Editor's Note: We are posting this story from our September 2007 issue as part of our in-depth report on the recent salmonella outbreak.

If a natural pathogen, or a perpetrator, contaminates food, lives will be saved if the tainted product can be quickly detected, then traced back to its point of origin so the rest of the batch can be tracked down or recalled. The following technologies, in development, could help:

Microfluidic Detectors—Botulinum bacteria produce the most poisonous toxin known. They and similar agents, such as tetanus, could be detected during food processing by microfluidic chips—self-contained diagnostic labs the size of a finger. The University of Wisconsin–Madison is crafting such a chip, lined with antibodies held in place by magnetic beads, that could detect botulism during milk production. The chip could sample milk before or after it was piped into tanker trucks that leave the dairy and before or after it was pasteurized at a production plant. Other chips could detect other toxins at various fluid-processing plants, such as those that produce apple juice, soup or baby formula.

Active packaging—E. coli, salmonella and other pathogens could be detected by small windows in packaging, such as the cellophane around meat or the plastic jar around peanut butter. The “intelligent” window would contain antibodies that bind to enzymes or metabolites produced by the microorganism, and if that occurred the patch would turn color. The challenge is to craft the windows from materials and reactants that can safely contact food. Similar biosensors could react if the contents reached a certain pH level or were exposed to high temperature, indicating spoilage. And they could sense if packaging was tampered with, for example, by reacting to the pressure imposed by a syringe or to oxygen seeping in through a puncture hole.

RFID Tags—Pallets or cases of a few select foods now sport radio-frequency identification (RFID) tags that, when read by a scanner, indicate which farm or processing plant the batch came from. Future tokens that are smaller, smarter and cheaper could adorn individual packages and log every facility they had passed through and when. The University of Florida is devising tags that could be read through fluid (traditional designs cannot) and thus could be embedded inside the wall of sour cream or yogurt containers. The university is also developing active tags that could record the temperatures a package had been exposed to.

Edible Tags—Manufacturers often combine crops from many growers, such as spinach leaves, into a retail package, so tags affixed to bags might not help investigators track contamination back to a specific source. ARmark Authentication Technologies can print microscopic markers that indicate site of origin directly onto a spinach leaf, apple or pellet of dog food using a spray made from edible materials such as cellulose, vegetable oil or proteins. Also, the tiny size would be hard for terrorists to fake, making it harder for them to sneak toxin-laced counterfeit foods past inspectors and into the supply. As an alternative, DataLase can spray citrus fruits or meats with an edible film in a half-inch-diameter patch that is then exposed to a laser beam that writes identification codes within the film.