Brewing an Oak Aged Sour Beer (Part 1)

I gave up alcohol for Lent, an unfortunate sacrifice when you brew beer as a hobby. While I am not drinking beer, I like to keep a batch fermenting and did not give up making alcohol, just drinking it (sorry, I’m a lawyer). To avoid the disappointing circumstance of brewing a beer that’s past its prime before I can even drink it, I decided to make a beer that would not finish until well after Easter. This beer will likely not be ready until the summer of 2023, far longer than anything I have ever brewed.

I am making a beer best described as a barrel or oak aged sour. Traditionally, these beers spend many months in oak barrels or foeders, which allows the beer to turn sour and, at the same time, mellow the sourness with oak sweetness familiar from many wines and bourbon. While plain old brewers’ yeast (Saccharomyces Cerevisiae) can do its job in just a couple of weeks, the Brettanomyces and lactic acid producing bacteria that give sours their complex flavors and tartness take months or years to complete work. Oak aged sours hit at the sweet spot of beers that are worth making yourself as they are a) expensive and b) hard to find.

My local grocery store with the best beer selection (Meijers) usually has a barrel aged sour from Jolly Pumpkin (Calabaza Blanca, Bam Biere, or Oro de Calabaza) but that’s it. I love Jolly Pumpkin. Its beers go for about $12 per four pack or about the same for a larger glass bottle, which is a good deal considering the oak aging and all. Grocery stores have an increasing number of non-barrel-aged sours, but these are usually made using a quick souring process or using recently discovered brewers’ yeasts that produce acidity. Some of these quickly soured beers are excellent, such as Dogfish Head SeaQuench Ale, but I do not find them to be close to the flavor and balance of a barrel aged sour.

Bargain!

I will go out of my way to get barrel sours that are not available in my area, some of which are quite expensive. When I went on vacation to Colorado last year, I visited New Belgium and Crooked Stave which both make amazing and creative barrel aged sours and it really got me excited to make my own.

New Belgium’s L’amour en Cage, La Folie, and Tart Lychee in Fort Collins, Colorado.

If I had to pick a favorite barrel aged sour, I’d go with Petrus from Brouwerij de Bandere. Petrus, a sour pale beer from Belgium, has just the perfect balance of sour, spiciness, and oak along with a great backstory. Beer (and whiskey) writing legend Michael Jackson discovered Petrus on a trip to Belgium and first imported it to America. As told by Belgian Smaak, Brouwerij de Bandere did not even sell Petrus as an independent product when Jackson first encountered it and, rather, used the beer as blend stock for its Oud Bruin. Over the brewery’s objections as it believed the beer too sour, Jackson convinced the brewers to export a batch to America and Jackson even gave the beer its name. Judging by a visit to the Brouwerij de Bandere website, Petrus and a family of newer beers with the Petrus name are now some of the brewery’s primary offerings.

Petrus, and the great American sour beers such as those coming from Jolly Pumpkin, New Belgium, and Crooked Stave, have complex flavors and sharp acidity that go great with food or can stand on their own. I would pick these beers over many great wines any day.

But I can’t say that I enjoy all barrel aged sours. Some have more of an acquired (or off putting) taste that I’ve seen described as “barnyard” or “horse blanket.” My wife has instructed me not brew anything venturing into “horse blanket” territory. However, sours are unpredictable and can change dramatically over time. The difference between a great sour and a bad sour comes down to brewing method, age in the bottle, and, more so than other styles, luck.

After much consideration, I have decided to commit to the long and risky experiment of making a barrel aged sour. Not owning a barrel or a foeder and not willing to conduct a risky 60-gallon experiment, I had to do my best to replicate the oak aging process in a 5-gallon carboy. As recommended by Michael Tomisare in his excellent American Sour Beers book, I brewed a light beer that I enjoy drinking to serve as the base for my first aged sour. I used a Bell’s Oberon clone, one of my favorite beers to make and one that I always wondered how it would taste as a sour. Instead of a barrel, I am using toasted American oak cubes. I boiled the cubes before using to sanitize them and, wow, did that smell good in an oaky vanilla way confirming my belief that you can accurately describe bourbon as oak flavored vodka.

Oak cubes smell very nice.

For the yeast and bacteria, I selected Roeselare blend from Wyeast. Roeselare consists of a blend of a Belgian style ale strain, a sherry strain, two Brettanomyces strains, a Lactobacillus culture, and a Pediococcus culture and requires aging up to 18 months. I substantially reduced the hop bitterness from the Oberon recipe because hops can interfere with bacteria growth and, plus, after 18-month of aging I must imagine that the hops would be quite degraded.

Part 2 will come out in a year or so.

Cooling the wort in the snow.

Interdiu Sour Ale – 5 Gallons Extract Batch

AmtNameType%/IBU
8.0 ozCarapils Malt (Briess) [Steep] (1.5 SRM)Grain5.9 %
2 lbsLME Wheat Bavarian (Briess) [Boil] (3.0 SRM)Extract23.5 %
0.10 ozWarrior [17.60 %] – Boil 60.0 minHop5.8 IBUs
2 lbsDME Wheat Bavarian (Briess) [Boil] [Boil for 15 min](3.0 SRM)Dry Extract23.5 %
4 lbsLME Wheat Bavarian (Briess) [Boil] [Boil for 15 min](3.0 SRM)Extract47.1 %
1.0 pkgRoeselare Belgian Blend (Wyeast Labs #3763) [124.21 ml]Yeast
3.00 ozAmerican Oak Cubes – Medium Toast (Secondary 30.0 days)Flavor

Boil oak cubes briefly to sanitize.

Primary fermentation at 72° F for 30 days.

Secondary fermentation at approximately 68° F of 17 months or until desired taste achieved.

Bottle condition and carbonate to 2.3 vols with 3.6 oz corn sugar.

Tasting Notes:

2/2/2022 – Brew day.

2/26/2022 – Peppery Saison taste. Watery.

3/13/2022 – Transferred to secondary fermenter. Saison and cider with diacetyl yeasty taste.

The Roeselare yeast fermented extremely vigorously, blowing out the top of the fermenter after a couple days.
The wait begins. Interdiu Sour (left) next to a cider (right) that I am aging.

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