Chitin solution properties

Amylopectins. — The effects of acrylamide graft copolymerization on the solution properties of amylopectin have been discussed. Amylopectin has been dyed with DyAmyl-L and used in this form as a substrate for the assay of a-amylase. Amylopectin has been treated with isocyanate derivatives of 4-amino-( 1,1-dimethyl ethyl)-3-(methylthio)-l,2,4-triazin-5(4/f)-one ( metribuzin ) or acid chloride derivatives of 2,4-dichlorophenoxyacetic acid ( 2,4-D ) and 2,2-dichloropropionic acid ( dalapon ), to produce controlled-release polymeric pesticide systems. The solvent system utilized for these reactions, a lithium chloride or bromide salt in AW-dimethylacetamide, allows dissolution of the reactant salt and facilitates analysis of the polymer product by such techniques as i.r., U.V., and n.m.r. spectroscopies and gel permeation chromatography. Derivatives of other naturally occurring polysaccharides, including amylopectin, cellulose, chitin, and dextran, were also prepared. 

Fibres were first developed by Austin [60] and then by Hirano [61-63] in solvents mentioned previously, especially the DMAc/LiCl system. The fibres were obtained by wet-spinning [63]. A recent review presents the different fibres obtained from chitin solution and some of their physical properties [27]. In addition, chitin solutions may be casted to obtain films [64,65] or regenerated under sponge or bead conformation in dependence of the use. Fibres were often proposed for textile applications [66-68]. 

In contrast to chitin, the presence of free amino groups along the chitosan chains allows this macromolecule to dissolve in dilute aqueous acidic solvents through the protonation of these groups and the formation of the corresponding chitosan salt. It is therefore important to realize that the polyelectrolyte character of chitosan influences its solution properties. 

Kienzle-Sterzer C., Rodriguez-Sanchez D., Rha C., Solution properties of chitosan Chain conformation, Chitin, Chitosan, Relat. Enzymes, Proceedings of the Joint US-Japan. Seminar on Advances in Chitin, Chitosan, Related Enzymes, 1984,... 

Rinaudo, M., and Domard, A. (1989) Solution Properties of Chitosan, in Chitin and Chitosan, G. Sjak-Braek, T. Anthonsen, and P. Sandford (eds.), Elsevier, New York, p.77... 

Contrary to chitin, chitosan is a relatively soluble biopolymer. The solution properties of a chitosan depend on its average DD and the distribution of the acetyl gronps along the main chain [146]. Various solvents and processes for spinning chitosan fibers have been developed [138, 147, 148]. In recent years, chitin/chitosan fiber spinning process and their novel applications have been continnously studied. 

Shell wastes from shrimp, crab, and lobster processing industries are the traditional source of chitin. However, commercial production of chitosan by deacetylation of crustacean chitin with a strong alkali appears to have limited potential for industrial acceptance because of seasonal and limited supply, difficulties in processing, particularly with the large amount of waste of concentrated alkaline solution causing environmental pollution, and inconsistent physico-chemical properties (Chatterjee et ah, 2005). 

The main structural constituents of Saccharomyces cerevisiae yeast cell wall are glucans and mannans with a minor proportion of chitin (Walker 1998). Manno-proteins are located in the outer layer of the yeast cell wall and determine most of the surface properties of the wall. Vasserot et al. (1997) studied the capacity of yeast lees to adsorb anthocyanins in an attempt to reduce the detrimental effects of charcoal on the color of red musts and wines. Experiments based on model wine solutions revealed that yeast lees possess a greater affinity for anthocyanins than... 

Smoke condensates are obtained by condensing smoke in water or another solvent. They may be further fractionated, purified or concentrated. The fractionation steps have two purposes to obtain products of interesting olfactory properties and to reduce the concentration of undesirable by-products from the smoke. Only the water-soluble fraction is used. The organic phase will be abandoned because a work up of the tar fraction is too expensive. The smoke solution will be filtered in order to remove polycyclic aromatic hydrocarbons (PAHs). According to a Russian patent [18] it is also possible to use 2% chitin and 0.5% chitosan for removing PAHs almost quantitatively. Afterwards the components of the smoke solution may be concentrated by distillation. The resulting product will be processed into smoke flavouring preparations. 

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