**8.2 Spray drying**

Another technique used in food processing is spray drying, which is employed for a variety of purposes including enhancing probiotic stability. Due to its suitability for large-scale industrial applications, affordability, and ease of scaling up, it is frequently utilized in the production of food products and bioactive chemicals [97]. When probiotics are dried using a spray technique, the liquid feed used for the encapsulating wall and the probiotics are both atomized into a hot gas drying chamber where the wet droplets are heated to a high temperature [6]. Emergence of dried solid particles is caused by the rapid creation of crusts. The primary disadvantage to this approach is the application of osmotic stress and high temperatures, which might result in reduced viability and loss of activity. After being sprayed-dried in feed solutions with varied amounts of gum arabic, the viability of *L. acidophilus NCDC 016* cells was examined in a study [98]. The input air temperature increase caused a drop in encapsulation yield, which was addressed by raising the gum arabic content. It was once believed that the proteins in gum arabic were what caused the microbial cell wall to produce a protective layer. *S. cerevisiae var. boulardii* was also encapsulated by Arslan et al. [99] spray drying temperatures. Gelatine and gum arabic were the most viable wall materials for *S. boulardii* microencapsulation based on viability tests following spray drying and subsequent tests under simulated gastrointestinal tract conditions.

### **8.3 Extrusion**

Probiotic cells are also encapsulated through extrusion that involves the suspension of the bacteria in droplets of liquid which later gel or have membranes developed on their surfaces. Using coaxial air or liquid flow, submerged nozzles, vibration technologies for the jet break-up, and other methods, one can obtain the droplets pouring from a nozzle [6]. The droplets then enter a solution that will harden them. Particles of different sizes, morphologies, and mechanical strengths are created by varying the processes and materials used to produce gel beads. This technique of encapsulation is simple, affordable, and highly kind to microbial cells. However, its slowness restricts its use on an industrial scale. The targeted release potential of the gel beads was proven by the encapsulated *B. adolescentis* cells' log reduction values, which ranged from 2.0 to 2.6. In addition, the gel beads disintegrated when exposed to circumstances simulating intestinal juice. The probiotic *L. acidophilus KBL409* was encapsulated in alginate and alginate-chitosan, and then, all samples were incubated for 1 or 2 hours at 37°C with simulated stomach fluids (pH 1.5) before being exposed to simulated intestinal fluids (pH 6.5) for the next 2 hours. The largest percentage of survivors were found in the alginate/chitosan capsules [100]. To protect the microbial cells and extend shelf life, Apiwattanasiri et al. [101] suggest using silk sericin as a wall material and coating layer for probiotic encapsulation.

#### **8.4 Emulsion-based system**

Two immiscible liquids combine to produce an emulsion when an emulsifier (stabilizing agent) is present. The technique of creating an emulsion is simple and comprises the rapid mixing of the two phases (continuous and dispersed phases)

*Lactic Acid Bacteria: Review on the Potential Delivery System as an Effective Probiotic DOI: http://dx.doi.org/10.5772/intechopen.111776*

while adding one phase over the other, which, if appropriate, also contains an emulsifier. Although it is easily scaled up, this process' primary limitation is that it generates particles of various sizes. Zhang et al. [102] developed secondary emulsions to contain *Ligilactobacillus salivarius.* The main emulsion was created by the emulsification of melted anhydrous milk fat with whey protein isolate or sodium caseinate in a neutral aqueous phase. This emulsion increased the encapsulation efficiency by up to 90% and improved the thermal and storage stability of *L. salivarius.* The probiotic survived the simulated gastric and intestinal digestions at a higher rate due to more cross-linking with calcium ions [102]. When *Lacticaseibacillus paracasei* was encapsulated in a milk-based water/oil emulsion, El Kadri et al. [103] found that the probiotic was more viable than free cells throughout 28 days of storage at 4°C, and this is due to the fact during storage the emulsion remained stable, and the encapsulated *L. paracasei* had a survival rate that was much greater than the free cells. To encapsulate the probiotic *L. casei* on an alginate matrix, flaxseed mucilage was employed. The encapsulation effectiveness was more than 95%, and stability and survival rates of the probiotic in simulated gastrointestinal conditions were evaluated [104]. As a result, *L. casei's* resistance to the negative effects of the simulated digestive system was strengthened by the introduction of flaxseed mucilage [104].
