One of the most user-friendly “sour” styles is one that I don’t see brewed all that often—which is unfortunate, because it’s one of the easiest to get right. I’m talking about the oud bruin, or Flemish brown ale. It shouldn’t be in-your-face sour, so if you undershoot the acidity, you’re still in good shape. It’s also more malt-driven than other acidic styles, so there’s a cushion of flavors to help balance if you go too sour. Finally, one of the riskier steps—oak-aging—is optional. All of that makes oud bruin a good “starter” style for those who want to get more adventurous, while advanced brewers can have a lot of fun and really dial in their preferences.
Style: Flemish brown and red ales are very similar—in fact, Belgian brewers have been known to use the terms interchangeably; their beers exist on a spectrum of color and flavor, despite regional differences. Both exhibit fruit flavors, both are sours, both can benefit from some “aged” sherry-like flavor. Where there are differences, the “red” ales might lean more toward berry-and-cherry notes, while the darker “brown” ales may rely on the darker fruit flavors of fig and raisin. While the red ales of West Flanders tend to have a characteristic acetic touch that can lead to a bright acidity, the browns of East Flanders tend to avoid acetic flavors and have a softer, more subtle lactic acidity. They can finish a bit sweet, balanced by the acidic bite rather than by bitterness. The recipe and flavor profile are layered and nuanced, but more complexity comes through mixed-culture fermentation and aging.
Ingredients: This recipe leans strong and dark for the style, but that’s a lesson learned from finding many lighter oud bruins to be underwhelming. We start with a base of pilsner and Munich malt, with lighter layers of biscuit malt, wheat malt, British crystal (65L), and Special B—a swirling mix of delicious character malts that should bring flavors of toast, toffee, shortbread, dark fruit, burnt sugars, and more—plus plenty of complex sugars for the bugs to chew. Finally, a dash of Carafa adds deeper color and some deep toast, but not roast (which would be a fault in this style). Hops are easy enough: about 20 IBUs of anything at the top of the boil; lower-alpha hops such as Styrian Golding might be nearest to authentic. The yeast-bug pairing is the same I use on my Flemish red—Wyeast 1007 German Ale and 3763 Roeselare Ale Blend—and I trust the recipe to keep the acidity balanced.
Process: The mash and boil are pretty standard. Chill and pitch the German Ale yeast first, starting the fermentation relatively cool. After primary fermentation is complete, rack to secondary, add the Roeselare, and tuck it away for a few months before tasting. Do what you can to minimize oxygen pickup—purge with CO2 if possible. When the balance is where you want it, package and store it cold to slow down further acidification. Oak-aging is unusual for this style, but it can add some fantastic flavors—I recommend oak chips at medium-plus toast, for just about a week before packaging.