How to extract chitin from the crustacean (hard) shells?
While there exists many extraction methods of the chitin from the crustacean shells, the principles of chitin extraction are relatively simple. The proteins are removed by a treatment in a dilute solution of sodium hydroxide (1-10%) at high temperature (85-100°C). Shells are then demineralized to remove calcium carbonate. This is done by treating in a dilute solution of hydrochloric acid (1-10%) at room temperature. Depending on the severity of these treatments such as temperature, duration, concentration of the chemicals, concentration and size of the crushed shells, the physico-chemical characteristics of the extracted chitin will vary. For instance, the three most important characteristics of the chitin i.e., degree of polymerization, acetylation and purity, will be affected. Shell also contains lipids and pigments. Therefore, a decolorizing step is sometimes needed to obtain a white chitin. This is done by soaking in organic solvents or in a very dilute solution of sodium hypochlor
