How to get WLP540 to finish the job?

[frankvw]

A fellow home brewer (bless his soul) gave me a bottle of first-generation WLP540 sludge, which I used to brew a dubbel. I mashed at about 67C (172F) for a balance between body and fermentability. I pitched about 2 cups of sludge about 3 weeks old (kept at 2-4 degrees C / 35-40F). I splashed the wort into the fermenter to aerate it because I don't have the equipment (gas cylinder, regulator and bubbllng stone) to oxygenate it. The data sheet for WLP540 says that this yeast benefits from extra oxygenation, but with my modest equipment I don't have the means to accomplish that.

The bottle of sludge had developed considerable pressure, proof that even at fridge temperatures this yeast is still active.

Fermentation started at 18C (64F) and was underway by the next morning. I ramped up the temperature by half a degree to 22C (72F) because I wanted to keep the production of higher alcohols in check.

However, fermentation seems to have stalled at a SG of about 1.040 (OG was 1.075). It's been sitting at 1.040-ish for a week now. I've raised the temperature to 25C (77F) but so far nothing seems to be happening.

What can I do to get this dubbel to a reasonable SG?

// FvW

 

[cladinshadows]

The yeast, fermentation, or oxygenation is likely not to blame - that mash temp is absurdly high. You probably overpitched significantly which would help overcome the under oxygenation. However, a 1.040 FG is lower than I'd expect for that mash temp. Mash temp for a balanced wort sugar profile is more like 152F.

Edit: see if you like the flavor at 1.040. if not you can either dump it or use brettanomyces as a secondary yeast to dry it out into something very interesting.

 

[Smellyglove]

Do you measure with refractometer or hydrometer? If you've measured with refractometer take a sample and measure with hydrometer. 1.040 from 1.075 is very high.

 

[dmtaylor]

Do you measure with refractometer or hydrometer? If you've measured with refractometer take a sample and measure with hydrometer. 1.040 from 1.075 is very high.

I agree. Also wonder, have you properly calibrated all your instruments including your hydrometer or refractometer, as well as your mash thermometer?

 

[frankvw]

that mash temp is absurdly high.

My mistake. Being metric, I messed up the conversion from Celsius to Farenheit. I mashed at 67C which is 152.6F. My bad!

 

[frankvw]

Do you measure with refractometer or hydrometer? If you've measured with refractometer take a sample and measure with hydrometer. 1.040 from 1.075 is very high.

I use a hydrometer and thermometer combo. I wear varifocals which makes a refractometer almost impossible to read for me. Also, I find a hydrometer generally to be more accurate and reliable, but that's just me.

 

[smata67]

Here is some reading:

https://www.homebrewtalk.com/fixing-a-stuck-fermentation-101.html