I have about 1.5 gallons of a sour belgian quad I brewed with my brew club in a corny keg right now. I was thinking about what to do with the keg when its done. If I want to ensure the next beer I put into it doesn't go sour, I was thinking of the following cleaning scheme: Fill with boiling water, seal lid, let stand for a good while until it cools. Empty and rinse with room temperature water a few times. Change all of the rubber gaskets Run through my keg washer with warm water and pbw for 15 minutes Will that do the trick? Also, would it be possible to just rack another beer into this keg immediately after I finish the sour belgian quad with hopes of that new beer souring? I'd store the keg at room temperature for several months and pull the pressure release valve every so often to vent. I believe souring to some degree is an oxidative process, so I'm not sure if this will work all that well (if at all) though. I also believe that, while there would be some bugs in the keg it wouldn't be like refermenting with a whole pitch so this might just be a waste.
Option 2. Brew up a Saison, throw that puppy in there, and let her go. Pour some pints this summer and enjoy. That will be delicious. Maybe a touch of French Oak. Yum! Small (minute) amounts of O2 can be beneficial, but not necessary.
I like jbakajust1's answer. Brew a beer that would go great with the bugs in the keg - or could stand on its own entirely. Rack the new beer directly into the uncleaned kicked keg. See what happens. Win-win as far as I'm concerned. BTW, I do have a keg dedicated to sours, currently holding a Brett'd Blueberry Berliner for summer time. But, if I was going to try to rid my keg of wild yeast and bacteria, I would follow your plan exactly. Maybe a a 5 minute max soak in bleach solution.
Thanks guys. One more quick question / distinction: When you both say to throw a new beer into the sour keg, do you mean unfermented wort or a beer already fermented in primary regular beer yeast? If the former, would drinking krausen make it bitter and nasty? If the latter, wouldn't I have to make sure I used a prefermented beer that had a fairly high finishing gravity to ensure the bugs had something to chew on? If the prefermented beer had a fairly low finishing gravity, would throwing in some maltodextrin be a good food source for the bugs?
Speaking for myself, I would add fermented wort to the keg and maybe mash a little higher. Maybe not if it were a Saison. I think you would just have to play around with this for a while. Maybe collect and freeze some additional wort if you don't want to go the maltodextrin route.
I would ferment the batch of Saison with the 3724 or 3726 strain, even the 3725, let it finish off, then rack it to the keg. I have used 3726 in conjunction with RR dregs at bottling, FG was 1.005, turned out really well after a year in the bottles. It went through a diacetyl bomb phase, then the Brett cleaned it all up. Son't worry about the FG being low, the bugs and Brett will get after what remains. It may not be warheads sour, but it will have a good complexity.
I dont dedicate kegs to sours. I replace the o-rings. I keep the big ones to reuse when I have another sour to keg. I boil the removable parts. I clean and sanitize the main keg part as I would with any other beer.
It sounds like a lot of people are using very hot water when rinsing their kegs. That should do the trick for the inside, so long as you make sure you get the dip tube filled. Replace the o rings and make a saison next, just in case.
If your keg is clean there may be some microbes remaining in the soft gaskets. However, the cell counts on those bugs will be very, very low. If you keep your kegged beer cold (which I assume you do since that's kind of the point of kegging) then those bugs will never, ever cause any appreciable changes in the beer. This is assuming standard cleaning and sanitizing practices. I have made many "wild" beers with mixed cultures and Brett over the years and I have never had any issues with unintentional souring or cross contamination despite using the same equipment for funky and clean beers. The only special precautions I take are to rinse with very hot water and then sanitize with a slightly stronger than normal iodophor solution after anything plastic comes in contact with bugs. That plus cold storage is more than enough to insure clean beer.
I have two pin-lock kegs that I just use for sours. That way the disconnects are also dedicated to sours, too.
