Long ferment for Kolsch, tastes like apples

[tripeland]

I brewed a Kolsch 16 days ago and it is still bubbling once per second. It must be fermenting still as it is set up with a spunding valve set at 5 psi. Pitch temperature started at 60F and held for the first 10 days or so. Set it to 65F about 6 days ago. I took a gravity sample and was at 1.010 from a 1.046 OG. It smelt like apple juice. Tasted like apple juice with bittering from the hops.

Is the apple taste because it is still fermenting? Or I didn't have as much yeast as I thought and underpitched? Will it mellow?

Recipe was mostly pilsner malt with a little bit of wheat malt, mashed at 148F. Yeast was Wyeast 1007 from a starter. I made the starter from an over built previous starter that was stored in a sanitized jar in a fridge for a few weeks. I think my process should be free from infection, but can't be eliminated I suppose.

I'm a bit concerned the ferment is taking so long. Normally it is done by around day 7.

 

[Qhrumphf]

As acetaldehyde is produced as an intermediary during the fermentation process, if you're still fermenting it's not surprising it'd be there.

Underpitching a cool fermentation can certainly explain the sluggishness.

Pomme esters are typical of those yeasts. So if you underpitched, that could be the issue as well.

Ethyl hexoanate (sp?) is an ester often with a more red apple character, where acetaldehyde is more green apple and cidery (though fresh cut grass or latex paint are other descriptors, I often perceive the latter).

I wouldn't panic until it's done fermenting. It may well clean itself up.

 

[dmtaylor]

Wyeast 1007 ferments slow in my experience. Best thing you can do is to warm it up. Go ahead and set to 72 F. Acetaldehyde vaporizes at 70 F, so if that's the issue and you keep it cold, it will stay in there forever. But warming it up and letting it sit for a good 2-3 more weeks should see reduction in the apple character, whether that's acetaldehyde or an ester, either way I think.

Good luck.

 

[Comfort_Zone]

Raise the temp, get it to at least 70F, at this point your Ester profile is set but my guess is that it's acetaldehyde. Let the yeast finish its work then enjoy.

 

[tripeland]

Thanks for feedback. I would describe it as an apple juice or cider smell/taste. Not sure I can differentiate green or red apple from it.

I have set to 72F and will let it sit there for a couple more weeks. Hopefully the flavour dies down.

 

[Qhrumphf]

Warm will speed it up. But the yeast should in theory metabolize into ethanol or take back up acetaldehyde regardless. It doesn't need to be 70+. I'd probably keep it 67-68 and no higher.

If there's more there than the yeast can chew through, warm won't help much. In that event, I would try krausening it.

 

[tripeland]

Update: I let it sit at 72F for about a week, cold crashed and have it on gas for last couple days. The apple taste has gone! Taste it much better but not 100%, there is a strong bitter aftertaste that I hope will mellow after a longer cold conditioning.

 

[couchsending]

Update: I let it sit at 72F for about a week, cold crashed and have it on gas for last couple days. The apple taste has gone! Taste it much better but not 100%, there is a strong bitter aftertaste that I hope will mellow after a longer cold conditioning.

Is it still rather hazy?

1007 doesn’t like to flocc. That strong bitter aftertaste most likely is yeast. 2565 is the same way.

For future Kolschs I’d recommend wlp029. It’s faster and floccs better. Easier to use yeast.

 

[dmtaylor]

For future Kolschs I’d recommend wlp029. It’s faster and floccs better. Easier to use yeast.

WLP029 is fine, but....... it's actually a super clean yeast of ENGLISH origin.......

But yeah, it's very clean and easier to use, I'll give it that.

 

[couchsending]

WLP029 is fine, but....... it's actually a super clean yeast of ENGLISH origin.......

But yeah, it's very clean and easier to use, I'll give it that.

I’m aware but it’s also the yeast used by one of the bigger producers of the style in Cologne..

I’m going to blend 2656 and gy021 next time in hopes that the gy021 will help to drag some of the 2565 down with it.

 

[tripeland]

Is it still rather hazy?

1007 doesn’t like to flocc. That strong bitter aftertaste most likely is yeast. 2565 is the same way.

For future Kolschs I’d recommend wlp029. It’s faster and floccs better. Easier to use yeast.

It is quite hazy still. Will a long cold condition be enough to drop the yeast?

 

[couchsending]

It is quite hazy still. Will a long cold condition be enough to drop the yeast?

Hopefully yes. Maybe no?

 

[tripeland]

The beer was mostly finished by family this Easter and has mostly cleared by now. Taste was great!