Finding a natural, safe, environmentally friendly way to prolong the freshness of fruits and vegetables has several advantages. Finding a way that uses no refrigeration and creates no waste? That would have huge advantages, and scientists may have found the solution in silk.
It's a promising, but not thoroughly tested, method, according to Science Alert. Researchers took fibroin, the insoluble protein found in silk that makes it tough, and created a spray-on coating for fruits and vegetables. The coating is flavorless and odorless. They sprayed this solution on at varying thicknesses, the thickest coating being 35 microns. To the human eye, it's barely visible, and the coated produce doesn't look any different than the non-coated produce.
Anyone who has ever forgotten about a bunch of bananas sitting in the fruit bowl for four or five days knows what happens when you remember they're there (or when the smell reminds you they're there). Unless you put them in a smoothie or use them for baking, they are unlikely to go uneaten. But here's what happened when bananas were tested with the silk fibroin for nine days.
As you can see, the banana with the silk fibroin coating looks like you could still peel it and eat it as-is after nine days. The uncoated one is best used as a smoothie or banana bread ingredient.
A similar experiment was done with strawberries for seven days, and the strawberry with no coating became rotten and inedible-looking. The strawberry with the maximum amount of coating looked as if it was about as fresh as it had been seven days before. Both experiments were chronicled in the Scientific Reports section of Nature.
As for the safety of the edible coating, the researchers concluded "the detection values [of toxins] were significantly below the toxicity levels in drinking water, as per World Health Organization guidelines."
Of course, much more testing needs to be done before this edible silk fibroin coating can be sprayed on fruits and vegetables at your local grocery store. If the method turns out to be safe, the implications go far beyond keeping the bananas on your counter from turning brown so quickly.
A startling amount of fruits and vegetables (as well as other fresh foods) go bad during transport. In the U.S. and other developed countries, refrigeration and various techniques are used to keep foods from turning bad, but in developing countries, access to refrigeration is not as prevalent. About 1.6 billion people have no access to refrigeration, and this is one of the reasons about 25 percent of the world's food is lost to spoilage.
If this silk fibroin coating is proven effective, safe and nontoxic, it could make a big difference in the amount of food lost to spoilage and an even bigger difference in the lives of the people who go hungry all over the world.