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Packaging films fight bacteria and help the environment

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Packaging film from plant proteins

Packaging films fight bacteria
and help the environment
By harnessing the properties of natural ingredients, Clemson University scientists are developing packaging films that protect foods against harmful bacteria and may one day help protect the environment.

One of the new films is made from a corn protein, called zein, and includes two natural antibacterial agents. Nisin is a protein that is produced by bacteria and is widely used to prevent spoilage in cheese and liquid eggs. Lysozyme is an enzyme found in egg whites, as well as in human tears, that prevents bacteria from multiplying. Both ingredients are approved for use in foods by the federal Food and Drug Administration and the Department of Agriculture.

Early research results have shown that the antibacterial film reduced the numbers of listeria bacteria on meat products. The film was particularly effective when it also included another antibacterial ingredient – lauric acid, a fatty acid found in foods. The test film was not able to reduce the numbers of salmonella bacteria, but did prevent them from multiplying.

Other studies showed that the antibacterial agents were also effective when they were added to commercial food packaging films. However, the antibacterial properties were not as effective against listeria when nisin alone was used in the corn-based film on refrigerated processed cheese.

In addition to fighting bacteria, the corn-based films can be recycled as animal feed and are biodegradable. This would reduce the amount of packaging waste that is sent to landfills. A second biodegradable film has been developed that is made of soy protein and coated with a layer of corn protein. The soy and corn combination film provides a more effective water vapor barrier than film made from soy alone.

Other studies are testing a film made from chitosan that is produced from discarded shrimp and crab shells. Chitosan has natural antibacterial properties that make this film interesting for possible medical uses, such as treating burn victims, as well as for packaging foods. Future work will test the chitosan film’s effectiveness on processed meats.

The scientists acknowledge that these new films offer exciting possibilities, but that more work is needed before they are ready for commercial use. In the future , however, films made from natural ingredients could make food safer, protect the environment, and offer a new market for farm and seafood products.

Packaging film technical articles
For more information, contact Paul Dawson, Clemson Food Science and Human Nutrition Department.