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CELS News Story
Spring, 2007
Search for not-so-invisible ink can ensure your food is safe to eat
By: Rudi Hempe, CELS News Editor and Reporter
---------------------------------------------------------Ever wonder how fresh that pre-packaged meat is in the grocer’s refrigerator?
Ever wonder whether it was subjected to a food spoilage incident en route from
the processing plant to the store?
Spurred on by shocking news stories about contaminated and spoiled food,
consumers are becoming increasingly concerned about food safety and
questions like those above are not that unusual. Increasingly, people want
assurance that the foods they buy are safe and of high quality and two chemists
at URI are setting out to provide them with one tool that could give consumers
peace of mind.
Dr. William B. Euler, chair of the Department of Chemistry and Dr. Brett L. Lucht,
a professor in that department, were awarded a CELS CARES (for Community
Access to Research and Extension Services) grant recently by the College of the
Environment and Life Sciences to further develop an ink for barcodes that will be
a tattle-tale indicator whether the food product was subjected to higher than
desirable temperatures.
The award, one of nine given out by CELS for research projects, is unusual not
only because of its subject but also because it was granted to researchers
outside of the college.(The competition for CELS CARES research grants is open
to all on the URI campus.)
“In an increasingly complex food system, consumer protection is paramount,”
says Dr. Nancy Fey-Yensan, assistant director for land grant programs and a
professor in the CELS Department of Nutrition and Food Sciences. “This
proposal addresses a unique and much needed approach to improving food
safety which has significant potential to reduce food-borne illness and improve
public health for all Americans. In fact, the technology Drs. Lucht and Euler
propose could also easily be applied to improving the safety of a range of
pharmaceutical and biological substances.”
Euler and Lucht have been working on thermochromic pigments (pigments that
change color when subjected to temperature changes) for years.
It all started in 1998 when Dr. Otto Gregory, a URI professor of chemical
engineering, called Euler one day. It seems there was a bake ware company in
Georgia that approached URI seeking a pigment that could be added to the bake
ware to indicate whether it was too hot to touch.
Gregory asked Euler whether some polymers could be developed to provide the
solution. Euler’s response was –“Of course, polymers can do everything!”
Euler brought in Lucht because of his expertise in the field and they set out on
the project. They encountered some difficulties. For example the bake ware
company’s marketing department wanted a pigment that would turn red when it
was hot and blue when it was not. That was a problem, relates Euler because the
thermochromic pigments did not change to the colors desired by the marketing
department or as Euler put it, “The physics did not cooperate with sociology.”
Another problem was that there was no guarantee that the pigment would
change colors repeatedly every time the bake ware was placed in an oven.
But the big problem was trying to find a company that was willing to make the
investment of scaling up the manufacturing of the pigment from lab to full-fledged
production.
Then about three years ago, Flint Ink (a major producer of inks for the printing
industry) saw the Euler/Lucht website describing thermochromic pigments and
contacted them.
Flint Ink was interested in a thermochromic ink that could be applied to barcodes
to indicate food spoilage on meat and dairy products. Once again the Euler/Lucht
team got busy. The CELS CARES grant will help them fine-tune the ink.
They currently are working with Accent Ink of Los Angeles (Flint Ink changed
hands and they dropped their interest in thermochromic pigments but a new ink
company, Accent Ink, decided to go forward.)
How it works is this. A special barcode labeling machine using thermochromic ink
deposits the ink and the code on the food product at the processing plant. If the
food product is subjected at any time to temperatures that affect it adversely, the
label changes-- a red bar appears rendering the UPC code incapable of
transmitting data.
A firm called Sira Technology will actually produce the system. At the processing
plant special labelers will be needed. But at the other end—the markets—
standard barcode readers can be used.
Lucht said what remains to be done is to determine what range of temperatures
is desired—whether there should be a sudden change in color or a gradual one.
He says they may end up with several inks with different reference points.
The thermochromic inks are not reversible—once the ink has been triggered by
exposure to inappropriate temperatures, they cannot be changed back. Lucht
says there are some time/temperature indicators already in use by the military.
But these are stickers costing about $1 each –too expensive to be put on
individual packages. Rather to save money, the military uses the stickers on
large quantities such as case lots or whole pallets.
The thermochromic pigments they are working on will be used in very small
amounts affecting the price of the product by only one or two cents, they say.
The same type of barcodes would be useful for other types of products such as
biologicals and pharmaceuticals, says Lucht.
But the greatest use will be for food products that are temperature sensitive.
“This is a food safety tool for end consumers,” says Euler, “telling them whether
the food has been stored properly from the processing plant to the store.”