Katie asked: “Can you just leave cheese in the fridge and it’ll turn into aged cheese?”
Far in the back of the fridge dwells a wedge of cheese as old as a toddler. Is it wonderfully sharp by now and complex in flavor? Or will you want to use the extra-long tongs when you drop it in the trash?
As I hear myself say almost constantly, it depends. If the cheese has been sitting there in plastic wrap, left to its own devices, it will have undergone a series of microbiological processes that don’t improve cheese. It’s probably covered in green or gray mold, withered, slimy, and undesirable.
But if you’ve been tending to the cheese, giving it fresh air, turning it over; checking the humidity level and temperature of its surroundings; patting and rubbing it affectionately to maintain the proper moisture and microbes on its surface; then it’s probably thriving, evolving, and improving with age.
If that sounds like a full-time job, well, it can be. Attending to the needs of a cheese as it ripens is called affinage, and it is done by a professional called an affineur. Some affineurs work for cheesemakers, and others are associated with wholesalers, markets, restaurants, and cheesemongers. Affinage adds value to a cheese; though, as the Oxford Companion to Cheese says, “it is almost impossible to make a bad cheese good by maturing, but very easy to ruin a good one.”
A cheese undergoes constant changes throughout its existence, starting from its birth and continuing after it enters your home, although the action slows down at refrigerator temperatures and without air. Over time, dozens of enzymes from the milk and from added cultures transform the chemistry of the cheese. Sugar becomes lactic acid, the crucial difference between mild cheddar and sharp cheddar. Milkfat is hewn into smaller molecules, including butyric acid, one of the primary components responsible for “cheesy” flavor. And proteins break down in a long chain of chemical reactions that produce a vast spectrum of flavor and texture complexity.
(That’s just the basics; I’m not even touching upon all the drama that happens within mold-ripened cheeses, which are complicated ecosystems unto themselves.)
Moisture loss is also critical: During aging, water slowly migrates from the center of the cheese to its surface, and evaporates. A soft cheese like Camembert can be 60 percent water when it’s sold; Parmigiano-Reggiano less than 30 percent, which gives it not only a grateable consistency but also highly concentrated flavor.
Evaporation is why affineurs pay such close attention to airflow and humidity. Too little evaporation—as in the sad story of the cheese tightly wrapped in plastic—and moisture just builds up on the surface of the cheese, providing a friendly environment for unwanted mold to grow. Too much evaporation and the whole cheese becomes a dry rind, good for frico but not much else.
Carefully aging cheese at home is likely more than the average person wants or needs to do, but extending its shelf life (with our recommended multi-layered approach) will let it be its best.
I’ll never forget when a French friend of mine saw me putting a nice soft Morbier in the fridge and shrieked “No! You’ll kill it!” Cheese isn’t a living creature, but its fans treat it like it is.