Clay-based anti microbial packaging keeps food fresh

London : Scientists have developed a new packaging film with clay nanotubes and antibacterial essential oils that can prevent microbial growth and over-ripening of fruits, keeping them fresh for longer. 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 US Department of Agriculture, about 30 to 40 per cent of the food that farmers produce in the country goes to waste, researchers said. Over the past two decades, scientists have been developing alternative ways to preserve food, with an extensive focus on packaging.

Bacterial contamination and permeability to both oxygen and water vapour 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. However, 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, Unal 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 vapour and other gases from escaping. In addition they keep ethylene from building up by absorbing it.