Can you over ferment?

[beerkrump]

Trust me.

Over all those authors and their "anecdotal" work? Nah.

It's obvious that you have it stuck in your head that yeast requires sugar to do anything. Just be aware that there are processes that move compounds in and out of the yeast cell with little or no loss of energy. Some of these are slow to finish.

Much of this "clean up" is done in a transitional period between the fermentation phase and the stationary phase. None of this is like a light switch, one second yeast is munching sugars and the next, boom, dormancy.

Also, from the article I referenced...

Table I
Diacetyl formation in three yeast strains.
Day_________Diacetyl Level (mg/L)
_____W-206____W-34/70____W-308
1_____.18_______.15________.18
3_____.25_______.20________ .48
5_____.23 _______.18________ .92
7_____.18 _______.14 ________.75
9_____.14 _______.09 ________.65

As we can see, the diacetyl level is dropping from day 7 to day 9. This is occurring after active fermentation has stopped.

You asked for documentation from a brewing scientist. I found you some, but you refuse to accept it.

 

[ChshreCat]

Just because you don't understand it, that doesn't make it not true.

 

[o4_srt]

So the taste of green beer is simply because of yeast still in suspension????

Seems kinda hard to believe, as green beer doesn't taste very yeasty

 

[ayoungrad]

Indyking, the problem I had with your original post is that you said:

It's the possible myth that yeasts clean up after themselves and improve the quality of the beer with prolonged primaries.

I think you either stated yourself incorrectly or misunderstand what people have previously said.

A good number of people on here suggest not transferring to secondary and instead just leaving the beer in the primary fermenter. No one has suggested that a "prolonged primary" exists. I don't even know what a prolonged primary is. Some people have simply suggested to leave the beer in the primary fermentation chamber for longer and forgo transferring it into a secondary fermenter.

The same clean-up will occur in either chamber. Yeast will help metabolize diacetyls, sulfur compounds and volatile fatty acids. They need sugar but there is always some small amount left even after primary fermentation is "complete". This happens if the beer is left in the primary fermentation chamber or if it goes into a secondary fementation chamber. Most of the yeast go dormant when concentrations fall to very low levels but not 100% of them. Some people just feel that the risks of oxidation (or infection) involved in transferring to a secondary fermentation vessel are greater than any theoretical gain in clarity.

Again, I don't know if the issue here has been a misunderstanding or misinterpretation but there is no such thing as "prolonged primary fermentation" and I have not seen such a concept suggested on this site.

 

[ayoungrad]

Sorry but one other thought here.

Using bold letters for something that clearly flies in the face of popular opinion (be it correct or incorrect opinion) is always going to result in people responding from all directions.

And saying "don't fight me on this" or "trust me" is only more of the same.

I don't know Indyking's background. But I do know that even if it involves a PhD in biochemistry, it is certainly not the only PhD in biochemistry in the world and likely not the only one on this site either. There are scientists, engineers and doctors all over this site.

If you bring up an new thought or idea, why not phrase it as such and have a discussion. Even you admit to feeling a "fight" response from the board on this thread. And it is because how your thought was stated.

Is it everyone else with the issue or is it you?

 

[BrewKnurd]

Sorry but one other thought here.

Using bold letters for something that clearly flies in the face of popular opinion (be it correct or incorrect opinion) is always going to result in people responding from all directions.

And saying "don't fight me on this" or "trust me" is only more of the same.

I don't know Indyking's background. But I do know that even if it involves a PhD in biochemistry, it is certainly not the only PhD in biochemistry in the world and likely not the only one on this site either. There are scientists, engineers and doctors all over this site.

If you bring up an new thought or idea, why not phrase it as such and have a discussion. Even you admit to feeling a "fight" response from the board on this thread. And it is because how your thought was stated.

Is it everyone else with the issue or is it you?

:rockin:

 

[Indyking]

Every once in a while I see minor pieces of information here that I think it may be wrong, but I don't bother to argue because I'm either not sure or it's just not worth it. But the yeast-cleaning-up-after-fermentation-is-complete thing has gone too far unquestioned I think.

I have strong reasons to believe brewing yeast cells stop any significant metabolism after their main source of energy, sugar, is depleted. I have showed evidence, some less but other purely scientific to prove my point. I'm not a microbiologist but I do have a cell biology background and my PhD was done in a microbiology lab sharing knowledge with a majority of microbiologists, though all of them were bacteriologists.

The idea supported by many here is to not use a secondary fermentation and ferment your beer beyond that period where final SG has been reached, so the yeast can clean-up after themselves and result in a better final product. That just doesn't happen IMHO. I never actually secondary any Ale as a matter of fact and I also keep my primary way beyond after fermentation is complete because I simply believe that stretching that time allow solids, including inactive yeast, to sediment better maximizing the appearance and possibly flavor of the beer. It has nothing to do with yeasts cleaning-up anything. They can't do it without energy and after fermentation is complete, their source of energy is gone and they become dormant.

In the case of D-rest, like I said before, John Palmer himself in the latest edition of his book How to Brew states that it is important to do it in the right time before lagering, which is before fermentation is totally complete, so the yeast will have substrate available to clean up the diacetyl. A lot of people will tell that they actually do a successful D-rest after fermentation is finished. I believe that is wrong too.
Fermentation in lagers is very slow. It may have long passed the peak of fermentation where airlock activity is typically noticed, but there is still some residual fermentable sugars available for the D-rest, only it's very scarce, hence the need to increase the temperature to activate the almost dormant yeast.

Look. I'm sorry for the bold letters, OK, sometimes I just can't help it. You can believe whatever you want too. I'm not asking you to believe in what I'm saying about this, but perhaps you all will think about it whenever that perception comes across again.

Finally, I brewed an English Brown Ale about 3 weeks ago, which I have bottled half of the 5 gal batch right after fermentation was completed and will bottle the other half after resting the remaining in the primary vessel for a month. After all have been carbed, I will taste them in a blind fashion to see if I can tell them apart. Because I don't likely have the most accurate palate in the world, barely that, I'm looking for BJCP-certified folk here who is willing to degust them as well in the same fashion. I highly suspect there will be a noticeable difference between them, not because of the famous, or infamous, yeast clean-up paradigm, but for the reasons aforementioned in this post.

Cheers!

 

[BrewKnurd]

Finally, I brewed an English Brown Ale about 3 weeks ago, which I have bottled half of the 5 gal batch right after fermentation was completed and will bottle the other half after resting the remaining in the primary vessel for a month. After all have been carbed, I will taste them in a blind fashion to see if I can tell them apart. Because I don't likely have the most accurate palate in the world, barely that, I'm looking for BJCP-certified folk here who is willing to degust them as well in the same fashion. I highly suspect there will be a noticeable difference between them, not because of the famous, or infamous, yeast clean-up paradigm, but for the reasons aforementioned in this post.

Cheers!

This is not an experiment which in any way proves your theory, so I'm not sure why its relevant. All you prove is that there is a difference between a shorter primary and a longer primary, NOTHING about WHY that happens.

 

[Indyking]

This is not an experiment which in any way proves your theory, so I'm not sure why its relevant. All you prove is that there is a difference between a shorter primary and a longer primary, NOTHING about WHY that happens.

I never said I'm doing this experiment to prove my theory. My theory is out there for whoever is interested in a second opinion. My experiment is to prove my other hypothesis that beer benefit from long resting after fermentation is complete for other reasons that has nothing to do with yeast cells cleaning up, as already mentioned.

 

[camus]

My beer tastes much better if it sits in the primary longer, even if I do a secondary, longer in the primary is better.

Sent from my iPhone using HB Talk

 

[BrewKnurd]

My experiment is to prove my other hypothesis that beer benefit from long resting after fermentation is complete for other reasons that has nothing to do with yeast cells cleaning up, as already mentioned.

Right, so to be totally clear:

Your hypothesis is: Beer benefits from long resting after fermentation is complete for reasons that have nothing to do with yeast cells cleaning up.

You plan to test this by: Comparing a beer with a long time in primary to a beer with a shorter time in a primary.

How do you plan to tell if the effects are do additional settling etc in primary vs additional contact with yeast in the primary? Again, all you can prove with this is that there is a difference. Not the mechanism for the difference.

 

[o4_srt]

I never said I'm doing this experiment to prove my theory. My theory is out there for whoever is interested in a second opinion. My experiment is to prove my other hypothesis that beer benefit from long resting after fermentation is complete for other reasons, as already mentioned.

How does the experiment prove this exactly? In both cases, yeast is still in the beer.

In order to prove that yeast has no place in the finishing of the beer, you would need to completely remove it.

1 batch of normally made homebrew, allowed to ferment and age for a month, with another batch fermented, then immediately filtered as soon as FG is stable, and allowed to age for the same amount of time. Both batches brewed, fermented, and force carbed concurrently.

Open one of each side by side, and note differences. If there is none, repeat experiment, but add a cold crash to the yeast free batch to further narrow your conclusion, since you are hypothesizing that the suspended solids in the beer have a role in cleaning up the byproducts.

If, after removing the yeast, and suspended solids, there is no change in flavor, I think aging on yeast could be proven to be a false concept.

If there is a difference in the original experiment, aging on yeast would have to have some merit, since the only difference between each batch would be the presence of said yeast.


In your proposed experiment, you are altering the fermentation time. Your hypothesis does not regard fermentation time, rather, yeast presence, so your experiment is flawed.

In order to prove your hypothesis, your variable must be the presence of yeast, otherwise, you cannot draw any conclusions about such presence, only that varying amounts of time in primary affects flavor, which is already an accepted concept.

 

[BrewKnurd]

In order to prove your hypothesis, your variable must be the presence of yeast, otherwise, you cannot draw any conclusions about such presence, only that varying amounts of time in primary affects flavor, which is already an accepted concept.

Thank you for fully typing what I was too lazy to. Well done.

 

[o4_srt]

Thank you for fully typing what I was too lazy to. Well done.

I'm on the clock, otherwise, I probably wouldn't have

 

[BrewKnurd]

I'm on the clock, otherwise, I probably wouldn't have

i was being called to dinner, that's my excuse and i'm sticking to it.

 

[Zamial]

Just because you don't understand it, that doesn't make it not true.

You win. I concede my argument based on the pure logic and tears of insidious laughter this statement has produced. Thank you cat, you made my day!

 

[Indyking]

I feel like I should not waste my time, but perhaps I was not clear...

The only reason I'm doing this experiment is too see if I really have to wait prolonged periods of time after fermentation is complete and before bottling/kegging to improve the taste of my beer. If there is an improvement with prolonged time, my rather simple experiment has no way to tell what factors caused the improvement. But in case of improvement, I believe it was not caused by yeast cleaning-up because that simply does not happen in fully fermented beer, which brings me back to this

 

[BrewKnurd]

I feel like I should not waste my time, but perhaps I was not clear...

The only reason I'm doing this experiment is too see if I really have to wait prolonged periods of time after fermentation is complete and before bottling/kegging to improve the taste of my beer. If there is an improvement with prolonged time, my rather simple experiment has no way to tell what factors caused the improvement. But in case of improvement, I believe it was not caused by yeast cleaning-up because that simply does not happen in fully fermented beer, which brings me back to this

You definitely weren't clear. I think it was probably the part where you explicitly stated that you were trying to prove that the improvement was due to causes other than yeast. Remember? When you said "My experiment is to prove my other hypothesis that beer benefit from long resting after fermentation is complete for other reasons that has nothing to do with yeast cells cleaning up, as already mentioned." You 100% stated that the purpose was to prove that the beer improved for reasons other than yeast. Your words, not mine.

 

[o4_srt]

I feel like I should not waste my time, but perhaps I was not clear...

The only reason I'm doing this experiment is too see if I really have to wait prolonged periods of time after fermentation is complete and before bottling/kegging to improve the taste of my beer. If there is an improvement with prolonged time, my rather simple experiment has no way to tell what factors caused the improvement. But in case of improvement, I believe it was not caused by yeast cleaning-up because that simply does not happen in fully fermented beer, which brings me back to this

You previously stated that you believe in aging, but do not think that yeast plays a part in the agin process, as you hypothesized that yeast stop functioning as soon as fermentation is complete. That statement is what started this current conversation.

I'm not necessarily fighting against you, I am curious as to what exactly happens post fermentation myself. If I had the force carb and filtering capability, I would definitely perform the experiment. Until someone steps up and does it, we are all just speculating with no practical proof other than obscure scientific journals, an what happens in the lab isn't always the same as what happens in the field.

 

[Indyking]

You definitely weren't clear. I think it was probably the part where you explicitly stated that you were trying to prove that the improvement was due to causes other than yeast. Remember? When you said "My experiment is to prove my other hypothesis that beer benefit from long resting after fermentation is complete for other reasons that has nothing to do with yeast cells cleaning up, as already mentioned." You 100% stated that the purpose was to prove that the beer improved for reasons other than yeast. Your words, not mine.

Read the statement again slowly. Are you sure? Do you want change your mind? How many times I have to repeat.

Perhaps this helps:

Prolonged resting after fermentation is complete = better beer possibly

Cause: Unknown.

Could it be because the now dormant yeast cells cleaned-up who knows what in the absence of food for energy? I don't think so.

So what's the cause then? Remains unknown but that is not what the experiment is about!

You previously stated that you believe in aging, but do not think that yeast plays a part in the agin process, as you hypothesized that yeast stop functioning as soon as fermentation is complete. That statement is what started this current conversation.

I'm not necessarily fighting against you, I am curious as to what exactly happens post fermentation myself. If I had the force carb and filtering capability, I would definitely perform the experiment. Until someone steps up and does it, we are all just speculating with no practical proof other than obscure scientific journals, an what happens in the lab isn't always the same as what happens in the field.

Good point. I think what happens is that, just like during lagering, the solid matter has more time to sediment resulting in fewer undesirable byproducts on suspension. Or, perhaps, some organic molecules that could give off flavors fade away just with the aging process, who knows.

 

[o4_srt]

It is well known and undisputed that aging is beneficial, the exact reason has merely been speculated, not proven. I don't see a need for your experiment.

 

[BrewKnurd]

Read the statement again slowly. Are you sure? Do you want change your mind? How many times I have to repeat.


Perhaps this helps:

Prolonged resting after fermentation is complete = better beer possibly

Cause: Unknown.

but that's not WHAT YOU SAID. You said "My experiment is to prove my other hypothesis that beer benefit from long resting after fermentation is complete for other reasons that has nothing to do with yeast cells cleaning up, as already mentioned."

Which includes both the result of "beer benefit after fermentation" AND the cause of "for other reasons that have nothing to do with yeast cells cleaning up". You included both a result AND a reason in what you stated you wanted to prove.

But sure, feel free to make insulting statements like "read slowly, are you sure" if that makes you feel better about yourself.

 

[jonmohno]

Heres and experiment: Taste the beer at two weeks primary, then taste it at 4 weeks.See which is better.

 

[Yooper]

This is going nowhere. Take your silly argument somewhere else. The OP has long gone to sleep now, and so have we.

Keep on topic, or post no more. Thanks!

 

[Indyking]

It is well known and undisputed that aging is beneficial, the exact reason has merely been speculated, not proven. I don't see a need for your experiment.

There had been several posts here and in other forums where people challenge that view. I disagree it is a undisputed observation. I have myself defended the position of aging because I thought it improved the quality of my beer but I never really tested the 2 options in the very same batch. Perhaps, there is no correlation with the aging, so I will waste more time with it no more. Not that I don't have the patience to wait, but sometimes the aging falls in the way of my plans and can be an inconvenience. Not planning to test only one batch either. Will do the same thing in the next couple of ales from different styles.

Any BJCP-certified judge out there to assist me with this?

 

[Indyking]

This is going nowhere. Take your silly argument somewhere else. The OP has long gone to sleep now, and so have we.

Keep on topic, or post no more. Thanks!

So, do you call this nowhere? Really? It's a new idea. This is a forum and people should be open to new learning opportunities rather them reject them on the basis of something that has never been proved. Nowhere? Hardly.

 

[Indyking]

Heres and experiment: Taste the beer at two weeks primary, then taste it at 4 weeks.See which is better.

I'm being a bit more radical. I'm testing few days (right after fermentation was completed confirmed by SG reading) vs. 1 month aging in the fermenter.

 

[BrewKnurd]

This is going nowhere. Take your silly argument somewhere else. The OP has long gone to sleep now, and so have we.

Keep on topic, or post no more. Thanks!

sorry. i agree with your intervention. i will behave.

 

[BWN]

It has been entertaining to me.

 

[Yooper]

I'm being a bit more radical. I'm testing few days (right after fermentation was completed confirmed by SG reading) vs. 1 month aging in the fermenter.

Look, posting three more times to augment your position when told to STOP isn't helping.

Start a new thread if you feel that this requires more discussion. But ignoring a moderator's post telling you to stop as this has gone off-topic isn't really going to help.

I'm not saying "stop" because I have nothing better to do. You're talking the thread beyond off-topic, not listening to others' points, and bombarding the thread with posts. Take it to a new thread. Or be quiet. Seriously.