This week I have been struggling with stuff yeasty.....or have I? And that's kind of the problem.
A week or so ago I brewed a porter, not a style I had tried by BIAB. All the techniques came out; mash water treatment, based on Wheeler's Calculator, and a preboil of 30 mins with some gypsum to remove most of the carbonate. After cubing for a day, I pitched a vial of White Labs English Ale yeast, and left it to do its stuff.
I also decided to mash at a slightly higher temperature to produce a slightly sweeter, full bodied beer, as I like my dark beers this way! And I think that is where the problems started.
Mashing high tends to also produce non-ferment able sugars, hence the residual sweetness. So, even though I missed my OG by four points, I was confident I was going to get the kind of beer I wanted. Starting slowly at 1.055, the yeast never really started going, and after 5 days the bee looked spent. Taking a gravity reading, I was at 1.030, an attenuation of 45%, not the 63% I was quoted, and a full 10 points out. This site told me that I could correct my attenuation for a high mash....but I was still 6 points shy of target.
And so I hit the dilemma....stuck fermentation, or was I done? Even trickier was the fact that, although now 3.2% rather than the 5% I was aiming for, it tasted great (mocha, anyone?). Further fermentation might just dry it out a bit. Moreover, if it was stuck, a kick of priming sugar may cause the odd nasty explosion.....really not good.
I have tried rousing it, and leaving it in a warmer spot, and three days later nothing. Eventually, those nice people in t'Internetland suggested I try a Fast Ferment Test....this is a great idea! Perhaps I should do this all the time? 200ml of brew, over pitched and kept warm....if the gravity drops again I know the yeast has conked out and I repitch, if it stays the same I can keg with impunity! I started the FFT yesterday, so let's see how it goes.
Update on 16/6: FFT has been sitting in the airing cupboard for two and a half days. Justtaken a gravity reading....1.030. Looks like I'm good to barrel it!