3.2.2. Chitosan Use for Probiotic Delivery

Like other polymers, chitosan has been used to encapsulate probiotics. The bestperforming formulas were identified in combinations of chitosan with other biopolymers such as alginate, agar, or gelatin. The most used combination is with alginate, in which chitosan is used as a final layer of microcapsules (Table 6). This is because at pH 7, chitosan that is positively charged develops strong bonds with gelatin and agar, which are negatively charged [203]. What sets chitosan apart is its antibacterial properties as it is a cationic polysaccharide. The disadvantage of chitosan, however, is the need for solubilization in an acidic environment. Usually, acetic acid is used to solubilize the powder and obtain the coating-forming solution without turbidity, which occurs when a compound has not been fully solubilized [204]. Chitosan cannot be used individually as an encapsulating agent with a role in maintaining cell viability. This is because it increases cell membrane permeability, leading, in the end, to cell loss [205]. Due to this, chitosan is mixed with other natural substances when used as an encapsulating agent.


**Table 6.** Chitosan use for probiotic encapsulation.

Abbreviations: CFU/g, colony-forming unit per gram; CFU/mL, colony-forming unit per milliliter; SGF, simulated gastric fluids; and SIF, simulated intestinal fluids.

> Although the effectiveness of chitosan encapsulation has been demonstrated, it does not appear to be the best biopolymer for probiotic encapsulation. Besides the fact that it cannot be used individually and produces turbidity, the obtained microparticles are usually larger in size, more porous, wrinkled [213], sticky, and the aggregation is worsened [211]. However, utilization of chitosan should not be limited as chitosan improves potential bioadhesion and facilitates the controlled release of bacteria [213].
