Biomedical engineers have found a novel way to extend the life of common perishables such as fruits through a special coating of silk.
It's unfortunate that the world is wasting a lot of food. About a third of food products either gets lost or wasted each year. However, if a fourth of the food is saved, such an amount could instead be used to feed 870 million people, according to the Food and Agriculture Organization (FAO) of the United Nations.
While some of the food is purposely wasted, much of the produce is damaged due to poor cooling or storage facilities, which is more common in developed countries.
Biomedical engineers from Tufts University may have found the answer by combining a solution with biocompatible silk.
While silk may appear delicate, it's one of the strongest materials in the world. However, it owes such feature to fibroin, a kind of protein that acts like collagen. Collagen is the body's fibrous protein that holds many elements, including bones, tendons, and tissues together. In other words, it helps give the body cohesiveness.
Silk's fibroin is unique in the sense that it makes the material biodegradable, making it sustainable, stable and protected.
When combined with annealed water or vacuumed water vapor, it allows delicate types of food to last longer than they should because of the formation of beta sheets.
Take, for example, strawberries, which have a very short shelf life of one to two days when left on the counter.
However, when the researchers dipped strawberries in solutions with 1 percent fibroin to create degrees of different thickness of beta sheets, repeating the process four times, they noticed that the sheet with a thickness of 27 to 35 microns preserved the fruits very well. They remained juicy and firm.
"The beta-sheet content of the edible silk fibroin coatings made the strawberries less permeable to carbon dioxide and oxygen," said Fiorenzo Omenetto, senior author.
Simply put, the beta sheet acts like a cling film, only that it’s invisible and very durable.
They repeated the steps on bananas, which ripen once they are harvested, and produced good results: that is, the sheets tended to delay the ripening process and preserved the firmness.
Although the experiments didn't cover changes in texture and taste, this technique spells a huge impact on food preservation, particularly in developing nations where millions don't have a reliable supply of electricity.
"[W]e could potentially both preserve and add therapeutic function to consumable goods without the need for complex chemistries," said Benedetto Marelli, another study author.
The findings are featured in Scientific Reports.
Photo: Gerwin Sturm | Flickr
