Kolsch WLP029 Long Slow Gravity Drop

[micraftbeer]

I'm on Day 20 post yeast pitch on a Kolsch. I started cold, around 56f, as I've had good luck with that before. After about a week, it was looking like things were finished, but as I kept waiting for my Tilt to show 2-3 days of flat SG, it just keeps slowly dropping.

I was initially thinking I'd just ride it out to two-week point and surely it would be done. But it still hasn't flatlined.

Any thoughts?

 

[RM-MN]

If you have a hydrometer, pull a sample and see how it compares to the Tilt. Pull a second sample in 3 days and compare again.

 

[AdjunctBrewer]

What was the grist, mash schedule and yeast pitch rate? 1st gen yeast? Is that temp accurate? 74F?

 

[micraftbeer]

What was the grist, mash schedule and yeast pitch rate? 1st gen yeast? Is that temp accurate? 74F?

It was a slightly smaller batch, 4 gallons into fermentor vs my typical 5.5 gal.

One pouch of fresh WLP yeast (best before 3/25/2025, and pitched on 12/19/2024). No starter, probably could've used one since I was fermenting pretty cold, but I was expecting a smaller volume into fermentor than I got. 2 minutes of bottled oxygen applied through stone before yeast pitch.

Temp was accurate, matched between Tilt and temperature controller. I cranked it up today to see if it would accelerate whatever drop was going on.

55% Pilsner malt
37% Brewers malt
8% White wheat
145F for 40 min
158F for 20 min
168F for 10 min
Mash pH 5.29
Mash efficiency 79%
OG 1.044
FG 1.005

 

[micraftbeer]

I couldn't take it any more and close transferred it to a keg to cold crash tonight. I was worried maybe there was an infection. But I smelled no off aromas and didn't taste anything funny. Of course taste was hard to assess since the beer had no carbonation and was 75F.

 

[day_trippr]

Did you compare the Tilt reading to a hydrometer - or even a refractometer - first?

Cheers!

 

[micraftbeer]

Did you compare the Tilt reading to a hydrometer - or even a refractometer - first?

Cheers!

The FG number of 1.005 was from my refractometer (corrected based on the OG).

 

[Halfakneecap]

Pitching that cold with no starter is my guess. I always make a starter no matter what the pitch temp is but i think its probably more important when pitching cold.

I use 029 quite a lot, and it always works fast at 15c and above for me.

I think it'll be fine

 

[micraftbeer]

I had always thought that if I'd under pitched or had too challenging of a ferment for the yeast I would have trouble starting and/or slower fermentation rate at the start. Since this one started fine, I thought I was in the clear.

I guess there's more than one way for yeast to show you you've asked too much of them.

 

[dmtaylor]

Dang, this sure seem like it might be contaminated. But of course, after it does finally flatline, as long as it tastes good then go ahead and enjoy it.

I for one don't think underpitching or cold fermenting would have done this kind of thing. My bet is contamination by some possibly neutral yeast.