If you hang out on the internet much, you’ve probably come across video/photos/email similar to the following, in which a McDonald’s Happy Meal doesn’t appear to rot:
What does this mean? Are McDonald’s burgers made out of undigestible material, meaning you can eat as many as you want and not get fat? Or are they a miraculous, non-spoiling food source that could feed hungry millions in places without access to fresh produce or refrigeration?
Well, J. Kenji López-Alt of the Burger Lab has found a more mundane yet scientific answer, by comparing spoilage of a McDonald’s Quarter Pounder with a homemade control burger using good, honest, all-natural ingredients. Both burgers ended up with pretty much the same lack of mould or visible rot.
The main reason seems to be that the burgers in question are small enough to quickly dehydrate when left out on the kitchen bench. Together with the fact that the burger patties are essentially sterilised in the cooking process, they lack both starting mould spores and the environment in which to grow them.
This was further verified by sealing a McDonald’s burger in a plastic bag, which caused it to grow mould just like that loaf of supermarket bread you’ve left for too long.
The moral of the story? Don’t believe everything you see on the internet, at least not without thinking about what it actully means. And one demonstration on YouTube is not the same as a controlled experiment…
For the proper study, with control burgers and everything, head on over to the Burger Lab at Serious Eats.