Technically, chitin is a polyanacetylglucosamine, characterized by the presence of a charged NH group and an acetyl group CH3CO. In nature, no organism produces pure polyanacetylglucosamine, but all arthropods produce partially acetylated polysaccharides, often contaminated with heavy metals and amino acids. Some species of fungi also produce chitin. In practice, the term chitin has come to mean generically the material that is produced in nature, rather than the pure molecule. The processed form, in which the deacetylation is between 30 and 70 per cent, is called chitosan. Chitin is insoluble in water and must be dissolved in acid; chitosan is water-soluble.
Aside from its structural function in arthropods, chitin plays other important roles in nature. It contributes to keeping the oceans clean. The chitin released by the shells of molting organisms falls to the sea bed where it forms a powerful chelating agent, attracting heavy metals, especially transition metals, and providing nuclei for the manganese nodules found on the ocean floor. At the other end of the spectrum, chitin is metabolized by the human body to produce glucose, and it has been adopted by advocates as a nutraceutical dietary supplement. Rats have been said to starve after eating chitosan because it absorbs nutrients and bacteria that participate in digestion as it passes through the gut. It is used in weight loss remedies on the market but may be dangerous.
The composition of harvested chitin is highly variable, even from a single source like lobsters. The amount of metal and amino acid contaminants will depend on water quality and on diet, and they can be quite difficult to remove. The industrial production of pharmaceutical or biomedical quality (i.e., pure) chitin from natural chitin may not yet have been realized successfully.
Shellfish wastes have a water content equal to two-thirds of the total. As such, the 15 million pounds of resource available in or near PEI would yield five million pounds of dry shell. This shell can be assumed to be about half mineral matter (mostly calcium carbonate), one-quarter protein suitable for use in animal feeds, and one-quarter chitin, as well as small quantities (one per cent or so) lipids, and a tiny quantity of very valuable red dye, xantheum. As such, the shell resource on PEI could yield up to 1.25 million pounds annually of chitin, as well as several by-products. PEI's situation may be highly advantageous, because its small size and the proximity of its shellfish processing operations facilitate storage and handling of the shells, which deteriorate within hours.
Historically, applications have included wastewater treatment, use for recovery of protein from egg wastes for animal feed, wound healing, crop protection (from fungi), glue, and color photography. The problem in higher end applications is consistency of the feedstock; every batch must be tested.
Unfortunately, there is probably no viable industry experience to draw on in this virtual case study. Some of the largest producers overseas produce chitin of unreliable quality. Those seeking to attain higher quality product have not been profitable, in part because of the problem of collection and preservation of raw material.