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Oud Bruin is the Flanders sour that doesn’t get the attention it deserves, it’s consistently overshadowed by its more photogenic red cousin, but the dark, malt-forward complexity of a well-made Oud Bruin has been one of my most interesting homebrewing discoveries. Brewing it taught me how Brettanomyces integrates with rich dark malt character in a way that lighter sour beers simply can’t demonstrate.
Oud Bruin style guide: the dark Flemish sour brown ale
Style overview: Oud Bruin (old brown) is a Flemish sour brown ale from East Flanders, Belgium, the darker, maltier, and often more vinous sibling of the Flanders Red Ale. Where Flanders Red is characterised by red-fruit acidity and a light red wine character, Oud Bruin features richer malt flavours (caramel, toffee, dark fruit, plum, raisin) integrated with lactic and acetic acid sourness. BJCP style parameters (23A): OG: 1.040–1.074. FG: 1.008–1.012. ABV: 4.0–8.0% (wider range than Flanders Red). IBU: 20–25. SRM: 15–22 (medium-dark brown to dark brown). Flavour profile: The Oud Bruin impression: rich, dark malt complexity (caramel, chocolate, dried fruit, plum, fig) combined with a moderate to assertive sourness (lactic and slight acetic acid), and secondary Brett complexity (leather, barnyard, dried fruit). The acidity is typically more assertive than Flanders Red and the malt character is richer and darker. Commercial benchmarks: Liefmans Goudenband (the definitive commercial example), Petrus Oud Bruin, Vander Ghinste Roodbruin. Grain bill for 20L: Pale malt: 3.0 kg (base). Munich malt dark: 1.0 kg. Crystal 60L: 400g. Crystal 120L: 200g. CaraMunich III: 200g. Special B: 150g (dark dried-fruit character). Chocolate malt: 100g (for colour and slight chocolate note, minimal). Optional: 50g Roasted barley (very small amount for depth, restrained). Target colour: 17–22 SRM (medium-dark brown). Total approximately 5.1 kg for OG 1.052. Hops: Target IBU: 20–25. East Kent Goldings or Styrian Goldings: 35–40g at 60 minutes. No late additions. Mixed fermentation (same approach as Flanders Red): The Oud Bruin requires mixed-culture fermentation with Saccharomyces + Lactobacillus + Pediococcus + Brettanomyces. Wyeast 3763 Roeselare Ale Blend is the standard homebrewing approach. Alternative: primary fermentation with Wyeast 3522 Belgian Ardennes or WLP510, then addition of mixed cultures in secondary. Timeline: primary 2–3 weeks → secondary mixed fermentation 12–18 months → oak aging (optional but improves complexity) → blending → packaging. Acetic acid character: Oud Bruin traditionally shows more acetic acid (vinegar note) than Flanders Red. This comes from Acetobacter activity during the long aging period, particularly if the beer is exposed to oxygen in the aging vessel. A slight acetic note is acceptable and traditional in Oud Bruin, it’s a defining character, not a flaw. However, excessive acetic acid (strongly vinegar-forward) indicates too much oxygen exposure. Maintain appropriate headspace management in aging vessels, or accept the acetic character if it develops naturally. Blending: Liefmans-style Oud Bruin achieves its complexity through extensive blending of multiple vintages at different stages of sourness. At home: if you have multiple batches at different stages, blend a portion of 18-month sour with a portion of 6-month less-sour to achieve balance. The blend can be adjusted at bottling time to calibrate sweetness vs. sourness. Indian homebrewing: The dark grain bill for Oud Bruin, Munich, Crystal, Special B, Chocolate malt, is available from Indian homebrew importers (Weyermann malts are the reference; available via HomeBrewers Association India and similar importers). Liefmans Goudenband is available at select Belgian beer-focused craft beer bars in Mumbai, Delhi, and Bangalore if you want to taste the reference before brewing. Patience with the 12–18 month timeline is the primary requirement anywhere in the world, including India.
Common Questions
What is the difference between Flanders Red Ale and Oud Bruin?
Flanders Red Ale and Oud Bruin are both mixed-fermentation Flemish sour ales and they’re easily grouped together, but they differ meaningfully in colour, malt character, regional association, and the balance of acidity types. Regional origin: Flanders Red (Oud Rood) is associated with West Flanders, the Rodenbach brewery in Roeselare is the anchor commercial producer, and the style reflects the character of West Flemish oak foeder aging. Oud Bruin is associated with East Flanders, Liefmans in Oudenaarde is the benchmark, with a distinctly darker, more malt-forward character. Colour and malt: Flanders Red is 10–16 SRM (medium amber to reddish-brown), grain bill dominated by Vienna and Munich malts that produce a red-amber colour and melanoidin malt character. Oud Bruin is 15–22 SRM (dark brown), grain bill includes significant Crystal 120L, Special B, and sometimes chocolate malt, producing rich caramel, toffee, and dark dried-fruit character that is more complex and darker than Flanders Red. Acidity balance: Flanders Red typically shows primarily lactic acid sourness, clean, bright tartness, with a minor acetic note acceptable but not dominant. Oud Bruin traditionally shows more acetic acid character (slight vinegar note) alongside lactic sourness, the acetic acid is considered a defining characteristic of the style, not a flaw, and reflects the East Flemish style’s longer and more oxidative aging. Fruit character: Flanders Red, red berries, cherry, pomegranate, light plum. Oud Bruin, dark dried fruit (fig, raisin, prune), toffee, slight chocolate, deeper fruit complexity from the darker grain bill. Sweetness: Flanders Red is typically drier and more refreshingly tart. Oud Bruin is often slightly sweeter and richer due to the higher crystal malt content and darker grain bill. For homebrewing: if choosing between the two styles, Oud Bruin is slightly more forgiving of a moderately acidic result, the rich malt complexity provides more “room” to hide imperfect acidity balance, while Flanders Red’s lighter malt character means the acid balance is more prominent and critical to the final beer quality.
