Project aims to turn prawn shells into bags

ENGINEERS at the University of Nottingham, UK, have embarked on a project to use prawn shells to make biodegradable shopping bags and food packaging.

The project will focus on Egypt, which has a large waste problem with non-degradable plastic packaging, which is causing environmental and public health problems. The researchers, led by materials engineering associate professor Nicola Everitt, chose prawn shells as their starting material, as these too pose a waste problem in Egypt, and are primarily composed of chitosan, which is a promising biopolymer with a number of potential uses, including in haemostatic bandages, food wrap and as a biopesticide. It is already in use as packaging for pharmaceuticals as it is antimicrobial, antibacterial and biocompatible.

To extract the chitosan, prawn shells are first exposed to acid, which dissolves the calcium carbonate within the shell structure. After this, the shells are exposed to an alkali, which breaks down the remaining chitosan structure into long, molecular chains. Once dried, it forms flakes which can be dissolved in solvents and made into polymer films.

The researchers hope to turn the films into supermarket carrier bags, and into an active polymer film which can absorb oxygen. This would extend food life and reduce waste. Everitt plans to launch the packaging in the UK as well as in Egypt if it is successful. The final part of the project will be to develop a commercial production process for the bags and the films.

“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. It could also make exports more acceptable to a foreign market within a 10–15-year time frame,” said Everitt.

The project is being funded by the Newton Fund and the Newton-Mosharafa Fund grant, as part of a scheme to tackle community problems around the world through science and technology.