Pressure-Fermented Lager Still has Krausen After 11 Days

[Clint Yeastwood]

I started pressure-fermenting a lager 11 days ago at 68 degrees. I had to open the keg because I couldn't take samples without adding a weight to the dip tube end. I saw a lot of what looked like krausen in there.

Shouldn't the krausen have dropped by now? Pressure fermenting is supposed to be fast.

The pressure is pretty high. I try to keep it at 15 because I read it somewhere, but it has crept somewhat higher a couple of times.

I managed to get a sample, and the SG is around 1.011, down from 1.054. Beersmith predicted 1.016. Beersmith doesn't seem to have any idea where beers are going.

The grain bill and hops look like this:

10 lbs​	Pilsner (2 Row) Bel (2.0 SRM)​	Grain​	2​	93.0 %​	0.78 gal​
12.0 oz​	Caramel/Crystal Malt - 10L (10.0 SRM)​	Grain​	3​	7.0 %​	0.06 gal​
0.80 oz​	Nugget [15.20 %] - Boil 60.0 min​	Hop​	4​	39.6 IBUs​	-​
1.00 oz​	Crystal [3.50 %] - Steep​

 

[rburrelli]

I do not think any software can predict final gravity accurately. It is really a guesstimate at best based on percentages of attenuation of the yeast used. Plus all the other factors of your process.

 

[VikeMan]

Shouldn't the krausen have dropped by now? Pressure fermenting is supposed to be fast.

For any given temperature: the higher the pressure, the slower the fermentation. That said, the presence of krausen doesn't necessarily mean that attenuation has not finished.

I managed to get a sample, and the SG is around 1.011, down from 1.054. Beersmith predicted 1.016. Beersmith doesn't seem to have any idea where beers are going.

Attenuation predictions are just that, predictions. That said, Beersmith takes yeast strain, mash temperature, and mash length into account when predicting attenuation. It does not consider the makeup of the grain bill.

 

[Clint Yeastwood]

I'm no fortune-teller, but it looks like this thing is headed for maybe 1.008, which is 0.006 lower than the first time I made it.

 

[Clint Yeastwood]

For any given temperature: the higher the pressure, the slower the fermentation.

The pressure-fermenting faction claims heat speeds fermentation up more than pressure slows it down, so pressure gives fast lagers with no loss of quality. It is true that this beer blew past 15 psi a couple of times, but I kept adjusting the pressure down.

 

[VikeMan]

The pressure-fermenting faction claims heat speeds fermentation up more than pressure slows it down, so pressure gives fast lagers with no loss of quality. It is true that this beer blew past 15 psi a couple of times, but I kept adjusting the pressure down.

Pressure slows it down. Heat speeds it up. Perhaps the "faction" could provide you with curves showing the data they have collected. As for "no loss of quality," as soon as warm fermented lagers start winning Best of Show medals, I'll consider the possibility. I haven't tasted a warm fermented lager yet that I would call world class. But maybe they have eluded me. Although I've tasted quite a few, I haven't actively sought them out.

It is true that this beer blew past 15 psi a couple of times, but I kept adjusting the pressure down.

How exactly are you adjusting the pressure? A spunding valve shouldn't need repeated adjustments.

 

[Bassman2003]

Quick in comparison to three weeks under high pressure (30 PSI). It is all relative. But, at 68F, 11 days is plenty of time depending upon your yeast health and quantity. But in general, pressure fermentation stresses yeast to varying degrees, so fermentation will be affected. Raising the temps is a way to gain some esters back and speed up what would be a "slower" fermentation than at atmosphere.

My pressure ales have been taking about 5-7 days to be complete.

 

[Bassman2003]

How exactly are you adjusting the pressure? A spunding valve shouldn't need repeated adjustments.

I have the Kegland spunding valve and it tends to creep up during fermentation. So I wind up dialing it back while the yeast are thumpin'

 

[Clint Yeastwood]

I wasn't trying to convince people who don't believe in pressure fermenting that pressure fermenting works. I was hoping to get input from other people who pressure-fermented to find out if my experience is normal. Your bad experiences with high-pressure beers are of interest and will be considered, but they are off the path in the context of this thread.

It's well-known that pressure-fermenting is faster, so there is no point in discussing that here. Since it's known to be faster, I am curious as to why I am 11 days in with a big layer of krausen.

I adjusted the pressure by turning the little knob until the reading decreased.

Pressure slows it down. Heat speeds it up. Perhaps the "faction" could provide you with curves showing the data they have collected. As for "no loss of quality," as soon as warm fermented lagers start winning Best of Show medals, I'll consider the possibility. I haven't tasted a warm fermented lager yet that I would call world class. But maybe they have eluded me. Although I've tasted quite a few, I haven't actively sought them out.



How exactly are you adjusting the pressure? A spunding valve shouldn't need repeated adjustments.

 

[Bassman2003]

I don't see anybody poo pooing pressure on this thread. But it definately does not speed up fermentation. It stresses the yeast so they often work slower. A recent lager of mine at 30 PSI took three weeks when it normally would take much less time. I do not know where you read that pressure fermentation speeds up fermentation? Temperature speeds up fermentation.

 

[Clint Yeastwood]

Quick in comparison to three weeks under high pressure (30 PSI). It is all relative. But, at 68F, 11 days is plenty of time depending upon your yeast health and quantity. But in general, pressure fermentation stresses yeast to varying degrees, so fermentation will be affected. Raising the temps is a way to gain some esters back and speed up what would be a "slower" fermentation than at atmosphere.

My pressure ales have been taking about 5-7 days to be complete.

This is helpful. So what would you do? I'm thinking I should reduce the pressure, take an SG in two days, and see if it's still moving. If it's not, and I still have foam, do I chill the keg and move to a dispensing keg?

All I know about the yeast is that it seemed, and still seems, vigorous. I only used one packet of 34/70. I read somewhere that this was adequate. Since brewing this beer, I've been making starters for everything.

 

[Bassman2003]

Well, the rule of thumb is that pressure ferments often need more yeast that non-pressure ferments. More healthy yeast because they are stressed. More stress=off flavors. One pack might be fine or it might be pushing it. Starters are always good. At this point, all you can do it wait.

 

[Clint Yeastwood]

I don't see anybody poo pooing pressure on this thread. But it definately does not speed up fermentation. It stresses the yeast so they often work slower. A recent lager of mine at 30 PSI took three weeks when it normally would take much less time. I do not know where you read that pressure fermentation speeds up fermentation? Temperature speeds up fermentation.

To me, this sure looks like a criticism of pressure fermenting:

As for "no loss of quality," as soon as warm fermented lagers start winning Best of Show medals, I'll consider the possibilty. I haven't tasted a warm fermented lager yet that I would call world class.

Regarding pressure speeding up fermentation, here's an example from a brewing site:

Pressure fermentation refers to beer that is fermented under a pressure that is higher than atmospheric pressure (0 PSI). Brewers ferment under pressure to reduce esters, speed up fermentations, and naturally carbonate.

Here's one from Kegland's site:

Faster fermentations. By fermenting under pressure, you are able to ferment at higher temperatures than normal, which in turn allows for a faster fermentation.

Lots of this stuff out there.

 

[VikeMan]

It's well-known that pressure-fermenting is faster, so there is no point in discussing that here.

As I said, for any given temperature, it's slower. I'm still waiting to see data (curves) on the tradeoff between temperature and pressure in small batch (homebrew) fermentations. Nobody seems to have that data, but many are perfectly happy to claim "pressure fermenting is faster" as some sort of general rule.

But we do know that it's not true that increasing temperature by any/every possible amount, combined with an increase in pressure by any/every possible amount causes a faster fermentation. There are necessarily tradeoff curves with a breakeven point.

Lots of this stuff out there.

Sure is. But somehow no data.

To me, this sure looks like a criticism of pressure fermenting:

I didn't bring up "no loss of quality." I simply responded to the claim. I wouldn't have mentioned quality at all otherwise.

 

[Clint Yeastwood]

You seem to think I'm an advocate of pressure fermenting, and that I want to defend it. I'm not for it or against it. I'm a person who is trying it for the second time, looking for advice from people who do it a lot. I have no idea whether their claims are true, and arguments about it are irrelevant to the thread.

I saw what you said about "given temperature," but obviously, I am fermenting at 68, as noted above, which is higher than the usual lager fermentation. If I was going to ferment at normal temperatures, I would not bother with pressure.

Your interest in data is also off the reservation. Maybe you're right. I just want to know if what's happening in my fermenter is normal.

 

[Pennine]

What yeast did you use? All my lager pressure ferments have been done in 7 days even at colder temps. This is the first I have also heard that pressure slows the fermentation down...

 

[Clint Yeastwood]

I used 34/70.

 

[Bassman2003]

It appears to me that Vikeman is commenting on warm fermented lagers, not pressure fermenting. Pressure fermenting is a tool in the toolbox. It does things to the beer, some styles benefit, some not as much. It offers a lot to experiment with, which makes it interesting and fun. In my experience, hop forward beers like IPA really benefit from pressure. The hops are accentuated a lot while aromas are very strong. On the flip side, estery ales might be dulled down under pressure. Lager gets cleaner, especially at normal lagering temps (which requires more yeast). Plus mouthfeel changes etc...

Temperature speeds up fermentation. Tons of healthy yeast speeds up fermentation. Great wort speeds up fermentation. From Christ White - anything above 15 PSI is toxic towards yeast. That does not mean that they can't operate, but as the ferment goes on, they have a more uphill battle. Because esters are suppressed, one can raise the temps and "sort of" get away with it while basically conducting a warmer ferment than usual. Less yeast is needed in comparison, but the beer will have more ale characteristics than before. Ferments might be quicker under pressure if the temps are higher than if no pressure was used. I do not think pressure speeds up fermentation in a like for like temperature situation. I could be wrong though as I have only been doing it for six months. I do think it is reported to speed up maturation time to some extent.

 

[VikeMan]

It appears to me that Vikeman is commenting on warm fermented lagers, not pressure fermenting.

IMO, when most people talk about pressure fermenting lagers (on this forum), they are really talking about increased pressure together with increased temperature. The original post is a case in point. But in post #3, I was actually talking about (just) fermenting under pressure, i.e. about how it doesn't, by itself, speed up fermentation, and in fact slows it down, in response to what could be taken as a general claim that (just) "pressure fermenting is supposed to be fast." When I replied to the claim of "no loss of quality" in post #3, I was talking about both together (beacuse that's what I was responding to), though I would have given a similar reply to a claim of "no loss of quality" for warm fermented lagers in general (with or without pressure). So two different contexts. Funny how forum discussions tend to branch off, which is why I usually quote to provide context.

Because esters are suppressed, one can raise the temps and "sort of" get away with it while basically conducting a warmer ferment than usual. Less yeast is needed in comparison, but the beer will have more ale characteristics than before.

I think you have it pretty much surrounded.

Ferments might be quicker under pressure if the temps are higher than if no pressure was used.

Yep, and "might be" is key. The point I tried to make in post #14 is that folks are wrong to claim that "pressure fermentation" (including a temp increase) always speeds up fermentation, because this obviously can't be true in all cases. There would be combinations with (relatively) smaller increases in temperature and (relatively) larger increases in pressure where the opposite is true.

I do not think pressure speeds up fermentation in a like for like temperature situation. I could be wrong though as I have only been doing it for six months.

You're not wrong.

 

[Pennine]

I used 34/70.

Yes your Krausen should have dropped and it should be done by now.

 

[Clint Yeastwood]

Yes your Krausen should have dropped and it should be done by now.

Thanks for the help. Do you think reducing the pressure is the right answer?

 

[Red over White]

Pressure fermentation is about hitting the right balance for your chosen yeast and your chosen parameters. Pitch rate, fermentation temperature, gravity, initial set head pressure if desired (isn't always required) will influence the end results. Learning your chosen yeast is really important and then you can manipulate the parameters up or down. I commonly see YouTubers sprinkle 1 sachet of 34/70 directly into 12P wort and immediately set 12-15 psi on it at room temperature, this isn't ideal, but it is super easy and people hit the like and subscribe buttons.

 

[Pennine]

Thanks for the help. Do you think reducing the pressure is the right answer?

I would imagine that is what is happening possibly too much pressure, or it could be the keg was shaken up before you took a look and it just foamed up.

 

[odie]

Pressure slows it down. Heat speeds it up.

bingo.

The thing about pressure fermenting is WHAT pressure? And WHAT temperature. Yeast will work in a wide temp range AND wide pressure range.

I've read some studies that looked into yeast under pressure. It seems that the pressure required to make yeast go dormant (stop eating sugars) is many times what would rupture your keg. it was in over a thousand PSI as I recall. I did not see where they detailed any activity drop and various pressure points. But it took insane pressure to get the yeast to stop fermentation.

The same study showed pressure at which yeast propagation/reproduction (multiply) is hindered, slowed or stopped was very low. I think as little as 15 psi can start hindering yeast production.

I've been trying to set my pressure around 5-10 psi for lagers for the first few days so that the yeast can grow. After a few days I will remove the spunding valve and let it rise to the PRV limit (25-30) so it carbs and finishes.

If you start off with too much pressure, your yeast pitch will not grow much, if at all. And then you have a small yeast colony which will then just take longer to finish the job. But it will not go dormant. It just won't grow much bigger than your initial packet so it's going to take longer for a small yeast colony to eat all that sugar. So high pressure setting would need either a larger pitch or more time.

Pressure does not make yeast ferment faster or slower IMO. But raising the temperature will increase the activity rate of those yeast to make it finish faster. Some mild pressure just suppresses undesirable effects of yeasts which are fermenting at higher than normal temperatures. Pressure allows you to raise the temperature (yeast speed).

 

[VikeMan]

The same study showed pressure at which yeast propagation/reproduction (multiply) is hindered, slowed or stopped was very low. I think as little as 15 psi can start hindering yeast production.

Pressure does not make yeast ferment faster or slower IMO.

All other things being equal, when you inhibit yeast growth, you also slow the fermentation, because there are less yeast cells to do the work.

 

[odie]

All other things being equal, when you inhibit yeast growth, you also slow the fermentation, because there are less yeast cells to do the work.

OK, the individual yeast cells don't slow down under typical pressures. But they reproduce slower or not at all, thus the colony size is smaller from lack of growth. Less yeast cells to do the same job.

So collectively, the fermentation process is slower.

Would that be how you see it?

 

[VikeMan]

OK, the individual yeast cells don't slow down under typical pressures. But they reproduce slower or not at all, thus the colony size is smaller from lack of growth. Less yeast cells to do the same job.

So collectively, the fermentation process is slower.

Would that be how you see it?

It's one factor. I think there may be others, but I'm not sure how they all fit together, so I won't speculate too much publicly. The other one that I will mention (and it's somewhat interrelated I think) is that I believe cell wall permeability and/or transport functions are inhibited by pressure. (I think I heard this from Chris White.) That would imply that it takes longer to get sugars into the yeast cells. I'll add that I haven't searched the literature on that one.

(Again, this is assuming no mitigation from increased temperatures.)

 

[Clint Yeastwood]

I would imagine that is what is happening possibly too much pressure, or it could be the keg was shaken up before you took a look and it just foamed up.

I had to release pressure in order to open the keg. Maybe this caused foam to appear.

 

[odie]

I had to release pressure in order to open the keg. Maybe this caused foam to appear.

yes that will. do you know what the pressure was before you opened it? Pressure dropping will cause the CO2 to break out. That's where foam comes from.

if the beer was lightly carbed, then not much foam. But if the keg was like at 30 psi when you opened it...then yes, lots of foam might be expected.

If I ever have to open a keg for any reason, I slowly vent the PRV in several steps to bring the headspace psi down without too much foam breaking out. So that when I open the lid, the pressure is almost nothing and any foam has dissipated.

 

[Bassman2003]

In the end, pressure fermenting can yield great results, but there are a lot of variables to play with. For me, I have settled on:

IPA - 1-2 Bar starting pressure (tank gas), start at 65F, raise to 70F with pressure, build/hold up to carbonation pressure
Lager - 0-2 Bar starting pressure, 50F fermentation, build/hold up to carbonation pressure
Belgians/Ales - 0 starting pressure, build and hold up to carbonation pressure
Hefeweizen - 0 starting pressure, start at 62F, raise to 68F with pressure, build and hold up to carbonation pressure

The most impact seems to be at the start of fermentation, so if you want the pressure impact, put some starting pressure on. I made an IPA with 2 bar starting pressure and the aroma was like nothing I had ever made. Amazing for just a 2 oz dry hop.

Pressure really makes the beers taste cohesive imho. Dare I say "professional?" The large conicals have a lot of pressure built into them, so this is the homebrew way to match the environment. I am not going back to zero pressure as my setup is built around it. It is just too cool, even if you only crank up the PSI at the end.

 

[Clint Yeastwood]

This stuff was at around 15. Actually, it was somewhat higher, now that I think about it.