# Chitin and Chitosan in the Alcoholic and Non-Alcoholic Beverage Industry: An Overview
## 3 Chitosan Applications in Beverages
### Clarification Agent, Metals and Contaminants Reduction
However, the high price of chitosan may be considered a disadvantage if compared to the bentonite and gelatin that are traditionally used in juice clarification [11]. Green tea beverage is colloidally unstable since it contains protein, phenolic compounds, free amino acids, polysaccharides, and pectin. Consequently, the limpidity of tea infusion could modify, producing the change of light scattering, the so-called tea cream [67]. The formation of complexes between monomeric or dimeric phenolic compounds and proteins to form a larger colloidal particle [68; 69; 70] during storage is responsible for the haze development in beverages Chitosan was able to coagulate the anionic compounds present in tea infusion, such as pectin and protein. Additionally, chelate metal ions selective and separate the suspended particles from beverages. [PERSON] et al. [6] showed that chitosan was able to clarify green tea infusions by significantly decreasing the haze-active proteins without a significant effect on the composition of the phenolic compounds. [PERSON] et al. [4] showed that chitin and chitosan were able to flocculate colloidal particles from beer; however, chitosan was found to be most effective at a concentration of 5 mg/L, presenting a higher flocculation activity. This occurrence could be elucidated based on charge density, as chitosan has a high charge density, and it is known that polymer adsorption improves as the charge density increased [71]. The pH of beer samples was shown to be between 4.5 and 4.7, which could affect the chitosan behavior, as the amino groups are protonated (positively charged) in an acid solution [7], and the beer particles in suspension are negatively charged; the molecules bind to chitosan's negatively charged surface via ionic or hydrogen bonding. Chitosan can bind with various metal ions i.e., chelating, such as cadmium, cobalt, manganese, copper, iron, zinc, lead, and mercury [72; 73]. The intrinsic pKa value of chitosan rigorously depends upon the degree of deacetylation, ionic strength, and the charge neutralization of -NH\({}_{2}\) groups. For fully neutralized amine functions with a degree of acetylation of not more than 50%, the pKa value is always between 6.3 and 6.7 [74; 75]. Therefore, at pH < 6.2, chitosan presented a positive surface charge due to protonation of the amine groups, which makes chitosan an excellent polymer to be used as a chelating agent [76], as protonation of the amine group leads to the sorption phenomenon of metal cations in acidic media because proton and metal cations compete for interaction with the amine group. [PERSON] et al. [77] successfully applied chitosan to remove arsenic from _Laminaria japonica_ Aresch juice. In urine, the reduction of the heavy metal contents with chitosan has been studied by several researchers and shown to be effective [20; 73; 78]. This practice is authorized by the OIV [12] to avoid wine iron and copper instability and to reduce heavy metals (iron, lead, cadmium, and copper) at a maximum dose of 100 g/hL. Studies were also performed to reduce wine contaminants by the application of chitosan, such as for the reduction of ochratoxin A [79; 80; 73]. The OIV [12] also allows the application of chitosan to reduce possible wine contaminants, especially ochratoxin A, at a maximum dose of 500 g/hL. It was also reported by [PERSON] et al. [81] that chitosan removed efficiency pesticides (54-72% with 0.05% chitosan concentration and 86-98% with up to 0.5% chitosan concentration) from grape juice during the clarification process.