Is there a particular method to souring a beer once fermentation is complete? For example if I make a 5 gallon batch of a pale ale and what to add some sour to it for a gallon batch can this be done?
Once fermentation is complete the only bug that would really add significant sourness is Pediococcus. It will take some time to work. You always want to pair it with Brettanomyces, since Pedio produces diacetyl and Brett will break that down.
Another option is a sour fruit like tart cherries. It might not take it all the way down to “sour”, but you should get noticeable tartness.
You can also blend in a sour beer as well.
I like Eric’s options, here!
Have you made the batch already? If so, a combo of pedio and brett cultures will give you sourness and funk in several months (8-12).
Sour fruit is a great option. Tart cherries or rhubarb are good options. With cherries, you can use puree (or puree frozen, thawed berries) and pitch lactobacillus before combining with the beer.
For clean acidity, I’m a fan of blending in acidic beer. Brew a small batch of wort with similar grain bill, but don’t add hops. Use a sour mash/sour wort method or ferment with a healthy culture of lactobacillus. I like Wyeast 5332 (Lactobacillus Brevis).
What about racking to a secondary and using dregs from a commercial sour?
Yup already made a batch. Although this has a higher IBU then I should be working with.
You need to be sure the dregs have Brett and Pedio. Lacto won’t have any food if the beer is already finished. Pedio can break down dextrins, so that’s why it is able to work even once the primary is finished.
You also might want to wake up the dregs by stepping them up once or twice before pitching.
Stepping up is crucial for pitching dregs into finished beer. Limit aeration during the step up - pedio grows more rapidly in the absence of oxygen.
I have found some brewery dregs to be more aggressive than others in terms of acid production:
Cascade
Side Project
Jolly Pumpkin
Not very helpful, since 2 of the 3 aren’t readily available. Maybe Eric or others can chime in with their favorites.
We get lots of Cascade here…sadly they are normally 30-40 a bottle.
I talked with a brewer tonight about this and we both agreed that blending with a sour worted beer is probably the best approach but if necessary - not advised as the best route however - you could add lactic acid to taste. I haven’t done it but it was suggested as a possible fix.
So that’s like a $25 bottle and a $10 pack of yeast…
…or at least that’s how I justify it to my wife.
HAHA, yeah I actually picked up a bottle of Cascade Vine today for around $25 so that may work.