Chitosan biopolymer is obtained from the chitin deacetylation process. Chitin is found in the cell wall of fungi and the hard skin of shrimp and crabs. Shrimp skin, as a major source of chitin, contains other substances such as minerals, proteins and pigments that must be removed during the chitin extraction process. In addition to the above, shrimp skin waste contains residual amounts of shrimp meat that must be removed from raw materials to reach pure shrimp skin. Therefore, in the process of chitosan production, there are key steps in preparing shrimp skin raw materials, de-proteinization, mineral removal, pigment removal and de-acetylation. Of course, it should be noted that to adjust or reduce the molecular mass of the final product, the molecular mass reduction step is added to the process. In the preparation of shrimp skin raw materials, shrimp waste is cooked in boiling water (95°C) for 30 minutes and then washed, dried and powdered. The protein is then removed from the shrimp skin powder using 8% sodium hydroxide solution (w/v) for 2 hours at a temperature of 55°C. The de-proteinized minerals are then removed using 2 M HCl solution for 30 minutes at a reaction temperature of 50°C. The removal of pigments itself involves two steps. In the first stage, the reaction is performed with pure acetone at room temperature for 10 minutes. In the second stage, decolorization is performed using 0.315% NaOCl solution. Chitin is now ready for decalcification. In the deacetylation phase, the goal is to produce chitosan with a degree of distillation above 85%, and low and medium molecular mass. We will achieve these results by adjusting the operating conditions. For this reason, at this stage, chitin is exposed to a reaction with 50% sodium hydroxide solution for 7-10 hours at a temperature of 95°C. Crude chitosan is produced. To purify it, we first dissolve it in 5% acetic acid solution (volumetric / volumetric) and then separate the supernatant solution and precipitate it with 20% sodium hydroxide solution. The precipitate is removed and then washed, dried and powdered. We now evaluate the molecular mass of the chitosan produced; The proposed process up to this point is expected to lead to the production of low molecular weight chitosan. If the molecular mass is greater than the desired value, the molecular mass reduction step is added to the process. This occurs from the reaction of chitosan with 85% phosphoric acid at 60°C and a reaction time of 4 hours.

Keywords: Chitosan, Deacetylation, Proteinization, Shrimp skin