Chitosan extraction process

Moreover, Crestini et al. (1996) reported that the yields of chitosan, viz., 120mg/L of fermentation medium under liquid fermentation conditions, and 6.18g/kg of fermentation medium under solid-state fermentation conditions are produced from the mushrotxn, L. edodes. Based on this data, it can be conad-ered that the cultivation of mushroom on solid support, which is the natural growing method of mushroom, might be the best cultivation method for the production of chitin and chitosan from mushrooms. The yield of extracted chitin and chitosan depends on mushroom species, harvesting time, and chitin and chitosan extraction processes and conditions (POchanavanich and Suntomsuk 2002, Yai and Man 2007a). 

Craveiro AC, Lima MB. Bioreactor system with chitosan semipermeable membranes and continuous extraction process, 2000 Brazil Patent Priority CAN 134 177457 AN 2001 164817. 

Rane KD, Hoover DG (1993) An evaluation of alkali and acid treatments for chitosan extraction from fungi. Process Biochem 28 115-118... 

The processes and conditions for the extraction of chitin and chitosan from mushroom were nearly same in the methods of Crestini et al. (1996) and Pochanavanich and Suntomsuk (2002), and were different in Mario et al. (2008) and Yen and Mau (2007a). Crestini et al. (1996) and Pochanavanich and Snntornsuk (2002) used IM NaOH at 121°C for 0.25 h for deproteination and the chitosan was extracted from the collected alkaline insoluble material using 1% acetic acid at 95°C for 8-14h. Mario et al. (2008) used 1M NaOH at 40°C for 15-17h for deproteination and the chitosan was extracted from the collected alkaline insoluble material using 5% acetic acid at 90°C for 3 h. The total yield of chitin, i.e., 85-196 mg/g of dried mushroom and only a low yield of chitosan, 10-40 mg/g of dried mushroom were obtained from different species of mushrooms by both chitosan extraction procedures (Table 1.3). 

Several procedures for the preparation of chitin and chitosan from different shellfish wastes have been developed over the years, some of which form the basis of the chemical processes used for the industrial production of chitin and derivatives (Femandez-Kim 2004). A representation of current industrial chitin processes are sununarized in Figure 2.3. Industrial techniques for chitin and chitosan extraction from different shell waste streams normally rely on harsh chemical processes due to covalent associations with other shell constituents. These methods generate large quantities of hazardous chemical wastes and partial DA of chitin and hydrolysis of the polymer may occur, leading to inconsistent physiological properties in the end products (Andrade et al. 2003, Kim and Mendis 2006). 

Keeping in mind the importance of chitosan, as well as its economic value as an industrial product, we must pay attention to its key physical parameter, i.e., turbidity. Depending on source, a marked difference is observed in aqueous solutions of chitosan and its derivatives in terms of their turbidity [33]. Turbid aqueous solutions of chitosan and chitosan-derived products greatly lose their commercial value. Such chitosan cannot be used as a commercial product and in some cases may have to be discarded. Therefore, the selection of source plays a pivotal role in the production of chitin and chitosan. Shepherd et al. [20] reported the production of chitosan from New Zealand Arrow squid Notodarus sloani) pens as well as the evaluation of the functional properties of this squid chitosan compared with chitosan extracted from crustacean sources. Squid pen chitin and chitosan were visibly cleaner than chitin and chitosan obtained from crab and crayfish. In addition, due to the lower mineral content of squid pen as compared to cmstacean shells, the demineralization process can be skipped to extract chitin, which also makes the production cheaper. As shown in Table 4, the squid pen chitosan is similar in... 

Hollow fibers have recently received attention with the objective of performing the simultaneous sorption and desorption of the target metal. Hollow chitosan fibers were prepared and the system was used for the recovery of chromate anions. The hollow fibers were immersed in the chromate solution while an extractant was flowed through the lumen of the fiber. Chromate anions adsorbed on the fiber were re-extracted by the solvent extractant. The hollow fiber acts simultaneously as a physical barrier that can make the extraction process more selective. (Vincent, 2000, 2001)... 

Chitin isolation processes are generally performed through the following consecutive steps raw material conditioning, protein extraction (deproteinization), removal of inorganic components (demineralization) and decolouration. This sequence is preferred if the isolated protein is to be used as food additive for livestock feeding. Otherwise, demineralization can be carried out first [10]. A brief account of these processes will be given below. A more detailed description of chitin isolation (and chitosan preparation) can be found elsewhere [5, 8, 11]. 

However, Yen and Mau (2007a,b) extracted chitin and chitosan using alkaline treatment, followed by decolorization and then deacetylation with concentrated sodium hydroxide solution. In their process, they used mushroom L. edodes from a mushroom farm and they did not purify the chitosan... 

The cost of microbial production of chitinous compounds is an important factor in evaluation of their suitability for industrial application. Intensive efforts have been made to optimize the fermentation process for the production of chitin/chitosan with a view to develop economically feasible technologies. The research has been focused on several major aspects improvement of the yields of chitin/chitosan by screening new microbial sources, and optimization of the fermentation conditions and extraction procedures. An understanding of the structure/function relationships of the... 

In terms of improving the quality of chitosan, partial autolysis plays a crucial role because it facilitates exposure of CaC03 directly to the chemicals used during the demineralization process. For the industrial practice of chitin extraction, this means that a shorter time and lower concentration of HCl may be adequate to demineralize and thus avoid damage due to the hydrolytic action of HCl on the polymeric backbone structure of chitin. However, it was found that the protein content after treatment of autolyzed biomaterial with 2% NaOH was similar to the protein content after standard 4% NaOH treatment. Obviously, this study could help... 

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