Attenuation issue with Pliny clone

I’m having a fermentation issue that I just can’t figure out. I’m doing a Pliny clone published in Zymurgy. I used a slightly thinner mash (1.5qt per lb), hit my numbers perfectly (152) and mashed for 75 minutes maintaining a temp of 149 to 152 (I have a HERMS set up) before raising the temp to 168 and mashed out.

After a 90 minute boil the OG was 1.070 (exactly as the recipe says in the Zymurgy recipe, although I did have to increase the grain bill to get that). 5.5 gallons into the fermenter and I aerated using O2 for 2 minutes and pitched a 1 liter starter (WLP001). The recipe says the final gravity should be 1.011 which seems impossible.

After 9 days in primary fermentation stopped at 1.022 (I set the temp at 65 which had the wort temp at 68 during the most vigorous phase). I took another reading yesterday and it was still at 1.022 so I raised the temperature to 75 and roused the yeast by shaking the fermenter (being careful not to splash) and fermentation started again within a couple of hours and was going fairly strong when I left for work this morning. I guessing that if I’m lucky I might get it down another 4 points to about 1.018. Still too high for a DIPA.

So how the heck do they get it to 1.011? Even with an optimistic attenuation of 80%, using Noonan’s formula it won’t go lower than 1.014 (((1-0.8)*(1.070-1)+1) = 1.014.

Any advice? I’m out of ideas. I’m guessing at the brewery they do a regular C02 burst to rouse the yeast to prevent it from flocculating too early, but 1.011 still seems impossible with an OG of 1.070 unless I'm missing something obvious.

Sounds like you did everything correct, the only thing I have to ask is how sure are you on the mash temps? Also, I think I over pitched with like a 3L starter of the real wort.

I mashed my pliny clone at 149-150 for 75 minutes. Ended up at 1.075 for the OG, and got to 1.011 for the FG.

The other thing is that the zymurgy recipe has some corrections made to it through the email newsletter thing, I can't remember what was wrong but I think the amounts were wrong somehow.

Well, that would be ~84% AA - high, but not impossible. I have had 85% AA with all-malt mashes (my last imperial amber was 1.081 -> 1.016, which is about 80% AA). Obviously, you know the right things to do to get high attenuation (low mash temp, attention to yeast strain and health, fermentation temperature). Assuming you stick to an all-malt mash (obviously, higher attenuation is easy if you add sugars) about the only other thing you can do is to play with added amalase enzymes. But presumably that's not what's done for Pliny.

I'm pretty sure of my mash temps as I have a Ranco temp controller hooked up to a thermowell on the outlet of the heat exchanger and there is only a 1 degree difference with what that is showing compared to the analog temp gauge on the mash tun.

I also checked Mr Malty's pitching calculator and the size of my starter was correct for the OG and volume, at about 1 liter.

It's a bit of a mystery this one. Next time I think I'll increase the OG by another 4 or 5 points and will mash lower, say 148 - 149.

Did you add the corn sugar as instructed in Zymurgy? In my limited experience, the only way to get that high kind of attenuation is through the addition of simple sugars. My Pliny clone hit 1.012, but started more around 1.067.

bdnoona said:

Did you add the corn sugar as instructed in Zymurgy? In my limited experience, the only way to get that high kind of attenuation is through the addition of simple sugars. My Pliny clone hit 1.012, but started more around 1.067.

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I put the corn sugar in at 15 minutes minutes from the end.

I think I might have found my problem. I scaled up the 2 Row from the original Zymurgy recipe (to 14.5 lb), but I left the Carafoam / Crystal at 0.5 lb each but forgot about the corn sugar which was originally at 0.4 lb. I now just boiled up another 0.4 lb, cooled and added it to the fermenter. Unconventional, but this might just do the trick...

Why do you think that adding more fermentables will lower your fg?

maskednegator said:

Why do you think that adding more fermentables will lower your fg?

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reverse physiology,

maskednegator said:

Why do you think that adding more fermentables will lower your fg?

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I might be smoking dope here, but this is my thinking:

I restarted fermentation by increasing the temp to 75 and roused the yeast which started up again but stalled after 1 day, but I got it down 1 point to 1021. I'm pretty sure it's still not finished (I've had beers with less fermentables with an OG of 1085+ that I've got down below 1020) so by adding corn sugar I'm giving the critters some simple sugars to digest which should increase the yeast population, increase the vigor of the ferment and give them a better chance of eating the longer chain sugars (from the 2 row) when the simple sugars are gone.

But as I say, I could be smoking dope.

Beers that high in SG - or anything over 1.060, really - benifit greatly from a pinch of Fermaid K 3-4 days into fermentation. The high alcohol makes them not want to eat any more sugars and stresses the yeast out. Fermaid K will give them the nutrients they need to properly finish out. Give it a shot on your next beer.

I just did the Pliny clone. I let it ferment out completely, then went back and added the sugar. FG is now 1.010 with WLP001.

Good luck.

Arch Hall JR - the stuff of nightmares

Jipper said:

Arch Hall JR - the stuff of nightmares

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"sorry about my face!"

maskednegator said:

Why do you think that adding more fermentables will lower your fg?

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Because alcohol is lighter than water, and simple sugars ferment out completely.

Jipper said:

Beers that high in SG - or anything over 1.060, really - benifit greatly from a pinch of Fermaid K 3-4 days into fermentation. The high alcohol makes them not want to eat any more sugars and stresses the yeast out. Fermaid K will give them the nutrients they need to properly finish out. Give it a shot on your next beer.

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I'm not familiar with Fermaid, but it sure sounds interesting. Maybe yeast nutrient is my problem. Previously I'd been using Servomyces which I just added 15 minutes from the end of the boil. For this batch I used a different nutrient. I forget what it's called or what the vendor is, but it's a powder which I added to the boil near the end. Maybe it was supposed to go into the fermenter.

I have a tripel on tap right now that went from 1.079 down to 1.009, so high attenuation isn't completely unheard of, but I don't think you could get that with your mash temperature. For that beer, I mashed down around 148-149 for 90 minutes, plus it included a pound of sugar to help dry it out a bit further.

Of course, a couple caveats: 1, it was using a Belgian yeast, with a pretty good attenuation, and 2, it was about as simple a grain bill as you could get, with just pilsner and pale malt. Still, I've gotten better than 80% attenuation out of WLP001 before.

Well it turns out my issue might be academic as this batch would appear to be cursed. Transferring to secondary last night and forgot to remove the stopper and I sucked 1/4 gravity of sanitizer / blow off from into the secondary. I wonder what that will do to the FG (not to mention the taste)...? Not the first time I've done that either. Needless to say I'm very annoyed with myself.