Why Pasteurization Can Be Good for Fermented Drinks

The subject of pasteurization doesn’t usually inspire poetry. I’m not a poet, but I am the beverage director at a natural wine–oriented spot in Oakland, California, called DAYTRIP, where I spend a lot of time trying to open natty-inclined minds to the value—beauty, even—of pasteurization. When we talk about it here in the U.S., it tends to prompt commentary from extremes: the Goop-reading libertarian homesteaders who wouldn’t touch pasteurized milk with a 10-foot pole, and then those concerned parents who live their lives to the letter of whatever the FDA publishes.

Both of these perspectives ignore a key truth about pasteurization: It can actually make some beverages, even fermented beverages, better. Or, as I like to half-jokingly tell the skeptics I work with and serve: Pasteurization can be sexy. For the most part when we’re talking about fermented beverages, pasteurization has very little to do with safety. Instead, pasteurization is a tool that allows producers to send their product out into the world without worry, is gentler than many added preservative alternatives, and can actually enhance certain flavors and characteristics in a drink.

Pasteurization is a form of heat stabilization, wherein sustained heat is used to slow or stop microbially derived transformation in a food or drink. The narrative in the U.S. and Europe is that the process was “invented” by Louis Pasteur, a 19th-century microbiologist based in the Jura region of France. However, heat stabilization had been used in sake for hundreds of years before Pasteur. In Japan, it gained prominence during the Muromachi period (1333–1578), at roughly the same time sake was transitioning from being a beverage made by monks to one made by independent breweries. In sake-making, heat stabilization is called hi ire (火入れ) and may happen once or twice, depending on what a brewer is trying to do.

Yoshihiro Sako makes sake at his brewery, Den Sake, in an industrial lot in West Oakland that also has a lumberyard, some Burning Man art projects and one of the Bay Area’s great soba spots, Soba Ichi. To pasteurize his sakes, which he makes from California-grown rice, Sako uses a rustic by-hand process called bin hi ire (瓶火入れ). Once the sake is bottled, Sako sets up a rig involving a cooler that’s fed hot tap water through a hose, a bain marie–type steam heater on top of a gas burner and, finally, a crate that is pumped full of cold hose water. The initial warm bath is to prevent shocking the sake and the glass bottle; the hot bath on the stovetop heats the sake to a little bit over 140°F; and the cooling tub gets the sake ready for storage. 

Sako also makes a small amount of unpasteurized namazake at Den. When sake is unpasteurized, the still-active koji continues to produce glucose and glutamates in the months after it’s bottled, making the sake more plush with sweetness and giving it an extra savory boost. These characteristics can be fabulous in a lot of sakes, but Sako doesn’t want them in all of his. “Namazake can change drastically over time, but the pasteurized one changes much more slowly,” Sako says. “The only significant difference between pasteurized and unpasteurized sake is that pasteurization removes some [microbial] elements in the sake that create change. Right after pasteurization, the flavor is different, and the pasteurized one becomes a little more slender. You can taste that the flavor becomes leaner and cleaner.” On the extreme side, badly stored unpasteurized sake can develop an out-of-balance explosion of lactic acid from the Lactobacillus fructivorans bacteria. The resulting flavor profile is known as hiochi-kin (火落ち菌), and is considered a flaw by a majority of sake professionals. But Sako’s approach—that neither his pasteurized or namazake is inherently better than the other, and that there is space for both—is reflective of how the world of sake is, for the most part, less dogmatic on the subject than the world of wine.

One of the reflexes from the natural wine world that’s developed in the last 10 or so years is to try to neatly map the technical ideas and concepts of wine onto other beverages. This is where we lose sight of what is specific about those drinks. Unified Ferments is a Brooklyn, New York–based company that makes lively, complex fermented sparkling teas, which have been embraced in a lot of natural wine–oriented spaces. Young Stowe, one of the co-owners, thinks that too many products in the growing nonalcoholic category are trying to mimic preexisting alcohol products, limiting the kind of exploration that could turn N/A into an interesting standalone category. “There’s a lot of things fermentation can do—it doesn’t have to be the idea of wine,” Stowe says.

For years, Unified Ferments did not pasteurize its sparkling teas because the company didn’t have access to the right tools to do it affordably. This made cross-country distribution impossible, and selling to retailers and restaurants was stressful. Too often, after Unified Ferments had meticulously cold-stored and cold-shipped its product, a restaurant would contact the company to say something was weird with the bottles or that one was leaking. Once or twice, a bottle even blew up. Later, Unified Ferments would learn that the sensitive ferments were being stored at room temperature rather than refrigerated. 

For Stowe, just because “quality” wines aren’t pasteurized, force-carbonated or carefully controlled doesn’t mean he shouldn’t use those tools for his own drinks. “Our bottles, from our perspective, are basically unchanged by pasteurization,” he says. “And we think there are some things that are actually improved by it.” Unified Ferments makes its products with a wide range of fine teas, and Stowe and his colleagues noticed that teas with an oxidative, malty or roasty element—commonly found in oolongs and black teas—were enhanced by heat stabilization. They’re not sure whether it happens through caramelization, the Maillard reaction or some other chemical transformation, but the impact is noticeable and tasty. 

Eden Cidery is based in Newport, Vermont, a small town at the southern terminus of a lake that’s mostly in Canada. The company began as an ice cider producer, but today, Eden also makes a line of herb- and tincture-infused cider-based aperitifs with Deirdre Heekin; a number of sparkling ciders in bottles, kegs and cans; and other orchard-specific bottles and experimental stuff. Eden recently pasteurized its first batch of cans—a tactical decision and a transformative moment. Up until then, the cidery had been adding a preservative called Velcorin to some of its canned products to ensure that, regardless of storage conditions in warehouses and at retailers, the ciders wouldn’t develop microbe-related off-flavors or explode. Using Velcorin wasn’t Eden’s first choice, but it was the best option short of investing in a ton of new equipment. After the addition of Velcorin, the cidery noticed a significant period where the cider was “shocked”: muted, with the appley-ness and acidity thrown out of whack. The pasteurized cans, by contrast, don’t have those negative results. According to Riley Duffie Bresnahan, national sales director for Eden, “Pasteurization makes the flavors meld together a little bit more.” 

Duffie Bresnahan emphasizes that Eden makes different choices depending on the scale and market for its products: “We wouldn’t pasteurize our bottles and our ice cider because the small batch size [typically 600 gallons for a batch of ice cider] allows us to control it.” In contrast, Eden’s canning runs are typically 6,000 gallons. “When it goes out in the world, we have such little control of how it’s treated, so pasteurizing allows us to have a little peace of mind.” 

Today, when food and wine geeks think of the Jura, they don’t think of Pasteur carefully heating up beet juice ferments in his lab in an attempt to prevent unwanted sourness. Instead, the Jura evokes juicy red wines, Comté cheese and nutty, oxidative white wines—none of which would ever be pasteurized, unless it’s truly some bottom-of-the-barrel stuff. But the idea that heat stabilization can only limit complexity is itself limiting. Pasteurization isn’t an on/off switch for complexity. Yes, it slows or stops microbial activity—which some might say is the “life” of the drink—but living, ever-changing microbial flavor isn’t the only definition of complexity. Without pasteurization, we would miss out on so much: in sake, a rich, centuries-long history; in cider, the ability to reach new audiences; and for fermented nonalcoholic beverages, the ability to go out into the world and blow people’s minds—without the bottle exploding.