Cheese Piercing 101

The key to any good blue cheese is the blue mold, obviously! Typically, when we see mold on cheese, such as when it's been left in the fridge for too long, the mold is contained to the outside surface. How does the signature blue mold get inside the paste of blue cheese? By piercing it!

Blue cheese is the name given to cheeses that contain cultures of one or two types of blue mold: Penicillium roqueforti or Penicillium glaucum. These molds thrive in low oxygen environments and feed on milk proteins. Blue cheese is aged in temperature controlled environments, traditionally in caves.

Blue cheese is made by first heating the milk, and then adding a starter culture which causes the milk to begin separating into curds and whey. Then, mold spores are added—either Penicillium roqueforti or Penicillium glaucum—along with rennet. Once curds form, the cheese is pressed into the desired shape, and is then salted and dried.

As it dries, the cheesemaker pierces the cheese with special needles to allow the mold to travel into the cavities and create the signature veining. The piercing can either be done by hand with a piercing tool, or with an automated piercing machine as shown in the video below.

The cheese is then left to age for the desired amount of time, typically 2-3 months. The longer the cheese is aged, the more pungent its flavor.

Piercing holes on a wheel of blue cheese.

Piercing blue cheese is a vital part of the production process. If you look closely at a wheel of blue cheese, you can see the holes where the wheel was pierced to allow the mold spores to travel inside.