Delayed Diacetyl

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Bill Lawrence
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Delayed Diacetyl

Post by Bill Lawrence »

Well I've brewed a few batches in my time but I have never had this happen to me before. Made a English Summer Ale and used the notorious Ringwood strain for fermentation. Now, I know I am taking a chance using this stuff but I like the results generally. I know that it likes O2 and I also know it will stall on you if you let it get too cold. I also know that the reason it is so notorious is because it will throw diacetyl if not treated well. Anyway, I fermented at almost 70F, oxigenated really well when pitching and left the beer on the yeast for a week and a half just in case. I also tasted the beer from primary to secondary then from secondary to the keg and while specifically looking for this problem didn't detect any more than you can get with many English strains (WLP02 and WLP04 come to mind). Anyhow I had a hankering for some bitter so I poured myself a pint and yeah, pretty buttery. It's not so bad I wont drink it but I wouldn't even bother putting this stuff into a contest because I know I'd get killed. I have made a couple of butter bombs in my sorted career but never have had a delayed reaction like this. I will of course monitor the situation to see if it gets worse but I really am not quite sure what is going on here, it doesn't taste infected. If it gets worse however, I will assume it's an infection but other than that I'm rather baffeled. Anybody run into this one before?
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TheMacheteMasher
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Re: Delayed Diacetyl

Post by TheMacheteMasher »

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Bill, think you pulled the batch too soon? The yeast in suspension can do this when crashing. There is an enzyme (alpha acetolactate) in some fining agents that buffer this. I too have seen delayed diacetyl with said dry stout which uses top cropping English square yeast. When I made it through the keg there were more yeast lees than usual. At that moment I realized I had rushed it. I found the enzyme by chance in a quest to understand what happened.
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Bill Lawrence
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Re: Delayed Diacetyl

Post by Bill Lawrence »

I'm pretty sure I didn't pull the beer off the yeast cake too soon as I have made that mistake before with WLP02 and I know I am dealing with a dodgy yeast strain here. Besides that I should have picked up the issue when doing my taste tests when transfering the beer if it was a situation where the yeast just didn't have time to clean the beer up. Also, I don't use fining agents so it can't be that. My guess is that perhaps the beer is infected and if so the situation will get worse and at the same time I would expect the carbonation to increase. Could be that the Beer Gods just decided it was time to make me humble (as if the Bluebonnet didn't do that already). I hope like hell it's not an infection however because I used that yeast to make an IPA which is still in primary. If that IPA is screwed up I'm gonna be pissed as I used alot of Amarillo on that beer and I hate to waste it (plus buying hops for IPA's is getting expensive). I will continue to do rigorous sensory testing on the beer in my continued attempt to figure out what is going on here.
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Jimmy Orkin
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Re: Delayed Diacetyl

Post by Jimmy Orkin »

Bill, did you raise the temperature at the end of the fermentation to encourage the yeast to completely finish?
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Bill Lawrence
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Re: Delayed Diacetyl

Post by Bill Lawrence »

No, because it was pretty cold when I made that batch I just fermented it in the house. I'm just set up for hot weather brewing so when the ambient temperature is cold I don't have an easy way to heat the stuff up. Maybe I need to use a heating pad in a situation like that. Still though, why wouldn't I taste the problem when doing the transfers, especially since the beer was at room temperature? By the way, the stuff tastes fully attenuated to me (not that I ever bother measuring the terminal gravity 'cause frankly I don't give a shit since at that point all I care about is taste). :D
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BrewerDon
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Re: Delayed Diacetyl

Post by BrewerDon »

I won't pretend to be an expert on this but I've found that most of my beer comes out better if I keep it on the yeast for 4 weeks (with a couple of exceptions). I just like giving the yeast plenty of time to clean things up.

Here is an excerpt from an article I found online that might explain what Bill is seeing:

"Diacetyl is produced by yeast during fermentation. It is sort of an indirect synthesis: first, they produce relatively tasteless alpha acetolactate (AAL) which is later oxidized in the beer to become diacetyl. If everything is going well, the yeast will then reabsorb and metabolize the diacetyl, removing it from the beer. Giving the beer appropriate time to mature in the presence of healthy yeast is one of the keys to eliminating butteriness."

If I'm reading that right, the buttery taste doesn't come until later, which is what Bill is seeing. I don't have it in front of me, but I remember reading in the book, Yeast, by Jamil and Chris White, that there is a test that you can do to see if AAL is present. You take a sample of the beer and warm it up to 80 or 85 degrees for some period of time (maybe 24 hours?). That speeds up the oxidation process and the AAL becomes diacetyl quicker. Then you taste your sample. If it tastes buttery, you can take some action like leaving the beer on the yeast longer, or doing a diacetyl rest, or Kruassening, or whatever.

Since I don't want to worry about any of that, I try to always just do the diacetyl rest and then leave the beer on yeast.
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Bill Lawrence
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Re: Delayed Diacetyl

Post by Bill Lawrence »

That makes perfect sense to me. The stuff is still drinkable but not competition worthy and actually, a bit of diacetyl in British Ales is somewhat enjoyable in moderation (and expected). Fuller's beers frequently have of touch of it also and as everyone knows, that's the official brewery in heaven. I generally don't let stuff sit on the yeast cake more than a couple of weeks and I generally don't get into this problem. I'm coming to the conclusion that maybe the Ringwood strain is more trouble than it is worth and I should go back to my old standby WLP02 which as luck would have it is the Fuller's strain. If I am willing to live with less attenuation Fuller's works otherwise I go with WLP07 which will dry things out a little more and is better for IPA's and the like. The main reason I used the Ringwood in this beer is because I wanted a really large amount of yeast to do my version of Dogfish Head 60. Oh well, I guess if this hobby was easy everyone would do it, right?
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BrewerDon
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Re: Delayed Diacetyl

Post by BrewerDon »

Bill,
Regarding your comment on not being set up for cold weather brewing, I struggle with that issue as well. If you are fermenting in a refrigerator or other small, enclosed box that can only cool and not heat I have a tip.

I have a fermentation refrigerator in the garage. When the weather drops below my fermentation temperatures, I stick a little lamp inside. If it is really cold, I use a higher wattage bulb. The heat from the bulb brings the temp of the inside of the frig above my fermentation temperature and then the refrigerator kicks on and cools back down. The down side is that light is bad for beer so I have to go to the extra step of wrapping up my carboys with dark towels.

It's not ideal but it works in a pinch. I usually only have to resort to this for a day or two at most for any given fermentation.
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Bill Lawrence
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Re: Delayed Diacetyl

Post by Bill Lawrence »

Yeah I was thinking about doing that. I need to go over to Sears or someplace similar and get one of those caged lights like they use for working on cars in the garage. The reason I haven't bothered before is because as you point out it only happens a couple times a year. :D
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