Blue Cheese

Let’s get one of those questions out of the way. Gorgonzola is not just the Italian name for blue cheese. Like Parmigiano-Reggiano and Gruyère, it is a unique style of cheese manufactured according to specific regulations defined by European Union law. These regulations, which are divided into two tiers called Protected Designation of Origin (PDO) and Protected Geographical Indication (PGI), limit a given cheese’s production to a specific area and include standards for everything from ingredients to the size of the wheels to the number of days a cheese must be aged. Seven of the imported blue cheeses highlighted here have PDO or PGI status; the other two are trademarked and can each only be made by one specific company. The American cheeses are unique creations often inspired by blue cheeses made abroad but made here by specific cheesemakers in varying locations. American-made blue cheeses cannot be awarded PDO or PGI status.

Although these 14 blue cheeses vary in size, shape, flavor, and intensity, there are many similarities in how they’re made. In a lot of ways, the process is similar to the processes used to make other cheeses. The milk is heated; cultures are added for flavor; and rennet or enzymes are added to make the milk coagulate into curds, which are drained from the liquid whey and formed into wheels. But for blue cheese, strains of mold are added, either as a liquid to the milk or as a powder sprinkled over the curds. Later, after the wheels are formed, large metal needles are inserted into the wheels, creating holes that allow oxygen to enter and activate the dormant mold spores.

All blue cheeses are made with the same mold, Penicillium roqueforti. Cheesemakers select specific strains (or a combination of strains) to produce the colors, intensities, and flavors that they want in their cheeses. In order for the mold spores to grow properly, the cheese curds have to be the right size. Dean Sommer, cheese technologist at the University of Wisconsin–Madison’s Center for Dairy Research, explained that blue cheese curds are usually fairly big, about ½ inch in diameter, and form a wheel with an open structure. When the wheels are pierced, each needle creates “a highway for oxygen to enter into the interior of the cheese,” Sommer said. Those highways transport oxygen to the “streets” and “back roads” between the curds, allowing the spores to grow and develop flavor. If the curds are too small, they can collapse on themselves and restrict the flow of oxygen. When that happens, mold growth—and the development of flavor—is restricted to the hole created by the piercing needle, resulting in a cheese that’s fairly acidic and tastes more like feta than blue cheese. 

Depending on the size of the wheel and the style of the blue cheese, each cheesemaker customizes how and when the piercing occurs. It can be done manually by inserting an individual needle into the wheel at various intervals or mechanically by inserting a number of needles welded onto a large plate into the wheels in unison. Roquefort, for example, is pierced about 40 times while wheels of Bayley Hazen Blue are pierced about 100 times. Cheeses with comparatively softer curd structures that are more prone to collapsing, such as Gorgonzola, may be pierced twice over a period of several days to ensure proper mold growth inside the wheels. Adjusting their piercing processes is an important way that cheesemakers can control mold growth, producing everything from the delicate, marble-like blue veining of Stilton to the big, hollow pockets of mold typical of Roquefort. 

The milk is another major variable. Most blue cheeses, especially those made in the United States, are made with cow’s milk. There are a few notable exceptions, including Roquefort, which is made with sheep’s milk, and Valdeón, which is made mostly from cow’s milk and a bit of goat’s milk (and sometimes sheep’s milk). Compared to the grassy, tangy flavor of goat’s milk and earthy, gamy flavor of sheep’s milk, the flavor of cow’s milk is milder. But, depending on the breeds and their diets, even the flavors and colors of milks gathered from the same type of animal can vary. The milk of cows that eat a lot of fresh grass in summer will contain more carotenoids (plant pigments) and will appear darker in color, and the cheese made with it will have a yellow hue. According to David Gremmels, president of Rogue Creamery, a cheesemaker in southern Oregon, the flavor and composition of his herd’s organic milk is at its finest in the fall, so that is when he chooses to make his Rogue River Blue. Gremmels and other cheesemakers also stressed the importance of the milk’s freshness. The milks they use to make their cheeses sometimes come from their own herds and, in at least one case, can be transported from the dairy parlor where the cows are milked to the cheese vat in as little as 4 hours.

In many cases, the milk is treated in some way. It’s sometimes homogenized, a process that breaks down the fat globules so that they stay incorporated in the milk instead of rising to the top, which is not typically done with milk used to make other cheeses. “By breaking up the larger fat globules in the milk into smaller globules,” Sommer explained, “there will be more surface area of fat globules for the molds to act on, resulting in more flavor development.” In addition to generating bold blue cheese flavor, homogenized milk produces a cheese that’s very white in color and has a very creamy mouthfeel, two hallmarks of Danish blue cheeses and those inspired by them, including Point Reyes Farmstead Cheese Company Original Blue. Finally, the milk can be pasteurized at a high temperature to kill off potentially harmful organisms, treated at a relatively low temperature, or kept raw. In past comparisons of cheeses, we have sometimes found cheeses made with pasteurized milk to be milder than their raw-milk counterparts, but that is not the case with these blue cheeses. Due to the milk, mold, and cultures, even the mildest ones are rich in flavor.

Blue cheeses come in a number of shapes and sizes. Cashel Blue, from Ireland, is formed into 3.3-pound wheels, while wheels of Gorgonzola can weigh as much as 26 pounds. After the wheels are formed, they’re salted or placed in a salt brine. In addition to flavoring the cheese, the salt pulls moisture out of the wheel and starts the formation of a dry, firm natural rind that eventually grows mold of its own. Manufacturers encourage rind development for many styles of blue cheeses. On the other hand, the exteriors of rindless blue cheeses, including Roquefort and Danish blues, are intended to have very little mold growth and instead be relatively smooth and mild. If any mold does form on the exterior, it is gently scraped off. Cambozola, a sort of Camembert-Gorgonzola hybrid made in Germany, is an outlier among blue cheeses. After the wheels are salted, they are sprayed with a white mold that produces the type of rind usually found on soft-ripened Brie and Camembert. 

The particulars of the aging process—both the length of time and the temperature and the humidity of the environment—also affect the flavors and textures of all blue cheeses. To start the aging process, wheels are usually placed in relatively warm, high-humidity environments to encourage the growth of the blue molds. Then, to control the rate of mold growth and to allow the cheese’s flavors to continue developing, the wheels are transferred to cooler, drier locations. Sommer pointed out that although they’re not readily available to many manufacturers, natural caves are ideal spots for aging blue cheeses because their conditions are very consistent. (By way of comparison, he described how the air rushes in or out of a cooler each time its door is opened.) There is another advantage to aging blue cheeses in caves: Many, including the natural limestone caves of Roquefort-sur-Soulzon in France and the sandstone caves of Faribault, Minnesota, act as a natural “sink,” absorbing the ammonia gases that are naturally produced as the cheeses age and mature. 

During the aging process, the wheels are turned regularly to ensure that they mature evenly. As the Penicillium roqueforti spores grow and build flavor and the starter cultures break down the cheese at a molecular level, the mold digests both protein and fat, creating a variety of smaller molecules with savory, mushroomy, tangy, buttery, herbaceous, or other flavor notes. Some blue cheeses that are aged for long periods of time develop crunchy crystals called brushites, which are similar in texture to those found in Parmigiano-Reggiano or aged gouda. At varying points during the aging process, some manufacturers coat their wheels with wax or place them inside loosely sealed plastic bags or plastic wrap. Sommer explained that these wrappings create “microenvironments” of precisely the right humidity, allow some oxygen to penetrate the cheese, and also prevent air currents from drying out the exteriors of the wheels. Thus protected, the interiors of these cheeses can continue aging until the desired texture is achieved. In some cases, as with traditional Valdeón and Rogue River Blue, the wheels are wrapped with leaves that have been sterilized, often by soaking in alcohol or liqueur. The leaves imbue the cheeses with an earthy flavor (plus the flavor of the liquid they’re soaked in) and act as a moisture barrier, giving the cheese a creamier texture. Those leaves generally remain on the cheeses when they’re shipped, but most other cheeses are uncovered and wrapped in aluminum foil. All told, the aging processes of the different cheeses we looked at can take anywhere from eight weeks to nearly a year. 

The result of all the variations in manufacturing methods is a category of cheese with many distinct styles covering the full range of flavors: salty, sweet, acidic, bitter, and savory. Some are robust, piquant, and peppery, while others have a softer, mellower, earthy flavor. The textures of some are firm, but others are so soft that they’re almost gooey; they can be dense and fudgy or firm and crumbly. 

All the 14 blue cheeses featured here are unique and worth trying. They are listed by where they are made, with background information and tasting notes included to help you decide which ones suit your flavor and texture preferences. Whether you already love blue cheeses or are just beginning to explore them, I hope you’ll give a new one a try.