Waste shells are often just dumped in landfills or the sea.
The potential value of such waste is being long time ignored. Yet crustacean shells harbour many proteins, calcium carbonate and chitin that can be used by the industry. Chitin is a natural polymer containing nitrogen similar to cellulose, commonly found in plants.
Chitin is highly abundant on our planet and can be found in fungi, plankton, insects and crustaceans.
Chitosan is a product made by deacetylation of chitin using concentrated sodium hydroxide solution.
Chitosan has antibacterial, antifungal and antialgal properties.
Currently, chitosan has a limited use in pharmaceutical industry, cosmetics, textiles, and water treatment. Laila al Naamani is a PhD student of the College of Agricultural and Marine Sciences, Sultan Qaboos University (SQU).
Her work about chitosan production and bioactivity is supervised by Dr Sergey Dobretsov, director of Center of Excellence in Marine Biotechnology, and Head of the Department of Marine Science and Fisheries, SQU.
Laila’s results suggested that high quantities of pure chitosan can be extracted from shells of shrimps, blue crabs, lobsters and cuttlefish commonly eaten in Oman.
Her recent work published by Innovative Food Science and Emerging Technologies and Chemosphere journals suggested that chitosan can be used for active food packaging applications and prevention of biofouling.
Biofouling is referred to undesirable attachment and growth of organisms to submerged industrial applications. It is a global problem and worldwide countries spent more than US$15bn in order to manage and prevent biofouling. Yet current antifouling methods are costly and environmentally unfriendly.
Thus, there is a strong need to develop non-toxic solutions to prevent biofouling. Laila suggested of using chitosan- ZnO nanocomposite hybrid coatings to increase activity and stability of chitosan.
These hybrid coatings were made under the supervision of Professor Joydeep Dutta, the Chair of Functional Materials division at the KTH Royal Institute of Technology, Sweden. Laboratory experiments demonstrated that the hybrid coatings prevented growth of common marine microbes.
Additional mesocosm experiments using tanks containing natural sea water under controlled conditions showed that antifouling properties of chitosan- ZnO hybrid coatings are better than chitosan coatings alone.
The results of this study were presented by Laila during the International Congress on Marine Corrosion and Fouling (www.icmcf.com) in Toulon, France.
For her oral presentation she received an award from the European Society for Marine Biotechnology . Recently, the antifouling potential of the experimental chitosan-nanocomposite coatings made by Laila was highlighted in the publication of the European Coatings Journal.
Overall, the results of this PhD study demonstrate the high industrial potential of the crustacean waste.
In the future scientists should work out sustainable ways to use and refine crustacean shells, while government and industry should invest in utilising this abundant and cheap renewable resource.