52 replies to this topic

[Big Nake]

Had a BIG time butter bomb. Fermented US-05 at near lager temps,as far as dry yeast goes that yeast worked great at lager temps,however,I forgot to raise the temps back up to the recommended temps and instead went to keg with and served there after. Holy Sh-t, I shoulda poured it over my popcorn! It really pissed me off too because I had high hopes too. One of the few I had to dump, completely undrinkable and that aint sayin much,I drink nearly everything.

A similar thing happened to me a few times and here's why: I picked up a new (old) fridge and used it for cold secondary storage. I would ferment at cool temps (lager or ales), rack the beer to a secondary and then send it directly to a 35-38° fridge with no time at warmer temps. I immediately concluded that this was not good and stopped that process immediately in favor of allowing the secondaries to rest at room temp for some amount of time. Sorry about the butter-bomb Matt.

[davelew]

No this is right. How does this affect the conversation. Yeast make it, then take it up and get rid of it as fermentation ends/ after fermentation.MolBasser

My understanding was that healthy yeast in an all-barley wort have plenty of amino acids, don't need to synthesize them, and so don't produce alpha acetolactate. The exception being certain metabolic mutants which can't absorb certain amino acids from their surroundings and have to synthesize them all. Yeast from Wyeast/Whitelabs don't have this mutation in the original cells, although they can develop it given enough generations. I thought that certain strains of yeast had variations of some metabolic genes that were more likely to mutate, which is why some strains have diacetyl reputations, but that normal healthy yeast never synthesize leucine/isoleucine/valine and never throw diacetyl.In a commercial brewery with cropping and re-use of the yeast, diacetyl is a big potential problem, because all of the metabolic mutants could be in one physical location in a bottom-fermenting yeast (the original mutant and any cells that budded off of that one might be near to each other). When the yeast was cropped, one scoop of yeast could contain a lot of diacetyl-dumping metabolic mutants. Since normal techniques like acid washes won't get rid of mutated yeast cells, dealing with these metabolic mutants was historically a big issue for commercial lager breweries, which explains all of the research on diacetyl. I usually only use a single smackpack of yeast for two batches at most (a lawnmower lager and a high gravity gravity lager), and I haven't had problems with diacetyl.

[ThroatwobblerMangrove]

My understanding was that healthy yeast in an all-barley wort have plenty of amino acids, don't need to synthesize them, and so don't produce alpha acetolactate. The exception being certain metabolic mutants which can't absorb certain amino acids from their surroundings and have to synthesize them all. Yeast from Wyeast/Whitelabs don't have this mutation in the original cells, although they can develop it given enough generations. I thought that certain strains of yeast had variations of some metabolic genes that were more likely to mutate, which is why some strains have diacetyl reputations, but that normal healthy yeast never synthesize leucine/isoleucine/valine and never throw diacetyl.In a commercial brewery with cropping and re-use of the yeast, diacetyl is a big potential problem, because all of the metabolic mutants could be in one physical location in a bottom-fermenting yeast (the original mutant and any cells that budded off of that one might be near to each other). When the yeast was cropped, one scoop of yeast could contain a lot of diacetyl-dumping metabolic mutants. Since normal techniques like acid washes won't get rid of mutated yeast cells, dealing with these metabolic mutants was historically a big issue for commercial lager breweries, which explains all of the research on diacetyl. I usually only use a single smackpack of yeast for two batches at most (a lawnmower lager and a high gravity gravity lager), and I haven't had problems with diacetyl.

just 2 times? I've been using some 1056 for something like 8 batches now. I plan on using it one more time and that's it. Not b/c it's old so much as I'll be replacing it with denny's fav 50 yeast for a while and then maybe moving on to something else entirely (maybe pac-man).

[MolBasser]

My understanding was that healthy yeast in an all-barley wort have plenty of amino acids, don't need to synthesize them, and so don't produce alpha acetolactate.

This is incorrect.MolBasser

[MolBasser]

In a commercial brewery with cropping and re-use of the yeast, diacetyl is a big potential problem, because all of the metabolic mutants could be in one physical location in a bottom-fermenting yeast (the original mutant and any cells that budded off of that one might be near to each other). When the yeast was cropped, one scoop of yeast could contain a lot of diacetyl-dumping metabolic mutants. Since normal techniques like acid washes won't get rid of mutated yeast cells, dealing with these metabolic mutants was historically a big issue for commercial lager breweries, which explains all of the research on diacetyl. I usually only use a single smackpack of yeast for two batches at most (a lawnmower lager and a high gravity gravity lager), and I haven't had problems with diacetyl.

This is also wrong.MolBasser

[chuck_d]

As far as chuck_d's fancy-schmancy Siebel talk is concerned, I only have one reply...I like beer. Cheers to you guys. This is one reason why our board works so well... very good brewers (commercial & homebrewers) who like to share their experiences & bounce ideas around.

Haha, no doubt. Just trying to share what I can, but this thread got way technical before my last post :goodidea:And yeah, this is why I love this homebrew community, I've always moved around so much I never settled into a local homebrew club, so you guys are mine

Had a BIG time butter bomb. Fermented US-05 at near lager temps,as far as dry yeast goes that yeast worked great at lager temps,however,I forgot to raise the temps back up to the recommended temps and instead went to keg with and served there after. Holy Sh-t, I shoulda poured it over my popcorn! It really pissed me off too because I had high hopes too. One of the few I had to dump, completely undrinkable and that aint sayin much,I drink nearly everything.

Don't dump a d-bomb unless it's in bottles. If it's your own beer, you can rescue it. Add some strong healthy yeast, perhaps even a little fresh wort, raise the temps a little bit, and let the yeast clean it up. If the diacetyl is from bacteria though, dump that.

My understanding was that healthy yeast in an all-barley wort have plenty of amino acids, don't need to synthesize them, and so don't produce alpha acetolactate. The exception being certain metabolic mutants which can't absorb certain amino acids from their surroundings and have to synthesize them all. Yeast from Wyeast/Whitelabs don't have this mutation in the original cells, although they can develop it given enough generations. I thought that certain strains of yeast had variations of some metabolic genes that were more likely to mutate, which is why some strains have diacetyl reputations, but that normal healthy yeast never synthesize leucine/isoleucine/valine and never throw diacetyl.In a commercial brewery with cropping and re-use of the yeast, diacetyl is a big potential problem, because all of the metabolic mutants could be in one physical location in a bottom-fermenting yeast (the original mutant and any cells that budded off of that one might be near to each other). When the yeast was cropped, one scoop of yeast could contain a lot of diacetyl-dumping metabolic mutants. Since normal techniques like acid washes won't get rid of mutated yeast cells, dealing with these metabolic mutants was historically a big issue for commercial lager breweries, which explains all of the research on diacetyl. I usually only use a single smackpack of yeast for two batches at most (a lawnmower lager and a high gravity gravity lager), and I haven't had problems with diacetyl.

Yeah, as I mentioned it does not require amino acid deficient wort, it's just part of the yeast growth and metabolic processes. Healthy yeast do produce amino acids, and do throw diacetyl. I'm not sure where you got the the information that amino acid deficiency is a requirement for diacetyl production, and not just a factor that increases it. In fact wort that is too high in amino acids can increase diacetyl production. An all-malt wort is listed as factor that can increase diacetyl production, while adjunct use is a possible increasing factor. It's the high levels of amino nitrogen that increase it from all-malt worts. Also, pro breweries are not using bad yeast. It's almost entirely viable and vital. It is common in our homebrew talk to only discuss viability when talking about starters for newbies and shipping yeast from the stores, but vitality is the other half of the equation, and that's why pitching rate isn't the whole picture. Taking a fresh crop of yeast from your fermenter at the right time, pumping it into another fermenter and then pumping fresh wort right on top of it is about as good as you can get for yeast handling. While you're right that mitochondrial mutants called petites can produce more diacetyl, non-mutants produce diacetyl when handled perfectly and with perfect wort.

[MolBasser]

I can guarantee you that major breweries go through untold effort to make sure the yeast they pitch is of better quality than any homebrewers starter.And they are pretty much always successful in this endevour.MolBasser

[Mya]

I can guarantee you that major breweries go through untold effort to make sure the yeast they pitch is of better quality than any homebrewers starter.And they are pretty much always successful in this endevour.MolBasser

that's a mighty broad brush you are painting with there are some seriously anal homebrewers out there

[davelew]

Taking a fresh crop of yeast from your fermenter at the right time, pumping it into another fermenter and then pumping fresh wort right on top of it is about as good as you can get for yeast handling.

Is there an inspection or acid wash or other step between taking a crop and fermenting a new batch with it?

[davelew]

that's a mighty broad brush you are painting with there are some seriously anal homebrewers out there

I was going to comment on it, since I know a homebrewer who uses a scanning electron microscope on yeast cells, but then I saw the "major" modifier on breweries. If you restrict yourself to major breweries, they probably are even more anal.

[chuck_d]

Is there an inspection or acid wash or other step between taking a crop and fermenting a new batch with it?

No, an acid wash damages yeast, specifically it can cause issues with flocculation, and it is generally unnecessary. The only time you would likely want to acid wash your yeast is when you know the culture has been compromised by bacteria and you do not have a way of getting that yeast strain from elsewhere. Sterile samples are common in various steps of the brewing process as part of standard quality control measures. If you find a crop has been compromised, then you don't use that anymore and instead of acid washing it, you just get rid of it and go get that strain from elsewhere. Basser may have a little unilateral with his comment, but statistically it's pretty darn accurate. The main point being, it's not bad yeast, typically it's great yeast. Places that have bad yeast handling practices probably don't last very long.

[MolBasser]

The main point being, it's not bad yeast, typically it's great yeast. Places that have bad yeast handling practices probably don't last very long.

This.So very this.MolBasser

[chuck_d]

Here's a formula from Heyse, pp 184-186, to calculate how long a d-rest needs to be.

Dude, I must have pulled these formulas through a reference in another book. I was just searching for the dictionary that Heyse has for brewing terms between german and english and this thread came up... I'm guessing it came from the MBAA handbooks? Just cool to see the forum popping up on such specific brewing searches.