Affinage: the art and science of aging cheese

Part magic, part biochemistry, the aging of cheese is a subject that isn’t well understood even for cheese lovers. My recent two-week professional training with the Academie Opus Caseus gave me an eye-opening introduction to affinage. While its principles and techniques are pretty simple to understand, they take a lifetime to master. They also remind us of the importance of our environment, traditions, and the value of patience, honest labor, and passion.

Aging and Food Marketing

What comes to mind when you think of aged cheese? Did you think of strong smells and flavors? Visible mold maybe? You’re not alone. For many, aged cheese connotes old cheese, and old connotes strong smells and flavors and disturbing molds.

Gorgeous goat cheeses from Cheese Day, an event in Paris in January 2016. Note the blueing. I can assure you these were delicious cheeses!

Our modern convenient supermarkets only reinforce these thoughts. The more we seek to increase shelf life, reduce hygiene and safety concerns, and quickly and cost-effectively distribute food whenever and wherever, the more standardized our food becomes. While food safety is an undeniably good thing, it comes at a non-obvious cost: it’s changed the way we perceive food. We avoid fruit that doesn’t look perfect. We check “best by” dates as if, at the stroke of midnight, the product will spoil. Our concept of what is safe and edible is influenced by marketing, much to the detriment of cheese.

This is "brie" sold in the US. It is unequivocally industrially produced. Note the perfectly white rind that looks like it was applied as a coating instead of growing organically. The uniform yellow yet still chalky-looking paste is another clear indication. 

A well-ripened brie has a crust that's more mottled. Its paste will be a bit shiny.

So let’s address this point head on. To understand the aging process, we need to start with how cheese is made, which means coming to grips with the fact that best cheeses are a direct function of flora, which is the scientific yet less-threatening term for the bacteria and molds that contribute to taste, texture, smell, and appearance.

Connecting Flora to Flavor

Cheese comes from milk. Milk comes from animals like cows and sheep and goats. Animals eat grass and flowers and hay. Whether we imagine a bucolic pasture or a giant industrial milk operation, there is an entire ecosystem of flora, specifically bacteria and yeast and molds, that is an inescapable element of cheese making. Cheese is a living product since it comes from living things.

The enormous Salers cows are one of several breeds used for making Saint Nectaire.

A reminder that, even when well cared-for, flora are everywhere. These are Prim'Holstein cows at a farm in the Auvergne that produces farmstead AOP Saint Nectaire.

Cheese making starts off in the same fashion for virtually all cheeses. Milk is heated to at least the body temperature of the animal. Naturally occurring bacteria will cause the milk to “sour” and become acidic. If we stop there, we have yogurt. But let’s keep going and add rennet, which is an enzyme that causes the essential protein in milk, casein, to coagulate. The water separates from the milk solids (the protein, milk fat, and sugar in the form of lactose), which clump together. These are the curds, and they look a bit like panna cotta floating in a yellowish liquid we know as whey. If we stopped here and simply shaped curds and drained the whey, without aging, we’d have cheese, but it would be pretty boring. Aging completely transforms the curds. With our curds now separated from the whey, shaped and drained, let’s see how the flora go to work inside and out. At this point, even though it’s not developed, the cheese contains almost all the flora it will have for taste, texture and smell.

The process begins when rennet causes the milk solids to coagulate (into curds) and separate from the liquid (whey)...

The curds are placed in molds...

...which are then pressed and dried.

Rind development

A cheese’s rind begins to form during the initial drying process, but what happens next depends on the type of cheese. Many are washed in a dilute salt solution, or a solution with alcohol or cultures (bacteria). Soft blooming rind cheeses, like Brie and Camembert, are salted and washed with a solution containing penicillium molds from which they develop their white rind. Soft washed rind cheeses like Munster, Pont L’Évêque, and Langres are washed with dilute solutions that contain salt and or alcohol. Hard cheeses, like my favorite Ossau-Iraty, a sheep’s cheese from the Basque Country of France, are washed with a dilute solution of salt and bacteria, or a morge in French. Liquids and morges are added early on in the cycle. Later, the cheeses will be brushed or patted to spread the flora over the crust, turned regularly, carefully observed, and, of course, tasted!

Camembert ripens at Fromagerie Durand, the last farmstead producer of AOP Camembert de Normandie. 

Crust development serves a number of important purposes. Not only will we be adding aroma and flavor from the outside, we will be promoting activity inside the cheese as well. And, by promoting the growth of desirable flora on the crust, we simultaneously create competition such that the undesirable flora don’t flourish.

Rind development on my hands! I patted down mucor mold growing on the rinds of about 80 St Nectaires. 

Paste development

Inside the cheese, bacteria are busily breaking down the raw materials in milk, that is, the proteins, fats, and sugars. We don’t need to understand the biochemical reactions. What’s important is that we can see, taste, touch, and smell the evidence. For example, when you see holes in the paste of the cheese, that’s typically evidence of proteins breaking down. A camembert or brie will go gooey just under the crust as the fats break down. Sugar breakdown can create acidic flavors in goat and soft cheeses, for example.

These are "flights" of cheeses. Each row is the same cheese, just aged for different lengths of time. Row A is Camembert de Normandie. Row B is a goat's cheese from the Midi-Pyrenees region (Petit Blaja, aged by Mons). Row C is Langres, a washed-rind cheese from the Champagne region. Can you distinguish which cheese in each row is the youngest/oldest?

Saint-Nectaire at 6-7 weeks. Note the holes.

Caves & Environment

The affinage environment plays a central role in the development of cheese’s sensorial characteristics. Affinage rooms are often called caves in French, but this doesn’t necessarily mean a natural hole in the side of a mountain. It can be a room, or an abandoned railway tunnel, or even a trailer. Whatever its form, it must allow the affineur, or cheese ager, to carefully regulate humidity, temperature, and air movement, all of which can stimulate or retard bacteria and mold growth. For example, Roquefort are “put to sleep,” meaning they are kept at very low temperature (2-4 degrees Celsius) to ensure this beloved blue cheese is available outside the sheep’s natural lactation cycle. Were this not done, the mold would grow too quickly.

Wheels upon wheels of Beaufort, a fabulous cooked and pressed Alpine cheese. This is the Tunnel at Collange, where the Mons family has converted a former railroad tunnel into an affinage cave. 

The farm that produces the St Nectaire shown above has its own private stash. This cave is little more than a cool room. The cheeses in the two left-most racks are the youngest at around 2 weeks old. Every two racks represents another week of aging. The right-most racks are about a month old. 

The Art

While the essential mechanism of cheese aging is scientific, it is hardly regular. Changes in what the animals eat, the different times of year, variations in the weather or even the products produced… slight variations here and there can create a butterfly effect. Some of this variability we seek, for it contributes to taste. But variability also spells trouble when it leads to waste or spoilage.

Every cheesemaker or affineur ultimately has to decide how much of this variability she or he wants to manage. In simple terms, there are two approaches. One is to try to standardize by eliminating sources of risk, which is what industrial producers do. Through intensive farming techniques like controlled diets, highly regulated living and milking conditions, milk pasteurization, and machine driven aging, it’s possible to reduce variability and increase the scale of production. The primary downside of this is that standardized cheeses can be very boring. In the worst cases, they have the texture and taste of Playdoh. (Americans will know this taste from the insipid Bries we have been forced to eat for so many years. For French readers, this is the taste of a President camembert.)

The second approach is to accept the ecosystem yet standardize through consistent practices. Farms are ecosystems. Cheese making rooms and affinage caves are ecosystems. The more consistent the practices, the more consistent the cheeses will be. It helps to be disciplined and understand process control so that you can trace changes in output to traces in input. Relationships between farmers and makers, or makers and affineurs, are common. In fact, it’s just as important for the affineur to work with the distributors and retailers to ensure the cheeses are handled and stored properly. With fewer true controls in the system, there is definitely more variability in the end product, but there is also better cheese from the standpoint of taste, smell, and texture.

Another example of the same cheeses in each row at different ages. Age will make rinds grow thicker and more rustic and rugged. Paste will typically darken in pressed cheeses. The top row is called 1924 and is a blue cheese of mixed cow and sheep's milk. The middle is the tomme du Mon Pilat, a goat cheese. The bottom row is comté. Interestingly here, the left-most comté is about 7 months older than the middle cheese, which may be due to the fact that the middle cheese was made at the end of the milking season, when the milk typically has a lower water content.  

Food safety and the raw-vs-pasteurized debate

The fact that we're dealing with bacteria means that, regardless of one’s approach to managing variability, everyone from the farmer to the retailer has a responsibility for managing risk and food safety. Strong hygiene practices, regular milk and premises testing, traceability requirements that link a cheese from retailer back to producer, and regulations all serve to reduce risk.

There are different points of view, however, on milk treatment especially. Countries like France, where there is a long and valued tradition of raw milk cheese production that continues to this day, represent one end of the spectrum. Countries like Australia, where every cheese must be made from pasteurized milk represents the other. The United States finds itself somewhere in between. 

It is a scientific fact that raw milk cheeses, beyond being gastronomically more interesting, are perfectly safe to eat. Their production implicitly requires a strong sanitary orientation, and regulations and traceability practices have been highly effective in mitigating risk. Raw milk cheeses are starting to make a comeback in the United States, thanks in particular to organizations like Oldways and the ACS who have endeavored to partner with US FDA on the science.

In France, the story is different. For despite being a cheese-loving country, the vast majority of cheese consumed in France is industrially-produced and pasteurized, and these giant agribusiness producers continue to try to chip away at the regime that preserves tradition, the AOC/AOP program. AOC stands for appellation d’origine contrôlée and it entails a strict set of requirements as to fabrication, affinage, techniques, geographic origin, even the size of the cheese that must be followed. You can’t call something a Camembert de Normandie or a Comté if it’s not made in a specific region in a specific way. These designations apply not just to cheese, but to certain wines, butters, meats, fruits and vegetables, and even oils. (The program was expanded across the EU, where it’s known as AOP or appellation d’origine protégée. In English, it’s known as PDO or Protected Designation of Origin.)

Just an ordinary day in the Auvergne. France has many regions renowned for cheese, but the Auvergnats will tell you theirs is the best!

The final product

The science of affinage can be very interesting, but at some point it all goes out the window and you just have to eat the cheese to figure out whether it’s any good! The proof is in the pudding, as the saying goes.

As part of the training we learned techniques for sensorial analysis, which entails far more than just tasting. A visual examination of the rind and the shape of the cheese can tell you a lot about external and internal flora, how humid or dry the cheese might be, and what techniques were used in making it. By smelling the rind and the paste, one can pick up incredible scents of fruit or herbs, nuts or butter, toast and caramel, both sweet and sour milk, or the alcohols that some cheeses give off. Taste brings us not just an indication of salty, sweet, sour, and bitter, but also the lovely meaty or mushroomy umami that characterizes a ripe Brie. We feel what the pros call “trigeminal” effects on the sides of mouths and jaws, like piquant sensations or even the taste of minerals.

And of course, there are always indicators when the cheese goes “to the dark side,” as Laurent Mons and Sue Sturman from Academie Opus Caseus like to say. Like when goat cheese is aged so long it becomes hard and tastes soapy, or when Bries become ammoniated, or a chemical reaction takes a bad turn and creates the smell of baby sick.

During our training, we were shown cheeses that went to the "dark side". Note the imperfect crust on the left-most cheese (a non-AOP version of Selles-sur-Cher). The second cheese (a Munster) wasn't turned and dried on one side. The third (St Félicien) has visible blueing and shouldn't. The first (Gaperon) has yellow mold that has caused it to dry and harden, almost like a golf ball.

Tips to buying great cheese

It’s easy to be intimidated by cheese. Like wine, it can feel like a very esoteric product to get to know. That said, there are a number of ways you can ensure you’re buying something good.  

1.     Smell and taste your cheese

You may feel ridiculous doing it, but put it up to your nose. Smell it. Then taste it. Any legitimate cheese monger should be happy to give you a taste of their product.

Looking for ideas? Do a tasting of cheeses in the same families. Here is a plate of three pressed cooked cheeses along with three blue cheeses. Can you recognize any of these just on sight?

2.     Ask questions.

If there is anything I have found, it is that people who love cheese love talking about it as much as eating it. You can find out a lot about your cheese as well as the monger’s perspective on cheese by demonstrating your own inquisitiveness. There are three questions you can use to stimulate discovery.

  • I got <insert cheese> the last time I was here. Do you have anything that is similar?
  • Is there something you can recommend that you like that is maybe a little out of the ordinary or that I might not have heard of?

If you’ve got someone you really feel confident in, you can ask about food and wine pairings. But start with the basics.

A wonderful and well-traveled American cheesemonger named Brie (yes, that's his real name). You learn a lot when you ask questions.

3.     Build up your own database

You’ll learn more about the cheese the more you eat. If you like blooming rind cheeses like Camembert and Brie, try a Chaource, or even a young goat cheese. If you usually go with cow’s cheeses, try a sheep’s cheese, or get one of each: cow, sheep, and goat. Experiment with geography: get a cheese from Burgundy, like a washed rind Soumaintrain and eat it with one of the gentle red wines from the same region. If you have access to enough variety, doing “flights” of cheese (the same cheese at different ages) is a great way to explore affinage techniques specifically, particularly if you like the cheese in question. This can be done fairly easily with Comtés.

A picture from Fromagerie Cantin in the 7e arrondissement of Paris. Marie-Anne Cantin is a second generation affineur and comté is one of her hallmarks. Of the seven tall soldiers in the bottom right of this picture, the five right-most are comtés ranging from 2012 to 2016. 

Get out there and eat cheese!

I hope this post has been helpful in demystifying cheese aging. More importantly, I hope it encourages you to try artisanal cheese, regardless of where it comes from. While my focus has been on French cheeses, there are terrific ones made all over Europe, in the UK, and the US. Make friends with your local cheese monger. You won’t regret it.