title: Structural characterization of chitin and chitosan obtained by biological and chemical methods.
abstract: Chitin production was biologically achieved by lactic acid fermentation (LAF) of shrimp waste (Litopenaeus vannameii) in a packed bed column reactor with maximal percentages of demineralization (D(MIN)) and deproteinization (D(PROT)) after 96 h of 92 and 94%, respectively. This procedure also afforded high free astaxanthin recovery with up to 2400 μg per gram of silage. Chitin product was also obtained from the shrimp waste by a chemical method using acid and alkali for comparison. The biologically obtained chitin (BIO-C) showed higher M(w) (1200 kDa) and crystallinity index (I(CR)) (86%) than the chemically extracted chitin (CH-C). A multistep freeze-pump-thaw (FPT) methodology was applied to obtain medium M(w) chitosan (400 kDa) with degree of acetylation (DA) ca. 10% from BIO-C, which was higher than that from CH-C. Additionally, I(CR) values showed the preservation of crystalline chitin structure in BIO-C derivatives at low DA (40-25%). Moreover, the FPT deacetylation of the attained BIO-C produced chitosans with bloc copolymer structure inherited from a coarse chitin crystalline morphology. Therefore, our LAF method combined with FPT proved to be an affective biological method to avoid excessive depolymerization and loss of crystallinity during chitosan production, which offers new perspective applications for this material.
authors.affiliation: Universidad Autonoma Metropolitana, Biotechnology Department, Laboratory of Biopolymers. Av. San Rafael Atlixco No. 186. Col. Vicentina, CP 09340, Mexico City, Mexico.
authors.forename: Neith
authors.initials: N
authors.lastname: Pacheco
authors.forename: Mónica
authors.initials: M
authors.lastname: Garnica-Gonzalez
authors.forename: Miquel
authors.initials: M
authors.lastname: Gimeno
authors.forename: Eduardo
authors.initials: E
authors.lastname: Bárzana
authors.forename: Stéphane
authors.initials: S
authors.lastname: Trombotto
authors.forename: Laurent
authors.initials: L
authors.lastname: David
authors.forename: Keiko
authors.initials: K
authors.lastname: Shirai
mesh_terms: D000143:Acids / Q000737:chemistry; D000468:Alkalies / Q000737:chemistry; D000818:Animals; D019149:Bioreactors; D002686:Chitin / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D048271:Chitosan / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods*; D019344:Lactic Acid / Q000378:metabolism; D048191:Lactiplantibacillus plantarum / Q000502:physiology; D033561:Penaeidae / Q000737:chemistry* / Q000378:metabolism; D014866:Waste Products; D024341:Xanthophylls / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D000143:Acids; D000468:Alkalies; D014866:Waste Products; D024341:Xanthophylls; D002686:Chitin; D019344:Lactic Acid; C005948:astaxanthine; D048271:Chitosan