For those who fear food poisoning: Someday, packages of frozen food may carry little gauges that certify the food inside is still fresh, just as battery packages carry indicators that show the batteries are fully charged.
Scientists at Sandia National Laboratories in Albuquerque, N.M., have developed a package indicator that changes color when a package of food defrosts during shipment and then is refrozen. This provides a warning to consumers that the food may not taste fresh when prepared or might even harbor disease.
The indicator is made with an inexpensive wire that acts as a sensor by "remembering" several shapes. At different temperatures, the wire assumes different shapes. In the Sandia device, once the wire is warmed above freezing, it changes shapes and tears a piece of colored paper in the process.
"Many inventions are simple," said Mo Shahinpoor, a co-developer of the device. "It's just that nobody thought of this before."
A federally financed agency is exploring the possibilities of commercializing the Sandia device.
Pub Date: 6/28/98