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Chapitre D'ouvrage Année : 2023

Extraction of chitin, preparation of chitosan and their structural characterization

Résumé

Chitin is a natural polysaccharide produced abundantly by biosynthesis in algae and fungi of the plant kingdom, as well as arthropods, mollusks, and other taxonomic groups of the animal kingdom. It consists of a sequence of monomers of N-acetylglucosamine and is found in three forms (α, β, and γ) which differ according to the arrangement of the chains in the crystalline region. Chitosan is the main high-value derivative of chitin. It is obtained by N-deacetylation reactions. Chitin and chitosan are copolymers consisting of units of N-acetylglucosamine and D-glucosamines linked by β- (1 → 4) glycosidic linkages. The major structural parameter is the degree of acetylation (DA), defined as the molar fraction of acetylglucosamine units. When the DA exceeds 50%, the copolymer is substantially insoluble in dilute acid solutions and corresponds to chitin. The chitosan name applies when DA is below 50%; the smaller the DA, the more soluble the copolymer is in acidic solutions. Methods for chitin and chitosan extraction from biomass are considered (Kurita, Broussignac, and laboratory processes) and compared to prepare samples with definite characteristics relative to the intended applications. The roles of the source (and the type of chitin) and the process will be discussed. Structural analysis will be presented to determine the DA using different techniques (spectroscopic, potentiometric, or conductimetric), which will be compared. The techniques to characterize the pattern of acetylation are discussed relative to the properties depending on this pattern. Finally, solution properties are addressed. Concerning these determinations and solution properties, special care must be taken to avoid macromolecular aggregates; this can be achieved by choosing appropriate solvents and solution concentration domains.
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Dates et versions

hal-04209617 , version 1 (18-09-2023)

Identifiants

Citer

Jacques Desbrieres, S. Elkadaoui, A. Tolaimate. Extraction of chitin, preparation of chitosan and their structural characterization. Handbook of Natural Polymers, 1 (6), Elsevier, pp.123-151, 2023, 978-0-323-99853-6. ⟨10.1016/B978-0-323-99853-6.00010-3⟩. ⟨hal-04209617⟩
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