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Wild Yeast or Infection

About three weeks ago I made a ten gallon batch of robust porter, then split it into two five gallon fermenters. One a standard robust porter and the other a robust raisin porter. After two weeks in primary and no movement on the hydrometer, I racked both to secondary. I parboiled the raisins and froze them, on the day I racked, I added them to the fermenter that was tobe the raisin porter. After a week, I took a sample of the raisin porter and it is sour and a white film has begun to form on the top. The beer does not taste or smell bad, it just has an sour profile to the taste. Do I have an infection or a wild yeast? And, should the batch be pitched?

If it doesn’t taste or smell bad why would you dump it? I make a gruit every year with redwood tips. This last year was the first batch I have made using my CF chiller and the redwood clogged it. Because of the way I am set up I had to pour the wort through a strainer on my back deck. It picked up something from out there and has definitely soured, but everybody loves it. I believe mine is lacto because it is sour after only a few weeks, also lacto grows on unmashed grains and I have some of those spilled below my deck where it is probably a good breeding ground for bacteria.

Thanks IPA. My inclination was to keep it since it seemed fine and the thing that changed was the addition of the sour profile; however, I was unsure since in the years I have been brewing, I haven’t ever run across something of this nature. I have taken a few samples since I racked it and the sour profile is becoming slightly subdued and other creaters are emerging, so I think I will let it run its course. It is becoming interesting.

Don’t automatically dump it. You can always do that, but you can’t undo a dump.

Yeah, this is the first time it happened to me too. I plan on saving some of the yeast/whatever beasties it picked up for future brews.

I’m definitely seeing this through. A white film (pellicle) is forming on the top now. I am just not sure about leaving it in the glass carboy with the airlock still in it as I understand that wild yeasts need to feed on some oxygen. Also, I am not exactly sure how long to age the beer on the wild yeast. I read on White Lab’s site that depending on the strain it could be as long as eight months, that is assuming I introduced a strain that is the same or similar to that of White Lab’s. Any suggestions on the duration and the oxygen consumption the yeast may or may not need? I do plan to open the carboy tomorrow in order to add Alder chips to the mix, perhaps, the chips themself will contain some oxygen giving the yeast its desired fix.

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