Obtention Processes and Main Characteristics

The occurrence of chitin and chitosan is discussed with emphasis on the main biomasses used as industrial raw material to produce the former polymer. Some potential sources which nowadays are not important for sustaining large scale production are highlighted as well. The main procedures used to extract alpha-chitin from crustaceans shells and beta-chitin from squid pens are presented and its advantages and drawbacks are discussed. The production of chitosan via Ndeacetylation of chitin is addressed with emphasis on thermochemical processes based on the alkaline treatment of chitin. Some unconventional processes are focused as well, mainly the ultrasound-assisted deacetylation, which allows the efficient conversion of beta-chitin into extensively deacetylated chitosan of high molar weight. The main characteristics of chitin and chitosan, namely; the average degree of acetylation (¯DA), the pattern of acetylation (PA), the average degree of polymerization (¯DA) and dispersity (Ð) are addressed and its influence on some polymer properties are also discussed.

Keywords: Alpha-chitin, Beta-chitin, Crustaceans shells, Chitosan, Freeze - pump out - thaw deacetylation, FPT process, Squid pens, Sponges, Thermochemical deacetylation, Ultrasound-assisted deacetylation, USAD process.