Fecal glow could improve meat safety

Workers who process animal carcasses might soon use a laser scanner to identify contaminated meat. Researchers at the Department of Agriculture and Iowa State University in Ames have devised a technology that exploits the unique fluorescent properties of digested plant matter in feces. Under the laser, the surface of a carcass lights up if it’s tainted with feces, which can carry dangerous bacteria.

Currently, each meat inspector in a packing plant visually examines hundreds of carcasses per hour. Contaminated sections are cut away and discarded. However, visual inspection can’t always distinguish harmless blemishes from spots of fecal matter.

To assist inspectors, Jacob W. Petrich of Iowa State and his colleagues built a device that shines blue or green laser light at a spot on a carcass and measures how much light comes back at various wavelengths.

In experiments using a handheld prototype, Petrich and his colleagues found the digestion products of chlorophyll, a plant component, fluoresce at about 670 nanometers (nm), which is visible as red light. Feces, which contain these products, and meat contaminated with even trace amounts of feces also emit 670-nm light under the laser, but uncontaminated cattle carcasses don’t fluoresce at that wavelength, the researchers report in the May Journal of Agricultural and Food Chemistry.

The researchers have patented their technology and licensed it to a Florida-based firm, which plans to market devices large enough to scan an entire carcass as it moves down a processing line, Petrich says.

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