DNA Test Identifies Animal Species in Food Products

THOMAS SCHLUMPBERGER

August 1, 2004

It’s not always easy to identify a contaminating species in food. Animal meats often undergo a tremendous amount of processing before being sold as the final food product on supermarket shelves. The end product rarely resembles its whole animal predecessor, making it extremely difficult to distinguish between species that might be present, often allowing contamination to go undetected and food authenticity to go unchecked.

Fig. 1—The bioMérieux FoodExpert-ID® Array. The presence of unwanted or unknown animal species in food can have a rang…

Fig. 2—A strand of RNA (purple) will partner with its matching strand of DNA (green). However, if the bases aren’t complementary, the strands won’t fit together.

Fig. 5—Shining a laser light on the microarray causes the tagged RNA fragments that hybridized to glow. This microarray shows the presence of goose DNA in the feed sample but no cow, sheep, or pig DNA.

Fig. 6—An Affymetrix scientist injects a sample into a microarray for testing. If RNA in the sample matches a DNA probe on the array, there will be a perfect complement and the RNA will pair with its partner probe.

Fig. 7—The scientist analyzes a scanned image of an array. Computer software interprets the image into a data file that is analyzed to generate results.

Fig. 8—A computer readout from a scanned microarray shows the genes that are detected by a single GeneChip® probe array. When zoomed in on, scientists can see the different levels of fluorescence coming from the individual probe locations. Some probes detect their complementary sequence (strong intensity, white and red features), and some do not (weak intensity, blue and black features).