Sometimes it seems as if fresh fruits, vegetables and meats go bad in the blink of an eye. Consumers are left feeling frustrated, often turning to less expensive processed foods that last longer but are less nutritious. Now scientists report that they have developed a packaging film coated with clay nanotubes packed with an antibacterial essential oil.
The film provides a one-two punch, preventing over-ripening and microbial growth, which could help improve the shelf life of perishables
The researchers are presenting their results at the 254th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features nearly 9,400 presentations on a wide range of science topics.
People around the world have been trying to preserve fruits, vegetables and meats since ancient times. From the traditional methods of salting or fermenting to the more modern methods of canning, freezing or wrapping in plastic films, food preservation has always been important. According to the U.S. Department of Agriculture, about 30 to 40 percent of the food that farmers produce in the country goes to waste. Sometimes, busy people just don’t have enough time to eat all of the fresh food they buy, but other times food spoils at the grocery store because consumers avoid purchasing imperfect fruits, vegetables and meats.
Bacterial contamination and permeability to both oxygen and water vapor are major issues that scientists are addressing. Another challenge is to prevent too much ethylene from building up around foods. Ethylene is a compound naturally released by fruits and vegetables that aids in the ripening process. But an excess of ethylene trapped underneath the packaging film can cause food to over ripen and rot.
To meet the demand for multi-functional packaging, Ünal’s team started with a polyethylene film. To scavenge for ethylene and provide a gas barrier the group incorporated clay “halloysite nanotubes,” which are small, hollow cylinders. The nanotubes prevent oxygen from entering the film, and prevent water vapor and other gases from escaping. In addition they keep ethylene from building up by absorbing it. The researchers loaded these nanotubes with a natural antibacterial essential oil found in thyme and oregano called carvacrol and coated the inner surface of the packaging film with the loaded nanotubes to kill microbes.