Originally Posted by DisturbdChemist
Do you know how I can keep that warm? Maybe a crockpot or on the stove at the lowerest setting, or on the stop in pot of warm water? I want to get this right and not mess up a good batch of beer
Dregs are just the stuff at the bottom of the bottle. It's where all the yeast and bacteria settle, just like when the yeast settles in your homebrew.
Depending on how much you want to sour and how sour you want it will affect what technique you take. Living in Texas, you probably do not have a furnace -- and even if you did, it's not running in these temperatures. I typically do sour mashes in a half gallon glass growler with foil over the top. I mash and sparge enough of the grain bill for 1/2 gallon from the boil volume. I bring it to a quick boil to sanitize, then cool to 120F. I fill the growler up to a couple inches from the top and toss in some grain. Then depending on how sour I want the beer I will let it sour ferment for a certain number of days. I can tell when the bacterial fermentation gets going because I'll get a thick brown krausen. It smells like rotting creamed corn. Do not be alarmed. The smell might might carry past boil into the fermenter but I assure you by the time fermentation is done it is cleanly lactic.
To keep it warm I fill the sink with hot water and put the growler in it. I drop a thermometer in the sink and periodically pull some of the water and bring it to a boil in the microwave. Then I add back. It's an imperfect system but I can keep it in the 85-120F range for most of the day (you may want to think about doing this over the weekend) and get it really hot when I go to bed so it won't cool off too much. Once the krausen gets going you shouldn't have a problem with anything getting in there and making a mess of your sour mash. That's why I say the first few days are most important, just like with yeast fermentations.
If you are just going for some tartness, go 1-3 days from when the krausen appears then add it to the beginning of the boil to reach full boil volume. If you want serious sourness, boil the rest of your beer (you may want to divide out the hops for the sour portion to make sure your bitterness is appropriate), pitch your yeast in the clean portion and after a week, do your sour mash and let it go 3-5 days from krausen (if the krausen drops you need to stop the sour mash) then boil it, cool it and pitch with your clean portion.
As you can probably tell, it's an imperfect process. It might be easier to just add lactic acid at bottling.
This technique will give you a berliner weisse kind of sourness. It won't give you the complex sourness or complex flavors you get in lambic, etc. because you don't have brett and you don't have those long fermentation processes developing complex flavors. It will still make great, refreshing beer.