Why McDonald's Hamburgers Don't Rot

Are McDonald’s* hamburgers immune to natural processes like rotting? There’s some evidence that they are, but a truly scientific inquiry into the matter has been lacking – until now. J. Kenji Lopez-Alt of Serious Eats tested nine different hamburgers of varying sizes (both homemade and from McDonald’s) to find out. Contrary to popular belief, the non-rotting phenomenon isn’t due to the mysterious chemical composition of the burgers. “[T]he burger doesn’t rot because its small size and relatively large surface area help it to lose moisture very fast,” writes Lopez-Alt. “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?” (HT: Chris Blattman) *Interestingly, the McDonald’s website doesn’t use the word “McDonald’s” at all except in its copyright tag; the golden M does all the work. [%comments]


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  1. David Chowes, New York City says:

    The burgers I make at home are about 6 oz. McBurgers are 1 oz. each. Ergo, the McSmall version (I believe) has 1/6 the capacity to rot.

    As far as the BigMac goes — well, I can’t comment without a
    scrupulous scientific study.

    Generally when burgers are very much cooked… The limit is burnt ash — which, of course is just carbon and that does not have the posibility of rotting. My home made burgers are as rare as they can be — close to raw. A far more potential rotten conundrum.

    The McArch logo does impress me — other companies would die for such branding recognition.

    Now that we’ve setteled this important issue… On to nuclear proliferation, global warming, world peace…

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  2. Drill-Baby-Drill Drill Team says:

    A science teacher in Maine has a 12 year old unwrapped Hostess Twinkie that is not growing mold, spoiling or rotting. The Twinkie will graduate high school in a few years and pretty soon head to college.

    Preservatives may preserve food, and maybe even your body.

    Eat more Twinkies, it is the secret of eternal youth!

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  3. Arvin Bautista says:

    I’m all for companies being transparent and all, but I always thought it was kinda silly that McDonald’s would respond immediately to the first accusations, especially by saying “our burgers do TOO rot!” It seemed so childish and defensive.

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  4. Clancy says:

    What about the bun? Any bun or roll I’ve had at home becomes mold city after a week or two unless its in the freezer. What fungicides are in that bun?

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  5. Mike K. says:

    Anti-McDonald’s campaigners always use the hamburger for this stunt. Because a quarter-pounder, being larger and slower to dry out, would show some rot.

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  6. Rosewood says:

    I was on vacation when the results were published and missed it. Thanks! Kenji writes amazing articles.

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  7. Eric M. Jones says:

    Upon the urgings of a whining 5-year old, I just had lunch at McD’s. I had the Caesar salad with grilled chicken.

    Really, really good.

    And the 5-year old liked the Happy Meal.

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  8. Mantonat says:

    A banana fell behind my refrigerator and was there for what I am guessing was 12-14 months before I found it when doing move-out cleaning. The banana had shrunk considerably and was hard as a tree branch, but showed no signs of rot or mold. Food sometimes just dries out before it can do either, especially in low-humidity climates.

    It’s very trendy these days to demonize McDonald’s, but take a look in your fridge. How old is that ketchup, mayo, or soy sauce? How old is the stuff in your pantry (shortening, flour, pancake syrup)? People get used to the idea of buying packaged food at the grocery store with the expectation that they can still eat it a year or two later, but criticize companies for using preservatives. At least nobody was claiming that those year-old hamburgers were still edible.

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