US researchers combine crab shells and tree fibers for flexible packaging solution

25 Jul 2018 --- Researchers at the Georgia Institute of Technology have created a compostable material derived from crab shells and tree fibers which, the team believes, could provide a more sustainable alternative to flexible plastic packaging used for fresh foods. The new 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.

“The main benchmark that we compare it to is PET, or polyethylene terephthalate, one of the most common petroleum-based materials in the transparent packaging you see in vending machines and soft drink bottles,” says J. Carson Meredith, a professor in Georgia Tech’s School of Chemical and Biomolecular Engineering. “Our material showed up to a 67 percent reduction in oxygen permeability over some forms of PET, which means it could in theory keep foods fresher for longer.”

Cellulose, which comes from plants, is the planet’s most common natural biopolymer, followed next by chitin, which is found in shellfish, insects and fungi.

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

“We had been looking at cellulose nanocrystals for several years and exploring ways to improve those for use in lightweight composites as well as food packaging, because of the huge market opportunity for renewable and compostable packaging, and how important food packaging overall is going to be as the population continues to grow,” Meredith continues.

The research team also included Meisha Shofner, an Associate Professor in the School of Materials Science and Engineering and the Interim Executive Director of the Renewable Bioproducts Institute, John R. Reynolds, a Professor in the schools of Chemistry and Biochemistry and Materials Science and Engineering, and Chinmay Satam, a graduate student at Georgia Tech.

The team had been looking into chitin for an unrelated reason when they wondered if it might have use in food packaging.

“We recognized that because the chitin nanofibers 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 adds.

Packaging meant to preserve food needs to prevent oxygen from passing through. Part of the reason the new material improves upon conventional plastic packaging as a gas barrier is because of the crystalline structure of the film.

“It’s difficult for a gas molecule to penetrate a solid crystal because it has to disrupt the crystal structure,” Meredith says. “Something like PET on the other hand has a significant amount of amorphous or non-crystalline content, so there are more paths easier for a small gas molecule to find its way through.”

Environmentalists have long looked for renewable ways to replace petroleum-based materials in consumer products. With the amount of cellulose already produced and a ready supply of chitin-rich byproducts left over from the shellfish food industry, there’s likely more than enough material available to make the new films a viable flexible-packaging alternative, according to Meredith.

Still, there’s more work to be done. To make the new material eventually competitive with flexible packaging film on cost, a manufacturing process that maximizes economy of scale will need to be developed. Additionally, while industrial processes to mass produce cellulose are mature, methods to produce chitin are still in their infancy, Meredith concludes. In addition, more research is also needed to improve the material’s ability to block water vapor.

Innovation in biodegradable/compostable packaging solutions on the rise
Rising demand for more environmentally-responsible consumer products is driving innovation in biodegradable and compostable packaging solutions. Public concern for the environmental impact of everyday packaging materials – particularly plastics – has intensified, creating market opportunities for creative, forward-thinking and sometimes entirely unusual biodegradable/compostable packaging.

While the commercialization of innovative biodegradable/compostable packaging may be a challenge in itself, the popularity of this packaging type is on the rise. Innova Market Insights reports a 40 percent increase in new food and beverage products packaged in bio-based/biodegradable material (CAGR 2013-2017). Meanwhile, a survey found that more than 35 percent of German consumers, 25 percent of UK consumers and more than 25 percent of US consumers consider bio-based and/or biodegradable/compostable packaging important in food and beverage choice (Innova Market Insights, 2015).

Read more about recent and sometimes surprising innovations in biodegradable/compostable packaging solutions here.

Edited by Joshua Poole