Been having some issue with beers I don't want too dry over attenuating. My London III regularly goes to 80%+ and I just did a Scottish Light (now Heavy) that went from 1.034 down to 1.005. My London III beers I generally just put washed yeast in a 2L starter (probably underpitching according to some calcs if I get up to 7.5% ABV.) The SCottish was Edinburgh that I had made a 2L starter of about 6 weeks ago. These are all for batches around 6G. Any advice? How do I make my yeast less happy?
What are your mash schedules for these beers? Are you providing pure oxygen for the yeast? What temperature are you fermenting at? Are you using any simple sugars?
Didn't list because they vary but I usually shoot for 152 on my IPAish beers (I BIAB). Generally going 2 row base, 10 Munich, 10% flaked wheat or flaked oats, and then 10% Caramel 20 or Malted Oats depending on the beer. The Scoth Ale I shot for 154 but did finish close to 148 as it was a cold day and I was in the garage, still prob 151 avg though. I generally mash an hour, then dunk into some hot water for extra efficiency (I run slightly under 70, although I think it's do too crowding in my 10g pot. The Scotch had less grain and was closer to 75%)
If we know the exact parameters for each beer, we could predict what the avg attenuation should have been. Otherwise, all I can say is that it sounds high, but can't say how bad.
If you are getting lower than expected attenuation (i.e., for a given mash schedule/yeast) then a contamination would be my first guess. Cheers!
That's kind of the point though. The trend consistently takes place over multiple, styles, yeasts, and mash temps. Generally getting 80 + from yeasts that should top out at 75. No off flavors to speak of. My ferments are usually on the cold side if anything 65 ish for a few days then raise a degree a day.
Yeast strain is just one factor in attenuation. Every ale and lager strain can go 80+, depending on the fermentability of the wort. The attenuation ranges given by the yeast vendors are at best indicative of what to expect with worts typical to the style the strain is used for, and at worst, useless. I'm not saying that there isn't something unusual going on with your beers. But the first step would be determining if there really is. You mention a trend of over attenuation, but where is your expectation of normal attenuation coming from?
As others have said, there are other reasons for beer attenuating highly. That said, it never hurts to give your equipment, especially anything plastic/porous, a good, thorough nuking.
