Empa has developed a cellulose protective coating for fruit and vegetables in cooperation with Lidl Switzerland.
The bottom of the 10-day-old bananas is coated with a protective cellulose layer. Image: Empa, Lidl Switzerland

Plastic packaging in the food trade contributes significantly to the increase in plastic waste. On the one hand, the films and boxes protect fruit and vegetables from rapid spoilage; on the other hand, the packaging pollutes rivers and oceans and pollutes the food chain as microplastics. While oranges and lemons can be kept for weeks in the fridge at home without plastic film, cucumbers, for example, do not tolerate the dry air, become soft and may end up in the rubbish. If they are sealed in plastic film, they stay crisp for longer.

The Swiss Federal Laboratories for Materials Testing and Research (Empa), together with Lidl Switzerland, has now developed a protection for fruit and vegetables based on renewable raw materials. Researchers in Empa’s Cellulose & Wood Materials laboratory have developed a protective cellulose coating as part of the “Rübli hilft Gurke” („Carrot helps cucumber”) project that can be applied to fruit and vegetables and keeps them fresh significantly longer. Tests have shown that the coating can extend the shelf life of bananas by over a week and significantly reduce food waste. “The big goal is that such natural coatings can replace a lot of petroleum-based packaging in the future,” says Gustav Nyström, head of Empa’s research department. A preliminary study that has been running since 2019 has been successfully completed and the main study has been started.

The novel coating is made from pomace (the residues of squeezed fruit and vegetable peels), which is further processed into “fibrillated cellulose”. Whereas the plant residues were previously disposed of in biogas plants or directly on the field, they are now used to create a protective coating for fresh fruit. Depending on the results of the study, the protective cellulose coating is either sprayed onto the fruit or applied in an immersion bath. The coating is non-toxic, can be easily washed off and, since it is harmless to consumers, can even be consumed. However, the potential of the cellulose coating is far from exhausted, as it is possible to add vitamins, antioxidants, etc. to it. The cellulose coating is to be tested and further improved over the next two years together with Lidl Switzerland and a fruit and vegetable supplier. The aim is for the new technology to be used in all of the more than 150 Lidl shops in Switzerland after the successful main trial.

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