Help: Fermentation stuck

[jbritt]

I've read a lot of threads about what to do with a stuck fermentation but I am skeptical if its actually possible. So I am looking for a fool proof way if someone has it.

I brewed a NEIPA starting gravity 1.062. I pitched one package of K-97 (yes, not enough). It fermented (not vigorously) for a couple days then slowed quite a bit. I took readings throughout because it seemed like I may be in trouble. Basically it is stuck at 1.03 and hasn't moved. Its been a week and a day. I pitched US05 a few days ago with no change.

Is there anything verifiable that could be done in this situation or am I stuck with a 4.3% NEIPA?

 

[mac_1103]

A fool-proof way to unstick a fermentation? I dunno, maybe glucoamylase, but you're not going to wind up with the beer you thought you were brewing if you go that route. Kinda depends on why it's stuck in the first place.

 

[jbritt]

A fool-proof way to unstick a fermentation? I dunno, maybe glucoamylase, but you're not going to wind up with the beer you thought you were brewing if you go that route. Kinda depends on why it's stuck in the first place.

Just looking for things people have done that actually worked for them. I've only ever tried pitching more yeast to no avail

 

[day_trippr]

Basically it is stuck at 1.03

This looks suspiciously like someone using a refractometer to determine FG without using a compensating calculator to account for the presence of alcohol.
Amiright?

Cheers!

 

[jbritt]

This looks suspiciously like someone using a refractometer to determine FG without using a compensating calculator to account for the presence of alcohol.
Amiright?

Cheers!

Hydrometer

 

[day_trippr]

Too bad, that would have been easy
Had someone just yesterday using a refract on fermented beer without adjustment, thought I had another.

Anyway...confronted with a similar scenario I would pitch a starter at high krausen and hope for the best...


Cheers!

 

[jbritt]

Too bad, that would have been easy
Had someone just yesterday using a refract on fermented beer without adjustment, thought I had another.

Anyway...confronted with a similar scenario I would pitch a starter at high krausen and hope for the best...


Cheers!

I was wondering if that would be the best last ditch effort. Any suggestions on yeast?

 

[day_trippr]

Could you back up a tad and give us a grain bill and a mash temperature profile?

I don't have any brilliant suggestion on yeast strain to use at this point. You're well under pretty much every strain's alcohol tolerance and attenuation abilities - even K-97 - so in theory pretty much anything ought to move the needle - unless there's something inhibiting progress. I suppose I might give wlp099 a try if there was any hope...

 

[passedpawn]

Add alpha amylase. Your homebrew shop will have it. It will not hurt your beer, and very well might help. It's the same enzyme that was already in your grain, so it's not a foreign or unnatural ingredient being added.

Add 2 tsp into a 5g batch, let it warm to room temperature, and give it at least 2 weeks. Wait until you're SURE the gravity isn't changing any more, then package. It should (might) allow your beer to continue fermenting down to ~ 1.010.

Don't add gluco amylase. It's not a normal beer enzyme and likely will dry out your beer, probably not in a good way for a NEIPA.

 

[G_robertus]

I second the request for more information. Is your hydrometer showing correct readings in water and sugar solutions? Usually not the cause, but it's best to rule it out. Did you taste the sample? Was it too sweet? And just another question to rule things out, you did use an actual hydrometer and not a pill or anything?

Pitching dry yeast won't work in beer that has fermented as long as yours has, or not that fast. Pitching active yeast is your best chance if there are fermentables left. Adding dry hops might also release enzymes to drive FG down if fermentable sugar is the problem. It won't help if your yeast was/is not up to it though. When you don't pitch enough healthy yeast fermentation tends to drag along very slowly, but it can get there eventually. You can check whether it's a yeast issue or availability of fermentables by adding some sugar to see if it kicks up again.

If that all does not work and you have verified that there is active yeast in there, you could add sugar (or extract) to up the ABV with no/minimal influence on FG. You would have to go to double or triple strength to offset your FG though, so it might not be what you're looking for.

 

[jbritt]

Could you back up a tad and give us a grain bill and a mash temperature profile?

I don't have any brilliant suggestion on yeast strain to use at this point. You're well under pretty much every strain's alcohol tolerance and attenuation abilities - even K-97 - so in theory pretty much anything ought to move the needle - unless there's something inhibiting progress. I suppose I might give wlp099 a try if there was any hope...

I am wondering now if the mash temp was the problem. I mashed at 156 and grain bill was 45% 2 row, 45% flaked oats, and 10% flaked wheat.

I'm just starting to try to understand more about the science of brewing like water chemistry and enzymes. So any info on that would be helpful.

I was trying to go for a fuller bodied beer with the high mash temp, but does that mean fg will be higher, and how much higher? I see on the curves I was not at the peak of beta amylase, how does that affect fermentability and fg?

When you are using grains that have high potential gravity, but your mash temp is higher, how do you determine approximately what your fg will be? I usually mash at 149 so I would assume fg of around 1.015 so it was easy to know the outcome relatively

 

[jbritt]

Add alpha amylase. Your homebrew shop will have it. It will not hurt your beer, and very well might help. It's the same enzyme that was already in your grain, so it's not a foreign or unnatural ingredient being added.

Add 2 tsp into a 5g batch, let it warm to room temperature, and give it at least 2 weeks. Wait until you're SURE the gravity isn't changing any more, then package. It should (might) allow your beer to continue fermenting down to ~ 1.010.

Don't add gluco amylase. It's not a normal beer enzyme and likely will dry out your beer, probably not in a good way for a NEIPA.

Its possible that it could get down that low by just adding alpha amylase?

 

[hotbeer]

Maybe I missed it, but what is the ambient temperature where the fermenter is? Or if you know the internal temp the beer is maintaining, then what is that?

If you are using a ferment chamber, then ambient temp is the inside temp of the chamber. Not the temperature of the air on the outside of the chamber!

 

[mac_1103]

I was trying to go for a fuller bodied beer with the high mash temp, but does that mean fg will be higher, and how much higher? I see on the curves I was not at the peak of beta amylase, how does that affect fermentability and fg?

The primary determinant of wort fermentability is neither alpha- nor beta-amylase, but limit dextrinase, which is optimally active at 140-145F.

https://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1999.tb00020.x

Assuming that your mash thermometer is accurate, your pH was in the right ballpark and you mashed long enough to fully gelatinize the starches, then you should have had plenty of alpha amylase activity. So I'm not sure that adding more alpha will help and buying beta or limit dextrinase is probably not a realistic (i.e., remotely affordable) option.

 

[passedpawn]

Its possible that it could get down that low by just adding alpha amylase?

Yes. In fact, it's likely (if the original problem was mash temps as I suspect). I've used it with success in the past

https://www.homebrewtalk.com/thread...ermentation-mountain-ae-to-the-rescue.212926/

 

[jbritt]

Yes. In fact, it's likely (if the original problem was mash temps as I suspect). I've used it with success in the past

https://www.homebrewtalk.com/thread...ermentation-mountain-ae-to-the-rescue.212926/

Cool I'll try that. Do you think its worth also adding a starter or just the amylase?

 

[day_trippr]

I would go with just the amylase enzyme to begin as your yeast didn't disappear, they just ran out of food they could actually digest. I've used amylase enzyme by simply adding to the fermentor and in a day or two suddenly things were happening...

Cheers!

 

[passedpawn]

^^ exactly. No additional yeast needed.

 

[jbritt]

Just put 2 tsps in so I'll update after a while if anything seems to be changing

 

[jbritt]

I would go with just the amylase enzyme to begin as your yeast didn't disappear, they just ran out of food they could actually digest. I've used amylase enzyme by simply adding to the fermentor and in a day or two suddenly things were happening...

Cheers!

So if alpha amylase works, what happened in the mash? Assuming temperature probe was accurate, would it have to be a time issue?

 

[jbritt]

The primary determinant of wort fermentability is neither alpha- nor beta-amylase, but limit dextrinase, which is optimally active at 140-145F.

https://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1999.tb00020.x

Assuming that your mash thermometer is accurate, your pH was in the right ballpark and you mashed long enough to fully gelatinize the starches, then you should have had plenty of alpha amylase activity. So I'm not sure that adding more alpha will help and buying beta or limit dextrinase is probably not a realistic (i.e., remotely affordable) option.

But assuming all of that, what causes fermentation to stop? Temperature was right and there should have been plenty of yeast (eventually). The only thing I can think of is probe is either wrong or the mash wasn't long enough

 

[passedpawn]

So if alpha amylase works, what happened in the mash? Assuming temperature probe was accurate, would it have to be a time issue?

It's a temperature and time issue. And it might be a YOU issue. We weren't there, so who knows what really happened to your mash.

At elevated mash temperatures, enzymes will cleave those big sugars in the wort into fermentable sugars. Things can go wrong: maybe you have a lot of grains that don't have "diastatic power" (low enzymes). Maybe, for whatever reason, the temperatures were very high (or low).

The original enzymes would have been denatured (destroyed) in the boil, but you can fix that by adding them to the fermentor. However, your beer will go to the "limit of fermentation", which for barley wort is between 85% and 90%. This is for amylase enzymes. Gluco is much higher.

 

[IslandLizard]

I am wondering now if the mash temp was the problem. I mashed at 156 and grain bill was 45% 2 row, 45% flaked oats, and 10% flaked wheat.

As other said, check your thermometer for accuracy.
Also, depending on how and where in the mash you probed, the actual temps could have varied quite a bit throughout the tun.

156F is getting toward the upper mash temp limit (158-160F), where beta-amylase is being denatured at a high(er) rate. Beta-amylase produces a more fermentable wort, so a 4-degree deviation upward could leave you with less fermentable wort.

It's probably a combination of several factors, sadly stacking up against your favor this time. It happens.

 

[jbritt]

As other said, check your thermometer for accuracy.
Also, depending on how and where in the mash you probed, the actual temps could have varied quite a bit throughout the tun.

156F is getting toward the upper mash temp limit (158-160F), where beta-amylase is being denatured at a high(er) rate. Beta-amylase produces a more fermentable wort, so a 4-degree deviation upward could leave you with less fermentable wort.

It's probably a combination of several factors, sadly stacking up against your favor this time. It happens.

Yes that is definitely true. Is there a way to calculate roughly what fg will be as you go up in mash temperature or is that just trial and error on the same recipe? Obviously yeast has a lot to do with it

 

[jbritt]

It's a temperature and time issue. And it might be a YOU issue. We weren't there, so who knows what really happened to your mash.

At elevated mash temperatures, enzymes will cleave those big sugars in the wort into fermentable sugars. Things can go wrong: maybe you have a lot of grains that don't have "diastatic power" (low enzymes). Maybe, for whatever reason, the temperatures were very high (or low).

The original enzymes would have been denatured (destroyed) in the boil, but you can fix that by adding them to the fermentor. However, your beer will go to the "limit of fermentation", which for barley wort is between 85% and 90%. This is for amylase enzymes. Gluco is much higher.

Thanks, appreciate the info

 

[IslandLizard]

Yes that is definitely true. Is there a way to calculate roughly what fg will be as you go up in mash temperature or is that just trial and error on the same recipe? Obviously yeast has a lot to do with it

There must be studies for estimating an FG range based on the various variables involved, but I've never seen one.

As homebrewers a qualitative method is probably the closest we can get. Qualitative, as in larger, smaller, higher, lower, more, less, etc. rather than (more precise) numbers. For example: "mashing at the higher temps of the range will produce lesser fermentable wort.

So on your brew system with your methods, doing certain things produces a certain wort. For example, when you want more fermentable wort, you can experiment with lower mash temps, and/or longer mash durations, maybe even as long as overnight at 146F. Wrap a few moving blankets, a heating blanket, or one of those ferm wraps around that tun, placed in a warm area.
Keep good notes, so you may be able to make closer predictions when you interpolate or even extrapolate (values), such as mashing overnight at 150F or 154F.

 

[IslandLizard]

Let me add, many Lager brewers tend to mash low and long, even overnight at 140-146F, for an ultra-fermentable wort. They also tend to use (high diastatic) Pilsner Malts and very little, if any, adjuncts or Crystal and Caramalts.

As @mac_1103 mentioned in #14, Limit Dextrinase is key in breaking down those (unfermentable) dextrins.

 

[hottpeper13]

^^^^ you have ~50% flaked grain. When I do this I split the main base malt with 50/50 pilsner/ pale ale malt and do a 2 hour mash at 152*. Pils malt has the highest DP of any base malt.

 

[jbritt]

Added the amylase a couple days ago and fermentor bubbled consistently within an hour of adding the amylase. It continued that way for about 24 hours so I assumed it was working. But I took a reading today and same gravity lol so maybe I just have to take an L on this one.

 

[passedpawn]

Added the amylase a couple days ago and fermentor bubbled consistently within an hour of adding the amylase. It continued that way for about 24 hours so I assumed it was working. But I took a reading today and same gravity lol so maybe I just have to take an L on this one.

Better be patient. If it's working, it might take some time.

Those bubbles might have been the CO2 that was already in the beer, coming out due to the powder being added.

Are you bottling when it's done?

 

[jbritt]

Better be patient. If it's working, it might take some time.

Those bubbles might have been the CO2 that was already in the beer, coming out due to the powder being added.

Are you bottling when it's done?

Kegging. I had to use my keezer as a fermentation chamber for 2 lagers anyway so it will sit for a while