So a few weeks ago some people I knew were passing around an article on Facebook about an “experiment” some woman had done which showed that a McDonald’s meal wouldn’t decompose. The interpretation by many was that this was proof of how unhealthy McDonald’s food is because it is apparently “too full of preservatives” and it is somehow “unnatural” because natural foods rot. Some people have even gone so far as to argue that there are artificial materials within McDonald’s food such as plastic!

Of course, all of these arguments are variations on the naturalistic fallacy, and they can be easily disproven with some simple experimentation. In fact, a number of home-grown experiments have been performed which show that the reason why McDonald’s food, and any kind of food for that matter, doesn’t decompose in these examples is because it is allowed to dry out. And if you know anything about preserving food (hint: think beef jerky), one way to do it is to simply dehydrate it. If the food dries out, then there is no moisture to support the growth of mold, bacteria, and other microorganisms which would otherwise decompose it. Essentially, the food is mummified.

For more details on this subject, I suggest looking at following article which takes a very detailed & scientific look at the question:

The Burger Lab: Revisiting the Myth of The 12-Year Old McDonald’s Burger That Just Won’t Rot (Testing Results!) [Photographs: J. Kenji Lopez-Alt] A few weeks back, I started an experiment designed to prove or disprove whether or not the magic, non-decomposing McDonald’s hamburgers that have been making their way around the internet are indeed worthy of disgust or even interest. By way of introduction, allow myself to quote myself. This is from myprevious article: Back in 2008, Karen Hanrahan, of the blog Best of Mother Earth posted a picture of a hamburger that she uses as a prop for a class she teaches on how to help parents keep their children away from junk food… The hamburger she’s been using as a prop is the same plain McDonald’s hamburger she’s been using for what’s now going on 14 years. It looks pretty much identical to how it did the day she bought it, and she’s not had to use any means of preservation. The burger travels with her, and sits at room temperature.Now Karen is neither the first nor last to document this very same phenomenon. Artist Sally Davies photographs her 137 day-old hamburger every day for her Happy Meal Art Project. Nonna Joann has chosen to store her happy meal for a year on her blog rather than feed it to her kids. Dozens of other examples exist, and most of them come to the same conclusion: McDonald’s hamburgers don’t rot. The problem with coming to that conclusion, of course, is that if you are a believer in science (and I certainly hope you are!), in order to make a conclusion, you must first start with a few observable premises as a starting point with which you form a theorem, followed by a reasonably rigorous experiment with controls built in place to verify the validity of that theorem. Thus far, I haven’t located a single source that treats this McDonald’s hamburger phenomenon in this fashion. Instead, most rely on speculation, specious reasoning, and downright obtuseness to arrive at the conclusion that a McDonald’s burger “is a chemical food[, with] absolutely no nutrition.” As I said before, that kind of conclusion is both sensationalistic and specious, and has no place in any of the respectable academic circles which A Hamburger Today would like to consider itself an upstanding member of. …

Just to jump to the end of the article, here are the results of the extensive testing performed:

The Results Well, well, well. Turns out that not only did the regular McDonald’s burgers not rot, but the home-ground burgers did not rot either. Samples one through five had shrunk a bit (especially the beef patties), but they showed no signs of decomposition. What does this mean? It means that there’s nothing that strange about a McDonald’s burger not rotting. Any burger of the same shape will act the same way. The real question is, why? Well, here’s another piece of evidence: Burger number 6, made with no salt, did not rot either, indicating that the salt level has nothing to do with it. And then we get to the burgers that did show some signs of decay. Take a look at both the homemade and the McDonald’s Quarter Pounder patties: Very interesting indeed. Sure, there’s a slight difference in the actual amount of mold grown, and the homemade patty on the right seems to have shrunk more than the actual Quarter Pounder on the left (I blame that mostly on the way the patties were formed), but on the whole, the results are remarkably similar. That a Quarter Pounder grows mold but a regular-sized McDonald’s burger doesn’t is some pretty strong evidence in support of Theory 3 from above. Because of the larger size of a Quarter Pounder, it simply takes longer to dehydrate, giving mold more of a chance to grow.

So folks, the bottom line is that McDonald’s food behaves just like any other kind of food. If you let it dry out, it won’t rot; if you keep it moist so that bacteria & mold can grow on it, it will rot. If you don’t believe me, just feel free to conduct your own test – more on how to do that in the article I posted above.

And for those of you who want to make a big deal out of this thing, that McDonald’s food is supposedly bad for you because “it won’t rot”, then I think you really need to find something else to get concerned about because this one is just a fool’s errand.