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Why does Swiss Cheese Have Holes?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Swiss cheese, or fromage Suisse, has holes in it due to the fermentation process used to create the cheese. Cheese is made by introducing bacteria to milk, which begins to curdle as the bacteria eat and produce lactic acid. Another byproduct of the digestion process is often carbon dioxide gas, which in some cheeses is trapped inside the rind, forming bubbles in the finished cheese product. Swiss cheese is the most well known for this, with some types having holes as large as walnuts.

A number of cheeses are marketed under the name of "Swiss" cheese. The true version is Swiss Emmental or Emmentaler, produced in a particular part of Switzerland. Emmental has a protected origin designation, which means that only cheese prepared in that area of Switzerland, and in a certain way, can be labeled with this name. It has the creamy texture and large holes most consumers associate with Swiss cheese.

A thick wedge of fontina cheese.
A thick wedge of fontina cheese.

Other holey cheese is made in various parts of the world and labeled as Swiss because it uses the same bacteria and a similar fermentation practice. Some dairies also specialize in the manufacture of Lorraine Swiss, also known as baby or lacy Swiss. It has much smaller holes than Emmentaler, because the cheese is not allowed to age as long. The longer the cheese cures, the larger the holes will be.

A sandwich made with Swiss cheese.
A sandwich made with Swiss cheese.

Swiss cheese is made by adding Propionibacter shermani and other cultures to milk after it has been warmed. If the cheese in question is Emmental, the milk is not pasteurized. In the United States, this cheese is usually made with pasteurized milk. The bacteria forms curds in the milk, which are pressed into heavy molds and briefly allowed to soak in a brine bath, forming a wheel of cheese. The brine bath forms a thick rind on the cheese, which is then placed into ripening caves to mature.

A salt brine gives cheese more flavor and extends its longevity.
A salt brine gives cheese more flavor and extends its longevity.

As cheese ages, the Propionibacter shermani bacteria inside continue to eat, producing carbon dioxide. In looser cheeses, the gas would slowly move through the cheese and escape through the rind. Swiss cheese, however, is densely packed and has a very thick rind, so the gas cannot escape, forming bubbles instead. A briefly aged Swiss will have smaller bubbles and a mild, buttery flavor. More mature products, such as Emmentaler, will have larger holes and a more assertive flavor.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a DelightedCooking researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a DelightedCooking researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

FastPaced

I love to use the pungent, pock-marked Swiss cheese in fondue. To start, just melt three tablespoons of butter in a fondue pot on medium heat. Once the butter is melted, add 3 tbsp. flour, 1 tsp. salt, 1/4 tsp. pepper, 1/4 tsp. garlic salt, and a dash of nutmeg. Then, slowly and gradually add 3 cups of milk to the mixture. Turn heat to low and add cheese in by handfuls, slowing stirring each time more cheese is tossed in. After everything is totally melted, add a dash of Worcestershire. The end result is a wonderfully flavorful Swiss fondue. Serve with French bread, crackers, or whatever you prefer. This makes a great appetizer.

pistachios

The holes in Swiss cheese have even inspired the world of medicine and medical terminology. The dark spots that show up in the brain during a CT scan are often the result of old age. This wearing-down and deterioration of the brain in geriatrics is often referred to as "Swiss cheese brain" because the dark spots look like holes.

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    • A thick wedge of fontina cheese.
      By: Lsantilli
      A thick wedge of fontina cheese.
    • A sandwich made with Swiss cheese.
      A sandwich made with Swiss cheese.
    • A salt brine gives cheese more flavor and extends its longevity.
      By: Okea
      A salt brine gives cheese more flavor and extends its longevity.
    • Fermenting bacteria creates bubbles in ripening cheese, leading to holes.
      By: Tim UR
      Fermenting bacteria creates bubbles in ripening cheese, leading to holes.