I don’t know how long this fast-food myth has been making the rounds, but it has been around quite a few years. The idea that certain commercial food products never spoil is a common one, and with the kind of shelf life we see in packaged foods, and the preservatives that are used, I can see why. People have believed that Twinkies never go bad for a long time. Even though hamburgers are not packaged foods, we don’t know what may be in fast food, and a lot of people consider it to be more “laboratory food” than real food. You have to wonder.
If you’ve ever left a McDonald’s hamburger or cheeseburger sitting out, you may have noticed that, indeed, it seems to hold up very well. There are YouTube videos and images that seem show indestructible hamburgers. So, are they rot-proof?
The fact is that no food is rot proof, including McDonald’s hamburgers. McDonald’s has been dealing with this rumor for a long time. McDonald’s Canada, which seems to be in an answering mood these past few years, finally dealt with the question on their question and answer site. They actually asked a food scientist named Keith Warner, who is the Program Director at the University of Guelph’s Department of Food Science.
Warner explained that the cooking process at McDonald’s removes a lot of the moisture from the bread and the burger patty. Things that are dry do not rot as fast as things that are moist, or kept in moist environments. Microbes are just like us in that they need water. They also tend to prefer warm environments. When it is dry they do not grow very fast, if at all.
Since a McDonald’s hamburger is already fairly dry to begin with, and since it dries out even further when you leave it out are room temperature, you end up with a dry and hard hamburger instead of a rotten one. You will notice that other dry foods do not rot very quickly either. Why do you think dried fruits hold up so well? And a hunk of dried out French bread will stick around a long time! If you wrap a McDonald’s hamburger up in plastic wrap, holding in the moisture, it will rot faster. As well, if you put it in a humid room, like the bathroom, it will tend to spoil faster.