A team of bioengineers from the University of Nottingham and Nile University in Egypt are developing a new substitute for conventional plastic carry bags using a material made out of shrimp shells. This biodegradable alternative to the more conventional polythene made from fossil fuels that is used in shopping bags is not only greener, but can also extend the shelf life of foodstuffs,

Plastic carry bags may be a convenience, but they're also a major headache for developing nations like Egypt that not only must deal with them in terms of disposal, but also as a source of water contamination in the very crowded North African country. One alternative would be bioplastics made from plants, but that isn't feasible in Egypt, where most cultivation is for the production of food and cotton.

To help remedy this, the research team is looking at chitosan, which is a man-made polymer made from shrimp shells that are already a waste problem for the country. The aim of the research is to produce a biopolymer nanocomposite material suitable for Egyptian conditions that can do the job of polythene in shopping bags, yet is inexpensive and biodegradable.

Chitosan film made from lab-grade chitosan(Credit: University of Nottingham)

Chitosan is made from shrimp shells that have been treated with acid to remove the calcium carbonate, then an alkali solution is used to induce the mixture to form a polymer in the form of flakes. These flakes can them be processed into a plastic film using conventional manufacturing methods.

Chitosan is particularly attractive because it's already finding applications in the food packaging and medical industries because it's not only biocompatible, but has antimicrobial and antibacterial properties. In addition, it absorbs oxygen, so it prolongs the shelf life of many foodstuffs.

Everett hopes that the such chitosan packaging will be attractive to British manufacturers, but the team's research first needs to concentrate on identifying the best production route for manufacturing the material into suitable shopping bags and food packaging.

"Use of a degradable biopolymer made of prawn shells for carrier bags would lead to lower carbon emissions and reduce food and packaging waste accumulating in the streets or at illegal dump sites" says Dr Nicola Everitt from the Faculty of Engineering at Nottingham who is leading the research. "It could also make exports more acceptable to a foreign market within a 10-15-year time frame. All priorities at a national level in Egypt."

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