Why Does Swiss Cheese Have Holes?

MM100 Culture vs Flora Danica Culture and beyond!

Why Does Swiss Cheese Have Holes?

Ever wonder, “Why does Swiss Cheese have holes?” Well, the answer can be found in the culture!

Most cheeses have essentially the same four ingredients:  Milk, Culture, Rennet, and Salt.  But that second ingredient, culture, comes in all kinds of different varieties that will produce very different results in taste, texture, and aroma. 

Primary Culture vs Secondary Culture

When learning how to make cheese at home, most cheeses start with either a mesophilic (warm loving) culture or a thermophilic (heat loving) culture, or sometimes both.  These are known as primary cultures and their main role is lactic-acid development.  This acid development begins right at the beginning of the cheesemaking process when the culture is added to the slightly warmed milk.  The culture, or bacteria, starts consuming the lactose in the milk and converts it to lactic acid, thereby changing the pH level of the milk and getting it primed for coagulation.  We often refer to this stage as “ripening.” 

While a general mesophilic variety such as MM100 is the most widely used and is very versatile in many types of cheeses, especially the softer and fresher ones, there are other mesophilic cultures such as Flora Danica that are also very popular.  Flora Danica culture is a type of mesophilic culture that has a sweet, buttery aroma and taste.  It is popular in soft cheeses such as Cream Cheese, Crème Fraiche, and Brie & Camembert. It also produces a small amount of carbon dioxide gas which gives the resulting cheese a more open structure such as with Gouda, Edam, Havarti and Feta.

Secondary cultures, also known as adjunct cultures, are added along with primary cultures to create other features in your cheese, such as those that make Swiss cheese have holes.  In this case, the secondary culture is Propionic shemanii which is a big gas producer and is responsible for the “eyes” that are characteristic of many Swiss types of cheese, particularly Emmental, Jarlsberg, and Baby Swiss.  These cheeses have a warm stage during their aging period that allows the cheese to expand while the carbon dioxide is produced, thereby allowing for eye development.  Not all Swiss cheeses have holes, yet they still taste like a Swiss cheese.  That’s because Propionic shermanii also creates that distinctive, nutty flavor than is part of what Swiss cheeses are known for.  When the cheese is aged at cooler temperatures, it won’t be able to expand as much as then the eye development will be minimal.

Adding Culture

Beyond why Swiss cheeses have holes, other secondary cultures also create distinctive features in many well-known cheeses including:

Penicillium candidum:  gives Brie & Camembert their bloomy, white rinds

Penicillium roqueforti:  gives blue cheeses their blue veins and distinctive blue flavor

Brevibacterium linens:  gives washed rind cheeses, such as Taleggio and Epoisses, their orange, sticky (and stinky!) rinds

When you understand the role that primary and secondary cultures have in the development of flavors and textures in your cheeses, you can begin to experiment with different varieties and strains to get just the outcomes you desire!

Swiss Cheese Recipe

(adapted from the On Demand “Emmental” class at www.theartofcheese.com)

  1. HEAT MILK: Heat 2 gallons of milk to 70 degrees.
  2. CULTURE:  Sprinkle ¼ tsp of Thermophilic culture and ¼ tsp Proprionic shermanii onto the milk.  Continue stirring and heating the milk to 90 degrees.  Let ripen for 15 minutes.
  3. COAGULATE:  Dilute 1/2 tsp of liquid rennet in ¼ cup cool, non-chlorinated water and add to the ripened milk (for goat milk, reduce by 10-20%).  Stir, cover, and let set for 30 minutes.
  4. CUT: Check for clean break and when ready, cut curd into 1/4 inch cubes using a knife or a whisk.  Let rest for 5 minutes.
  5. STIR:  Stir the curds for about 15-20 minutes, breaking down any you may have missed.
  6. HEAT:  Slowly heat the curds to 120 degrees over 30-40 minutes.
  7. CONTINUE STIRRING:  Turn off the heat and continue gently stirring for 30-40 minutes longer.  Let settle.
  8. SCOOP CURDS:  Line a colander with cheese cloth moistened in the whey and place over a bowl or pot.  Scoop the curds into cheese cloth.
  9. FILL FORM:  Place the partially drained curds in the cheese cloth into a form/mold and press at 10-12 pounds for 15 minutes.
  10. FLIP/PRESS:  Remove from the form, flip, and return to the form and press with 15-20 pounds for 1 hour.  Then remove, flip and return to press with 20-30 pounds for 12 hours or overnight.
  11. SALT: Remove from press and place in 18% saturated brine (1 part salt to 5 parts water).  Brine for 12-18 hours (up to 24 hours for larger wheels), flipping once half way through.
  12. AIR DRY:  Remove from brine, pat dry and air dry for 1-2 days until dry to the touch. 
  13. BEGIN AGING:  Place in aging container and begin aging with lid on at 50-55 degrees.  During the first week, flip daily and remove any excess moisture that builds up in container. If mold begins to appear on the rind, wipe down with a cloth dampened with brine (1 cup water with 2 tsp salt).  After the first week, do this every few days.
  14. AFFINAGE:  After two weeks, move the container to a warmer place, ideally around 65 degrees.  Continue flipping every few days, wiping out any excess moisture, and wiping off any mold that develops with a brine-soaked cloth, for 1 month.  You’ll notice the wheel begin to expand as the Proprionic bacteria do their job. 
  15. AFFINAGE continued: After 1 month at the warmer temperature, place the container back in your aging cave and age at 50-55 degrees for another 3 months.  You can continue to wipe off any mold that develops with a brine-soaked cloth or you can oil the rind with olive oil every few days to keep it nice and supple.

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