Well... a group of pathologists actually performed a pathologic analysis on 8 different fast food hamburger meat. No... they did not identify the fast food chain where they got the meat.
What they found was both reassuring as well as alarming. Here are the key interesting findings:
• Actual meat content in a typical burger is only 12% (range: 2.1%-14.8%). The meat itself did appear normal which is reassuring. Most of the burger is actually made of water comprising 49% of the weight (range: 37%-62%)
• No brain tissue was seen in any samples (especially important when considering mad-cow disease is localized in brain tissue and can be transmitted to humans who eat contaminated tissue causing fatal Crutzfeldt-Jakob disease).
• Besides meat, other tissue types were seen including connective tissue, blood vessels, nerves, and fat (all expected in meat/muscle).
• However, cartilage and bone was also found in some samples, perhaps accrued during the butchering and processing of the meat.
• Plant material was also unexpectedly found which may have been added as a way to add bulk to the meat.
• Intracellular parasites (Sarcocystis) was also seen in a few samples which is why meat should always be cooked prior to eating (whether burger or restaurant grade A meat).
So there you have it... fast food hamburger meat actually does contain meat, though it only makes a small part of it.
Fast food hamburgers: what are we really eating? Annals of Diagnostic Pathology 12 (2008) 406–409