Within the gables of a crumbling gray row house facing a cobblestone lane in the shadow of Brussels’s Tour du Midi, a bit of magic is unfolding. As a venerable brewer shuts the front doors to his family-owned brasserie three floors below, a gentle breeze wafts through open windows and louvred vents. Swirling currents of air percolate through the brewery’s attic, dispersing a unique blend of microbes carried aloft from the banks of the Senne. The microorganisms settle upon a shallow open vat of tepid, turbid wort and begin the years-long process of transforming malt sugars into lambic, pride of the Pajottenland.
Such sepia-toned scenes are as romantic and alluring as the myth of the Wild West, but successful spontaneous fermentation leaves less to chance than legend suggests. Airborne bugs do make their way into Belgian wild ales, to be sure, but it is largely the resident microbes—caked on walls, joists, and barrels—that hold the signature terroir found in every bottle of lambic, gueuze, kriek, and framboise.
Indeed, the virtuosos at Brasserie Cantillon recently gained a bit of press for having sprayed down the brick walls and wooden rafters of their new building with a healthy dose of the brewery’s elusive lambic. The goal? Ensuring that the new location maintains the same blend of critters as the old one. It takes years—more than a century, in fact—to develop just the right mix for a classic example such as Cantillon Gueuze.