The Brewing of an Oud Bruin – Part 1 - Brain Sparging on Brewing


Sour beer, saisons, farmhouse beer, homebrewing, ramblings

September 25, 2010

The Brewing of an Oud Bruin – Part 1

I have recently decided to make a long term project of developing an oud bruin that is economical and possibly faster than a normal oud bruin, since it is a beer that takes over a year, if not two, to come together as a great beer. Hopefully I will have put something together within a six to seven month timeframe. When it comes to sour beers, I enjoy slightly to moderately sour beer. Tart, is probably a more accurate description of my preference. My goal here will be to produce something along the lines of Petrus Oud Bruin, which is agreed upon as a not very sour beer. Personally, I really enjoy this beer. It’s one of the few sour beers that can be found in Texas. (I have found the New Belgium sours and we are awash in the Lindeman’s lambics. The two non-fruit limbic produces, the gueuze and faro are both enjoyable.) The benefit of taking inspiration from Petrus Oud Bruin is that since it is not extremely sour or terribly brettanomyces flavored, the process can be shortened to reach the final product. (Petrus Oud Bruin is safely better described as complex and tart than the mouth puckering sour of many other sour beers.)
What is an oud bruin, anyway?
An oud bruin is a Flemish beer style that translates as “old brown”. It is actually an aged pale ale made of all or mostly pilsner or pale malt. It is usually hopped to 25-30 IBUs and then left to age with saccharomyces, brettanomyces, lactobacillus, and pediococcus for a year or more in oak casks to develop into a sour beer. This hopped sour beer is then blended with a fresh, young malty brown ale. As it ages in the bottle the brett will continue to consume residual sugars and add more brett flavors to the beer.
This beer is different from the Flemish red ale style of beers. Oud bruins are traditionally East Flemish beers, while the red ales are West Flemish beers. Red ales are more vinous, like wine, and considerably more sour. They are not traditionally blended beers. It starts and finishes as the same red ale. This beer also takes over a year to produce. There is disagreement over what is an oud bruin – some classify both browns and reds as oud bruins, some switch the characteristics across the names, some treat all of them as red ales. There’s a good reason for the confusion: some producers of both styles label their beers as the opposite of what the characteristics of the beer should make it. Even Petrus Oud Bruin describes itself as a “Flanders Red Ale” although it is not. I’m not really sure why there is confusion across the names. It’s likely that the appellation “oud bruin” applied to all sour red-brown beers, with West Flanders more commonly making them in the red style and East Flanders in the (probably cheaper) brown/blended style, and in the beer categorization of the late twentieth century labels got all mixed up.
Let’s chat about blending!
Blending of beer is generally attributed to English beer but it was adopted by Belgian brewers and publicans that learned in England or from the English. To be very brief and unfair to the larger history, I’ll limit the discussion to porters, because that’s typically where the blending process is considered to have originated. When porters first hit pubs, they were sent out from breweries in casks, like all other beers. Casks are porous, being made of wood, so they allow spoilage microorganisms, such as brett, to get into the beer, especially since casks would be reused and these guys would take up residence in the casks in between use. If beer wasn’t quickly drank, it became “sick” and soured. Generally this is avoidable in most beer styles, but for some reason the English people got a real hankering for soured beer. The problem is that properly soured beer takes a long time to mature, so they were rare products. Traders began buying casks of beer and aging them for sales to publicans (bartenders of pubs). Eventually brewers and publicans realized they could just age beer themselves and cut the middlemen traders out.
Since soured beers were rare, they could demand a higher price. Also, since the publican or brewer had to sit on the investment (the cask) instead of quickly selling it to buy more beer to sell to their patrons, it demanded a higher return to make the aging a profitable market. Since us working stiffs couldn’t afford to buy aged beer all the time, publicans would offer several products. Young beer would be sold cheapest; aged beer would be the most expensive. In the middle were blended products that combined the flavor of the old beer with the sweetness of the new beer.
This process is still continued by some of the Irish Stout producers. Guinness, for example, sours a portion of the wort to give the stout that bitter taste. I’m not entirely sure why porters developed a craze for old beer, but it did. Then porter died off, replaced by the next fad. This process of aging beer probably employed more than just porter. I also suspect that publicans blended whatever they could get their hands on. Pale Ale and Stout? A black and tan! So on and so forth. The Belgians picked up this concept and have used it to give us gueuze, oud bruins, and probably some other stuff I’ve never heard of. One important difference is that English blending often occurred in the pub (like ordering a black and tan at a bar), while Belgians took to blending both in the pubs and in the bottle.
While I’m not necessarily interested here in discussing the intricacies of Belgian blending practices, it is worth pointing out that any time you bottle (or cask, keg, etc.) a beer with brett and associated bacteria with beer fermented with only saccharomyces eventually brett & co. will eat up whatever is left over time, giving the beer a more sour/tart flavor as it stays in the bottle. The significance for this purpose will be to try to diminish brett from taking over in the bottle and making the final oud bruin product more sour than preferred.
Building the Concept
So now that I have the basics down, it’s time to start mapping out the recipe. I know that I need two recipes: the pale ale and the brown ale. The pale ale is straight forward as far as the pre-fermentation recipe goes, but it needs to age in a way that will impart some brett and acid characteristics along with some slight oak flavor. It needs to age, but since the goal is to reduce aging time, I will want to find ways to cut down the time. The brown ale just needs to be something nice and malty. Because the aged pale ale will add a lot of flavor, it is not necessary to make the brown ale either chocolately or hoppy. I also plan on making this a four gallon batch – three gallons brown and one gallon pale ale. The reason is that I can use a gallon jug for the pale ale so I don’t have to use up a bucket or corny keg for a long period of time for a 1-1.25 gallons. The brown ale will be brewed in a keg, but it shouldn’t be there for more than a month.
Starting off with the aged pale ale, I’ve adopted the recipe from Wild Brews by Jeff Sparrow. The grain bill is 90% pilsner and 10% carahell. To be honest, I’m not really sure what carahell is, but since it’s a cara, it must be for head retention. I’ll use my trusty supply of Fuggles, because that’s what I have, I’m cheap (I said it before!) and Belgian beers often use English hops. I’d rather use EKG, but I have Fuggles. So here’s the one gallon pale ale recipe:
Grain bill:
2 lb Pilsner
.25 lb carahell
Boil Additions (90 min boil):
90 min .25oz Fuggles
15 min .13oz Fuggles
5 min .07oz Fuggles
OG 1.061
FG 1.016
IBU 26.7
ABV 5.88
So far, a pretty generic blond, right? So it needs some sourness, some slight oak flavor, and some brett flavor. To get sourness, I am going to do a sour mash of about 32 ounces. I may change this number depending on how my sour mash limbic-esque beer turns out. (In that case I soured 1/6 of the mash.) The sour mash will get added at the start of the boil. For oak I plan on adding a small amount of oak chips after primary fermentation is complete. Maybe just half an ounce. Since they will be fresh oak chips, they will impart a lot of flavor so I don’t want to go overboard. Now, what about yeasts? I plan on doing this 100% brett. I am going to culture from a bottle of Orval and build up a good size starter, because using brett for primary fermentation requires a high pitching rate and lots of aeration. Primary brett fermentation will allow some brett flavor to come through. I will ferment the pale ale for 6 months. Around month 5 if the beer looks and tastes ok then I’ll brew the brown ale and prepare for mixing.
The brown ale is pretty basic, too. I know a lot of oud bruins use corn as an adjunct but I’ve passed on the corn this time.
Grain bill:
3 lb Munich
1.75lb Pilsner
1.25lb Vienna
Boil Additions (90 min boil):
90 min .5 oz Fuggles
10 min 1 tsp Irish Moss
Ferment with WY1338
OG 1.055
FG 1.016
IBU 14.4
ABV 5%
This one will probably stay in the fermenter to age for about a month before it gets mixed up, just to make sure all those young beer components have been cleaned up. As you can see, more Fuggles make their way into the recipe. You don’t want to add more hoppy flavors to this beer because the aged pale ale will add enough flavor that you wouldn’t want hops to compete for flavor (ruining all the hard work in aging the pale ale.)
Blending Time
My concern with blending beers in this case is that in the course of bottling, the brett from the aged pale ale will start chomping on the leftover sugars in the brown ale and cause bottle bombs. Two things will help deter that event. First, I will be bottling in champagne bottles. I am going to use plastic corks and wire cages, because I don’t have a corker and it’s way cheaper to reuse corks. Champagne bottles are produced with the ability to withstand 9 vol. of CO2, which is way more than I should ever get. Also, I will cold crash the aged pale ale. I don’t have much fridge space to be able to cold crash a keg or bucket, but the gallon jug does fit in the fridge. Cold crashing will help reduce the brett in suspension, resulting in a lower concentration of brett in the bottles. Since brett is a slow moving yeast, the saccharomyces from the brown ale will eat all the sugar they can, carbonating the bottle, and hopefully leaving the brett very little remaining to consume.
Once it is bottled, I will wait a few weeks before giving it a go. Since I am only making four gallons, I will want to be slow in my consumption of this beer. Well, assuming it is good. If it sucks I’ll drink it down fast to make room for better stuff. I hope it turns out ok, so I can see what long term effects the brett will have in the bottle.
Wrapping Up
So that’s Part 1 of this adventure. I probably won’t get around to brewing this until November or December because I already have a lot of brewing left to do for the year, so I will end up with a completed product by the middle of next year, just in time to celebrate the end of the school year. I plan on walking through the whole process with careful notes so I can replicate the process in the future, as well as sharing what I learn.


  1. This is a bit incorrect. Oud Bruin's are generally aged in stainless steel, not oak. This probably was used in the past at some point is not usually included in modern brewing. They typically should not have a Brett character, neither is Brett used (or should be used intentionally) in the fermentation(Once again, the brett could have been introduced at some point in time when they were using oak casks for these beers.) The blend of beers is actually from an older "brown" and a younger "brown." Using an aged pale ale in place, especially when considering pale malts were not available until quite recently,(relatively speaking) is creating an entirely different style. Not trying to rain on your parade but I'm making a very similar brew, also using brett (reason was to make something slightly different than an oud bruin/ little more complex; although, most very good examples(Goudenbaud, Rodenbach, especially the Rodenbach grand cru) have plenty of complexity to offer) You might not like these as they are pretty sour but are great representations of the style. Never had to Petrus though, gotta go grab that.

  2. I agree that oud bruins are aged in steel, no longer in oak. I desired some oak flavor to add some complexity to my recipe, even if it was a little off tradition.

    I disagree that oud bruins never have some brett characteristics. In doing some research on this project I saw that some oud bruins do (or at least did) have brett character. Given how the end result turned out I would avoid the use of brett in a future version because the brett character is a bit overwhelming.

    Petrus makes its oud bruin by combining an aged pale ale with a sweet, dark brown ale. If you look at Wild Brews, it discusses this process along with basic outlines of recipes that I used in modeling this process.