# Chitin and Chitosan in the Alcoholic and Non-Alcoholic Beverage Industry: An Overview
## 3 Chitosan Applications in Beverages  
### Clarification Agent, Metals and Contaminants Reduction  
In beverages such as fruit juice, clarification is an important step in the production process mainly to remove pectins and other compounds, which are present in the juice. Juice limpidity and homogeneity are the two major characteristics of clarified juices and are achieved by the complete removal of all suspended solids [58]. Chitosan coagulates the anionic suspended particles such as pectin and protein and consequently, their separation from beverages is fast and their turbidity decreases [6; 10; 59; 60]. This behavior is related to the chitosan physicochemical properties associated with the presence of amine functions [31]. According to [PERSON] et al. [61], the concentration of chitosan used in the clarification process and pH in addition to the initial juice turbidity to be treated are important variables for the coagulation process using chitosan and consequently to reach the desired limpidity. [PERSON] et al. [62] also showed that besides the chitosan concentration, the pH value is an essential factor for the juice turbidity to decrease, as all samples of passion fruit juice at pH 6 presented higher turbidity removal after the treatment with chitosan. Additionally, [PERSON] et al. [6] showed that the optimal pH for green tea clarification using chitosan was at pH 5.5. It was observed a concentration-dependent, leading to higher turbidity reduction in juices when chitosan content was increased [60; 62]. It was also shown that chitosan with a higher deacetylation degree is more effective in protein flocculating, this could be related to the augmented charge density from the free amino groups [63]. Several works have reported the positive effect of the application of chitosan as a clarifying and protein stabilization agent for apple, grape, lemon, orange, passion, acai juices, and green tea [6; 59; 60; 62; 64], and grape must and wine [13; 14; 15; 16]. The application of fungal chitosan as a firing agent to facilitate settling and clarification, as well as a treatment to prevent protein haze in grape must and wine, is allowed by the International Organisation of Vine and Wine (OIV) [12], enology resolutions, OIV/OENO 336B/2009 and OIV/OENOO 337A-2009, at a maximum dose of 100 g/hL. Chitosan is mentioned in the literature as being a good clarification agent for grapefruit juice both with and without enzyme treatment [65] and a significantly effective clarification agent for apple juice [8]. More recently, [PERSON] and [PERSON] [10] showed that chitosan can be an alternative clarification agent to produce pomerangate juice with an excellent limpidity and with quality characteristics, such as pomerangate juice clarified with bentonite and gelatin. Chitosan has been shown to reduce the acidity of the fruit juices; according to [PERSON] et al. [59] the tittatable acidity of grape juice clarified with bentonite-gelatin and chitosan were 3.24% and 3.10%, respectively. Furthermore, [PERSON] et al. [66] showed that chitosan enriched juices had a higher pH value of 4.2 as compared to their original pH of 3.2; this effect could be due to the polycatonic nature of chitosan and thus, its acid-binding properties. It was described that the turbidity of apple juice decreased 73.3% after the application of chitosan for 90 min. [PERSON] et al. [60] likewise showed that apple juice clarified with fungal chitosan at 0.7 g/L and 40 \({}^{\circ}\)C achieved the maximum juice limpidity. [PERSON] and [PERSON] [11] showed also that apple juice clarification with traditional fining agents, such as bentonite and gelatin, was less effective than chitosan in decreasing the turbidity of apple juice; these results are following the previously shown by [PERSON]  
Figure 1: Chitin (**A**) and chitosan (**B**) chemical structure. et al. [59] who also described bentonite or gelatin to be less effective than chitosan during juice clarification.