Chitosan is a hydrocolloid made from Chitin. Chitin is one of the most common biomolecules on earth. It is the main structural component of arthropod exoskeletons and fungal cell walls. Most Chitosan used for wine fining comes from shrimp shells. Even though shrimp-derived chitosan is non-allergenic, many people prefer a vegan alternative. This vegan Chitosan comes from the fungus Aspergillus Niger. Chitosan is insoluble in pure water, so you have to make a solution with dilute acid (vinegar).Chitosan is often used in conjunction with other fining agents, such as Kieselsol.Refrigerate your Chitosan Solution. It should last several months.