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Diacetyl Question

K

KellerBrauer

Greetings Group - it?s a well known fact that toward the end of the fermentation, the beer temperature should be allowed to rise slightly so the yeast can get active and has a chance to ?clean up? after itself to remove the Diacetyl.

My question is: Does the yeast continue to clean up after itself during bottle conditioning?  It seems to me that it would.
 
You bet it does.The active secondary fermentation in the bottles wakes the yeast up and it goes back to work. It will work until either finished munching or brought to a temperature where it goes dormant. This assumes the alcohol level isn't high enough to kill it.
 
BOB357 said:
You bet it does.The active secondary fermentation in the bottles wakes the yeast up and it goes back to work. It will work until either finished munching or brought to a temperature where it goes dormant. This assumes the alcohol level isn't high enough to kill it.

Correct, I believe that most ale yeasts are in the range or 8% max alcohol content except for Belgian Strains that typical max out at 10-15%.

Most lager strains max out at 8%. but most are actually less.
 
Okay thanks!  I don?t believe the alcohol level is a factor in this case. I?m wondering more about diacetyl.

Thanks for your input!
 
KellerBrauer said:
Okay thanks!  I don?t believe the alcohol level is a factor in this case. I?m wondering more about diacetyl.

Thanks for your input!

The best way to minimize Diacetyl is a long boil 90 minutes followed by a quick chill and then pitch the yeast as soon as you can.

Let the beer go 2 weeks in primary and raise the temp w bit the last 3 days. Will help to clean up an potential residual off flavors.
 
Ck27 said:
The best way to minimize Diacetyl is a long boil 90 minutes followed by a quick chill and then pitch the yeast as soon as you can.

Let the beer go 2 weeks in primary and raise the temp w bit the last 3 days. Will help to clean up an potential residual off flavors.

Dicetyl is a yeast derived flavor compound and does not come from the boil.  You may be thinking of Dimethyl Sulfide (DMS) which is a creamed corn type of flavor/aroma and comes from the grains.
 
Oginme said:
Ck27 said:
The best way to minimize Diacetyl is a long boil 90 minutes followed by a quick chill and then pitch the yeast as soon as you can.

Let the beer go 2 weeks in primary and raise the temp w bit the last 3 days. Will help to clean up an potential residual off flavors.

Dicetyl is a yeast derived flavor compound and does not come from the boil.  You may be thinking of Dimethyl Sulfide (DMS) which is a creamed corn type of flavor/aroma and comes from the grains.

I have ended up with diacetyl from boils and have had people comment on it before.
 
Diacetyl, or 2,3-Pentanedione, comes from the breakdown of FAN (Free Amino Nitrogen) which comes from the wort.  The yeast metabolizes the FAN in the production of proteins and one of the breakdown products is Diacetyl.  A good fermentation with healthy yeast will consume the diacetyl during the maturation phase (post-vigorous growth).

The levels of FAN are a function of the barley varieties used and the malting process. 

You can get a recurrence of Diacetyl from the oxidation of Acetohydroxy acids in the beer.  Acetohydroxy acids are a byproduct of yeast fermentation which the yeast cannot consume..  Again, healthy yeast will limit the production of these Acetohydroxy acids.

[citations: How to Brew by John Palmer, Malt by John Mallett, Tasting Beer by Randy Mosher, Yeast by White and Zainasheff]

If you have any reference which support your claim, please cite it.  I am always open to being wrong and learning!

Edit: forgot a reference source
 
Oginme said:
Diacetyl, or 2,3-Pentanedione, comes from the breakdown of FAN (Free Amino Nitrogen) which comes from the wort.  The yeast metabolizes the FAN in the production of proteins and one of the breakdown products is Diacetyl.  A good fermentation with healthy yeast will consume the diacetyl during the maturation phase (post-vigorous growth).

The levels of FAN are a function of the barley varieties used and the malting process. 

You can get a recurrence of Diacetyl from the oxidation of Acetohydroxy acids in the beer.  Acetohydroxy acids are a byproduct of yeast fermentation which the yeast cannot consume..  Again, healthy yeast will limit the production of these Acetohydroxy acids.

[citations: How to Brew by John Palmer, Malt by John Mallett, Tasting Beer by Randy Mosher, Yeast by White and Zainasheff]

If you have any reference which support your claim, please cite it.  I am always open to being wrong and learning!

Edit: forgot a reference source

Thanks Oginme - I have practiced your recommendation since the dawn of my all-grain Brewing, including this brew.  However, I have an unusual condition that has occurred with a Great Lakes Brewing Christmas Ale clone I recently made.  Going into the bottle, the beer tasted fantastic and I would easily say I nailed the clone.  But, after week 1, I tasted it and it had a flavor I tasted only once before in my Oktoberfest I brewed last March.  That?s why I was wondering if diacetyl can still be absorbed even after the beer is bottled thinking maybe I didn?t let it set long enough after active fermentation.

Maybe I?m being a bit premature with my curiosity, but I don?t understand what could have happened after it was bottled.  I checked to see if there was a commonality in Ingredients between my Oktoberfest and the Christmas Ale and maybe this taste was produced by the same ingredient.  But no luck.  Neither recipe shared the same ingredient.

Puzzling.  My bottle sanitizing process has never let me down.  So, I guess I?ll wait a couple more weeks and see how it develops.  It?s not an offensive flavor by any means.  I just don?t think it belongs in my beer.

Thanks for your input!

PS - BTW, your assessments on brewing chemistry are spot on.  Dimethyl Sulfide is forced from the wort in the form of vapor during the boil.  Diacetyl is produced by yeast during fermentation and later consumed by yeast after fermentation is complete.  The book, Yeast, by Chris White (White Labs) was quite clear on the subject.
 
Whoever has been giving me negative karma please stop, or you will probably be banned.

Thanks for that interesting bit about diacetyl I don't ready enough about compounds really I just brew damn good beer. \Any good books you would recommend on the subject?
 
KellerBrauer said:
Thanks Oginme - I have practiced your recommendation since the dawn of my all-grain Brewing, including this brew.  However, I have an unusual condition that has occurred with a Great Lakes Brewing Christmas Ale clone I recently made.  Going into the bottle, the beer tasted fantastic and I would easily say I nailed the clone.  But, after week 1, I tasted it and it had a flavor I tasted only once before in my Oktoberfest I brewed last March.  That?s why I was wondering if diacetyl can still be absorbed even after the beer is bottled thinking maybe I didn?t let it set long enough after active fermentation.

Maybe I?m being a bit premature with my curiosity, but I don?t understand what could have happened after it was bottled.  I checked to see if there was a commonality in Ingredients between my Oktoberfest and the Christmas Ale and maybe this taste was produced by the same ingredient.  But no luck.  Neither recipe shared the same ingredient.

Puzzling.  My bottle sanitizing process has never let me down.  So, I guess I?ll wait a couple more weeks and see how it develops.  It?s not an offensive flavor by any means.  I just don?t think it belongs in my beer.

Thanks for your input!

PS - BTW, your assessments on brewing chemistry are spot on.  Dimethyl Sulfide is forced from the wort in the form of vapor during the boil.  Diacetyl is produced by yeast during fermentation and later consumed by yeast after fermentation is complete.  The book, Yeast, by Chris White (White Labs) was quite clear on the subject.

Thanks, KellerBauer.  One of the reasons I included the section on the Acetohydroxy acids is that this in particular may be what you are experiencing.  A bit of stressed fermentation combined with a little bit of Oxygen could lead to development of diacetyl in secondary or even in the bottle, although with a bottle conditioned beer, I would have thought that more unlikely.  For the first part, the addition of sugars for the secondary fermentation would promote additional yeast activity which should consume the oxygen which may have been introduced during bottling.  Additionally, any diacetyl hanging around would have been just that much more  metabolic materials for the yeast to consume. Anything that might fit your situation here?

I could see the breakdown of acetohydroxy acids into diacetyl after forced carbonation and bottling into improperly CO2 flushed bottles.  With little yeast and no sugars to promote any yeast cells to action, the diacetyl would be able to hang around.

 
Ck27 said:
Whoever has been giving me negative karma please stop, or you will probably be banned.

Thanks for that interesting bit about diacetyl I don't ready enough about compounds really I just brew damn good beer. \Any good books you would recommend on the subject?

Answered by Oginme earlier in the thread:

[citations: How to Brew by John Palmer, Malt by John Mallett, Tasting Beer by Randy Mosher, Yeast by White and Zainasheff]
 
BOB357 said:
Ck27 said:
Whoever has been giving me negative karma please stop, or you will probably be banned.

Thanks for that interesting bit about diacetyl I don't ready enough about compounds really I just brew damn good beer. \Any good books you would recommend on the subject?

Answered by Oginme earlier in the thread:

[citations: How to Brew by John Palmer, Malt by John Mallett, Tasting Beer by Randy Mosher, Yeast by White and Zainasheff]

I'll look at the yeast book :) I've read the others :)
 
Oginme said:
Thanks, KellerBauer.  One of the reasons I included the section on the Acetohydroxy acids is that this in particular may be what you are experiencing.  A bit of stressed fermentation combined with a little bit of Oxygen could lead to development of diacetyl in secondary or even in the bottle, although with a bottle conditioned beer, I would have thought that more unlikely.  For the first part, the addition of sugars for the secondary fermentation would promote additional yeast activity which should consume the oxygen which may have been introduced during bottling.  Additionally, any diacetyl hanging around would have been just that much more  metabolic materials for the yeast to consume. Anything that might fit your situation here?

I could see the breakdown of acetohydroxy acids into diacetyl after forced carbonation and bottling into improperly CO2 flushed bottles.  With little yeast and no sugars to promote any yeast cells to action, the diacetyl would be able to hang around.

Thanks, Oginme, for your input.  Yes, your suggestion is quite possible.  The flavor I?m I?m referring to is a buttery-creamy-slick kind of flavor on the palate, more in the background than up front, if that makes any sense.

You mention ?stressed fermentation?.  I?ve seen that statement before, but I?m not certain what it means.  The fermentation of this brew was quite abnormal - atleast from my experience.  The yeast is Wyeast, American Ale II.  It started a little slower than normal - about 10 hours after started was pitched.  The fermentation seemed fine after that; I was pleasantly surprised the kraeusen layer was only 1/2 - 3/4? thick.  Then on day 4, the kraeusen blew up to about 3?.  It was very shiny, smooth, creamy and rocky looking.  It remained throughout the remainder of the fermentation and never went away.  On day 11, 12 and 13, my FG was steady at 2 points below target.  So racked to the secondary.  The kraeusen layer was still unchanged.  The beer, while yeasty tasting, tasted fine.  It remained in secondary for 4 days, then I bottled it.  At bottling, it tasted incredible.  I was quite pleased with my accomplishments.  Then on week 1 sampling, I taste what I think may be diacetyl.

OG = 1.072 (target: 1.078)
FG = 1.020 (target: 1.022)
Attenuation: 70.8%
Starter: 1270 mL, 4.29oz. DME, Stir plate

Week two in the bottle is Tuesday. I?m hoping this flavor I?m referring too is gone.  Meantime, any additional thoughts are appreciated.
 
'Buttery, creamy, slick' pretty much describes the taste of diacetyl.  Butterscotch is another common flavor description.  Usually it comes with the odor of butter or honey-like aromas. 

WY1272 is my go-to yeast for most American styles.  The fermentation profile you describe matches it pretty closely.  It is slow moving for the first 48 to 72 hours and then kind of explodes in growth and fermentation activity.  About 48 hours after the 'explosion' it is pretty much over with active fermentation and takes about 4 to 6 days to clean up and for the majority of the yeast to flocculate and fall out.

I start fermentation on the low side: 62?F to 64?F and allow it to rise after the first 24 hours up to around 68?F.  It does require a rise after that to 70?F to 74?F to completely finish off and clean up.  I think the very rapid period of fermentation produces a lot of the by-products.  Here is where an ample pitch of healthy yeast will help control the off-flavors.

Your attenuation is pretty close to what I experience with WY1272.  Your starter looks to be pretty good size to create about 274 billion cells with that amount of DME and the volume of the starter.  This should be enough to make for a healthy pitch.

By stressed fermentation, I am referring to a significant under pitch of yeast cells or yeast with weak cell walls.  Here the yeast cannot keep up with reproduction since they are responding to the surrounding sugar concentration.  The under pitch means that the cell walls of the newest generation tend to thin out and are not as efficient at gating the flow of sugars in or by-products out.  A pitch of yeast with weak cell walls has that problem from the beginning.

If I see weak cells in my cell counting (stained with Methyl blue stains dead cells all blue, weak cell walls will turn blue but there is no significant staining or a weak blue color on the interior of the cells), I toss in about 1.25 grams of yeast nutrient per 10 liter batch to help them sustain the growth.  They also need a good dose of Oxygen for them to catalyze into sterols which are used for building cell walls. 

To be honest, I have not encountered the conversion of acetohydroxy acids post fermentation.  I would give it a good 3 weeks in the bottle and, if you can, raise the temperatures for the second fermentation up to mid 70's F.  Pop a bottle before refrigerating to see if you can still smell the diacetyl.  Refrigeration will suppress the off-gassing of the 2,3-pentanedione but it is really apparent at room temperatures.  Diacetyl was commonly used in cinemas because the odor of the diacetyl spreads so readily and entices the customers to buy the popcorn.  Personally, I don't like the smell and it turns my stomach in those concentrations.

 
Greetings Oginme - you have given me a lot to consider.  First, I don?t believe I allowed the final stages of fermentation to be warm enough.  I fermented at 61 degrees to minimize any possible ester production.  Then I simply opened my fermentation chamber door and allowed the beer to raise to room temperature of 66-68 degrees thinking that would be sufficient.  Apparently not.

I think I?ll check the beer on Tuesday to assure it?s properly carbonated, then I?ll move my bottles to a warmer area, 72-74 degrees.  Hopefully that will help minimize the diacetyl.

Thanks a lot for your scientific input.  I?ve learned a lot with this batch, that?s for sure!
 
Yeah, when I want esters from WY1272, I usually start at around 68?F and allow the fermentation to climb up naturally to 72?F to 74?F.  Nice esters, not too overwhelming.  I've only done this specifically with an American wheat recipe I've been working on which is based upon Belma, Citra, Azacca, and Huell Melon all added with less than 20 minutes in the boil and the majority in the whirlpool and dry hopped.  My next version will most likely be all whirlpool as that last one was still way too hoppy.
 
That sounds like a very interesting beer.  My goal with my Christmas Ale clone was to try and move the ginger and cinnamon forward and I was afraid any ester production might cover or hide those flavors.  So, I went with the recommended low end of the fermentation.

Speaking of, I decided to go ahead and move my ale to a warmer place sooner rather than later.  I want whatever yeast may be left in suspension to get back to work to clean up whatever mess they made a couple weeks ago!
 
Why bother tasting after 1 week of bottle conditioning? That's just not enough time. I only start tasting after 2 weeks in the bottle if I'm getting impatient and usually wait for about 3 weeks before I even crack the first bottle to make sure the yeast is done and has mostly fallen out. Most beers taste best after yet another week conditioning in the bottle before hitting the fridge.

BTW - I don't think any yeast ester flavor will ever cover up the flavors of ginger or cinnamon. Those flavors are just too overpowering.
 
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