Oud Bruin not sour enough

Happy day after Thanksgiving.

I kegged an Oud Bruin yesterday that I brewed 11/27 of last year with the Roselare blend. Tasted pretty good, but not sour enough, unfortunately.

I’ll go ahead and carb it up since it’s already in the keg fridge, but then will let it sit in the basement for another 4-6 months. Would it make any sense to toss some lacto in there? Or will it continue to sour on its own?

Thanks in advance.

I wouldn’t add much CO2- don’t carbonate- and let it sit at room temp. I think carbonating and/or refrigeration might stop any further souring.

In my experience, that blend doesn’t get too sour on the first pitch. Your next pitch should be better. At this point your options are (a) give it more time at room temp, (b) pitch more bugs and/or dregs, (c) add fruit and/or blend it with something you have on hand, and/or (d) brew a second batch with the cake and blend the two in 6-12 months.

Let it sit in the keg with the pressure relief valve open for a few weeks. That will expose it to oxygen, and give you the sourness you are looking for. Lactic sour is not the same as acetic which is characteristic of Old Bruin and Flemish Red. My best sour beers have been made with a variety of yeasts, low hop bitterness, and exposure to Oxygen. You can put some plastic wrap around the pressure relief valve or the top of the keg to keep any other critters out.

Adding brett or lactic will give you some character, but not the acetic character you are looking for.

Technically, I think the ppm of lactic acid is still higher than acetic acid in a flanders red. And acetic is even lower in an oud bruin. Wild Brews says acetic acid is “generally not evident in Flanders Browns”. But I know what you’re saying, and I wouldn’t try to talk anyone out of adding a little acetic acid to the mix. Opening the pressure value for a few weeks may work this time of year, but I wouldn’t recommend it during warmer times of year. I tried doing this for a week in the dead of summer and the beer turned undrinkable soon after.

You are probably correct about the ppm of lactic. The acetic is the flavor you are looking for though. It has been a couple of weeks since I have had a Goudenband, but I definitely remember the acetic. Yes. The Bruin is far less sour than the Reds, but I think a bruin without acetic and lots of lactic just tastes like an infected brown ale. I have only had a couple of commercial oud bruins so I am not an expert. I am sure there may be some that have a lactic character.

I created a great acetic character in my first sour by leaving the relief valve open on the keg for more than a year. This was in Texas where my house temp is 78 degrees from April to October, and only slightly lower during the other months of the year. I also kept a red in secondary in a glass carboy with plastic wrap over the lid for a few months. This also worked.

Our club did have a batch go bad though. It was stored for 3 years in a bourbon barrel. One month it was great, and the next month it was acetone (finger nail polish remover.) This barrel was kept in a cool room at 65-70 degrees year round. Luckily this has only happened once.