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Yu S, Peng G, Jiao J, Liu P, Li H, Xi J, Wu D. Chitin nanocrystals-stabilized emulsion as template for fabricating injectable suspension containing polylactide hollow microspheres. Carbohydr Polym 2024; 337:122176. [PMID: 38710562 DOI: 10.1016/j.carbpol.2024.122176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 05/08/2024]
Abstract
One of the promising applications of rod-like chitin nanocrystals (ChNCs) is the use as particle emulsifier to develop Pickering emulsions. We reported a ChNC-stabilized oil-in-water emulsion system, and developed a Pickering emulsion-templated method to prepare polylactide (PLA) hollow microspheres here. The results showed that both non-modified ChNCs and acetylated ChNCs could well emulsify the dichloromethane (DCM) solution of PLA-in-aqueous mannitol solution systems, forming very stable emulsions. At the same oil-to-water ratios and ChNC loadings, the emulsion stability was improved with increasing acetylation levels of ChNCs, accompanied by reduced size of droplets. Through the solvent evaporation, the PLA hollow microspheres were templated successfully, and the surface structure was also strongly dependent on the acetylation level of ChNCs. At a low level of acetylation, the single-hole or multi-hole surface structure formed, which was attributed to the out-diffusion of DCM caused by the solvent extraction and evaporation. These surface defects decreased with increased acetylation levels of ChNCs. Moreover, the aqueous suspension with as-obtained PLA microspheres revealed shear-thinning property and good biocompatibility, thereby had promising application as injectable fillers. This work can provide useful information around tuning surface structures of the Pickering emulsion-templated polymer hollow microspheres by regulating acetylation level of ChNCs.
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Affiliation(s)
- Sumin Yu
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China
| | - Guangni Peng
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China
| | - Jiali Jiao
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China
| | - Peng Liu
- Shanghai Isiris Medical Co. Ltd., Shanghai 201400, PR China
| | - Huajun Li
- Medical College, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China
| | - Juqun Xi
- Medical College, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China
| | - Defeng Wu
- School of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu Province 225002, PR China.
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Vadalà R, De Maria L, De Pasquale R, Di Salvo E, Lo Vecchio G, Di Bella G, Costa R, Cicero N. Development of a Chitosan-Based Film from Shellfish Waste for the Preservation of Various Cheese Types during Storage. Foods 2024; 13:2055. [PMID: 38998559 PMCID: PMC11241246 DOI: 10.3390/foods13132055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Revised: 06/24/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024] Open
Abstract
The global concern about the use of disposable plastics has fed the research on sustainable packaging for food products. Among the virtuous materials, chitosan emerges as a valid alternative to conventional polyethylene films because of its abundance in nature. In this work, a novel film for food wrapping was developed by exploiting shellfish waste according to a vision of circular economy. Compared to previous studies, here, novel ingredients, such as polyvinyl alcohol (PVA), fibroin, and essential oils, were used in a synergistic combination to functionally postpone cheese deterioration. The fermentative procedure applied for the obtainment of chitin contributes to filling the existing gap in the literature, since the majority of studies are based on the chemical pathways that dramatically impact the environment. After pretreatment, the shrimp shell waste (SSW) was fermented through two bacterial strains, namely Lactobacillus plantarum and Bacillus subtilis. A deacetylation step in an alkaline environment transformed chitin into chitosan, yielding 78.88 g/kg SWW. Four different film formulations were prepared, all containing chitosan with other ingredients added in order of decreasing complexity from the A to D groups. The novel films were tested with regard to their physico-mechanical and antioxidant properties, including the tensile strength (12.10-23.25 MPa), the elongation at break (27.91-46.12%), the hardness (52-71 Shore A), the film thickness (308-309 μm), and the radical scavenging activity (16.11-76.56%). The performance as a cling film was tested on two groups of cheese samples: the control (CTR), wrapped in conventional polyethylene (PE) film; treated (TRT), wrapped in the chitofilm formulation deemed best for its mechanical properties. The volatiles entrapped into the headspace were investigated by means of the SPME-GC technique. The results varied across soft, Camembert, and semi-hard cheeses, indicating a growing abundance of volatiles during the conservation of cheese. The bacterial growth trends for mesophilic, enterobacteriaceae, and lactic acid bacteria were expressed as the mean colony forming units (CFU)/mL for each type of cheese at different sampling times (day 2, day 8, and day 22): the highest load was quantified as 8.2 × 106 CFU/mL at day 22 in the CTR Camembert cheese. The TRT samples generally exhibited inhibitory activity comparable to or lower than that observed in the CTR samples. The sensory analysis revealed distinctions in cheese taste between the TRT and CTR groups.
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Affiliation(s)
- Rossella Vadalà
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
| | - Laura De Maria
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
| | | | - Eleonora Di Salvo
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
| | - Giovanna Lo Vecchio
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
| | - Giuseppa Di Bella
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
| | - Rosaria Costa
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
| | - Nicola Cicero
- Dipartimento di Scienze Biomediche, Odontoiatriche e delle Immagini Morfologiche e Funzionali, University of Messina, 98168 Messina, Italy; (R.V.); (L.D.M.); (E.D.S.); (G.L.V.); (G.D.B.); (N.C.)
- Science4life S.r.l. Start Up, 98168 Messina, Italy;
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Birkenfeld V, Gorb SN, Krings W. Mandible elemental composition and mechanical properties from distinct castes of the leafcutter ant Atta laevigata (Attini; Formicidae). Interface Focus 2024; 14:20230048. [PMID: 38618230 PMCID: PMC11008964 DOI: 10.1098/rsfs.2023.0048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/18/2023] [Indexed: 04/16/2024] Open
Abstract
Leafcutter ant colonies are divided into castes with the individuals performing different tasks, based mostly on size. With the mandibles, the small minims care for the brood or the fungus, whereas the larger minors and mediae cut and transport plant material, with the ant size positively related to the material size. The mechanical properties and composition of the mandible cuticle have been previously tested in the soldiers as the largest caste, revealing that the cutting edges contained high contents of the cross-linking transition metal zinc (Zn). With regard to the smaller castes, no data are present. To study how the mandible size and function relates to its mechanical properties, we here tested the mandibles of minims, minors and mediae by nanoindentation. We found that the hardness (H) and Young's modulus (E) values increased with increasing ant size and that the mandible cutting edges in each caste have the highest H- and E-values. To gain insight into the origins of these properties, we characterized the elemental composition by energy-dispersive X-ray analysis, revealing that minors and mediae possessed higher content of Zn in the cutting edges in contrast to the minims containing significantly less Zn. This shows, that Zn content relates to higher mechanical property values. Additionally, it shows that all of these parameters can differ within a single species.
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Affiliation(s)
- Valentin Birkenfeld
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1–9, 24118 Kiel, Germany
| | - Stanislav N. Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1–9, 24118 Kiel, Germany
| | - Wencke Krings
- Department of Functional Morphology and Biomechanics, Zoological Institute, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1–9, 24118 Kiel, Germany
- Department of Cariology, Endodontology and Periodontology, Universität Leipzig, Liebigstraße 12, 04103 Leipzig, Germany
- Department of Electron Microscopy, Institute of Cell and Systems Biology of Animals, Universität Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
- Department of Mammalogy and Palaeoanthropology, Leibniz Institute for the Analysis of Biodiversity Change, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany
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Correa KCS, Facchinatto WM, Habitzreuter FB, Ribeiro GH, Rodrigues LG, Micocci KC, Campana-Filho SP, Colnago LA, Souza DHF. Activity of a Recombinant Chitinase of the Atta sexdens Ant on Different Forms of Chitin and Its Fungicidal Effect against Lasiodiplodia theobromae. Polymers (Basel) 2024; 16:529. [PMID: 38399907 PMCID: PMC10892911 DOI: 10.3390/polym16040529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/09/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
This study evaluates the activity of a recombinant chitinase from the leaf-cutting ant Atta sexdens (AsChtII-C4B1) against colloidal and solid α- and β-chitin substrates. 1H NMR analyses of the reaction media showed the formation of N-acetylglucosamine (GlcNAc) as the hydrolysis product. Viscometry analyses revealed a reduction in the viscosity of chitin solutions, indicating that the enzyme decreases their molecular masses. Both solid state 13C NMR and XRD analyses showed minor differences in chitin crystallinity pre- and post-reaction, indicative of partial hydrolysis under the studied conditions, resulting in the formation of GlcNAc and a reduction in molecular mass. However, the enzyme was unable to completely degrade the chitin samples, as they retained most of their solid-state structure. It was also observed that the enzyme acts progressively and with a greater activity on α-chitin than on β-chitin. AsChtII-C4B1 significantly changed the hyphae of the phytopathogenic fungus Lasiodiplodia theobromae, hindering its growth in both solid and liquid media and reducing its dry biomass by approximately 61%. The results demonstrate that AsChtII-C4B1 could be applied as an agent for the bioproduction of chitin derivatives and as a potential antifungal agent.
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Affiliation(s)
- Katia Celina Santos Correa
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
| | - William Marcondes Facchinatto
- Aveiro Institute of Materials, CICECO, Department of Chemistry, University of Aveiro, St. Santiago, 3810-193 Aveiro, Portugal;
| | - Filipe Biagioni Habitzreuter
- Sao Carlos Institute of Chemistry, University of Sao Paulo, Ave. Trabalhador Sao-carlense 400, 13560-590 Sao Carlos, Brazil; (F.B.H.); (S.P.C.-F.)
| | - Gabriel Henrique Ribeiro
- Brazilian Corporation for Agricultural Research, Embrapa Instrumentation, St. XV de Novembro 1452, 13560-970 Sao Carlos, Brazil; (G.H.R.); (L.A.C.)
| | - Lucas Gomes Rodrigues
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
| | - Kelli Cristina Micocci
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
| | - Sérgio Paulo Campana-Filho
- Sao Carlos Institute of Chemistry, University of Sao Paulo, Ave. Trabalhador Sao-carlense 400, 13560-590 Sao Carlos, Brazil; (F.B.H.); (S.P.C.-F.)
| | - Luiz Alberto Colnago
- Brazilian Corporation for Agricultural Research, Embrapa Instrumentation, St. XV de Novembro 1452, 13560-970 Sao Carlos, Brazil; (G.H.R.); (L.A.C.)
| | - Dulce Helena Ferreira Souza
- Department of Chemistry, Federal University of Sao Carlos, 13565-905 Sao Carlos, Brazil; (K.C.S.C.); (L.G.R.); (K.C.M.)
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Zhang Y, Zhang H, Chen Z, Gao J, Bi Y, Du K, Su J, Zhang D, Zhang S. Crustacean-inspired chitin-based flexible buffer layer with a helical cross-linked network for bamboo fiber/poly(3-hydroxybutyrate) biocomposites. Int J Biol Macromol 2024; 259:129248. [PMID: 38191108 DOI: 10.1016/j.ijbiomac.2024.129248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/29/2023] [Accepted: 01/03/2024] [Indexed: 01/10/2024]
Abstract
Marine biological resources, serving as a renewable and sustainable reservoir, holds significant import for the utilization of composite material. Hence, we produced bamboo fiber/poly(3-hydroxybutyrate) (BF/PHB) biocomposites with exceptional performance and economic viability, drawing inspiration from the resilience of crustacean shells. Polyaminoethyl modified chitin (PAECT) was synthesized using the alkali freeze-thaw method and introduced into the interface between BF and PHB to improve interfacial adhesion. The resulting chitin fibers, characterized by their intertwined helical chains, constructed a flexible mesh structure on the BF surface through an electrostatic self-assembly approach. The interwoven PAECT filaments infiltrated the dual-phase structure, acting as a promoter of interfacial compatibility, while the flexible chitin network provided a greater capacity for deformation accommodation. Consequently, both impact and tensile strength of the BF/PHB composites were notably enhanced. Additionally, this flexible layer ameliorated the thermal stability and crystalline properties of the composites. This investigation aimed to leverage the distinctive helical configuration of chitin to facilitate the advancement of bio-reinforced composites.
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Affiliation(s)
- Yi Zhang
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Huanrong Zhang
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Zhenghao Chen
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Jian Gao
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Yanbin Bi
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Keke Du
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Jixing Su
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Dongyan Zhang
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Shuangbao Zhang
- Key Laboratory of Wood Material Science and Application (Beijing Forestry University), Ministry of Education, Beijing 100083, China; Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China.
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Morales-Jiménez M, Palacio DA, Palencia M, Meléndrez MF, Rivas BL. Bio-Based Polymeric Membranes: Development and Environmental Applications. MEMBRANES 2023; 13:625. [PMID: 37504991 PMCID: PMC10383737 DOI: 10.3390/membranes13070625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 06/20/2023] [Accepted: 06/24/2023] [Indexed: 07/29/2023]
Abstract
Nowadays, membrane technology is an efficient process for separating compounds with minimal structural abrasion; however, the manufacture of membranes still has several drawbacks to being profitable and competitive commercially under an environmentally friendly approach. In this sense, this review focuses on bio-based polymeric membranes as an alternative to solve the environmental concern caused by the use of polymeric materials of fossil origin. The fabrication of bio-based polymeric membranes is explained through a general description of elements such as the selection of bio-based polymers, the preparation methods, the usefulness of additives, the search for green solvents, and the characterization of the membranes. The advantages and disadvantages of bio-based polymeric membranes are discussed, and the application of bio-based membranes to recover organic and inorganic contaminants is also discussed.
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Affiliation(s)
- Mónica Morales-Jiménez
- Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional (CIIDIR-Unidad Oaxaca), Instituto Politécnico Nacional, Calle Hornos 1003, Colonia Noche Buena, Santa Cruz Xoxocotlán 71230, Mexico
| | - Daniel A Palacio
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Edmundo Larenas 129, Casilla 160-C, Concepción 4070371, Chile
| | - Manuel Palencia
- GI-CAT, Department of Chemistry, Faculty of Natural and Exact Science, Universidad del Valle, Cali 25360, Colombia
| | - Manuel F Meléndrez
- Departamento de Ingeniería de Materiales (DIMAT), Facultad de Ingeniería, Universidad de Concepción, Edmundo Larenas 270, Casilla 160-C, Concepción 4070371, Chile
- Unidad de Desarrollo Tecnológico, 2634 Av. Cordillera, Parque Industrial Coronel, P.O. Box 4051, Concepción 4191996, Chile
| | - Bernabé L Rivas
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Edmundo Larenas 129, Casilla 160-C, Concepción 4070371, Chile
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Li J, Song R, Zou X, Wei R, Wang J. Simultaneous Preparation of Chitin and Flavor Protein Hydrolysates from the By-Products of Shrimp Processing by One-Step Fermentation with Lactobacillus fermuntum. Molecules 2023; 28:molecules28093761. [PMID: 37175194 PMCID: PMC10179846 DOI: 10.3390/molecules28093761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 04/17/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
One-step fermentation, inoculated with Lactobacillus fermentum (L. fermentum) in shrimp by-products, was carried out to obtain chitin and flavor protein hydrolysates at the same time. The fermentation conditions were optimized using response surface methodology, resulting in chitin with a demineralization rate of 89.48%, a deproteinization rate of 85.11%, and a chitin yield of 16.3%. The surface of chitin after fermentation was shown to be not dense, and there were a lot of pores. According to Fourier transform infrared spectroscopy and X-ray diffraction patterns, the fermented chitin belonged to α-chitin. More than 60 volatiles were identified from the fermentation broth after chitin extraction using gas chromatography-ion transfer spectrometry analysis. L. fermentum fermentation decreased the intensities of volatile compounds related to unsaturated fatty acid oxidation or amino acid deamination. By contrast, much more pleasant flavors related to fruity and roasted aroma were all enhanced in the fermentation broth. Our results suggest an efficient one-step fermentation technique to recover chitin and to increase aroma and flavor constituents from shrimp by-products.
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Affiliation(s)
- Jiawei Li
- Key Laboratory of Health Risk Factors for Seafood of Zhejiang Province, School of Food Science and Pharmacy, Zhejiang Ocean University, Zhoushan 316022, China
| | - Ru Song
- Key Laboratory of Health Risk Factors for Seafood of Zhejiang Province, School of Food Science and Pharmacy, Zhejiang Ocean University, Zhoushan 316022, China
| | - Xiaoyu Zou
- Key Laboratory of Health Risk Factors for Seafood of Zhejiang Province, School of Food Science and Pharmacy, Zhejiang Ocean University, Zhoushan 316022, China
| | - Rongbian Wei
- School of Chemistry and Bioengineering, Guangxi Normal University for Nationalities, Chongzuo 532200, China
| | - Jiaxing Wang
- Research Office of Marine Biological Resources Utilization and Development, Zhejiang Marine Development Research Institute, Zhoushan 316021, China
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Novikov VY, Derkach SR, Konovalova IN, Dolgopyatova NV, Kuchina YA. Mechanism of Heterogeneous Alkaline Deacetylation of Chitin: A Review. Polymers (Basel) 2023; 15:polym15071729. [PMID: 37050343 PMCID: PMC10097213 DOI: 10.3390/polym15071729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
This review provides an analysis of experimental results on the study of alkaline heterogeneous deacetylation of chitin obtained by the authors and also published in the literature. A detailed analysis of the reaction kinetics was carried out considering the influence of numerous factors: reaction reversibility, crystallinity and porosity of chitin, changes in chitin morphology during washing, alkali concentration, diffusion of hydroxide ions, and hydration of reacting particles. A mechanism for the chitin deacetylation reaction is proposed, taking into account its kinetic features in which the decisive role is assigned to the effects of hydration. It has been shown that the rate of chitin deacetylation increases with a decrease in the degree of hydration of hydroxide ions in a concentrated alkali solution. When the alkali concentration is less than the limit of complete hydration, the reaction practically does not occur. Hypotheses have been put forward to explain the decrease in the rate of the reaction in the second flat portion of the kinetic curve. The first hypothesis is the formation of “free” water, leading to the hydration of chitin molecules and a decrease in the reaction rate. The second hypothesis postulates the formation of a stable amide anion of chitosan, which prevents the nucleophilic attack of the chitin macromolecule by hydroxide ions.
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