Microbiology

The characteristic large holes in Swiss cheese are formed due to the metabolic activity of the bacterium Propionibacterium sharmanii. During the fermentation process, this bacterium ferments lactate to produce carbon dioxide gas, which forms bubbles trapped in the cheese matrix. These bubbles create the iconic ”holes” or ”eyes” in Swiss cheese. The production of propionic acid also imparts the distinct nutty flavor of the cheese.