Edible silk may warn if food contaminated

TUFTS UNIVERSITY Researchers at Tufts University have discovered how to use silkworm silk to make transparent "edible optical" devices that display a hologram or change colors when they come into contact with an unwanted substance such as E.coli or salmonella. To make sure you're not eating contaminated spinach or tomatoes, you might someday want to sprinkle special silkworm silk on your salad.

Researchers at Tufts University in Massachusetts say they've discovered a way to make "edible optics" from the silk that can be used as sensors for E.coli, salmonella and other potentially deadly contaminants.

By manipulating the natural optical traits of silk, researchers could "program" the sensors to display a hologram warning or change color when they come into contact with unwanted bacteria, the researchers say.

"This is something that would be similar to the hologram on your Visa card," said Tufts researcher Fiorenzo Omenetto.

Cheap, silk-based sensors that resemble transparent pieces of thin plastic could be tossed into a bag of produce, or even used to make the produce bags themselves, researchers say. Films made from silkworm silk could be used to coat salad tongs in a restaurant, or even be shredded and sprinkled on top of your food.

Omenetto says that in his experience, it has almost no taste.

Tufts researchers recently published academic papers explaining their silkworm sensors and filed for patent applications.

They expect to begin producing prototypes within a year. If they're successful, such sensors could possibly be on the market within the next several years. Sensors could be manufactured for as little as a few pennies each.

Scientists for years have been experimenting with different kinds of bacteria sensors for food. Researchers at Georgia Tech in Atlanta, for instance, have created electronicbiosensors that can identify bacteria in poultry plants, while scientists at Texas A&M University, Georgia Tech and other schools are experimenting with "electronic noses" and other types of semiconductorbased sensors designed for food safety.

What makes the Tufts sensors unique is that they're natural, organic and completely edible, . They're also biodegradable and don't require refrigeration.

"You don't have to eat it, but if you do it's okay," he said. The same can't be said about electronics based sensors.

To make the sensors, Tufts researchers boil the cocoons of Bombyx silkworms, then extract sericin proteins — the glue-like substance that holds the cocoons together. The purified silk is then poured into molds and dried.