I challenge you to name a better combination than Swiss cheese on a Reuben sandwich. Mozzarella on an Italian hoagie? It’s good, but not essential. Cooper Sharp on a cheesesteak. Excellent, but you can also use Cheese Whiz (or both if ya nasty). Swiss cheese is iconically a Reuben cheese, and just as iconic is its distinctive holes. And that leaves me asking: Why are there holes in Swiss cheese?!
Why does Swiss cheese have holes?
Every full moon, when the edelweiss is in full bloom, Swiss cheese makers leave their wheels of cheese in the foothills of the mountains. And that’s when the Cheese Gnomes get to work. The Cheese Gnomes emerge from their toadstool homes and eat holes through the cheese, gorging themselves sick. In the morning, the cheese makers retrieve their cheese; the block with the most holes in it is the Cheese Gnomes’ favorite and that cheese maker wins a goat.
Just kidding. So, how does Swiss cheese get its holes, really? Swiss cheese has holes because of bacteria. There are three specific bacteria used, and I am not going to name them here because they have insanely long scientific names. The important thing to remember is that while two of them are gobbling up the cheese and producing lactic acid, the third is consuming that lactic acid and releasing carbon dioxide.
It’s this carbon dioxide that forms bubbles and, ultimately, the holes in Swiss cheese. And Swiss cheese with holes that are bigger mean the cheese has stronger flavor, since the fermentation process was allowed to go longer.
At least, that’s what science deemed to be true for many years. It turns out, that’s not the hole (sorry) story. What causes holes in Swiss cheese, actually?
In 2015, scientists announced that flecks of hay are actually responsible for the holes in Swiss cheese. According to the BBC, “Agroscope, a government agricultural institute, said ‘microscopically small hay particles’ would fall into buckets collecting milk, and develop into bigger holes as the cheese matures. The process affects only some Swiss cheeses, such as Emmental and Appenzell.” Researchers tested this theory by adding hay dust to milk and making it into cheese, observing it over 130 days. As the cheese aged, they saw that there was a correlation between the amount of hay particles in a particular cheese and the number of holes.
In an article from Popular Science, John Jaeggi, a researcher at the University of Wisconsin’s Center for Dairy Research, explained it thusly: “The Swiss are saying that the fine dust from hay powder is forming the nuclei and curd texture. Those are the spots where the gas forms and you get the eye [hole] development.” So, yes, bacteria is responsible for the holes in Swiss cheese, but it gets the opportunity to make the holes because of hay particles.
Apparently, Swiss cheese holes have been getting smaller over the years, and some experts theorize that it’s because modern milking methods have kept the hay out.
Is Swiss cheese really from Switzerland?
Yes, Swiss cheese originated in Switzerland. The cheese debuted in the 14th century in the Emmental region of Switzerland, which is why you’ll sometimes see Swiss cheese called Emmental cheese. It is a medium-firm cheese traditionally made with raw cow’s milk. In the United States and other countries, Swiss cheese is made with pasteurized or part-skim cow’s milk.
The cheese is so intrinsically Swiss that it is classified with geographical indications and thus has specifications it has to meet to be called Emmental cheese: It must be made with natural ingredients, it must have a round shape with a natural rind, and it must be aged in cellars for four months. It also can only be produced in certain areas of Switzerland or else it cannot bear the Emmental name.
What are some other fun facts about Swiss cheese?
I’m glad you asked!
- The holes in Swiss cheese are called eyes. If Swiss cheese has no holes, it’s referred to as blind.
- The USDA has specifications for how big the holes in Swiss cheese can be. If the holes are too big, the cheese can’t be sliced correctly. This implies there’s someone out there measuring Swiss cheese holes.
- Swiss’s sister cheese is Gruyère and the two are often combined in dishes like gratin or fondue.
- An American version of Swiss cheese is called Baby Swiss, named for its much smaller holes—lesser fermentation—and milder taste.
- If you don’t put Swiss cheese on your Reuben you are dead to me.