Decomposing Hamburgergate: Now with 100% more science!


Periodically, over the last year, I've wasted a day or so screaming at my computer screen about how photos of a McDonald's hamburger failing to rot were not a sign that the food was somehow artificial or dangerous, but, rather, just what happens to meat products and bread when you leave them out in the open air. Think about the last hunk of baguette you didn't finish. Same thing. Basically, the food dries out before it has a chance to rot.

I'd been concocting a scheme to try this out at home, pitting a McDonald's burger against one made at home from free-range beef and organic bread. Luckily for my husband, Serious Eats up and did what I'd merely threatened.

In the picture above: A real, live rotting McDonald's hamburger. Notice the plastic bag, which traps moisture and prevents the burger from drying out before the mold sets in.

Interestingly, because he ran this experiment with an impressive level of thoroughness, J. Kenji Lopez-Alt figured out that large McDonald's burgers (as opposed to the single-patty Happy Meal size) will, in fact, rot in open air. As will home-made burgers of similar proportion. It's only the small ones that get mummified. His conclusion:

The burger doesn't rot because it's small size and relatively large surface area help it to lose moisture very fast. Without moisture, there's no mold or bacterial growth. Of course, that the meat is pretty much sterile to begin with due to the high cooking temperature helps things along as well. It's not really surprising. Humans have known about this phenomenon for thousands of years. After all, how do you think beef jerky is made?

Read the full experiment (includes graphs!) at Serious Eats



  1. People really think they don’t rot?

    McDonalds would be making a much bigger fortune if they had actually invented non-rotting hamburgers.

    1. I heard this claim retread on NPR just last week. (Thankfully the person actually making the claim was a nutrition advocate, not a reporter.)

  2. “Periodically, over the last year, I’ve wasted a day or so screaming at my computer screen about how photos of a McDonald’s hamburger failing to rot were not a sign that the food was somehow artificial or dangerous”

    Heh heh. Me too.

  3. This makes me happy. I’m glad someone is actually applying science to these things.

    It’s very much a fad to rag on how bad fast food is that it’s gotten to the point where even totally ridiculous things are believed.

    Hooray for people using logic and science.

    1. Same thing. They’re frozen, then deep fried, then doused in salt.
      Which would take care of the moisture in just about any living organism.

      Too bad a thousand words are not worth a picture.

  4. Perfect timing — made a bet on this topic with a McDonalds-denier 6 days ago, and now I’ve won the tidy sum of 5 golden samolians, woo! “No dog food for Victor tonight.” ;-)

  5. Well I sure can sleep easy knowing that someone is defending McDonalds. I mean just IMAGINE what would have happened if people actually BELIEVED that their hamburgers were crap? That was a close call.

    1. No-one is defending McDonalds. But no-one is defending “sheltered” people who have never seen dry meat before either.

      The idea that food must immediately turn to green slime and/or grow fur past its expiry date is responsible for both a lot of food poisoning (“It looks fine!”) and a lot of perfectly good food being turfed because the magic date line has been crossed (“I don’t care, it’s expired it goes in the trash!”).

  6. Sad that BoingBoing has published the story not once but twice. At least one person cares about science on here.

  7. Eww, why are you trying to ENDORSE eating at Mcdonalds? If anything we should all be trying to shut them down.

  8. Haha. I’m totally going to McDicks for lunch right now.

    To the haters: occasional indulgence is good for the soul! You only live once.

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