There’s actually a very reasonable explanation to why some types of cheese have holes, and it has nothing to do with mice.
As a kid, I always believed that mice sneak into the cheese factory and nibbled through the big rolls to form holes. As I got older, I understood that that could not be true, but i never really took the time to find out how or why the holes come to be.
Sadly, real life is very different from a Tom & Jerry episode and mice don’t live that close to cheese. If they did, you’d probably never put it in your mouth.
The truth lies in how some types of cheese are made. The holes you see in a big wheel of Swiss are actually called “eyes”, and they are simply byproducts.
Cheeses like Emmental get their great flavor the same way they get their eyes, tiny bacteria that turns milk into cheese. While all cheeses are made with the help of bacteria, only some create eyes.
One of the bacteria used in the production process are called P. shermani. It consumes the lactic acid made from other bacteria and turns it into carbon dioxide. The gas forms bubbles, and once they are big enough they pop, making a hole in the wheel.
So next time you’re having a delicious piece of cheese, remember that the hole is nothing more than a bacteria fart.