointestinal conditions during 90 days of storage [73]. The emerging technology of probiotic protection is the 3D method. [PERSON] et al.