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.
