[beerstache]

I read this procedure in a Guinness clone recipe to get the sour taste and am wondering if it works or if I am wasting good beer for this.  One week before brewing, put 24 oz. of guinness in a bowl and let it sit out for 4 days to get sour.  Freeze until brew day.  On brew day remove and thaw.  Then boil it for 10 minutes before flameout and add at flameout.
Has anybody tried this?  Are there any other methods to get the sour taste?
Thanks everybody!

[tschmidlin]

You could do a sour mash like you were making a Berliner weisse - mash in the night before and let it sit overnight before mashing out and sparging.  I would start by just doing a portion of the mash, maybe 5-20%, and then adding the rest of the grain and mashing normally the next day.  That will help keep it from getting as sour as a Berliner weisse.

That's just one idea, you could also add acid, acid malt, do a full lacto/brett batch and blend it, add a bottle of lambic, whatever.  Obviously some of the ideas are better than others

If you go with their method you could add some grains to speed up the souring of the Guinness.

[beerstache]

Thanks.  I'll try adding some grains then taste it before freezing to see if it's what I want or not.

[denny]

Or do it the easy, controllable way and just add a little lactic acid at the end of fermentation.

[skyler]

I JUST did this!

About a week before your brew day, mash 2 oz of base malt with 1 cup of water in a coffee thermos or a mason jar or something. Let the micro-mash sit there at ambient temperature, sealed in the jar/thermos for the whole week, and then add that mash to your full dry stout mash at sparge - works great. My dry stout has a very subtle sour/umami quality like that in Guinness.

[beerstache]

Denny,
How much lactic acid should I add?  When in the process?  In the mash or kettle boil?
Thanks for the tips.
Tom

[mabrungard]

It is my understanding that the soured wort addition is blended after fermentation.  You definitely would not want to add acid to the mash since that will drive the mash pH too low which will produce a thin and tart beer. 

Mash it right, sour it later.