Diacetyl

[beerguy2009]

I just experienced my first home brew competition last weekend and had a great time.One of the main comments I got from the judges was there seemed to be diacytel in my beer.
I have looked online for answers about how to reduce/ eliminate the amount left in the finished beer but I am still a bit confused. I usually leave my beer in the primary for a couple weeks. I don't transfer to a secondary. I use Starsan to sanitize and do my best to practice good sanitation.
Now that I am aware of this, I think I have had this in several batches I have made.
Any ideas what I can do about this? Could it be that I use plastic fermenter buckets? I did find a few scratches in one of my buckets.
I currently have a Pumpkin ale that has been in the fermenter for 2 weeks. Anything I can do at this point to eliminate this problem in that batch?

 

[EdWort]

I use buckets too and don't have that problem. Leave it in the bucket for another week and let the yeast clean up after themselves.

 

[Cellarbrau]

What yeast are you using?

 

[Mongrel]

What yeast are you using?

This, plus how much yeast, and what temp are you pitching/fermenting at?

 

[dogbar]

Using starters, properly aerating the wort before pitching, and controlling fermentation temperatures are all ways to decrease diacetyl production.

 

[beerguy2009]

So am I not leaving the beer in the fermenter long enough?
I used everything from Safeale 05 to Danstar Nottinham to Wyeast American Ale II Activator.

 

[beerguy2009]

I pitch at about 75 degrees. I aerate by closing up the fermenter and shaking it for several minutes.

 

[Mongrel]

I pitch at about 75 degrees. I aerate by closing up the fermenter and shaking it for several minutes.

And what temp are you fermenting at? Temp control really helps.

 

[beerguy2009]

I ferment at 68 degrees.

 

[BBL_Brewer]

Really, you should pitch the yeast at or below the temperature you plan to ferment at. Pitching at higher temperatures may be contributing to the problem as well.

 

[beerguy2009]

I have always pitched at around 75 degrees. So cooling to 65 to 68 may help?

 

[beerguy2009]

I read that warming up the beer after it has finished fermenting can help. Could I still do that to the Pumpkin ale that has been in the fermenter for 2 weeks or is it too late.

 

[duckmanco]

I have always pitched at around 75 degrees. So cooling to 65 to 68 may help?

In short, yup. Take us-05, s-04, 1056 or most English or American ale yeast for instance. I cool in with those to 60 or 62 or so and let them free rise to 66-68 for the first three days or so for a nice clean ferment. After the third day or so (depending on OG of beer etc) I typically pull the fermentor out of the swamp cooler and let it finish up at ambient room temp.

That method has worked like a charm for me. Ymmv of course, but from what I've gathered, cooling in a touch low and letting the beer free rise allows a cleaner ferment, and that the first three days of fermentation are the most critical with respect to controlling temps.

If you don't have one a 5 dollar swamp cooler is the single best thing other than full wort boils that I have ever done to make better beer.

 

[beerguy2009]

I think I may have found my problem.
So I have a basement that stays around 68 degrees year round. Do I still need a swamp cooler? It that used to cool the wort? I just need to cool my wort further.

 

[diS]

Fermentation temperature is usually few degrees higher than ambient temperature, and it will start to falling down at the end of fermentation.
Best thing you can do to reduce diacetyl is to pitch at 2-4 degrees lower than desired fermentation temperature, keep temperature low and then few days before end of fermentation increase 5-10 degrees to allow yeast to clean unwished flavors including diacetyl.

 

[Cellarbrau]

Fermenting at 68-70 degrees will probably fix your problem. If not, try dailing in the pitching and aeration rates. You won't need a diacetyl rest if you do those 2 things adequately.

I'd imagine your beer is quite hot and estery as well. I remeber my Nottingham ferment that got up to the mid-70s. Not good.

 

[Yooper]

I pitch at about 75 degrees. I aerate by closing up the fermenter and shaking it for several minutes.

I have always pitched at around 75 degrees. So cooling to 65 to 68 may help?

As everybody else said, start much lower (60 degrees is fine) and keep the fermentation temperature at the lower end of the yeast strain's temperature range until the near the end of primary, and then you can allow it to rise to near the yeast strain's upper limit of its optimum temperature range. So, for a yeast strain that "ferments at 62-72 degrees", I'd pitch at 60 and let it rise to 62-64 where I'd keep it until fermentation is nearly finished and then let it rise up to 68-70 at the very end of fermentation.

 

[beerguy2009]

So how cool is too cool? I do a partial boil then cool it with an imersion chiller. When I get close to the desired temp, I add the rest of the water at a cool enough temp to cool it the rest of the way. I just want to make sure I don't cool it too far (if that is possible).

 

[Yooper]

So how cool is too cool? I do a partial boil then cool it with an imersion chiller. When I get close to the desired temp, I add the rest of the water at a cool enough temp to cool it the rest of the way. I just want to make sure I don't cool it too far (if that is possible).

It's really not possible. I mean, even if it's too low for the yeast to be happy, it'll warm up eventually!

I'd shoot for a temp of around 60 degrees, plus or minus, and not sweat it if it's lower.

 

[beerguy2009]

Sounds like I need to brew and see if I found my problem with diacytel. I hope this will fix my brew. I know the one I made for the brew competition was well received by people who came to sample but the judges weren't too impressed. Oh well it was my first competion.

 

[beerguy2009]

Anything else I need to do to prevent diacytel in the finished beer?

 

[beerguy2009]

So would it be a bad idea to open my fermenter bucket with my pumpkin ale in it so I can sample it and see if there is diacytel in it?
I don't plan on bottling it for a day or two but thought I should check. I had read if there still is diacytel that letting it sit on the yeast longer may help. I just don't want to ruin my beer by exposing it to oxygen when I open it.

 

[Mongrel]

So would it be a bad idea to open my fermenter bucket with my pumpkin ale in it so I can sample it and see if there is diacytel in it?
I don't plan on bottling it for a day or two but thought I should check. I had read if there still is diacytel that letting it sit on the yeast longer may help. I just don't want to ruin my beer by exposing it to oxygen when I open it.

You should be opening your bucket to take gravity readings before you bottle anyway. Your beer will be fine.

 

[beerguy2009]

Thanks. I never worried too much about gravity reading until I bottled. I figured after 2 to 3 weeks, the beer would be fermented fully.
I think I will sanitize my racking cane and go through the hole for the airlock as it is an inch in diameter ( I use a rubber stopper).
That way I can take a gravity reading and check for diacytel.

 

[christo65]

Not to say you have it, but another culprit of diacetyl is lactic acid bacteria. Both Lactobacillus and Pediococcus are the primary culprits. Diacetyl is a by-product of the contamination and is an easy way for your nose to know you may have lactic bacteria present in your beer.

A common cause of it is from the grain dust getting into your cooled wort as grain husk contains l-bacteria. If you crush your grain in the same room as where you cool your wort, this could be a factor, though, I believe you said you do extract with grain, so typically not as big a deal.

Try your temperature changes first (though with S-05 & Nottingham diacetyl is not a typical byproduct). Some English/irish strains produce and expecially with lager strains where the fermentation is not active enough to scrub it out without warming for a diacetyl rest. If that doesn't work, change out all soft plastic (tubing, etc.) and redouble sanitation efforts and keep grain away from the cooled wort.

I have had a recent experience where several lagers turned very buttery after about 4 months in the keg and then went on to be quite lactic-ly sour a month or two later. What's interesting is that the original lagers won first place ribbons in a competition when "fresh" and then later earned high marks as sour beers a half year later for their clean lactic sourness! I've replaced the o-rings and completed total cleaning of the kegs plus replaced all other soft plastic. Even quit using one of my plastic buckets as it was getting old and needed a retirement.

 

[beerguy2009]

So I took a sample of the pumpkin ale I have in the fermenter and found that it did have a bit of a buttery smell to it so I must have diacytel still there. It has been in the fermenter for 2 1/2 weeks at 68 degrees. Based on what I have read I pitched yeast at too warm a temp. Is there anything I can do at this point to reduce the amount of diacytel or is it too late for this batch? Is it too late for a diacytel rest?
Also even though the room temp said 68 the temp of the beer was 72.