Williams Bros. Brewing Co. brewmaster Bruce Williams goes seaweed picking at Appin Bay on the west coast of Scotland.

It’s high tide in the world of so-called “superfoods,” and seaweed is in. Those translucent green chips you’ve seen your granola neighbor snacking on are but one of the many forms that ocean-grown algae can take. In recent years, restaurant menus have showcased seaweed salads and seaweed noodle plates. You can eat seaweed simmered into soup, blended with a smoothie or ground inside a pill. It’s come a long way past a simple a sushi roll.

And for good reason. The nautical vegetable (yes, seaweed’s a vegetable) is a phenomenal source of iodine, a nutrient essential to maintaining a healthy thyroid and regulating hormone levels. Its high calcium levels have also made it a popular replacement for dairy in paleo and vegan diets. Why wouldn’t brewers—who attempt making beer with every ingredient imaginable—experiment with seaweed?

Chances are you’ve already tasted several beers made with seaweed without even knowing it. Irish Moss, a type of edible red seaweed, has been used as a clarifying agent by commercial brewers and homebrewers for decades. The ground algae is usually added to the kettle along with hops; its negative electrostatic charge attracts sediment like a magnet, making it simpler for brewers to remove the clumps and produce a clean, clear wort.

But in recent years, seaweed’s been promoted from beer janitor to a bona fide, flavor-contributing ingredient. David Carlson, owner of Marshall Wharf Brewing Co. in Belfast, Maine, has been using sugar kelp grown in the Belfast harbor to make his seaweed ale, Sea Belt, since 2014. Working with local kelp farmers, Carlson puts a seafaring twist on the base beer, MacFindlay’s Scotch Ale, with six pounds of dried seaweed, the bulk of which is added to the boil kettle. (That amount of of dried seaweed, Carlson says, is the equivalent of 60 pounds of the fresh, wet stuff, and is about the size of a standard carry-on suitcase.)

“Having worked with oysters, we kind of knew what we were going to get out of it,” Carlson says. “The liquor in our oysters tastes like the ocean. In my mind, I was hoping the sugar kelp would come across that way as well. There’s definitely something in there that’s hard to put your finger on.”

Carlson says Sea Belt has become one of his most popular beers; he brewed it five times last year and is trying to build up to making it once a month. What’s behind the sudden desire for—or, at least, acceptance of—seaweed in our beer? Hard to say, but it may be tied to the rise in the popularity of gose, the saline German ale that helped the American palate become accustomed to saltiness in beer.

“It’s funny to see the trend with goses these days,” Carlson says. “When we get the dry seaweed, it’s coated in salt crystals. I feel like we could rinse it off and make a gose out of it.”

Carlson doesn’t claim to have come up with the idea for brewing with seaweed on his own; he credits Kelpie, a beer that’s been produced by Scotland-based Williams Brothers Brewing Co. since 1995, as his inspiration. Brewed with fresh bladderwrack seaweed grown of the Scottish coast, the dark, chocolatey brew is itself a nod to history: Before the mid-1800s, many Scottish alehouses close to the coast would fertilize their barley fields with seaweed. The algae, as you might imagine, infused the soil with a unique mineral blend that gave the barley an unmistakeable maritime flavor, which Williams Brothers recreates by stuffing fresh seaweed in among the barley in the mash tun.

Using kelp as a main beer ingredient is no walk on the beach, says Mark Osborne, owner of Adroit Theory Brewing Co. in Purcelville, Virginia. He first brewed his imperial seaweed and marshmallow stout, Death of Cthulhu, as a collaboration with fellow Virginia beer-maker Reaver Beach Brewing Co. The brewers determined that the best way to capture the kelp’s of-the-sea quality would be to incorporate it into the mash, but they failed to factor in how the dehydrated seaweed would react when exposed to water. It immediately swelled in size and became thick as jelly.

“It clogged our machinery in every way possible,” Osborne says.

Despite the difficulties of working with seaweed, Adroit Theory produced another batch of Death of Cthulhu in late 2016, and other breweries have kelped out their beers as well. New Zealand-based Garage Project makes its Umami Monster with kombu (a type of edible kelp common in Asian cuisine), fermented bonito flakes, smoked malt and sea water in an attempt to capture the essence of the savory flavor known as umami. The beer is brewed once or twice a year depending on how much kombu brewers are able to forage from New Zealand’s beaches. Blue Point Brewing Company in New York also adds seaweed to its 7.7% IPA, Prop Stopper, to augment the beer’s hops with a saline snap, and The Collective Brewing Project in Fort Worth, Texas, gives its ramen-replicating gose, Cup O’Beer, an authentic umami note with seaweed-cured Japanese sea salt. If nautical nonsense be something you wish, you should probably try them all.


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