Chitin is the second most abundant natural polymer in the world after cellulose, since it is synthesized by a huge number of living organisms.
However, up to now the main commercial sources of chitin have been seafood waste, typically shells from shrimps, crabs and lobsters. In industrial processing chitin is extracted from crustaceans by acidic treatment to dissolve calcium carbonate followed by alkaline extraction to solubilize proteins. Chitin can also be found in fungi, insects and octopuses.
The structure of Chitin
Chitin is also known for its derivatives that are obtained by further processing. Chitosan is one of the most well-known chitin derivatives.