Christmas seasonal fermentation stopped at 1.017

[surista]

Brewed a Christmas seasonal a couple of weeks ago. It's a recipe I've done once or twice, so I'm familiar with it and know how it generally comes out (for those interested, it's based largely on Gordon Strong's Holiday Prowler).

I was pretty close to spot-on for original gravity (1.060 measured, vs estimate of 1.058). I used a yeast starter, using fresh yeast. Fermentation started *very* quickly and was quite robust (see below). BTW, I'm using a Tilt Hydrometer with a Brewjacket (great combo, btw) so temperature was stable. The Tilt was calibrated before use.

Anyway, the gravity reading went from 1.060 to 1.019 in like two days, then didn't move for a couple of days. I shook the fermenter a couple of times just to shake things up a bit and in case the Tilt was stuck in krausen or something - no change. Bumped the temperature up a bit - no change.

Basically it's stalled at 1.017, versus the estimated FG of 1.007. That seems like an awfully high FG, especially since I've always gotten to 1.010 or below the previous times I've done this recipe.

I'm assuming that the beer itself will probably be fine, just not as strong as I had planned (probably closer to 5% or so instead of 6-7%). But I do have some dry yeast on hand. Would adding some to the fermenter and leaving it for a few more days be meaningless, too much of a risk, or worth trying?

 

[Gnomebrewer]

Hmm, I've never personally seen or used a TILT, but every second thread that comes up on here with gravity problems is someone using one of them. Try measuring gravity with a normal hydrometer.

WLP002 is notoriously lazy. It's like a teenager - let it go to sleep and it doesn't want to get up. Unlike a teenager it works well when it's awake though. I find racking to secondary (I know, an unpopular practice) works better to wake it up than shaking or stirring does.

 

[surista]

Sorry, should have clarified:

- I wasn't using WLP002, which wasn't available, I used WLP007 (Dry English Ale), which is supposed to be good for higher-gravity beers.

- I took a normal hydrometer reading (both at the start of fermentation and after about eight days) and the Tilt was spot on. 100% confident that the Tilt isn't the problem.

I've had beers where the FG didn't get to where I had expected, but I don't recall a case of having it stop coming off such a rapid, robust fermentation.

 

[RPh_Guy]

Did you at any point add yeast nutrient?

 

[kh54s10]

White labs lists the attenuation of WLP007 as 70 to 80%. Brewers Friend calculates your attenuation at 71%. This may be all you get from the initial yeast.

The recipe says to mash at 158F. That seems ridiculously high and would lead to a low attenuation. I have never mashed anything hotter that 154F.

 

[myndflyte]

The recipe says to mash at 158F.

OP you sure you mashed at 158F the last times you did it? I mashed BierMuncher's Octoberfest at 157F and got a OG of 1.060 and a FG of 1.023 which I sort of expected based on the mash temps. I'm surprised you were able to get it down to under 1.010 previously if you mashed at 158F.

 

[surista]

Well - here's a good lesson in keeping 'all things equal'!

I went back to my notebooks from previous brews of this recipe - two brews, one in 2015 and one in 2016.
First year, FG was 1.010, next year was 1.011. So I wasn't below 1.010. Both used WLP002.
I did indeed mash (well, steep) at 158F as I would have stuck right to the recipe for that.
However - both of those earlier brews were extract with steeping.

In the interim, however, I have converted to BIAB

I also just noticed something looking at the original recipe - it calls for OG of 1.058 and FG of 1.014.
I started out at 1.060, so maybe stopping at 1.017 is about where I'd need to be at in any case.
I was basing my estimated FG from Beersmith, not the final recipe.

Wonder why Beersmith gives such a different estimated FG? Either way, between going from extract to BIAB, and using a slightly different yeast etc, I guess I can stop worrying and just go with the beer as-is (which smells and tastes amazing, this is going to be awesome, if a bit lower ABV than planned - which may not be a bad thing).

I didn't use any yeast nutrients. Never have, actually.

 

[kh54s10]

FG estimates are just that. Estimates. They are based on equations from the expected attenuation of the yeast and other variables. All these variables lead to differences. Sometimes lower and sometimes higher. Since your OG was 2 points high and your FG was 3 points high, I would say you are just about right on.

Since your OG and FG were high your ABV should actually calculate out very close to what it should be.

I would not get to worked up about trying to hit predicted FG. You will drive yourself crazy.

 

[Calder]

The high FG is due to the 158 F mash temperature. You may want to make a note to mash lower next year. See what you think of the beer and decide if you need to change the temp.

 

[couchsending]

Comparing an extract brew to an all grain brew is apples to oranges. So much has to do with the base malt. The fact that 002 got you lower than 007 means to me that the extract was much more fermentability (especially as 002 doesn’t like complex sugars). If you had used 002 and mashed this grainbill at 158 it most likely would have finished at 1.020 or 1.022. This attenuation seems about right for 007 with a mash temp that high and Maris as your base malt.

Yeast nutrient is generally a good thing. It provides the necessary amount of zinc for yeast health among other things. It can however increase esters with some yeasts which for some beers might not be advisable. A Winter Warmer with English Yeast is a beer where increased esters might be a positive.

 

[isomerization]

Thumbs up to previous comments on mash temp and high(er) FG.

Also, remember that numbers are just numbers, your sensory perception is more important. I’m not saying to stop recording data, just don’t obsess over what it’s supposed to be. If you like the brew as is, repeat it again next year. If not, change a variable!