How Blue Cheese is Made at Twin Sisters Creamery

Looking at a wedge of blue cheese with lines of blue mold rippling through it, you might assume that the mold got there by being injected into the cheese.

I have heard this from time to time as an explanation to children or from one adult to another, of how this family of cheeses is made.

While blue cheese is poked with needles, they are not “injecting” the mold into the cheese; they are helping it to grow. The mold is already present in the cheese, but it needs air to flourish.

Blue cheeses, the like of which include Roquefort, Gorgonzola, and Cambozola, are made by a process that is initially similar to that by which other families of cheeses are made.

Last April, two of my curd nerd pals, Elle and Izzy, and I traveled north from Seattle to Ferndale, Washington, to help make some blue cheese.

Twin Sisters Creamery, which boasts a cute storefront where you can shop and taste cheese while you watch the cheesemaking process through a big glass window, is where we were headed to help owner-cheesemakers Lindsay and Jeff Slevin craft a batch of their original cheese, Whatcom Blue.

Lindsay, who worked previously as a cheesemonger and a distributor, had wanted to make a cheese that was approachable to people whether or not they thought they liked blue cheese. They use raw Jersey cow milk brought in from a local family dairy, Twin Brook Creamery of Lynden, Washington, to make a few batches each week.

They now also make Whatcom Farmhouse, a creamy table cheese that is reminiscent of a cheddar, Whatcom Farmhouse with Peppercorns, which is studded with whole black peppercorns. But at this creamery, Whatcom Blue is the true OG. (Whatcom is the name of the county in which Ferndale sits.)

The day that we were there was the first cheesemaking session since the cows went out to pasture after spending the muddy Washington winter in their warm barns, eating dry hay. Lindsay said that the milk may not yet carry the full affects of the pasture grasses, which would affect the milk’s flavor and fat contents—making it grassier tasting, albeit lower in butterfat than hay-fed, late-season milk which has the most butterfat.

When we arrived, the milk tank had just arrived at the creamery and Jeff was hooking it up to a hose that would gravity-feed the milk through the wall to the creamery and into the cheesemaking vat. Since the Slevins work with raw milk, they take pains to keep it at the correct temperature and to minimize the opportunities for the milk to come into contact with other surfaces.

Being involved in cheesemaking causes you to become overly aware of how filthy everything is outside. Because food safety is the primary concern, you have to make sure that you aren’t touching your phone or your camera and then touching the milk; you can’t just come in off the street in your regular old shoes; and you certainly can’t have your hair down and flying into the vat.

In the name of cleanliness, you wear sanitary rubber boots and a sanitary outfit that you change into before entering the make room. You have to walk through a stream of sanitizer before you enter, and you are constantly sanitizing your hand and your arms. You’d think that cheesemakers would have the driest skin as a result, but as Lindsay pointed out, the contact with the whey in the cheese vat moisturizes your skin and makes up for that constant sanitization.

Once the milk begins filling the vat, there is a lot of back-and-forth between the make room and the little laboratory-office just outside the door. Lindsay is constantly checking the temperature and pH of the milk; she tests samples and records times, dates, and a blur of numbers.

As a cheesemaker, you record everything—from the weather that day to who was in the make room with you to the exact temperature and acidity level of the milk at the moment you start working with it—on something called a “make sheet.” It’s like a transcript of the recipe that records every factor that might affect the quality of the milk and the cheese. If you have a fantastic batch of cheese, you look back at that day’s make sheet to figure out what concoction of fortuitous moves you might use to recreate that excellence in the future.

Artisanal cheese is special like that, because everything has an affect on the cheese. Even coming from the pasture, the milk might be affected by what corner the cows were eating in that day, whether or not something scared them, if there was rain, and also where the cows are in their lactation cycle, the ambient temperature, and so on and so forth.

An artisanal cheesemaker adapts her recipe to fit the milk she gets each day, as opposed to an industrial cheesemaker, who adapts the milk to fit his recipe so that it is the same every single day. There are variances present in the creation of artisanal cheese that just aren’t there in industrial cheesemaking—and the skill involved in making up for those variances is what makes artisanal cheeses so special in a world in which everything is manufactured to be the same.

Working with raw milk as they do, Lindsay and Jeff are providing an expression of the milk and the northwestern Washington terroir from which it came—and so every day’s make sheet will show a collection of different factors.

While data is being recorded, the milk hangs out in the vat, slowly being warmed. When the temperature reaches a certain point, Lindsay adds her bacterial culture, which includes starter cultures that will aid in the beginning of the cheesemaking process, and secondary cultures, which will have an affect on the cheese’s ripening, flavor development, and also provide it with its signature blue veins.

Mixing the starter culture

As you might expect, the blue mold culture, which is a freeze-dried powder, is blue. Yet it is the tiniest amount of mold in comparison to the big tub of milk into which is dumped.

Mixing the blue mold

The Slevins use about 500 gallons of milk to make around 650 pounds of cheese. It’s amazing that you can take a fluid substance and get more out of it than you started with—and that doesn’t even account for the gallons upon gallons of whey that will be produced as a byproduct of the process.

While we are waiting for the milk to set, Lindsay takes us out into the shop for pizza and a little cheese tasting. Through the window, we can see Jeff preparing the room for the physical parts of the cheese make. Lindsay has a timer going so we stay on schedule; it should take about an hour for the milk to set.

From right to left: Whatcom Farmhouse, Whatcom Farmhouse with Peppercorns, sour cherry relish, and Whatcom Blue.

After we have eaten and relaxed, Lindsay announces that it’s time to get back into the room.

We put on hair nets, change into the white cheesemaking gowns and guest booties, resanitize our hands, arms and fingernails, and walk through the stream of sanitizer to re-enter the make room. Then we get to watch while the rennet is added to make the milk coagulate and firm up.

Adding rennet to the vat.

Until this moment, the milk was gently being swirled by big, stainless steel paddles, ensuring that the cultures were evenly incorporated into the entire vat. Those paddles are turned off as the milk is left to coagulate. Lindsay knows about how long it should take, even if the time varies by each batch of milk, and she uses her fingers to check the curd formation at just about the right time to see how the vat is progressing.

Checking the vat’s coagulation progress.

I might also note that country music is playing in the make room this entire time. Lindsay tells us that she and Jeff have it up so loud sometimes that you can’t hear one another speak; they don’t need to talk while they make cheese—they have the entire process down to a science.

When the curds are formed, the physical work begins. Lindsay and Jeff bring in their cheese knives: big, metal harps with evenly spaced strings to cut the curds into the perfect size. Lindsay goes horizontally through the vat, and Jeff goes vertically through vat, slicing at a slow, even pace. Since one of the harps is missing a string, Lindsay follows Jeff with a long knife, using a practiced hand to slice exactly where that missing string should have cut through the curd (see cover photo).

A lengthwise slit in the vat before the curds are cut horizontally into cubes.

The paddles are turned on again, slowly mixing the gelatinous cubes in their whey. We helpers are allowed to dip our arms into the vat to help mix them up, ensuring that the curds don’t clump in odd shapes, just out of reach of the stirring mechanism. Izzy takes a lot of pictures, stopping occasionally (after sanitizing her hands, of course!) to help declump the curds. But Elle and I are have our hands and arms in the vat pretty much the entire time.

After all, you want the curds to be evenly sized as well as evenly dispersed. The more even everything is, the more likely it will be for the wheels to age uniformly.

As Lindsay will tell us several months later, that batch is one of the butteriest, creamiest batches of Whatcom Blue that they have had. She says that is due in part to the number of hands that were in the vat helping make the curds even and supple.

While we dutifully perform our clump patrol in the vat, Lindsay occasionally removes a small fingerful of curds and throws them at one of the stainless steel draining tables. She will know that the whey should be drained off when the marshmallow-like curds bounce at exactly the right angle. This is where the art of cheesemaking really comes in, because knowing when the curds are ready is about practice and feel rather than numbers and data.

Removing the paddles from the vat; they must be removed and re-installed in a specific order.

The curds bounce correctly, and the paddles are removed from the vat. Things start to happen at a very fast pace, and we almost feel a bit like we are in Lindsay and Jeff’s way—it really is a ballet that they practice together as they rush to get the curds drained and hooped before the pH gets to a certain level.

The whey is pumped out of the vat and into a whey-holding tank outside the creamery. A local farmer will come pick it up later to feed his pigs.

Curd scoops and the molds for the cheese wheels have all been sitting patiently in huge tanks of a food-safe sanitizer solution, but in this moment the scoops are put to action and the molds are lined up on tables as tightly as they will fit.


Scooping the curds into their molds is heavy, back-breaking work. The Slevins have plastic scoops that they use to swoop the curds out of the vat and evenly into the molds, which sit on a metal frame over the middle of the vat, held in place by a top frame with holes that perfectly match the placement of the cheese molds. As the molds are filled, they are rushed over to the draining tables, where they sit at a slight angle and their remaining whey drains off into buckets hanging just under each end of the table.

Jeff scooping the molds of curds away from the vat to their draining tables.

Each of us is allowed to help fill a table’s worth of molds. The tall, plastic cylinders seem so large compared to the compact wheels of blue cheese that Elle and I sell in our stores. The creamery will produce around 250 small, 2.5- to 3-pound wheels of cheese out of those molds.

We help out by pushing the curds around the vat so that they can be easily scooped up from a single position in the middle of the vat. No curd can be left behind and wasted!

We also help out by switching the heavy buckets off of the draining tables as they fill, and we get more molds out of their sanitizer pools as they are needed, placing them on the tables to await being filled.

And finally, after a pretty short amount of time and a whole lot of work, all of the wheels are molded and draining, and it is time to clean up the make room. The rest of the whey is pumped out, the vat is scrubbed and sanitized, all of the tools are scrubbed and sanitized, the floors are hosed down and sanitized. Everything must be thoroughly, truly cleaned.

We get to leave for the day, but Lindsay and Jeff will come back to the make room throughout the week to salt the wheels one day, and later to pierce them with needles so that the blue mold culture—the penicillium roqueforti, will come alive and flourish in the air that enters the wheel through those piercings. They will be flipping the wheels and aging them in their blue cheese room. And on other days of the week, they will make batches of Whatcom Farmhouse and Whatcom Farmhouse with Whole Peppercorns.

Wheels of Whatcom Farmhouse and Whatcom Farmhouse with Whole Peppercorns aging in cryovac so that they do not grow a rind.

This is the short version of how blue cheese is made. The cheesemaker becomes an affineur—a cheese ripener—after the cheeses leave the make room. She controls the wheels’ humidity and temperature, flips them, and charts their progress until they are ready to be wrapped up and shipped off for sale.

Three months later, Izzy (who, at the time, drove a cheese truck for one of our local distributors, Peterson Cheese) tells Elle and I that our cheese is ready, and that she has a wheel for each of us from the creamery. It is exciting to cut into that butterball of blue cheese that we helped make—sort of like having a baby, I suppose, but on a much smaller scale than that of the cheesemaker who produces hundreds of these cheese babies every week and follows them daily as they age and ripen and become ready for sale and consumption.

Proud cheese mama showing Izzy (left) and Elle (middle) her aging wheels.

While we sell Twin Sisters Creamery’s cheeses in our stores at PCC Community Markets and the cheeses are also available at other retailers in the Pacific Northwest, you can always stop in Ferndale, Washington, and pick up some Whatcom Blue straight from the source.

If Lindsay or Jeff is around, be sure to thank them for their hard work. And if they are making cheese, definitely give the process a peep through that big window in the showroom. Then you, too, will be able to see how blue cheese is made!

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