The Secrets of Aging Cheese: A Tour of Murray's Cheese Caves

If you look at most of our favorite cheeses, they have one thing in the common: They tend to have some age. While some cheeses are best eaten the day they're made, others take time. And mold. And the right temperature and humidity. And a bat cave to linger in until they're ready to emerge fully formed.

Murray's, the iconic Greenwich Village cheesemonger, has been aging their own cheeses since 2004 when they first built a modest 600-square-foot aging facility under their Bleecker Street store. In 2013, Murray's built a new set of caves, twice the size of the Manhattan facility, in Long Island City, Queens. The caves are part of an all-encompassing, state-of-the-art enterprise that combines Murray's aging, distribution, R&D, and administrative functions under one roof, and they're home to a lot of cheese.

In Europe, cheese was traditionally aged and preserved in actual caves before the advent of refrigeration. (Several styles are still produced this way, most prominently Roquefort, which according to EU law must be aged in southern France's Roquefort-sur-Soulzon caves.) Modern aging caves are what you see in the US, and excluding those built by cheesemakers solely to age their own products, there are only a few caves in the U.S. devoted solely to aging cheese. Some caves take entirely fresh cheeses from cheesemakers and age them from start to finish; other cheesemakers start aging cheeses themselves and let the caves finish them off.

Murray's caves are the oldest in the country. 2007 saw the opening of Greensboro, Vermont's Cellars at Jasper Hill, and two new caves opened last year: Crown Finish Caves in Crown Heights, Brooklyn distributes primarily to New York-area retailers, and Western New York supermarket juggernaut Wegmans has a massive 12,300-square-foot Rochester facility.

Cheese Aging 101

The overall guiding philosophy at the Murray's Caves, as described by Cavemaster Brian Ralph, is to take cheeses that arrive with "one note" and impart them with considerably more depth of flavor, like curing fresh pork legs into ham or fermenting grape juice into wine. Inside the lime-washed cinderblock caves, bacterial cultures accumulate in visible lines, not unlike the decades-worth of soot and spice that line old meat smokers.

And like smoking meat and making wine, aging cheese is no cakewalk. It's a time- and labor-intensive process that demands fanatical devotion to detail as well as considerable skill and patience. Brian's a former neurobiologist, and his assistant, Peter Jenkelunas, has a master's in food science.

Brian explained just what happens when a cheese ages in a cave. Some cheeses are aged externally, meaning bacteria and mold cultures on the surface of the cheese age it "from the outside in." Others age internally, meaning cultures directly inside the cheese age it "from the inside out."

With externally ripened cheeses, "mold or bacteria that cover the surface of the cheese digest their food by breaking down proteins and fats with enzymes," Brian explains. Different molds and bacteria use different enzymes and release different flavors and aromas into the cheese.

It's a similar story for internally ripened cheeses, but instead of enzymes being released by external molds and bacteria, here the enzymes are residual from the starter bacteria (the bacteria that begin the initial fermentation of the milk) and/or rennet."

Entering the Caves

Brian first leads me to a room replete with cleaning supplies and white clinical clothing that wouldn't look out of place in a hospital. To enter the caves, employees and guests must wash their hands, don lab coats, rubber boots, hairnets, and beardnets (most fashionable item of all); thoroughly scrub the boots with soap and solvent; and sign a form agreeing to the guest policy, which is mostly a list of personal hygiene regulations. All the fuss is to ensure that the cave aging process, which depends entirely on a tightly-controlled microbial ecosystem, isn't contaminated in any way. Among the instructions:

• "Visitors must be accompanied by a staff member at all times. You may not choose which one."
• "Tell your guide if you have any illness or disease that could present a food hygiene risk, no matter how embarrassing it might be."
• "Please wear the protective clothing given to you at all times when in the aging facility. Don't worry, it looks cool."

The facility is generally not open to the public, and the strict rules are only in place for employees and the rare occasions when visitors are allowed in.

After a brief trip through the load-in and packaging/prep rooms (both with characteristically tight entry/exit procedures for humans and cheeses alike), Brian and I head into the caves. Murray's has four separate caves onsite: the Washed Rind Cave, the Bloomy Rind Cave, the Natural Rind Cave, and the Alpine Cave. Different styles of cheese require vastly different mold cultures, temperatures, amounts of time, and moisture levels to age properly; you can't age a month-old Brie in the same room as a year-old Cheddar.

The Bloomy Rind Cave

The Bloomy Rind Cave is for soft-ripened cheeses like Brie that age from the outside in. Mold cultures from the cheesemaking process develop and mature on the rind of young, or "green" cheeses, then work their way inward. Highlights of the Bloomy Rind Cave include Selles-sur-Cher, Valençay, and Sainte-Maure de Touraine, all French goat cheeses aged for three to five weeks.

Given the short aging period and fragile nature of soft-ripened cheeses, Brian pays special attention to the temperature and humidity inside the Bloomy Rind Cave, which is kept slightly cooler and drier than the other caves. Lower humidity and cooler temperature ensure that the mold cultures don't Hulk out and grow too quickly. If they do, the cheeses will overripen and fall apart in a catastrophic process known as rind slippage, where the cheese slips off its rind like a snake shedding a layer of skin.

You can tell a properly aged bloomy rind cheese by the presence of a distinct creamline: A thin, gooey layer between the rind and the cheese that oozes just slightly when you cut it. That creamline is the result of enzymes on the rind digesting the proteins that bind the cheese's fat together, leaving a looser layer of dairy behind.

You can see that creamline in a slice of Saint-Maure, along with a lovely tang and a hint of lemon, all thanks to the work of Geotrichum candidum, a yeast-like mold also found on the Selles-sur-Cher.

The Alpine Cave

The Alpine Cave, the largest of the four, is in many ways the opposite of the Bloomy Rind Cave. The cheeses inside are harder, come in much larger wheels, and they're aged for months and years instead of days and weeks. Most importantly, these cheeses are aged internally (the only cave of the four like this), with the rind merely serving as a barrier to keep mold cultures and moisture from escaping.

The long aging time is necessary to "break [down] proteins and some fats which will create characteristic flavors in these cheeses, especially those that tend to be sweeter and nutty," says Brian.To ensure that the rinds don't dry out and crack, they're washed with water several times a week by the staff. (Younger cheeses at zero to five months are often washed with salt brines, which may include cultures, depending on the cheese).

Spring Brook Tarentaise, made in Reading, Vermont on a farm dedicated to teaching skills to inner city youth, arrives at Murray's about five to six months after production, and is sold after about 10 to 12 months of total aging. Brian has two wheels in the cave: a new arrival and a noticeably darker wheel nearing completion. While a sample of the younger cheese was certainly smooth and pleasant, it lacked the tang and spice of the older cheese. Additionally, the older cheese's texture stood out thanks to tyrosine crystals, small amino acid deposits formed by unraveling proteins as part of the aging process; they add a delightful meaty crunch to the cheese.

Marcel Petite Comte, a two-year-old French cheese is the other crown jewel of the Alpine Cave. Produced around the Jura mountains of eastern France and aged in the nearby Fort Saint Antoine, a former military installation with conditions ideal for aging cheese (possibly the most French thing ever described on the internet), this 72-pound behemoth tastes sublime. The flavors are challenging and complex—delicately smoky, sweet, and nutty—but still smooth and comforting. It's a cheese that would be just as welcome on a tasting platter as it would be melted on a sandwich (although at $35 a pound, you may want to go with the former).

The Washed Rind Cave

The Washed Rind Cave is home to many of the stronger-flavored and famously stinky cheeses, which as the name describes, includes many cheeses with water baths and brines. Washed rind cheeses are externally ripened, and the washes, which can include beer, wine, and cider, produce a variety of different flavors independent of the mold or bacterial cultures. Vermont's Barden Blue is aged in this cave, and it owes its strong flavor to its surroundings, as well as holes drilled in the side of each wheel that allow oxygen to creep inside and feed the cheese's defining Penicillium mold cultures.

According to Brian, "Depending how old the cheeses are, they will be washed with a certain percentage of salt water to help initiate halophilic [salt-loving] bacteria to begin ripening on the rind." These bacteria are responsible for the thiol compounds that lend washed rind cheese its signature meaty, pungent bite.

Outside the cave, two workers are carefully scrubbing 10-ounce, spruce bark-wrapped wheels of Greensward with a cider brine. This cow milk, Brie-like cheese is produced by Jasper Hill in Vermont (the same as the Vermont caves), and the wheels at Murray's were designed specifically for the menu at Eleven Madison Park. During the scrub, Brian leans down to smell the cheese, and notes hints of musty, basementy pu-ehr tea in the aroma, before sending it back into the cave. The wash is made using Virtue Cider from Fennville, Michigan.

The Natural Rind Cave

As you might guess from the name, cheeses in the Natural Rind Cave have rinds that form naturally as part of the cheesemaking process, as opposed to rinds added on afterwards for aging and preservation. Most of the cheeses in the Natural Rind Cave age externally like in the Bloomy Rind Cave, but given that most of the cheeses here are somewhat harder and physically larger, they require more time for their flavors and textures to properly mature, and some even feature varying degrees of internal ripening.

Cornelia, a semi-soft, buttery cheese from Point Reyes, California, is aged for about six months total, first in the Washed Rind Cave, then finished here. It's aged primarily using external bacteria, but some natural molds play a role later in the process. Hudson Flower, a sheep milk cheese from Old Chatham Sheepherding in Columbia County, New York, is one of the shorter-aged (three to five weeks) and softer cheeses in the Natural Rind Cave. However, it owes its strong flavor to a coating of hops, rosemary, and thyme, in addition to Penicillium candidum and Sporendonema casei molds.

On the firmer end is Montgomery's Cheddar from Somerset, England, which comes in 50-pound wheels that are wrapped in linen, rubbed with lard, and aged for over a year. But unlike many of the other cheeses in this cave, it's aged internally (hence the long aging time). Its rind forms in a different manner than the Alpine cheeses, which is why the Murray's sorting hat sends it to this cave.

The Cost of Aging

Making cheese takes plenty of work before it spends a day in an aging room. But if you wonder why some complex well-aged cheeses are particularly pricey (in the $30/pound range for several listed here), the answer can be found in the caves.

Running these caves isn't easy work, and the costs of labor, energy, and scientific expertise don't come cheap. But the reward is plain for anyone to see. Nothing tastes quite like a well-aged cheeses, and the only way to do it is the hard way.