**10. Structure and characteristics of microencapsulation**

The first and foremost step in all microencapsulation methods is to select a suitable material as a wall or membrane for the stability and properties of the particles produced in the microencapsulation [25]. These materials are used alone or in combination to form a layer. Covering microencapsulation with a double membrane can act as a barrier against external conditions [26]. The most important choice for the coating material is the Yield of the coatings. The finely coated probiotic in the final product must be degradable and create a boundary between the internal phase and the environment (permeability) and also be evaluation in opinion of cost [4]. The properties of the coating materials and their placement are the main determinants of the functional properties of the microencapsulation [26]. The materials used as coatings for bead can contain two or more layers of base materials [5, 26]. The properties of the coating materials and their shape are the main determinants of the functional properties of the coatings [5]. Microencapsulation must be soluble in water to maintain the coherence of their structure in the food matrix and the digestive tract [5]. Therefore, the materials used as coatings in the microencapsulation should have the following properties. Chemically with the main substance. Ability to form membranes around bacterial cells. Be able to protect bacterial cells against adverse environmental conditions. Be stable and economically viable [26]. To date, there has been no ideal coverage that fits all goals. Therefore, obtaining suitable coatings to create a balance point between the optimal properties, such as protection against moisture, acidity, high temperature, gas exchange (oxygen and carbon dioxide) [26]. The encapsulating agent should not be toxic, as it can directly affect the morphology, diameter and permeability of the particles. Selecting the right material for probiotic microencapsulation is essential for the stability and properties of the particles produced [25]. There is a wide range of natural or synthetic polymers, including: proteins (such as zein, soy protein, collagen, and gelatin), polysaccharides (such as cellulose, starch, alginate, and chitosan), and fats [26].

#### **10.1 Polysaccharide**

Polysaccharides are biopolymers composed of monosaccharaides. They have hydroxyl groups that may be intramolecular hydrogen bonded with water or other molecules. They are also influenced by the nature of the monomers of their substituent groups, which alter the molecular and functional properties [26].

#### *10.1.1 Anionic polysaccharides*

Alginate, gum Arabic, carrageenan, xanthan, carboxymethylcellulose, gelan are natural anionic polysaccharides that tend to be negative at pH values above pKa. And when they are lower than pKa, they are neutralized [26]. Ionic chemical elements such as Ca + 2 change the electrical charge properties of all ions. Such as alginate gel, which interacts with opposing groups on the polymer chain [27].

#### *10.1.1.1 Alginate*

Alginates are natural marine polysaccharides that are extracted from seaweed [28]. The most important applications of alginate are its stabilizing, gelling and water retaining properties [28]. Alginates are natural polymer chains consisting of 100.3000 monomer units in a chain rigid and somewhat flexible [26]. The ability to connect polymer alginate chains with polyatomic ions such as Ca + 2, Ba + 2, Sr. + 2 is through electrostatic bonding and hydrogel formation [26]. When a cation such as Ca + 2 participates in an interchain bond. It creates a three-dimensional network of gel and micro-and Nano-sized hydrogel bead in the microencapsulation of materials. Which has received much attention in recent studies [26]. One of the benefits of alginate is the formation of gels around bacterial cells. It is also safe and inexpensive. Some of the disadvantages attributed to alginate beads. The resulting beads are highly porous, which reduces the protection of bacterial cells in adverse environmental conditions. Another disadvantage of alginate bead is that it is sensitive to the effects of acid and is not compatible with the resistance of bead in gastric conditions [29, 30]. However, defects can be remedied by combining alginate with other polymer compounds, coating the bead with another compound, or structural modification of alginate using various additives [31].

#### *10.1.1.2 Gum Arabic*

Acacia trees are the main source of Gum Arabic. The chemical composition of Gum Arabic is complex and consists of a group of macromolecules composed of a large proportion of carbohydrates (97%) [32]. Gum Arabic (GA) is highly soluble in water and also has a relatively low viscosity compared to other gums [26]. The functional properties of gum Arabic are closely related to its structure, for example, solubility, viscosity, interaction with water and oil in an emulsion, determine the ability of fine coating in Gum Arabic [32]. Some researchers tested Gum Arabic as an indigestible polysaccharide, finding that Gum Arabic reached the large intestine without digestion in the small intestine [33]; Gum Arabic is gradually fermented by the bacterial flora of the large intestine, which produces short-chain fatty acids [34]. Therefore, it can be taken in large daily doses without side effects. Daily consumption of 25 and 30 grams of Gum Arabic for 21 to 30 days reduces total cholesterol by 6 and 10.4%, respectively [32]. Arabic gum is used as a stabilizer, emulsifier and as a coating in the food industry [33]. Solubility and properties of low viscosity emulsions by Gum Arabic enables the ability to retain and transfer the Trapped material in fine encapsulation. Gum Arabic with maltodextrin is a good choice for coating in microencapsulation [35].

#### *10.1.1.3 Carrageenan*

Carrageenans are extracted from red seaweed (*Rhodophyta*) and are composed of various mixtures of sulfated polysaccharides. Carrageenan is a neutral

#### *Food Health with Increased Probiotic Survival During Storage DOI: http://dx.doi.org/10.5772/intechopen.99382*

polysaccharide polymer that requires high temperatures to dissolve in large quantities. Potassium chloride is used to preserve and stabilize Carrageenan is a suitable coating material in encapsulation that contain flavorings and aromatic compounds. Forms a brittle, hard gel that melts when heated to low temperatures, forming soft, elastic gels in cold water while carrageenan is soluble. At present, carrageenan has not been widely studied for use in probiotic encapsulation [36, 37]. The properties of carrageenan gel are improved by mixing it with other coating materials such as vegetable oils, calcium alginate, and gums such as xanthan, gelan and locust bean gums by emulsion method [26].
