[jmitchell3]

Trying to track down the source of hot / solventy flavors in my first batch of Kolsch. 

Here's the process profile:

Cooled wort to about 63-64, transferred to fermentation bucket and dropped it into my fermentation freezer (temp controlled) for about an hour till it got down to about 61F.  Pitched my yeast starter (WLP-029, about 500mls into a 3.5 gallon batch, OG 1.052 FG 1.010).  Fermentation was crazy active at 12 hours...it just went nuts.  after 3 days airlock activity was down to almost nothing.  on day 6 bumped temp up to 63F for 24 hours, then crashed end of day 7 to 36F for 24 hours, then bottled (7/22) to condition at room temp for 3 weeks, then bottles went into the fridge for cold conditioning (about 8/16). 

After a week, brought a few out and served them at my local homebrew club to rave reviews.  Submitted to a comp (judged 9/1) and got feedback about hot / solventy flavors that I had not noticed in the first few bottles.  Busted out a bottle two days ago and immediately noticed the hot/solventy aroma and flavor.  Not sure why I had not picked that up before.

Question: Where in the world did these flavors come from?  Brewed the BCS recipe, which called for a fermentation temp of 60F.  White Labs recommends temps no less than 62F, and ideally 65-69F.  Any ideas where this hot / solventy thing came from? 

Looking back I probably should have let it sit on the yeast another week, then crashed and lagered even in primary for at least another week.  This could have given the yeast more time to clean up.  Can't imagine the off flavors came from too low a fermentation temp...

Any input would be greatly appreciated!

[klickitat jim]

Assuming its fusel alcohol, I'm not certain that keeping it on the yeast would cure it but look at it this way. If its there, why not try? If I had to venture a guess at the cause, my guess would be a temp calibration issue. Describe your temp control system and probe placement

[HoosierBrew]

+1 to temp accuracy. Also, I would never crash a 1.052 beer after a week. I like to give an average strength beer that extra week to clean up after itself, or at least verify my FG first. I see that you reached 1.010, but was that stable over successive readings ? 'Solventy' comments usually point to excessively high fermentation temps (the most likely culprit here), but also keep in mind that if your beer had not quite hit FG, the drastic temp change could have stressed the yeast into giving off 'off' aromas/flavors. Also, do you use a reliable thermometer? Inferior quality thermometers can be off several degrees F.

[dmtaylor]

You only pitched a pint size starter.  Might have underpitched, in which case you might have allowed some contamination to take hold in addition to the Kolsch yeast, causing the off-flavor.  Attenuation of 81% is also quite high for this yeast strain.  I get 75% average with a mash temperature of 150-153 F.  So again... the higher attenuation points to something weird going on.  How old was your yeast?  How active was the yeast starter?  Did you smell and taste the starter before pitching?

[Stevie]

Stressed yeast?

I'd go bigger with the starter, especially fermenting on the cool side.

[jmitchell3]

to the high attenuation, used the BCS recipe, mashed at 149.

to temp accuracy, double checked my temp probe on the controller with my thermapen, it was off by less than 0.5F.  for attachment, I tape a double folded handtowel to my plastic bucket and insert the probe between the towel and bucket wall. 

to pitching rates, used the brewersfriend pitching rate calculator for the yeast starter...only 3.5 gals in the fermenter, may have been a 1l starter, but I don't seem to have notes.  Yeast seemed ok.  As i recall it was a may batch (july brewdate).  I did not smell the starter.

guess an infection may be possible, but I'm not sure how it would have occurred, I'm pretty retentive about sanitation.  any other thoughts or suggestions?

[S. cerevisiae]

Solvent is ethyl acetate, which is an ester.  In addition to elevated temperatures, ethyl acetate can also be result of pitching too much yeast.  Hot is usually fusel oil, which can be the result of the wort being too FAN (Free Amino Nitrogen) rich, having too much dissolved O2, or fermenting at elevated temperatures.   If you are aerating/oxygenating your wort, you need to do it before pitching.   A lot of people pitch and then turn on their aeration pump, which is a no-no.

[dmtaylor]

Plastic bucket for fermentation, or glass or stainless?  Plastic goes bad with age.  The others do not.  Also check all your hoses, gaskets, soft stuff.

[jmitchell3]

Ok, i reviewing my notes, this is where I departed from my normal brewing procedure: I used brita-filtered water instead of store-bought spring water.  Is it possible that there could have been chlorine or chloramines that the filter didn't get that are causing the off-flavor?

[dmtaylor]

Well yeah... Brita is not a perfect filtration system... and actually no filter is as good as getting a pure chlorine-free water source.  So, you think you might have chlorophenols??  Does the off-flavor taste at all like Band-Aids or a medicine cabinet or a hospital?  If so, then yeah... there's your culprit.  If not, then that's probably not the issue.

[jmitchell3]

no definitely not bandaid.  so I guess that's not it. 

[dmtaylor]

One last word of advice before I head off to bed...

Don't ever take one or two judges' word for anything.  Get more beer geeks to taste that beer for you -- whether it's through local homebrew club members, or friends who won't try to be nice but will give you their honest and forthright opinions, or judges at additional competitions.  Get more opinions, and do NOT tell the others that they should be looking for "hot/solventy" flavors, and just see what they say.  It might truly be hot/solventy, or it might not.  It might have some other kind of off-flavors, or it might not.  If you can detect it yourself, then it's probably there.  But someone else might be able to help you characterize it, assuming you are not a BJCP judge yourself.  But anyway.... yeah, I always say that you should always enter a beer into at least THREE competitions if you really want to fully understand what's going on with the beer, because inevitably, one pair of judges will be totally screwed up, while the other two pairs will give you great feedback.  So it's entirely possible that you just got bum scoresheets.  It happens.  A lot.  All the time.  Everywhere.  If you can taste it then maybe it really is a problem.  But if you can't... then don't let the judges sway you to their opinion, because about 1/3 of the time, they're just flat out wrong.

I am BJCP Certified rank, by the way.  My opinions are my own and in no way reflect that of the BJCP.  I like the BJCP and everything I have learned from them.  But of course, individuals within the organization are humans with flaws.  Judges are not all perfect robots.

Okay, I'm sure you get my drift.  Later.

[eric.knuds]

It sounds like you crashed too soon. If you were priming in the bottle, I would transfer to bottles, then condition in bottles after carbonated. Crash once the beer is in bottles to let age.


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[jtoots]

If you are aerating/oxygenating your wort, you need to do it before pitching.   A lot of people pitch and then turn on their aeration pump, which is a no-no.

This is news to me...  I've always aerated after pitching.  Anyone else have thoughts on this?

[dmtaylor]

I don't see why it makes any difference at all.  But maybe he's right.  More experiments are needed.  My intuition tells me that it doesn't matter at all.