It was the perfect afternoon for a beer festival. On a bright August day with a high of 77°F, a handful of brewers poured for roughly 1,500 people on the sprawling, 19-acre grounds of Trillium Brewing Company outside of Boston. One of the stations was dedicated to Belgium’s famed Cantillon and Drie Fonteinen, which offered some of the most celebrated beers in the world. But on this Saturday, there was little wait for either. Instead, a line stretched in front of a table with machines that churned a cream-colored frozen slush. Of the six beers that Trillium poured for its Field Trip festival, the two that received the most attention were “foamy freezes” served from a slushy machine. Trillium’s coconut-pineapple foamy freeze was first to run out that day, followed soon by the pink lemonade variety. While novelty may have had something to it, Trillium’s foamy freezes also speak to the creative, sometimes counterintuitive nature of beer trends. Over the last 40 years, brewers have experimented with an array of flavors, processes and ingredients. They’ve turned classic styles into comfort foods like pastry stouts or hazy milkshake IPAs brewed with fruit purées and lactose. That brewers have dipped into frozen desserts akin to shaved ice or slushies is just another extension. Slushy beers don’t render the Belgian classics irrelevant, of course. They simply give brewers a new creative outlet, and perhaps better Instagram engagement. https://www.instagram.com/p/B9cPU4yFsZV/ At the same festival, Henok Fentie, the founder of Sweden’s Omnipollo brewery, served some of his beers beneath a soft serve-like topping also poured from a specialty freezing machine. Fentie, largely credited with popularizing this method, has brought slushy machines to festivals around the world for the last five years. A search of the brewery’s social media channels and related hashtags reveals scores of fluffy-topped beer slushies. Drinkers might be reminded of bia wun, sometimes called "jelly beer,” a Thai tradition where bottles of beer are inserted into a rumbling cooling vat. They emerge as single-serve, jelly-like slushies. To brew a beer slushy from scratch, you can’t simply pour ingredients into a slushy mixer, flip a switch and expect to produce a frosty treat with perfect consistency. Recipes must be able to withstand extreme temperatures and constant agitation. Because freezing can accentuate the sensation of bitterness, beers like hoppy IPAs often don’t fare well. Beers with more than 20 IBUs, a relatively mild level of bitterness, will likely be difficult to enjoy as a slushy. Instead, brewers largely opt for styles like gose, Berliner weisse or simple ales that can benefit from the addition of fruit purée. Some brewers brew a large batch of one style of beer and then siphon off a smaller portion to freeze. The ideal temperature for beer slushies is around 27°F. “We thought we would get a lot of backlash from some beer purists, but really, the response has been overwhelmingly positive. We sell out every time we put one on.”—Mike Pallen, owner, Mikerphone Brewing “For most of our Berliners that we convert into slushy, they are at five to six Brix [a measure of sweetness; one degree Brix equates to 1 gram of sucrose in 100 grams of solution], so we need to add simple syrup to get the Brix up to 15 or 16,” says Mike Pallen, owner of Mikerphone Brewing in Elk Grove Village, Illinois. Coca-Cola, for example, is 9 Brix. “For our sweeter stouts that we convert, less sugar is needed, since the starting Brix on those beers is higher.” Pallen started to make frozen beer last year and purchased factory slushy machines that cost approximately $5,000 each. The investment paid off. Every time one of the beers, called Mikeees, is made, he says, it quickly sells out. Mikerphone serves its Mikeees in 16-ounce glasses shaped like Solo cups, with thick straws. The brewery sometimes tops the beer with whipped cream and a cherry, a cocktail umbrella or a fruit garnish. “We thought we would get a lot of backlash from some beer purists, but really, the response has been overwhelmingly positive,” says Pallen. “We sell out every time we put one on.” https://www.instagram.com/p/CAdPYErFr1c/?utm_source=ig_embed It’s a similar story in Greeley, Colorado, where Kyle Carbaugh, owner/brewer of Wiley Roots Brewing Company, experiments with fruit slush beers. High-end equipment freezes beer down to its optimal temperature within six minutes, and the freezers kick back on every few minutes to maintain slushy consistency. This is preferable to the constant churn of typical slushy machines that can quickly break down carbonation. Last summer, Carbaugh experimented with to-go frozen beers. He purchased 12-ounce, BPA-free plastic pouches, filled them with CO2 and beer, and then froze them. The first batch of 100 pouches sold out in five hours, he says. As brewers continue to push boundaries, frozen beers can likely grow in popularity. Professional-grade machines could become a common sight at breweries alongside centrifuges and fermenters. While this summer’s beer festival circuit might be curtailed due to the novel coronavirus pandemic, brewers say they are going to continue to tinker with recipes. “We’re not going to mess with something like a traditional German lager,” says Carbaugh. “But beers like this are fun, and why not experiment? That’s what got so many of us into brewing to begin with.