Souring a portion of pre fermented beer

[MatchstickBrewingCo.]

I really love sour beers but don't know where to start when it comes to brewing one and don't want to try with a full 5 gallon batch.

Anyone know an easy way to run off a gallon of pre fermented beer from a batch of regular (non soured) beer into a gallon "carboy" during kegging in order to sour it?

Can I just collect that beer, pitch some lacto and/or brett, and let it sit for a while?

Any input would be greatly appreciated.

 

[ten80]

I have done this very thing before.

Look up kettle souring or sour mashing. In essence, you can run off some of your wort from the mash, sour it to taste, then boil and pitch yeast. The key is to minimize oxygen exposure and maintain temperatures around 110F during souring to prevent growth of enteric bacteria and promote the growth of lactobacillus.

 

[MatchstickBrewingCo.]

Sorry if that was confusing, I guess I meant POST fermented beer? I meant, while kegging finished beer if I can just fill the keg 4 gallons full and use the last gallon to sour separately.

 

[m00ps]

yeah, ive done this a number of times and its cool to compare the sour version vs clean version once the sour is ready

 

[MatchstickBrewingCo.]

What would you recommend I pitch into an IPA? I like a very tart type of sour, would Lacto alone be ok?

 

[KyleWolf]

Lacto alone will give you a good clean tartness, so that should work just fine.

If you just want the tartness the cheap, quick, and easy way is to add Lactic acid (can be found at your LHBS) directly to your beer prior to bottling/kegging. Another way is to add acidulated malt to your mash.

Not to highjack with a question, but how does everyone go about keeping their lacto culture at 110F? I don't suppose everyone has a microbial incubator laying around haha.

 

[jojacques]

Lacto alone will give you a good clean tartness, so that should work just fine.

If you just want the tartness the cheap, quick, and easy way is to add Lactic acid (can be found at your LHBS) directly to your beer prior to bottling/kegging. Another way is to add acidulated malt to your mash.

Not to highjack with a question, but how does everyone go about keeping their lacto culture at 110F? I don't suppose everyone has a microbial incubator laying around haha.

I would use an old unplugged fridge/freezer and hook up any kind of heating device to a temperature controller (heater, light bulb in a can, etc.)

That should do it.

 

[ten80]

Sorry if that was confusing, I guess I meant POST fermented beer? I meant, while kegging finished beer if I can just fill the keg 4 gallons full and use the last gallon to sour separately.

It may be too late to really "sour" the beer with Lactobacillus, as lacto doesn't do well in the presence of alcohol or hops. It is generally recommended to pitch Lacto in wort that has less than about 4 IBU, so pitching it into your IPA may not do anything.

You can definitely "funkify" the beer by adding Brettanomyces and letting it age for a while longer (3-6 months perhaps). Brett can even be added at bottling if you are certain there is little residual sugar left.

Your best bet for adding more sourness now is to add Pediococcus which does generate some acidity and funk. You also need to add Brett to help clean up after Pedio, otherwise your beer may have diacetyl and other off flavors. This is a slower process and may take over 6 months to complete. You can pitch a Roselare blend to get pedio, brett, and lacto into your beer. The Lacto won't do much, but the others will work a bit on the residual sugars. Your beer may end up very dry depending on your recipe.

Your last option is to add lactic acid directly to the beer (as mentioned above), but this results in a very one-dimensional sourness that has little depth or complexity. It might be a way to play with your beer and quickly see if it actually tastes OK with a lower pH.

 

[ten80]

Not to highjack with a question, but how does everyone go about keeping their lacto culture at 110F? I don't suppose everyone has a microbial incubator laying around haha.

I put my fermenter with sour mash on top of my water heater which is located in a small closet. Conveniently, the closet temperature is near 110 F.

Otherwise, I have used brew belts and sleeping bags to keep fermenters as warm as 95 F, but it is challenging to go any higher.