Shellfish, chitin from

Bioconversion of Shellfish Chitin Waste. In the quest of finding ways to utilize tne nutrients m shellfish processing waste, another avenue has been discovered. A process has been developed which bioconverts shellfish chitin to yeast single-cell protein (96-98). The product of this process is a protein-rich material wRTcfT can be used as an animal and aquaculture feed supplement. Since chitin s chemical structure is nearly similar to cellulose, the concept of this process was inspired from the bioconversion... 

A potential industrial method for the production and isolation of chitosan from the hyphal walls of Mucor rouxii as an alternative to the product derived from shellfish chitin has been reported. ... 

The isolation of chitin from shellfish waste consists of three steps deproteinization (DP), demineralization (DM), and decolorization (DC) whereby the order of the first two steps is generally considered irrelevant if protein or pigment recovery is not an objective (Shahidi and Synowiecki 1991). Chitin is further deacetylated (DA) to make chitosan or other products for a wide array of applications. Both chemical and enzymatic non-continuous batch methods are widely used on an industrial scale for the production of chitin, chitosan, and COS. 

Chitosan Chitosan has a molecular structure similar to cellulose. This material is produced from chitin, which is widely found in the exoskeleton of shellfish and crustaceans. Chitin is the second most abundant natural biopolymer after cellulose. Chitosan is a good adsorbent for all heavy metals. It has been estimated that chitosan can be produced from shellfish and crustaceans at a market price of 15.43 /kg. 

Chitosan comes from chitin, a substance that comes from the shells of lobsters, crabs, shrimp, and other shellfish. Supplement makers claim that when chitin is processed, the final product—chitosan—turns into a kind of fat magnet. This is a theory that may come from the longtime use of chitosan to purify dirty water for safe use by people. When chitosan is spread over water, oils and toxins rise up and cling to it. They can then be removed easily from the surface. 

Hattis, D. Murrayt A. E. Industrial Prospects for Chitin and Protein from Shellfish Waste MIT Sea Grant Report No. MIT-SG-ZV-J, 1977 pp 9y. 

A minor source of carbohydrates that should be mentioned, nevertheless, is chitin, a polymer of N-acetyl-D-glucosamine (see Fig. 8.2 c) that resembles cellulose in its structure and general behavior. Chitin is extracted at a 150 kt a-1 scale from shellfish waste [18], which is a tiny fraction of the amount that grows and decays every year. 

In the area of renewable materials, bulk oxypropylation of chitin and chitosan has been performed. Chitin and chitosan are abundant natural polymers obtained from shellfish, such as crab shell or shrimp shell. This solvent free reaction yields viscous polyols. Unfortunately, propylene oxide homopolymer is formed as a by-product but is easily separated. It should be noted that care was taken to minimize the risk involved in the use of toxic, flammable propylene oxide (the reagent in this process). 

Amino sugars, such as o-g)ucosamine, have an -OH group replaced by an -NH. The iV-acetyl amide derived from D-glucosamine is the monosaccharide unit from which chitin, the hard crust that protects insects and shellfish, is built. Still other amino sugars are found in antibiotics such as streptomycin and gentamicin. 

FIG. 9 Flowsheet for preparation of chitin, chitosan, and their oligomers and monomers from shellfish processing by-products. 

One approach to extracting valuable compounds from shellfish processing waste is through the use of marine microorganisms in a procedure referred to as solid state (substrate) fermentation, or SSF. SSF may prove to be an economically advantageous tool for the production of certain compounds from marine waste. For example, the marine fungus Beauveria bassiana can be used to produce chitinase from chitinous prawn waste. Without the fungus, this conversion step normally accounts for 12% of the... 

Chitin is a homopolymer of AT-acetyl-D-glucosamine residues and is a major structural component in the exoskeletons of crustaceans, mollusks, arthropods, and the cell walls of numerous fungi and algae. Owing to its widespread presence in both terrestrial and aquatic organisms, chitin is second only to cellulose as the most abundant biopolymer on the Earth (Shahidi and Abuzaytoun, 2005). On a dry weight basis, shrimp, crab, lobster, prawn, and crayfish have been reported to contain between 14% and 35% chitin, while deproteinized dry shell waste of Antarctic krill contains approximately 40% crude chitin (Haard et al, 1994). Crustaceans are the primary sources of chitin used in industry. Chitin can be extracted from shellfish and crustacean waste by mixing with a dilute add to induce demineralization, followed by a deproteini-zation step in a hot alkaline solution (Synowiecki and Al-Khateeb, 2003). 

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). 

While most processes for the production of chitin (and derivatives) from shellfish wastes entail a batch production using chemical, enzymatic, or fermentative methods, some research on novel techniques has been performed. 

Chitosan is deacetylated chitin that is swollen with water and dissolves in a water acetic acid mixture. This polymer is produced commercially from the base-catalyzed deacelylatlon of shellfish waste by Protan (Drammen, Norway). Chitin and chitosan exhibit good mechanical properties as well as low permeabilities ... 

Other biodegradable polymers include Konjac, a water-soluble natural polysaccharide produced by FMC Chitin, another polysaccharide that is insoluble in water and Chitosan, which is soluble in water. Chitin is found in insects and in shellfish. Chitosan can be formed from chitin and is also found in fungal cell waUs. Chitin is used in many biomedical applications, including dialysis membranes, bacteriostatic agents, and wound dressings. Other applications include cosmetics, water treatmenfi adhesives, and fungi-cides. y... 

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