*off* flavors during bottle conditioning

[sbaclimber]

I have been using WLP007 to brew my IPAs for a couple of years now with mostly good results. Attenuation und flocculation are great. Only problem I had been having is was way too many esters, but I got this pretty much under control by keeping a consistently low fermentation temp (17°C).
Now that I get a nice fairly clean beer right after fermentation, I have been able to better tell how the beer develops during the bottle conditioning and storage.
What I have noticed in both of my last two brews was an odd aroma / flavor that developed 2-3 weeks after bottling and diminished again about 6 weeks after bottling. I can't really pinpoint the flavor, I isn't fruity estery though (that aroma I definitely know from warm fermentation).
I would describe it as a bit more grassy or veggy...I guess. Definitely not a "fresh" flavor, a bit "funky", if you will...
The bottles are stored at a fairly constant temperature, but not nearly as cold as during fermentation, closer to 19-20°C. Not sure if that has anything to do with it.

Does anyone have any idea of what might be going on?

 

[The Brew Mentor]

After fermentation do you warm the beer up for a D rest?

 

[sbaclimber]

Yes.
I hold the primary fermentation at 17° for 14-17 days, then throw in the dry hops and warm the fermentor up to 19-20° for 2-3 days before bottling.

 

[The Brew Mentor]

That's still pretty cold. You may want to get up to 21-22° C for a longer period of time to speed the clean up. Say 5 days or so. You won't create any off flavors during this rest.
Try it and let me know.
Brian

 

[sbaclimber]

Okay, sounds like a plan. Thanks!

I've got a brew in the primary right now, so should be able to post up initial results in 3-4 weeks.

 

[The Brew Mentor]

I can typically finish my 8.1% IPA in 7-10 days , then warm up and dry hop for another 5-7 days.
Fermenting cold does a nice slow job, but staying in the optimal range helps the yeast complete their job quicker and still stay clean.
The 007 optimal range is 65-70°F so if you're going to ferment cooler, increase your pitch.
Brian

 

[sbaclimber]

The 007 optimal range is 65-70°F so if you're going to ferment cooler, increase your pitch.

Anything over 17°C has produced too many esters for my taste...
I have been doing 2l. "Pro" starters, calculated using the Starter Calculator here, to makes sure that my pitch is big enough.
Even at warmer temps and with aeration, the WLP007 has always fermented relatively slowly for me, so I will probably still leave it at 17° for 2 weeks before warming it up for another week.

PS, the think that still confuses me, is that these flavors aren't apparent during the first 2 weeks in the bottle....

 

[The Brew Mentor]

Getting the proper cell count can be tricky. Depending on the age of the yeast you're starting with, a 2L starter nay not be enough.
You may want to try the Chico strain (WLP001) at warmer temperatures.
Funny you called out that this off flavor is happening in the bottle.
I've had a finished beer that tasted good going into the keg and dry hopped in the keg, get that same flavor your talking about 1 time before. I pulled the keg from the cooler and let it warm up for 7-10 days and it went away.
I initially thought it was the dry hops that affected the flavor, but the off flavor that kept coming to the forefront was diacetyl.
Good Luck
Brian

 

[sbaclimber]

I would love to try WLP001, but haven't been successful finding a supplier here in Germany.

Edit: just found a supplier!

 

[The Brew Mentor]

I forgot you were in Germany. You can likely get Safale 05 which is the same strain.
Only thing with that yeast is that I get peach flavors when fermented too cool.
Good luck.
Brian

 

[Ozarks Mountain Brewery]

flavors coming from yeast aren't always just the issue, water can change the way the yeast performs and makes the beer taste, drinking water changes several times a year, what you have in your water is very important to the style you want

Colin Kaminski can explain this in great detail in this book or find the podcast from beersmith website

http://www.amazon.com/gp/product/093738 ... d_i=507846

 

[sbaclimber]

water can change the way the yeast performs and makes the beer taste, drinking water changes several times a year, what you have in your water is very important to the style you want

Thanks for the link! I've been wondering if the water might have something to do with the slow fermentation...

btw, this is my current water profile:
Ca+2 = 76
Mg+2 = 15
Na+ = 27
Cl- = 44
SO4-2 = 166
Alkalinity 55(HCO3)
pH = 8

I add a bit of calcium chloride to balance out the bitterness, but that's it.

 

[Ozarks Mountain Brewery]

your numbers are a little high, I think the slow fermentation is from the low temps and using a certain yeast thats known for that, I would try 05 yeast just as a test, its very clean.

http://www.ebay.co.uk/sch/i.html?_odkw= ... t&_sacat=0

Temperatures for fermentation are deceiving, the temperature reading should be the wort its self not the air, I know thats hard to do in a sealed container but the easiest way is to stick your vessel in water let it set for a couple of hours and read the water temp, the water will equalize with the wort and give you a true temp reading. The best temperature Ive found for 05 yest is 67 F or 19.5 C

another tid bit is if your trying to produce a light beer( you will almost always taste something that shouldn't be there) hoppy or dark beers will cover up yeast flavors in most cases.

 

[sbaclimber]

the temperature reading should be the wort its self not the air

I know it isn't the best, but I have a temp-strip and the probe from my frig thermostat on the side of my (plastic) carboy, both insulated from the air within the frig with a thick layer of foam.

another tid bit is if your trying to produce a light beer( you will almost always taste something that shouldn't be there) hoppy or dark beers will cover up yeast flavors in most cases.

That may well be at least a part of what is going on here. My base recipe right at the moment (past x brews) is ~93% german pale ale + ~7% carafoam...so, relatively light for an IPA.

 

[Ozarks Mountain Brewery]

not enough yeast will also create off flavors, they stress out trying to replicate enough to consume all the sugar they see try adding one more next time

 

[sbaclimber]

That's still pretty cold. You may want to get up to 21-22° C for a longer period of time to speed the clean up. Say 5 days or so. You won't create any off flavors during this rest.
Try it and let me know.
Brian

Update: warming up to 21-22°C in winter is turning out to be harder than I thought it would be...
The ambient temperature in my apartment is ~19°, so it looks like I am going to have to pick up a heating pad tomorrow.
The good thing is, I should be able to wire it up to my thermostat to enable heating as well as cooling in my "fermentation chamber".

 

[Ozarks Mountain Brewery]

19 should be fine, I think its the light beer and the yeast type

 

[sbaclimber]

not enough yeast will also create off flavors, they stress out trying to replicate enough to consume all the sugar they see

I've been chewing on this since you posted it. Seeing as there is no evidence of these flavors at the end of the primary fermentation, I kinda doubt I am underpitching, but I can certainly make a bigger starter next time.

Side note: The remaining bottles from the brew that had this funky taste back around new years have cleaned up nicely. 4 weeks later, and the flavor is gone.
Guess this may just mean that I will have to add a month to my conditioning schedule.

 

[Ozarks Mountain Brewery]

all of your thinking is right on par , some yeast just take longer, some have half dead cells when bought, some yeast is just plain difficult to manage, there's no way to really pin it down unless you test and test or try other yeast but great they aged well, at least you have good tasting beer now

 

[sbaclimber]

...at least you have good tasting beer now

what's left of it. I of course had to keep trying it (almost daily) to see how it was developing over time. :lol: