Mystery Meat Ingredient: Horse Burger Last week Sweden discovered that exports of meat labeled "Argentine beef tenderloin" from Hungary were in fact dyed pork. This week, the latest in the EU mystery meat saga has authorities in the UK and Ireland tracing the source of horsemeat that was found in frozen "mince" -- also known as "hamburger" -- that was on retail shelves in the two countries. The adulterated burger was discovered by Ireland's Food Safety Authority (FSAI) via DNA testing. Out of the sample of 27 burgers tested by the FSAI, 10 tested positive for horse DNA. One top of that, 23 samples tested positive for swine DNA, likely implying cross-contamination with pork processing. Some frozen lasagne packages also were discovered t...