Researchers have deviced means of preserving perishable foods like fruits and vegetables from getting rotten too quickly, escpecial while on transit to diverse destinations. A large share of the fruit and vegetables travel from one country to another before getting to the final destination for eventual consumers.
But while on that process, millions of tons are lost every year before they get that far. One of the main reasons is ethylene — a natural gas that many fruits and vegetables produce, which controls their ripening.
When fruits and vegetables are confined in closed packaging or containers during transport and storage, the concentration of ethylene in the air increases, accelerating the ripening process. As a result, a large share of the cargo ends up rotting before it reaches its final destination.
Now, new research led by the University of Copenhagen shows that ordinary clay could be part of the solution. “Clay is an interesting material because it is natural, cheap, nontoxic and found everywhere—and we can absorb it safely into the body.
Our thought was: Can we use chemistry and physics to modify clay so that it captures the gas and thus slows down the ripening process? We have succeeded in doing so,” says Associate Professor Heloisa Bordallo of the Niels Bohr Institute, who led the new study published in Applied Surface Science Advances.
First, the researchers tried to capture the gas with the clay in its natural form, and only a small amount was captured. By increasing the voids in the clay’s structure with a mild chemical treatment, the researchers made room for the clay to capture more gas—but without the gas escaping again—while keeping the material nontoxic.
Researchers have never succeeded in getting clay to absorb such large amounts of ethylene, which is why they believe the concept has potential for use in food packaging. “Now we know the fundamental physics and chemistry of the process that affects the clay’s ability to absorb and retain ethylene.
We didn’t know that before. So now we can control and optimise the process, which is necessary for it to be used in industry,” says Karina Kovalchuk, a member of Bordallo’s group at Lawrence Berkeley National Laboratory and first author of the study.
The research was led by Bordallo’s group at the University of Copenhagen in collaboration with her group members, Kovalchuk and Leander Michels at Lawrence Berkeley National Laboratory (LBNL). Degasser in food packaging According to the researchers, the results provide a kind of design manual for how to develop sustainable materials for food packaging that tackle the problem of ethylene.
“We imagine small bags or pads of powdered clay that can be placed with fruit and vegetables during transport and absorb ethylene—in the same way as the moisture-absorbing silica bags that often come in packaging when you buy, for example, shoes and electronics,” says Kovalchuk.
The research group is currently working on optimizing the chemical process to strike the right balance between effectiveness and environmental friendliness. They are also investigating whether they can make the clay capture even more ethylene and retain it even longer.
Next, the clay material will be tested in food packaging, and the researchers hope the concept can then be brought to market. The new material not only has the potential to reduce food waste. Another consequence of the ethylene problem and long transport times is that fruit often does not develop its full flavor.
