That sour taste... from GUINNES... how to get it?

[Bilsch]

The third approach is rather stupid. Just leaving wort sitting around for three days is asking for trouble. No specific inoculant, no temperature control, no pre adjusting the pH to avoid nasties. Simply hoping what ever falls out of the air into the wort is lacto shows a complete lack of understanding this topic.

 

[Bramling Cross]

For a 5gal batch, take two cans/bottles of Guinness and put them in a jar and foil the top. Let sit 4-6 days to sour, then put the resulting liquid into the boil with 10min left.

Damn, that's some clever....assuming they don't pasteurize.

 

[youngdh]

Acid malt is what I use.

 

[cactusgarrett]

Damn, that's some clever....assuming they don't pasteurize.

Yeah, I've done it and it works. Haven't done a side-by-side, but I like the results.