Guinness and Souring

[OswaldvW]

I have read numerous times about people suggesting souring a small portion of Guinness to add to their wort for that "authentic" flavor. I have also heard people just as Jamil Z. say the sourness is nothing but a myth and there is no need for the sour (same as with the peated malt for Scottish ales).

So, my question is, where is the evidence for either argument? I am simply curious.

 

[FarmerTed]

I'm pretty sure that Guinness does sour/brett some of their stout, but I couldn't tell you if it goes into all of their beers, or just the Foreign Export. I don't think the beer tastes sour at all. They probably just add a few percent to the final product.

I did find this with a quick search:

Q: Someone told me that Guinness intentionally added sour Guinness to their beers. Is that true?

A: Yes, part of the process is to blend in some specially soured Guinness. The following was extracted from the Homebrew Digest. I believe the original author was Martin Lodahl, but I may be mistaken: "...they have a series of huge oaken tuns dating back to the days before Arthur Guinness bought the brewery, which they still use as fermentors for a fraction of the beer. The tuns have an endemic population of Brettanomyces, lactic acid bacteria and Lord knows what else, and beer fermented in it sours emphatically. They pasteurize this and blend small quantities of it with beer fermented in more modern vessels."

I don't know about the authenticity of it, but that's pretty much what I've either read or heard before. There was a guy on the sunday session a while ago who brews at Summit, and he used to brew for Guinness. He may have talked about the souring process (may not, it was a while ago that I listened to it).

I also found this. It sounds pretty legit.

Sour 3%. Legend has it, and this is probably true, that Guinness still has some wooden vessels in the bowels of the brewery quietly souring away a portion of beer to be blended at 3% in to un-soured beer for complexity. This harkens back to the true origins of porter/stout being a blend of old (soured) and young beer. Guinness used wood from 1759 to 1963. Another point towards what made them famous.

I think Jamil's complaint is probably more about brewers who over-sour or over-funk their stout, and present it as an classic example of the style.

 

[Calder]

BJCP guidelines (13A dry stout) say "A small percentage (3%) of soured beer is sometimes added (generally by Guiness only) ......."

BJCP guidelines (9B and 9C, Scottish Heavy and Export) say the peat flavor is yeast derrived, but adds you can use peat malt sparingly to replicate it.

BJCP guidelines (9E, Strong Scottish); it indicates peat malt would not be out of place and would add complexity.

There are no hard and fast rules, just guidelines. Make what you want, how you like it.