# Encapsulated Probiotics: Potential Techniques and Coating Materials for Non-Dairy Food Applications
## 4 Biomaterials Utilized for Probiotics Encapsulation
### Carbohydrate Polymers
#### 4.1.3 Gums  
Xanthan gum has been proven as an excellent embodiment in conferring protection against harsh gastrointestinal conditions and elevated temperatures (up to 90 \({}^{\circ}\)C for 5 s) to probiotics. It is an exopolysaccharide obtained through fermentation by _Xanthomonas campestris_ from agro-industrial wastes [79]. Xanthan gum possesses an anionic character, is non-toxic, biodegradable, biocompatible, highly soluble in cold and hot water, and has excellent gelling properties. Furthermore, it has excellent heat and acid stability and is highly resistant to gastrointestinal digestion and enzymatic decomposition [41, 82]. The study of [PERSON] et al. [33] indicated the protective effect of Xanthan gum on the viability of _L. acidophilus_ incorporated in bread under simulated gastric and intestinal conditions compared to using alginate alone. Xanthan gum has a negative charge structure that could bind to H\({}^{+}\) ions and minimize the effect of an acidic condition on the probiotics. Unfortunately, it has some limitations. It is susceptible to microbial contamination, unstable viscosity, and uncontrollable hydration rate, as well as producing gels with poor shear resistance, mechanical strength, and thermal properties when used solely [41, 83]. Therefore, to enhance the coating properties of Xanthan gum in probiotic encapsulation, it is combined and used with other biomaterials, including alginate, chitosan, gellan, and \(\beta\)-cyclodextrinrin [41]. In contrast to alginate beads, the combination of xanthan and gellan gums produces capsules with higher resistance toward acid conditions [1, 41]. Gellan gum is a microbial polysaccharide, industrially produced through fermentation by _Sphingomonas elodea_ and _Pseudomonas elodea_. It is available in two forms, low acyl gellan gum (deacylated; Kelcogel) and high acyl gellan gum (acylated; Gelrite). Upon cooling, gellan gum with lower acyl contents (gel setting temperature: 40 \({}^{\circ}\)C) forms a more rigid and brittle gel, whereas gellan gum with higher acyl contents (gel setting temperature: 65 \({}^{\circ}\)C) tends to produce gels with a softer and more flexible texture. In probiotic encapsulation, low acyl gellan gum is commonly used [41]. In general, gellan gum is negatively charged, non-toxic, biocompatible, biodegradable, relatively cheap, and water-soluble. Gellan gum has high resistance against heat, enzymatic degradation, acidic environments, and swells in alkaline conditions, allowing it to be suitable as a controlled release polymer. However, the gel formed by gellan gum is considerably poor in mechanical strength and unstable in physiological conditions. The high gel-setting temperature (80-90 \({}^{\circ}\)C) of gellan gum also causes heat injuries to probiotics. Usually, it is used in combination with other biomaterials such as gelatin, sodium caseinate, and alginate in probiotic encapsulation [44, 84]. Gellan gum has been used to increase the thermal stability of probiotics in a study on probiotic bread [32]. Results demonstrated that the gellan gum (1.5%) coating layer increased the survivability of _L. Sporogenes_ encapsulated in alginate beads 24 h after baking. Gum Arabic (or gum acacia) is another common biomaterial used in probiotic encapsulation. It is an arabinocalatan polysaccharide-protein anionic complex that provides surface activity, foaming abilities, and emulsifying characteristics. Gum Arabic possesses acid stability, high water solubility, and low viscosity even at a high concentration [41]. Gum Arabic has high water solubility, relatively low viscosity, and good film-forming and emulsifying properties, which reduces the hygroscopicity and degree of caking of the obtained powder. At the same time, it can prevent complete dehydration of probiotics during the drying process and storage. Hence, gum Arabic has been extensively used in spray-drying [78]. For instance, gum Arabic provided good protection to _L. acidophilus_ from spray-drying damage. The viability of _L.