Emmental

Emmental is a hard yellow Swiss cheese named for the Emme Valley in the canton of Bern, made from cow's milk and best known for the large, characteristic holes, or eyes, that form throughout the wheel as it matures. The holes are produced by carbon dioxide released by Propionibacterium freudenreichii bacteria during a warm aging phase unique to this style of cheesemaking. Emmental has a firm texture and a mild, nutty, slightly sweet flavor, and it has been so widely copied outside Switzerland that its holed appearance became the generic template many people picture when they hear the term Swiss cheese.