Diacetyl Problem

[b_thomas]

Well I cracked open another of my first batch of beer and it has a sweet buttery taste. It was a James Squire Amber Ale clone so I bought some today to do a comparison test, and well lets put it this way, the homebrew ended up down the drain and the Amber Ale I'm drinking as I type this.

I think the main fault was using brown sugar for bottle priming, however still being a newbie I'd like to see what other things cause Diacetyl problems and is it something that will go away if I let the rest of the bottles age or should I just drain the lot and use them for my Dunkelweizen (which managed to turn out a treat).

 

[Adamt]

What yeast did you use for your amber ale clone? What was your fermentation temperature/schedule?

 

[b_thomas]

Safale S-04, optimum temperature was 18-24C and I have a feeling I was at a minimum at the top end of that range
Fermentation had stopped after about 3.5 days. So are you suggesting I cooked my beer?

 

[Adamt]

Diacetyl is most commonly found in beers fermented with lager yeasts. However I think it can also be produced by some bacteria.

Fermenting at that high a temperature (especially with an english ale yeast) can give you a cocktail of mainly unwanted compounds. I'd say likely it isn't diacetyl, but a combination of other things like higher-order alcohols (that taste "hot), esters (fruity flavour compounds), and phenolics (taste like bandaids smell).

 

[Stuster]

Adam's on the money there. Other possibilities are that you racked it too soon, or that there was some oxidation in the fermentation. How long before you racked/bottled it? Any chance it was splashed around a bit?

 

[b_thomas]

I bottled about 4 days after I noticed that fermentation had stopped. So about 1 day after taking my final hydrometer reading.

 

[Stuster]

Doesn't sound like that was the problem then. What was your recipe?

 

[b_thomas]

Can't exactly recall of the top of my head, but it was

1 Can of Hopped Extract (1.7kg I think)
1kg of Amber LME
.25kg of Crystal Malt
Williamette x 24g infused at the end
and the Yeast as above.

 

[Online Brewing Supplies]

Well I cracked open another of my first batch of beer and it has a sweet buttery taste. It was a James Squire Amber Ale clone so I bought some today to do a comparison test, and well lets put it this way, the homebrew ended up down the drain and the Amber Ale I'm drinking as I type this.

I think the main fault was using brown sugar for bottle priming, however still being a newbie I'd like to see what other things cause Diacetyl problems and is it something that will go away if I let the rest of the bottles age or should I just drain the lot and use them for my Dunkelweizen (which managed to turn out a treat).

Diacetyl problems can be hard to identify as there are many causes.
some of the major causes are.

Infection by gram-postive lactic acid bacteria.This is a big one to watch out for but hard to find without lab tests.

Redox reactions caused by excess oxygen.

Yeast cells that have mutated and cease to be good diacetyl reducers.Healthy yeast produces Valine which inhibits diactyle formation.See next point.

Your wort compostion could be lacking in Valine which is an amino acid and inhibits the production of diacetyl.This is a bigger problem when not brewing an malt beer.You mentioned that you used brown sugar to prime with so this is a possibilty.
So there are many things to concider and there is always yeast that are just big diacetyl producers.These yeast need to have a diacetyl rest.
Get all the above right and you will not get diacetyl.Till then keep trying to eliminate the causes.
GB

 

[b_thomas]

I dont think it was an oxygen problem, although now im freaking out about my Dunkelweizen that I racked into a secondary, everything was done via a syphon (tap to tap method) but there was still what I'd consider to be a fair amount of splashing, though it may be just my inexperience.

I used malt for the wort it was just in the bottle priming that I used sugar.

As for sanitation I was very particular but who knows I may have just been unlucky

 

[Stuster]

One last thought, how long has this beer been bottled? But really, it's extremely hard to tell what's wrong with your beer without tasting it. Is there somebody experienced local you could get to have a taste of it? LHBS owner? Another local brewer? Sometimes that can help sort it out more easily than over the net.

 

[Darren]

Hey b_t

Those dry yeasts produce quite alot of diacetyl. I suspect you are using a whole pack of yeast in quite a small batch (25 litres, 1.045 OG)? You could easily halve that and enjoy the benefits of yeast consuming the diacetyl for you.

cheers

Darren

 

[b_thomas]

One last thought, how long has this beer been bottled? But really, it's extremely hard to tell what's wrong with your beer without tasting it. Is there somebody experienced local you could get to have a taste of it? LHBS owner? Another local brewer? Sometimes that can help sort it out more easily than over the net.

Well my partner used to work in perfumes as soon as I put a glass of the stuff under her nose she claimed it smelt of scotch, so I'm going to have to add in an alcohol problem too. She also said it tasted "sweet" though couldn't really say much about it being a butterscotch or not.

Also interesting insight you have there Darren.

 

[Stuster]

That sounds like fusel alcohols. Makes sense if the fermentation was a bit hot. Do you have much of a head on the beer?

Actually, remembered something, and apparently diacetyl can be produced by high initial fermentation temperatures. Might be the problem is not keeping temps down enough.

For those who are interested, more info here.

Causes of diacetyl in beer:

1. High pitching temperature >22 even if the chilling is set at normal fermenting temperature.
2. High fermentation temperature; or runaway fermentations.
3. Pitched too little yeast (at least 1% slurry).
4. Pitched too much yeast (old, tired yeast cells, early flocculation).
5. Oxygen exposure during primary fermentation, secondary fermentation, at transfers, or at packaging.
6. Crash cooling of beer at the end of primary fermentation without including any diacetyl rest.
7. Insufficient time allowed for warm conditioning for sufficient diacetyl reduction.
8. Type of yeast strain used some strains like Yorkshire Square fermentation strains (Old Speckled Hen) produce pronounced, but not unpleasant diacetyl levels in the beer.
9. Too early yeast flocculation and settling in the primary ferment.
10. Strains of Lactobacillus spoil beer by souring, producing turbidity and diacetyl. Diacetyl is generated by a different mechanism to that produced by brewers yeast. It most probably involves the condensation of active acetaldehyde and acetyl co-enzyme A. Pediococcus damnosus is especially common in breweries. It is particularly prevalent as a spoilage organism in beers fermented at low temperatures. Spoilage results mainly from the production of diacetyl. Other bacteria that produce diacetyl include Enterobacteriaceae and Obessumbacterium proteus.

 

[b_thomas]

I think the high pitch temperature killed the beer, I remeber it being a hot day (even with the air con on) and being rather impatient looks like im sinking it after all. No worries, all part of learning.

 

[dig]

Yeast cells that have mutated and cease to be good diacetyl reducers.Healthy yeast produces Valine which inhibits diactyle formation.See next point.

Your wort compostion could be lacking in Valine which is an amino acid and inhibits the production of diacetyl.

My understanding is that valine synthesis results in the metabolic by-product alpha-acetolactate, the diacetyl precursor. Most of this is dealt with internally, but some will escape from the cell depending on things like strain, temp, cell vitality, etc, etc. Once in the beer, acetolactate converts to diacetyl at a temperature dependent rate. Now, interestingly, yeast has an affinity for diacetyl and will actively take it up and use it in another pathway to restore acety-CoA levels (reducing diacetyl from a ketone to something else with a lower sensory threshold. Need to look that one up).

Yeah, so the crux is this: Yeast will only take up a certain amount of diac. Excessive diac due to bacterial spoilage... you're stuffed. Excessive acetolactate in you're beer... you'll become stuffed. Taking your yeast off before acetolactate has converted to diac and then been re-assimilated... again you'll end up stuffed.

 

[Thirsty Boy]

Darren's on the money with the pitch rate, and that quote Stu put in is a great little list.

If your wife said it tastes sweet... I suspect all the things the guys have said here, but most of all, that you racked it early. Did you take gravities?? Because I used the S04 yeast in a lot of my beer for a while, and I found that it tended to fall to the bottom before it was done completely. I haven't gotten Diacetyl out of it, but I leave my beer in primary for longer than most.

My routine with the S04 involved a gentle swirl to the fermenter every day after the krausen started to drop back (usually day three ish) , plus on the 4th or 5th day when it was really starting to slow down, put the temperature up by a degree per day till it hit 21 and hold it there till the gravity stabilised and for another day or two after that. Essentially a D rest.

Just a little off topic .... did anyone read the BYO gadget issue? If I were still using the S04 (I'm off it in favour of Nottingham) I would probably give the idea of a lazy susan under the fermentor a go. It was always a pain swirling that fermentor in a way that didn't pull air in.

 

[Stuster]

(reducing diacetyl from a ketone to something else with a lower sensory threshold. Need to look that one up).

dig, according to that article I linked to earlier, diacetyl is converted to acetoin and butanedoil. Glad to clear that important issue up. :lol:

 

[dig]

dig, according to that article I linked to earlier, diacetyl is converted to acetoin and butanedoil. Glad to clear that important issue up. :lol:

Cheers, couldn't remember what it was. Should have clicked on your link beforehand as that's a good little summary.

Interesting the mention of Maturex-L. Used to use this at a certain brewpub I worked at that was synonymous with diacetyl in its beers. Didn't work of course as the problem was a chronic pediococus infection.

 

[matti]

My routine with the S04 involved a gentle swirl to the fermenter every day after the krausen started to drop back (usually day three ish) , plus on the 4th or 5th day when it was really starting to slow down, put the temperature up by a degree per day till it hit 21 and hold it there till the gravity stabilised and for another day or two after that. Essentially a D rest.

Likewise-ish..

Diacetyl in ale yeast is quite easy taken care of.
I brew most of my ales at 16 degrees and then as Thirstyboy says: Once the yeast has flocculated a few point above final gravity, raise the temps to 18-20 and rock the fermenter gently every morning for 2 or 3 days and rack to secondary.
Racking always helps to finnish the beer off and because I CC all my ales it will sit on the yeast cake for another week or so prior to bottling.

Last year I did a Hobgoblin with Pumpy with a Yeasty beast called "Ringwood".
This yeast is famous for its diacetyl but I was succesful to bring down to accepted levels using above method.

thumb rule from Grumpys
1. one week in primary at 16-18
2. 2-3 days rest at 20
3. Rack
4. 1 week as cold as possible.
5. Bottle or keg.

There were seven steps but my memory fails yet again..... too many hops....

ps. i think the last rule was "send me a Bottle"