Buying ground beef comes with the assumption that it contains meat from cattle. But a new study has found some hamburger sold in the U.S. also contains traces of horse meat.

Researchers at Chapman University’s Food Science Program gathered 48 meat samples from local supermarkets and online specialty meat distributors and tested the DNA contained in them. The results showed 10 of the 48 samples were mislabeled—and that nine of the 10 mislabeled samples contained additional species. Two of the 10 included horse meat, which is illegal to sell in the U.S. for consumption.

Dr. Rosalee Hellberg, a food scientist and assistant professor at Chapman’s Schmid College of Science and Technology in Orange, California, and Chapman University graduate research assistant Dawn Kane suggested the mislabeling “appears to be due to either intentional mixing of lower-cost meat species into higher-cost products or unintentional mixing of meat species due to cross-contamination during processing.”

Another study of meat samples focused on the game meat industry. It examined 54 game meat samples and found 10 of them were potentially mislabeled. “Two products labeled as bison and one labeled as yak were identified as domestic cattle,” Reynard Loki wrote at AlterNet.

Mislabeling such as this may have been motivated by economic gain, according to researchers. The distributor in question sells yak burgers for $20 a pound, and sells ground beef products for $10 a pound.

-Noel Brinkerhoff

To Learn More:

Horse Meat in the U.S. Food Chain? Neigh It Ain’t So (by Reynard Loki, AlterNet)

U.S. Researchers Uncover Mislabeled Meat in Two Studies (by Joe Whitworth, FoodQualityNews.com)

Identification of Species in Ground Meat Products Sold on the U.S. Commercial Market Using DNA-Based Methods (by Dawn E. Kane and Rosalee S. Hellberg, ScienceDirect)

DNA Barcoding Reveals Mislabeling of Game Meat Species on the U.S. Commercial Market (by Charles A. Quinto, Rebecca Tinoco, Rosalee S. Hellberg, ScienceDirect)

Millions of Pounds of Meat Shipped without being Inspected (by Noel Brinkerhoff, AllGov)

USDA Moves Closer to Approving Horse Slaughter Plant in U.S. (by Matt Bewig, AllGov)

Meat Company Sues U.S. Government for Right to Open First New Horse Slaughterhouse in 6 Years (by Noel Brinkerhoff, AllGov)