True or False: McDonalds Hamburgers Never Mold?

People keep tagging me in, on FB (click here to like the BGG2WL page now!), to these photos and discussions surrounding the fact that McDonalds hamburgers “never mold.” The fries “never deteriorate.”

And, while it’s tempting to give in and spread the word – why? because f- McDonalds, that’s why! – I have to be honest. I find it pretty hard to believe that there are people out there whose houses are in such disarray that they’re keeping a burger for over two years… or, as it were, 14 years:

“I was showing some people how enzymes work and I thought a hamburger would be a good idea. And I used it for a month and then forgot about it,” David Whipple told the show’s hosts. “It ended up in a paper sack in the original sack with the receipt in my coat tossed in the back of my truck and it sat there for, I don’t know, two or three months.”

The coat was then moved to Whipple’s closet, where it remained until his wife dug it up along with the burger “a year or two” later.

“We pulled it out and said ‘oh my gosh, I can’t believe it looks the same way,'” Whipple said.

Now, I’m nobody’s scientist, but there are four things I know about bacteria, mold, and protecting-my-food-that-I’ve-bought-with-my-hard-earned-money: in order for bacteria to grow, they need moisture, air, warmth, and time. (Somebody help me out – isn’t darkness a factor, too? Or is that more about temperature than light?) With our own crude methods of cooking and preservation, we subvert these processes. Refrigerators are engineered to provide constant coolness, because warmth generally encourages molding (though it’s more beneficial to keep certain things out of the fridge, like certain kinds of breads.) It’s why we refrigerate our raw food materials. We seal things in air-tight containers; we submerge things in vinegar, sugar or salt; we cook things. It’s how we make our food an “inhospitable” environment to mold spores, which are in the air everywhere. That’s just how it is.

Part of the point of cooking things is to make things tasty, but also to kill any bacteria that might’ve gotten to our food prior to us bringing it home. Applying heat – and, essentially, salt – to food draws out the moisture (this is why salt is such a common preservative – it’s really the original preservative) and helps it to last longer. It dries out the food. You might be able to cook your food to a certain degree so that it’s still juicy, but you’re still drying it out and removing some of the moisture (water – think how vegetables, cooked down, leave water in the pan; fat – think of those George Foreman grill commercials where they talk about draining out the fat… as if a regular grill pan couldn’t do something awfully similar; blood – because, well, meat!) until it’s at the desired level. That’s why some people can make chicken breast deliciously juicy, and others turn chicken breast into hockey pucks. I’m just sayin’. Cook anything for too long, and you’ll get a hockey puck. That’s the point.

Why does this matter in the case of McDonalds, though? Even though I haven’t eaten there in years and, if forced to choose between eating a McChicken and jumping off a cliff, I’d gladly pull a Wile E. Coyote… I still think it’s weird for this to be the basis of people’s hate. “Their burgers don’t mold!” “Their fries don’t mold!” No, they don’t, but they’re a cooked food. Should they?

Luckily, a few years back, someone at Serious Eats took on this topic and angered his wife by keeping a few burgers on hand – some homemade, some from McDonald’s. I’ll only paste a few bits of his experiment:

Things we know so far:

1. A plain McDonald’s Hamburger, when left out in the open air, does not mold or decompose.
2. In order for mold to grow, a few things need to be present: mold spores, air, moisture, and a reasonably hospitable climate

Given those two facts, there are a number of theories as to why a McDonald’s burger might not rot:

1. There is some kind of chemical preservative in the beef and/or bun and/or the wrapping that is not found in a normal burger and/or bun that creates an inhospitable environment for mold to grow.
2. The high salt level of a McDonald’s burger is preventing the burger from rotting.
3. The small size of a McDonald’s hamburger is allowing it to dehydrate fast enough that there is not enough moisture present for mold to grow
4. There are no mold spores present on McDonald’s hamburgers, nor in the air in and around where the burgers were stored.
5. There is no air in the the environment where the McDonald’s hamburgers were stored

Of these theories, we can immediately eliminate 5, for reasons too obvious to enumerate. As for number 4, it’s probably true that there are no live molds on a hamburger when you first receive it, as they are cooked on an extremely hot griddle from both sides to an internal temperature of at least 165°F—hot enough to destroy any mold. But in the air where they were stored? Most likely there’s mold present. There’s mold everywhere.

Theory 1 is the one most often concluded in the various blogs out there, but there doesn’t seem to be strong evidence one way or the other. If we are to believe packaging and nutrition labeling (and I see no reason not to), there are preservatives in a McDonald’s bun, but no more than in your average loaf of bread from the supermarket. A regular loaf of supermarket bread certainly rots, so why not the McD’s? Their beef is also (according to them) 100% ground beef, so nothing funny going on there, is there?

In order for any test to be considered valid, you need to include a control. Something in which you already know whether or not the variable being tested is present.

In the case of these burgers, that means testing a McDonald’s burger against a burger that is absolutely known not to contain anything but beef. The only way to do this, of course, is to cook it myself from natural beef ground at home.

I decided to design a series of tests in order to ascertain the likeliness of each one of these separate scenarios (with the exception of the no-air theory, which frankly, doesn’t hold wind—get it?). Here’s what I had in mind:

• Sample 1: A plain McDonald’s hamburger stored on a plate in the open air outside of its wrapper.
• Sample 2: A plain burger made from home-ground fresh all-natural chuck of the exact dimensions as the McDonald’s burger, on a standard store-bought toasted bun.
• Sample 3: A plain burger with a home-ground patty, but a McDonald’s bun.
• Sample 4: A plain burger with a McDonald’s patty on a store-bought bun.*
• Sample 5: A plain McDonald’s burger stored in its original packaging.
• Sample 6: A plain McDonald’s burger made without any salt, stored in the open air.
• Sample 7: A plain McDonald’s Quarter Pounder, stored in the open air.
• Sample 8: A homemade burger the exact dimension of a McDonald’s Quarter Pounder.
• Sample 9:A plain McDonald’s Angus Third Pounder, stored in the open air

[…] On to the results. […] 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:

The Quarter Pounder and Homemade burger comparison. Credit: A Hamburger Today, Serious Eats

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.

While I generally and genuinely feel grossed out by even partially-remotely-sorta-somewhat-kinda feeling like I could be defending McDonalds, I need y’all to understand why I’m not buying into the “It doesn’t rot! Don’t eat it!” thing. No one really noticed that almost all of the burgers making this claim were happy meal burgers or regular hamburgers, devoid of vegetables and condiments (both considered harbingers of moisture.)

There’s also the curious case of the bun – is it, too, completely devoid of moisture? Considering the fact that McDonalds has to mass produce, store, transport, store, and then sell those buns, chances are high they’re doing everything they can to prevent the right person from eating the wrong bacteria. It should be a good thing, a marvel, even, that they’re able to preserve bread for this long. It’s not, however, advantageous to those of us doing the eating.

In short, there are a bajillion reasons to skip the stuff, but making inferences about its inability to rot in comparison to “real food” doesn’t, for me, cut the mustard. A little healthy skepticism has never hurt anyone.

Besides. Girl. That stuff is disgusting. C’mon.