Researchers have designed clay that can prevent fruits and vegetables from rotting too quickly.

Avocados from Chile, bananas from Costa Rica, tomatoes from Southern Spain, mangoes from Brazil. A large portion of the fruits and vegetables we eat have traveled across the globe before reaching store shelves here at home. But many millions of tons are lost each year before they get that far. One of the main reasons is ethylene – a natural gas produced by many fruits and vegetables that controls their ripening. When fruits and vegetables are enclosed in sealed packaging or containers during transport and storage, the concentration of ethylene in the air increases, speeding up the ripening process. As a result, a large part of the cargo rots before reaching end consumers, but now researchers may be on the way with a solution that could, in the long run, help reduce Danish food waste, which according to the Danish Veterinary and Food Administration amounts to nearly 900,000 tons annually and costs society about 11 billion DKK per year. Lime could be the solution New research led by the University of Copenhagen shows that ordinary clay can become part of the solution, writes the University of Copenhagen in a press release. "Clay is an interesting material because it is natural, inexpensive, non-toxic, and found everywhere – and we can safely absorb it into the body. Our idea was: Can we use chemistry and physics to modify the clay so that it captures the gas and thus slows down the ripening process? We have succeeded," says Associate Professor Heloisa Bordallo from the Niels Bohr Institute, who led the new study published in the journal Applied Surface Science Advances. Initially, the researchers tried to capture the gas with the clay in its natural form. A small amount was captured. By increasing the voids in the clay's structure with a mild chemical treatment, the researchers created space for the clay to absorb more gas without releasing it again. At the same time, the material remained non-toxic. It is the first time researchers have managed to get clay to absorb such large amounts of ethylene. Therefore, they believe the concept has potential for use in food packaging. According to the researchers, the results provide a kind of design manual for developing sustainable materials for food packaging that address the ethylene problem. They are currently working on optimizing the chemical process to achieve the perfect balance between effectiveness and environmental friendliness. "We imagine small bags or pouches with powdered clay that can be placed with fruit and vegetables during transport and absorb ethylene – similar to the moisture-absorbing silica packets often included in packaging when buying, for example, shoes and electronics," says Karina Kovalchuk. Although the study focuses on ethylene and food, the researchers point out that the findings could also be significant in other technologies where materials need to capture specific gases.