Material formed from crab shells and trees could replace flexible plastic packaging

Described in the journal ACS Sustainable Chemistry and Engineering, the material is made by spraying multiple layers of chitin from crab shells and cellulose from trees to form a flexible film similar to plastic packaging film. Cellulose is the planet's most common natural biopolymer, followed by chitin, which is found in shellfish, insects and fungi.

The team devised a method to create a film by suspending cellulose and chitin nanofibres in water and spraying them onto a surface in alternating layers. Once fully dried, the material is flexible, strong, transparent and compostable.

Prof J Carson Meredith, who led the research, said that the material could offer advantages over polyethylene terephthalate (PET), one of the most commonly used transparent packaging materials. "Our material showed up to a 67 per cent reduction in oxygen permeability over some forms of PET, which means it could in theory keep foods fresher longer," he said.

The team had been looking into chitin for an unrelated reason when they wondered if it might have use in food packaging. "We recognised that because the chitin nanofibres are positively charged, and the cellulose nanocrystals are negatively charged, they might work well as alternating layers in coatings because they would form a nice interface between them," Meredith said.