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Edible silk coating keeps fruit fresh for a week, scientists find

In addition to preservation, researchers say the silk solution could a serve as a delivery medium for various therapeutic additives.

By Brooks Hays
Researchers found that a water-based, edible silk solution keeps delicate fruits like strawberries fresh for up to a week without refrigeration. File photo by Ismael Mohamad/UPI
Researchers found that a water-based, edible silk solution keeps delicate fruits like strawberries fresh for up to a week without refrigeration. File photo by Ismael Mohamad/UPI | License Photo

BOSTON, May 6 (UPI) -- Silk may soon help save space in the refrigerator.

In recent experiments, researchers at Tufts University were able to keep fruit fresh for up to a week using an odorless, biocompatible silk solution.

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The key to silk's preservative powers is fibroin, an insoluble protein that can stabilize, protect and preserve materials. Testing proved it is safe to consume and biodegradable. At just 27 to 35 microns thick, the water-based silk solution is nearly invisible.

When scientists coated strawberries -- a particularly delicate fruit -- in the solution, the berries remained firmer and juicier after a week, while the uncoated berries were dehydrated and discolored.

The protective silk solution works by slowing fruit respiration, which prolongs firmness and prevents browning and decay.

"The beta-sheet content of the edible silk fibroin coatings made the strawberries less permeable to carbon dioxide and oxygen," Fiorenzo G. Omenetto, a professor of biomedical engineering at Tufts, said in a news release. "We saw a statistically significant delay in the decay of the fruit."

When tested on bananas, the silk solution prevented ripening, suggesting it's best suited to protect delicate, thin-skinned fruits that are bought at or close to peak ripeness.

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Researchers did not test whether or not the silk solution affected taste, but the study suggests the coating has no effect on texture.

The findings were published this week in the journal Scientific Reports.

In addition to preservation, researchers say the silk solution could a serve as a delivery medium for various therapeutic additives.

"Various therapeutic agents could be easily added to the water-based silk solution used for the coatings, so we could potentially both preserve and add therapeutic function to consumable goods without the need for complex chemistries," said study author Benedetto Marelli.

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