During affinage (the phase of maturing/aging cheeses), cheeses such as Emmental (Swiss cheese) are matured at higher temperatures to create holes in the interior.
Holes in cheeses are commonly known as eyes.
Maturing a cheese requires some form of heat and the heat favors the growth of certain bacteria such as P. shermanii (in full: Propionibacterium freudenrichii subspecies shermanii).
The development of these bacteria results in the release of carbon dioxide (CO2) in the form of bubbles, which ultimately form the holes in cheeses.
Cheeses with holes usually have an incredibly thick rind that prevents carbon dioxide from escaping.
Theoretically speaking the bubbles cannot escape through the rind, therefore, the CO2 bubbles can only multiply and grow within the cheese hence why cheese has eyes.
The Holes or Eyes in Cheese Can Be Controlled
The affineur is able to control the size and quantity of the holes or eyes.
What is an affineur?
An affineur is the person who takes care of the cheese, taking it to its optimal maturity or ripened stage.
When the affineur feels there are enough holes in the cheese, the temperature is lowered and the bacteria ‘go to sleep’ ceasing their CO2 production.
Why do Cheese’s ‘Eyes’ Cry?
During affinage, as the cheese matures, the salt added during manufacture forms back into crystals.
These salt crystals begin to draw out any remaining water, producing ‘watery eyes’ in the holes, a state that tells the cheese lover they are in the presence of a cheese at its finest quality.
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