Chitin and Chitosan

Chitin is the second most abundant natural polysaccharide on Earth — a polymer of N-acetylglucosamine that forms the exoskeletons of crustaceans (shrimp, crab, lobster), the cell walls of fungi, and squid pen — and in aquaculture it is primarily a processing-waste valorization story: heads and shells, which can account for 30-50 percent of raw shrimp weight, are rich in chitin, protein, and astaxanthin. Chitosan is chitin's deacetylated derivative, produced industrially by treating shells with alkali (deproteinization), acid (demineralization), and strong alkali again (deacetylation), with the degree of deacetylation governing its solubility and functionality. Chitosan is cationic and therefore acts as a natural flocculant, aggregating suspended clay, algae, and organic particles in pond and hatchery water — a gentle clarifier used in larvae and live-feed culture where chemical coagulants would be toxic. Within aquaculture itself, chitin oligomers and chitosan serve as immunostimulants in feed, enhancing non-specific immunity and disease resistance in shrimp and fish, and chitosan coatings are studied for feed and shelf-life applications. Beyond the farm, chitosan's biocompatibility drives biomedical uses — wound dressings, drug delivery, hemostatic agents — plus agricultural biopesticides, biodegradable films, and water treatment, giving processors a genuine secondary revenue stream that converts disposal cost into product value. Extraction is capital- and chemical-intensive, so recovery is economical mainly at large processing-plant scale.