Scientists have just found a way to keep our fruits and vegetables fresh for longer while also making our kitchens and supermarkets more sustainable. The unlikely ally is silk.

Omenetto et al., Scientific Reports

We use a lot of plastic, flooding our ocean and garbage dumps with huge islands of plastic. If we want to ensure a sustainable future, reducing plastic usage is one of the main things we’ll have to work on – but that’s pretty difficult when you consider that we use plastic to wrap up pretty much everything, especially our food. Speaking of food, reducing food waste is also vital for a planet with a growing population.

Now, a team of biomedical engineers at Tufts University in the US have found a way that manages to address both problems. They’ve developed a spray that coats food with an almost invisible layer of fibroin, a protein found in silk, which helps make it one of nature’s toughest materials. The spray keeps food fresh for much longer, as researchers demonstrated using strawberries and bananas.

The coated fruits were stored at room temperature, at 22 degrees Celsius (71 Fahrenheit). They were then compared to similar uncoated fruits. You can see the strawberries in the image above, and the results for bananas (presented below) are just as impressive.

Omenetto et al., Scientific Reports

“The results suggested that silk fibroin coatings prolonged the freshness of perishable fruits by slowing fruit respiration, extending fruit firmness and preventing dehydration,” the researchers wrote in the paper.

After nine days, the flesh of the coated bananas was still white, tasty and strong. When researchers placed a 200gram weight above the bananas, it didn’t sink in the coated bananas but went right through the flesh in the uncoated ones.

“The results suggested that silk fibroin coatings prolonged the freshness of perishable fruits by slowing fruit respiration, extending fruit firmness and preventing dehydration,” the researchers wrote in the paper.

The technology could realistically be implemented in the food industry, as silk fibroin “is generally considered flavourless and odourless, which are compelling properties for food coating and packaging applications”. If they can scale it up and make it economically feasible, this has a realistic chance of being implemented on a larger scale.

The lead researcher, Professor Fiorenzo Omenetto, said that he wants the world to move “towards processes that are more efficient and more naturally derived” and develop materials that “are closer to the things that surround us, rather than having more man-made, processed materials … for the general well-being of our planet”. Using a renewable and non-polluting resource instead of plastic is certainly a step in the right direction.

“It’s a wise way of thinking about how we manage the resources of our planet, to maybe use renewable systems as opposed to non-renewable systems,” he said.

“The pervasiveness of plastic and all the inorganic chemicals that leach out, albeit at very slow rates, can affect us in many ways.”

Journal Reference: Silk Fibroin as Edible Coating for Perishable Food Preservation.