Black Project Supercruise: Cofermenting with Wild Yeast

James and Sarah Howat of Denver, Colorado’s Black Project Spontaneous & Wild Ales love brewing with grapes, not just for the flavor contributions they provide, but also for the fermentation benefit.

Jamie Bogner Mar 14, 2018 - 3 min read

Black Project Supercruise: Cofermenting with Wild Yeast Primary Image

Black Project is dedicated to spontaneous fermentation—no pitched cultures, no inoculated barrels, just 100 percent coolship-cooled wort and the airborne culture that then ferments the beer.

With many of their spontaneous beers conditioned on fruit, they add the fruit to finished beer so that refermentation occurs but the basic character of their spontaneously fermented, lambic-inspired beer remains in balance.

With grapes, however, they take full advantage of the wild microflora—wild yeast and bacteria—that live on the skins of grapes (the same microflora that winemakers have used for millenia to ferment wine). That microflora, together with whatever the wort picks up through their coolship, handles all the fermentation duties.

“We crushed and destemmed the grapes in house, then did an extended maceration on them, punching them down every day and letting them soak on the skins,” says James Howat. “We did a free run to get a little lower acidity and tannin extraction (also because we don’t have a press that’s worth a damn), and it’s a little bit wasteful, but we got sixty-ish gallons of juice per thousand pounds of fruit. Then we took that juice and blended it with beer out of the coolship.”

Howat suspects that the wild culture from the grapes handled more of the fermentation load because the amount of wild yeast typically found on grape skins is much higher than that found in ambient air.

While the fruit they acquire from vineyards on Colorado’s Western Slope varies from year to year, they’ve developed some clear favorite varieties. “Cab Franc this year was really berry and jammy,” says Howat. “Merlot is more stereotypical ‘red wine’ to me—good tannin and nice acidity. Malbec was chocolatey in an almost bizarre way, but also fruity—like cherry hot chocolate, almost.”

Howat insists the relationship between sour beer and great wine is closer than most winemakers are willing to acknowledge. “There have been some studies that show that Brettanomyces plays a lot larger role, in fine red wines especially, than people talk about,” says Howat. “I think that’s great.”

Jamie Bogner is the Cofounder and Editorial Director of Craft Beer & Brewing Magazine®. Email him at [email protected].