I’ve taught hundreds of cheese and wine pairing classes across the United States. While cheese knowledge and preferences vary, there is one question I can count on being asked in every single class. It usually comes up when someone just fell in love with a new cheese.

“How long was this aged?”

Whether the cheese is a month-old Camembert or a three-year-aged Parmigiano Reggiano, the first question is almost always about how old it is. It’s never “how was this one made?” or “what did the animals eat?”, though those questions are equally important to the flavors of the finished product. At its most basic level, cheese is milk, rennet, cultures, and salt, and each tiny manipulation of those variables results in a different cheese.

“Every day the milk differs according to the season, the type of fodder that the cow ate, the temperature, and many other factors,” says Andrea Robuschi, a representative of Italy’s Parmigiano Reggiano producers’ consortium. Especially when the cheesemaker values complexity over consistency, the same cheese may vary drastically in flavor and texture from batch to batch.

But the idea of aging cheese carries serious mystique for some enthusiasts, largely thanks to cheese’s proximity to wine. Despite the fact that only 1 percent of wine is meant to be aged, we romanticize the mysteries of the aging process and too often attribute flavor nuances to age rather than to skilled, responsible farming practices. Most cheese on the market is aged a year or even less, and that is exactly the right age for it.

That said, age does play an important role in a cheese’s texture and flavor — just not always the one we think.

The Science of Aging Cheese

The work of aging cheese is called “affinage,” coming from the French verb affiner, which means “to refine.” When cheese ages, it loses moisture and undergoes changes in flavor and texture. “Both of those changes are the direct and indirect result of the breakdown of protein (proteolysis) and breakdown of fat (lipolysis),” says Pat Polowsky, founder of Cheese Science Toolkit, a technical resource for the cheesemaking community.

“Intact protein doesn’t really have much flavor,” says Polowsky. “But as it breaks down, smaller and smaller protein pieces called peptides are formed, as are free amino acids, which are the fundamental building blocks of protein.” These molecules may contain flavors themselves, or they may break down or react with other compounds to form flavors. For example, the eggy flavor in some cheddars is a result of amino acid breakdown.

In the same vein, fat breaks down into free fatty acids. “These smaller molecules can interact with our scent and taste receptors much more readily,” says Polowsky. He cites the piquant notes of provolone as an example of lipolysis-driven flavor. “These fatty acids can also go on to react to form other flavor compounds,” he says.

And that’s not all. Lactose, the sugar found in milk, is fermented into lactic acid at the beginning of the cheesemaking process. That lactic acid is broken down during the aging process. The eyes in Swiss Emmentaler, for example, occur because of lactic acid breakdown.

Avoid DIY Affinage

Not all cheese is suitable for aging. Cheeses like mozzarella, Brie, and fresh chèvre are meant to be enjoyed young. However, even styles that are meant for aging don’t age well without an expert at the helm. “A common misconception is that you can buy some cheap mild cheddar from the supermarket, vacuum-seal it, and age it in your fridge for a year or two for some well-aged sharp cheddar,” says Polowsky.

But cheddar that’s meant to be aged is made differently, with lower moisture and higher salt. “These factors control the microbes in the cheese,” Polowsky explains. If you tried aging a mild cheddar that was made to be eaten young, “these reactions go into overdrive and would end with a bitter, mushy, bad-tasting cheese.”

Additionally, says Polowsky, “The fridge is really meant to preserve cheese at the point the cheesemaker wanted it sold.”

Polowsky’s recommendation? “I suggest not aging cheese at home.”

And while I am not a cheese scientist, I have tasted Tillamook cheddar from the 1970s that someone aged in their fridge at home. I second Polowsky’s suggestion.

How Professionals Age Cheese

When cheese is aged by the professionals, the process looks quite different. The aging of Parmigiano Reggiano, for instance, “takes place under the strict supervision of the producer who regulates humidity and temperature,” explains Robuschi. After 12 months, the Consortium’s experts test each wheel, tapping it with a hammer and listening for defects that could compromise the quality if it were aged further.

The oldest Parmigiano you’ll find in the U.S. market is five years, and that’s rare. Two- or three-year wheels are more common, but still hard to find.

In Wisconsin, cheesemakers sometimes go even further in aging their products. “We like a very slow cure to bring out the flavors,” says Tony Hook, cheesemaker and co-owner with wife Julie of Hook’s Cheese Company in Mineral Point. Hook’s just released a 20-year cheddar, retailing at $209 per pound. Though the company’s 20-year batch is rare — less than 1 percent of production — Hook’s regularly sells 10-, 12-, and 15-year cheddars.

To age its cheese, Hook’s vacuum seals it and then puts it in a cardboard box with a wooden liner. It stays at about 38 degrees throughout the aging process. “I test one block along the way to make sure it’s developing the flavor like I want,” says Hook. The company’s older cheddars have less acidity, and fruitier, nuttier flavors. Texturally, they are both smooth and crunchy, flecked with calcium lactate crystals from the aging process.

“Most people, especially restaurants, prefer the price of a younger cheddar,” says Hook, who has been making cheese for 50 years. “Once or twice in a lifetime, they’re willing to spend the kind of money for a very aged cheese.”

Is very aged cheese worth the price? Perhaps. There is something special about tasting something that old. The flavors of Hook’s 20-Year Cheddar are exaggerated, and the texture is both cartoonishly crunchy and surprisingly smooth. Age is never the ultimate indicator of quality, but special cheese is special cheese.