A few months ago we wondered exactly how McDonalds could claim that their burgers are made with “100% pure USDA inspected beef; no fillers, no extenders [and] prepared with grill seasoning (salt, black pepper),” when over a period of 127 days, one photographer captured one disturbingly unchanged Happy Meal.
Well, thanks to J. Kenji Lopez-Alt and a much more generous helping of the scientific method, we now know: the reason why McDonalds burgers don’t grow much mold is not because of chemical preservatives, high salt levels, or a sterile manufacturing process. It’s because “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.”
Lopez-Alt started with a series of rigorous controls, in order to weed out which of the (above listed) possible reasons for a lack of decay:
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
After a test period of 25 days, our intrepid burger-naut found that most of the burgers did not decay, both the home made ones and the McDonalds ones. The exceptions were the larger patties, whether homemade or not, which developed a bit of mold at their centers.
Lopez-Alt has a lot of really interesting data and conclusions laid out in his post, which we highly recommend giving a read. But he sums it up succinctly:
So there we have it! Pretty strong evidence in favor of Theory 3: 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?
Now don’t get me wrong—I don’t have a dog in this fight either way. I really couldn’t care less whether or not the McDonald’s burger rotted or didn’t. I don’t often eat their burgers, and will continue to not often eat their burgers. My problem is not with McDonald’s. My problem is with bad science.
Certainly there’s stuff in Lopez-Alt’s findings that will please both McDonalds haters (Hah! Your burgers are basically jerky!) and McDonalds stalwarts (Hah! The burgers are just like any other burgers!), but most importantly his methods will please scientists, as they have pleased us. Do check out the whole post, with all its accompanying and appropriate pictures and graphs.