☰ menu   

Why Does Swiss Cheese Have Holes?

Swiss cheese is one of the most recognized styles of cheese in the world. While there are many cheeses that are native to Switzerland, most Americans use “Swiss” as a generic catch-all for the Swiss-style speckled with holes. 

The Hole Story

baby swiss cheese

Those holes in your cheese indicate a specific type of Swiss. This cheese’s proper name is Emmentaler because it originated in the Emmental region of Switzerland. Emmentaler is distinguished by extra-large holes and a unique flavor. So what in the world causes these gaps in your snack? They are due to a starter culture of bacteria added to the milk at the start of cheesemaking.

Once in the vat, this strain of bacteria, called Propionibacter shermani, consume lactic acid and release bubbles of carbon dioxide gas. These air bubbles become trapped in the rind of the cheese and slowly form holes, or “eyes.” Cheesemakers are able to control the size of the holes by changing the temperature to which they bring the milk, the acidity of the milk, or the aging time of the wheel. 

The Flavor of Love

The unique flavor of Emmentaler is also caused by our Propionibacter shermani friends. Carbon dioxide isn’t the only side product that is created when the bacterium eats lactic acid in the young cheese. When CO2 is released from lactic acid, the lactic acid is converted to propionic acid, which is responsible for the unique, pungent smell and flavor we associate with Emmentaler.

Emmentaler can vary widely in taste depending on the activity level of the Propionibacter shermani. Interestingly, flavor and the size of the eyes are related. Larger holes in the cheese mean a more intense and developed flavor. Cheese that has aged longer features increased flavor-enhancing bacteria. This may explain why American-produced Swiss, with its smaller air pockets, sports more mild and creamy flavors. European versions tend to be round, rich, and often nutty.


  • You can’t go wrong throwing a slice of Swiss cheese on a ham and cheese sandwich or a hot, buttery croissant.
  • Try it on a juicy burger or any number of grilled items.
  • If it’s happy hour, pair with a crisp Sauvignon Blanc or a smoky Merlot. 
Photo Credit: Cha già José via Compfight cc

Vanessa Lyons

Vanessa was an online editorial intern at culture. She grew up in New Hampshire enjoying her mother’s glorious cooking, which ignited a zeal for tasty cuisine. A stint at a specialty food and wine store only elevated this desire, specifically for cheese and any of its fermented accompaniments. When not attempting to bolster her cheese knowledge, she escaped to coastal Maine or locked herself in her bedroom to read Game of Thrones.