I think it has happened to somebody else in this forum but i can not find the post.The point is after a month or so a 5 gals Old Ale batch has started to ferment again,there ´s a 2 inches krausen foam atop the wort and airlock is bubbling every 5 secs. I took a sample ,it is sweet and a bit phenolic but there is no nasty or weird flavor,didn`t take a gravity measure though.Pitch was a bit high >- 73 F. I think it is sweet cos it must be under attenuated,but i don´t understand why it has stopped fermentation and then resumed while room temp. is colder now than when fermentation took off, i didn´t shake fermentor or somehow resuspend yeast. Edit : Sorry didn´t mention it is a Windsor dry yeast . OG was 1055
I can't really answer your question but I would take a gravity reading. And then another couple days later. Not rousing it and the cooler temperature don't seem like it has any good reason to start up again (which is what you seemed to be eluding to). But if it is under attenuated, maybe it's not such a bad thing?
I really don’t have a definitive answer but I can provide some additional information. I have used Danstar Windsor many, many times to make my English Bitter Ales. On a number of occasions I have had these beers produce ‘normal’ carbonation in my bottled beer despite the fact that I purposefully used less corn sugar for priming my Bitter Ales; I used 2 ounces vs. the 4 ounces I use for all of the other styles of beer that I make. I exchanged a number of e-mails with folks at Danstar on this topic and I was informed that the Windsor strain will not metabolize maltotriose sugar (most beer yeasts metabolize maltotriose). They theorized that I had some wild yeast in the beer which metablized this particular sugar and resulted in higher carbonation levels. Maybe your ‘renewed’ fermentation is wild yeast fermenting maltotriose? Cheers!
Your bud(s) at Danstar are basically correct. But it's usually not simply binary, i.e. 'can' or 'can't' ferment maltotriose. The ability to use maltotriose varies widely from strain to strain, with most lager strains being better at it than most ale strains. It's the thing that determines the characteristic 'typical' attenuation rates for each strain.
Maybe your ‘renewed’ fermentation is wild yeast fermenting maltotriose? I don´t think Sir, i have never used wild yeasts.I used a fresh pack of 11 gms dry yeast.It is a very weird situation, i thought fermentation was done after a good fermentation during the first week, as i always have seen this yeast behaves.Something i can figure could be a sudden reduction of room temp during a very cold night(almost winter here), but fermentation during the first week was at 68 F(average), i use gas heaters to hold room temp. and i am sure (cos i checked it 2 or 3 times a day) that fermentor thermometer temp. ranged between 64F-72F.
I don't think that you need to have ever used wild yeast for them to have been introduced to this batch...b/c they're wild. Sound sanitation practices?
Well i don´t know, i hope not ,but i can not assure that. I don´t think could be free wild yeasts inside the place i brew , i have never had this problem before.
The wild yeast is just floating in the air around you all the time. Even if you practice good sanitation it is always possible for some wild yeast that exists in the air to get introduced into the fermenter. The idea of pitching a lot of beer yeast (Windsor in this instance) is to have that yeast be the ‘dominant’ yeast and hopefully they will ‘muscle out’ the wild yeast that is present in the air. Needless to say but some wild yeast will make its way into your fermenter. No batch of homebrew is ever not infected by microorganisms other than the pitched beer yeast. Cheers!
I have never experienced ‘issues’ with the homebrewed beers I made with other yeast strains. I have only experienced ‘weird’ carbonations levels with Windsor yeast. Cheers!
