North American Indians recognized the effect of ground crayfish shells on wounds quite a long time ago. Crayfish shells contain chitin, a long-chain polysaccharide with an antibacterial effect when applied as a plaster, which also helps heavy burn wounds to heal faster as well as preventing scars. The goal of current research is to use chitin for nasal spray vaccinations, thus doing away with the need for needles. In his Konstanz-based Vegafood project office, Dr. Peter May is focused on sustainable breeding of crayfish with the aim of advancing industrial scale chitin research. European noble crayfish shed their skin several times a year, providing research institutions and chitin product manufacturers with access to crustacean carapaces.
European crayfish, and the noble crayfish species in particular, were eradicated in Europe in the mid-20th century due to a disease known as American crayfish plague. Since then, European crayfish consumers have had to import crayfish from other countries, in particular Eastern Europe, the Middle East and Africa. As there are no larger-scale noble crayfish breeding facilities in Germany and Switzerland despite the demand from the catering, pharmaceutical and cosmetics sectors, Dr. Peter May is planning to establish a noble crayfish breeding facility. He plans to construct economically sized 4,500-square-metre basins, and use waste heat to warm the indoor and outdoor basins, and spring and groundwater to maintain high water quality. May envisages using the waste heat produced by a cold store in the vicinity of the future crayfish breeding facility. He is also planning to supply restaurants with crayfish meat, and research institutions, pharmaceutical and cosmetics producers with crayfish skeletons (i.e. the carapaces). “Chitin is also the main component of the exoskeletons of insects and worms and the cell walls of fungi. However, crustacean shells are far more suitable for extracting chitin as they contain much larger amounts of the biopolymer,” May explained.
Japan and USA already provide considerable funding for research into this alternative raw material, which can be used for a broad range of medical purposes. Complex procedures are required to extract chitin from the crustacean shells. The shells are ground and dissolved in sodium hydroxide to remove protein. The powder is then dried and the calcium carbonate (chalk) removed with acid, resulting in chitin, a compound containing carbon, hydrogen and nitrogen. Chitin prevents the growth of fungi and bacteria. It also accelerates wound healing processes. Prawn fishermen have healthy teeth because they chew chitin-containing prawn shells, which counteract the activity of streptococci that causes caries, to name but one example.
Chitin is not readily soluble and needs to be processed before it can be used for medical and other applications. The treatment of chitin with sodium hydroxide leads to acetic acid, and finally to chitosan. “Chitosan contains sugar building blocks that contain nitrogen, is protein-free and is not rejected by the human body. When applied in the form of a plaster, it has an antibacterial effect and also absorbs fluid from wounds that is up to 50 times its own weight,” May explained, adding that the chitosan plaster is eventually dissolved enzymatically in the same way as surgical thread made from chitosan. Even heavy burn wounds can be effectively treated with chitosan, which improves wound healing by preventing the formation of scars.
Chitin also has the potential to do away with needle vaccinations. To this end, researchers are exploring the use of chitosan as a drug delivery system, making use of the biopolymer’s ability to form nanoparticles in aqueous solution. These chitosan nanoparticles are able to cross the nasal mucosa and increase the uptake of pharmaceutically active substances. Vaccinations might in future be given using nasal sprays instead of needles. Especially people with diabetes stand to benefit from such nasal sprays. Another positive property of chitosan is that its strongly positive charge attracts negatively charged ions, thereby binding blood lipids and reducing the risk of cardiac infarction and stroke. “Chitosan also binds heavy metals and can thus contribute to the remediation of soil and the purification of wastewater,” said May.
Further information:Dr. Peter MayVegafoodKreuzlinger Str. 47 b78462 KonstanzTel.: +49 (0)7531/ 2 66 28Fax: +49 (0)7531/ 1 62 84E-mail: dr.may(at)vegafood.de