what causes holes in swiss cheese

The characteristic holes in Swiss cheese are caused by carbon dioxide gas bubbles produced during the fermentation process. Here’s a simplified explanation:

1. Bacterial fermentation: Swiss cheese is made using a type of bacteria called Propionibacterium freudenreichii, which is added to the cheese milk. These bacteria feed on the lactose (milk sugar) in the milk and produce carbon dioxide gas as a byproduct.
2. Gas bubbles form: As the bacteria ferment the lactose, they release carbon dioxide gas, which gets trapped in the cheese. The gas bubbles form small pockets or holes within the cheese.
3. Expansion and contraction: During the aging process, the cheese is regularly turned and rubbed with salt. This process helps to distribute the bacteria evenly and encourages the growth of more bacteria. As the cheese ages, the gas bubbles expand and contract, causing the holes to grow and become more pronounced.
4. Enzymatic activity: The enzymes produced by the bacteria also contribute to the formation of holes. These enzymes break down the casein proteins in the milk, creating a network of tunnels and channels that allow the gas bubbles to move and expand.

The combination of bacterial fermentation, gas bubble formation, and enzymatic activity creates the characteristic holes in Swiss cheese. The size and distribution of the holes can vary depending on factors like the type of cheese, the aging process, and the specific bacterial cultures used.

Interestingly, the holes in Swiss cheese are not just aesthetically pleasing; they also play a role in the cheese’s flavor and texture. The holes allow oxygen to penetrate the cheese, which helps to develop the characteristic nutty, fruity flavors of Swiss cheese.