New Test May Detect Pathogens in PE Food Wrap

Searching for expiry dates and sniffing food to detect spoilage soon may be things of the past. A development in food packaging will alert consumers to the presence of the four major contributors to food poisoning: listeria, E. coli, salmonella, and campylobacter. These four pathogens account for almost 90% of all cases of food poisoning.

Studies by the Centers for Disease Control indicate that about 80 million cases of food-borne infections occur annually in the US.

Toxin Alert Inc., a biotechnology company in Mississauga, Ont., Canada, has developed a way to incorporate an antibody-based diagnostic test onto the inside of typical PE home storage wrap. These antibodies - proteins that react to a specific target - will warn consumers when dangerous bacteria are present in any food by triggering an alert sign on the wrap. If the wrap is shown to be "positive," it cannot be reused.

In the New Scientist (April 8, 2000), Kurt Kleiver explains, "The packaging uses separate layers to capture the pathogen and detect it. Toxin Alert coats the inside surface of standard PE plastic food wrap with antibodies specific to one of four food-poisoning organisms. This coating can be applied to form a pattern that could, for example, be the shape of a large X - though to start with, it is invisible. On top of this is a layer made up of a nutrient gel that holds another set of antibodies, which are attached to a colored chemical complex. Finally, there is a porous layer that makes contact with the food and allows disease-causing organisms to pass through to the nutrient gel beneath.

When a pathogen passes through the porous layer and reaches the gel, an antibody carrying the colored complex latches onto it. The captured - and now colorful - organisms diffuse toward the antibodies stuck to the inner surface of the plastic wrap. There they accumulate, making the X pattern.

Toxin Alert says the wrap could be adapted to detect pesticides or even proteins characteristic of genetically modified foods. It could be used by food packagers and retailers, as well as to wrap leftover food in the home.

Some researchers fear the wrap won't be sensitive enough to be useful. Mike Doyle, a microbiologist and director of the Center for Food Safety and Quality Enhancement at the Univ. of Georgia, says that laboratory tests for food poisoning work by culturing enough organisms from a sample to show up on the test. He thinks it's unlikely the food wrap will be sensitive enough to detect the very low levels of organisms that can cause disease. "They're going to give people a false sense of security. There are a lot of disease-positive products out there that aren't going to get picked up."

Other experts also express concerns about the technology. Dr. Douglas Powell, a food safety expert at the Univ. of Guelph in Canada, says, "There is a potential risk that it could lull people into a false sense of security and make them less careful with food preparation."

Toxin Alert personnel disagree. They say the product should be viewed as an added safety measure and that further testing is underway to ensure that the wrap will have the proper sensitivity to the pathogens.

At least four US-based companies are said to be examining the concept, and Toxin Alert is now in the process of licensing the diagnostic food wrap. A big hitch in getting the product to market, however, is producing the antibody.

In humans antibodies are the good guys, the cells that run around in our bodies attacking bad guys like E. coli. They are used regularly in diagnostics but are not produced in large amounts. Now Toxin Alert needs to mass-reproduce the antibodies to make its food wrap. This year the company began funding a four-year research project at the Univ. of Guelph to find the best way to do that.

In April 2000 US Patent 6,051,388, titled "Method and Apparatus for Selective Biological Material Detection," was issued to Toxin Alert.

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