lager yeast won't floc inside fermenter, but...

[chaosmaster]

I am having a problem. After 10 weeks of conditioning, the beer (lager) won't turn clear. Today's yeast volume reading is 20 million/ ml. However, if I pour it into a sample glass, yeast will settle immediately (in 10 minutes as I can see them at the bottom of the glass.) It will turn clear overnight. Yeast count drops to 5 million / ml. Why?

here are some the parameters:

yeast strain: unknown. (the same yeast flocs pretty well couple batches ago, I know this could be an older generation, but if it is old, it should not floc in the glass so quickly. )
beer: brown lager
temperature is 2.5-3C ( ~38F).
batch size (2.5 T conical fermenter, 3.5 meter high. ~ 10 foot)
OG. 1.050
FG, 1.010. (as of today, didn't change for the past month, so I assume it is final.)
pH: 4.1 (no change for a month)

I have tried shocking the beer with CO2 flush, didn't reduce the yeast suspension.

Any explanations and suggestions? I am considering adding CaCl2 solution or fining.

[beerking1]

Can't say I have any flashes of brilliance here, but a couple of thoughts:
1. I suspect it may be too late to add Ca and improve yeast health, thereby getting better flocculation. I think they have to incorporate the Ca with food.
2. I would go for finings first. If that does not work, you could always try the CaCl (or CaCO3, depending on your water and whether you are going for a malty or hoppy profile) later.

Good luck. Let us know what works.

[chaosmaster]

If we keg the beer, and left the keg at room temp, the beer can floc very well in couple days and at the bottom of the keg the yeasts settled into a large cake. No pressure change between the fermenter and the kegs. So, as an indicator to a possible solution, we have tried increasing temperature to 10C inside the fermenter for couple days, and.................

it didn't work! SOB!

Now we are preparing isinglass, will report on this.

[Kushal]

Sounds like you already looked under a microscope, but are you sure it's yeast and not chill haze?:confused:

[JoeV]

and I thought I was alone on this one. I have seen very similar results with lager yeast. Re-pitching seems to bring this about.

So I was thinking..could these be accumulated respiratory deficient mutants (ie pettiet mutants) smaller yeast...slower floc.

Or could the yeast have mutated to a non-flocculent strain, ie lost its flo genes due the stress of repitching.


On re-pitching lager yeast I have found the best (floc) results by doing the following

1. keep on ice after harvesting
2. Re-pitch within 24 hours of harvesting (or feed and aerate yeast)
3. Aerate wort, make sure there is enough ca+, FAN (free amino nitrogen), and so on in the wort.

[Sulfur]

You may have chaotic:p circulation going on in your tank, preventing a nice even sedimentation.

[BrewinLou]

Can't hurt to crash it to 32.

[Scott M]

Can't hurt to crash it to 32.

I agree here, get it real cold. Maybe they just don't know it's winter!!

[chaosmaster]

Kushal, no, it's not cold haze, i actually saw the creamy yeast at the bottom of the glass.
Sulfur: We only crop yeast frequently, and there has been no other disturbance for a month or so.
32F has been reached for couple days, didn't work.

The intriguing part is: Why the beer flocculated so fast once it left the fermenters? If it is because of the mutated yeasts, should the beer stay fuzzy when it is removed to another container?

Should lower pressure help flocculation? Now I just realized kegs' pressure is lower than that of the tanks.

[Sulfur]

is the volume the same as your other beers? If it's less, maybe you're not getting even cooling because your upper glycol zone is not covered (assuming you have one). In that case, you only have the lower cone zone cooling and could have some type of layering action going on with different temp profiles.

[canyon]

Sulfur has already posted what I am thinking that you might have convection going on for whatever reason. Rack the beer and let it settle in another fermenter or kegs and then rack again. Be sure and post your results for the enquiring minds that want to know! Good luck!:)

[chaosmaster]

Yeast is still suspending as of today. However, brown lager floc pretty well, yeast now is 5 million/ml. Pilsner is still high, but has reduced from 50 million to 25 million/cell.

I can understand racking, and settling, but why rack again after that? hmmm. let me know. I will rack the beer.

[beermkr]

I am wondering the same thing. I had a lager that stayed at 32 for over 6 weeks. It was still loaded with yeast when I filtered it. The other day I tried something. I hooked a CO2 line to the sample port and pressurized the tank. While it was filling the temp went down to 26 degrees. I have since raised all my tanks to 35 instead figuring that I have a layering problem at that low of a temp.

[chaosmaster]

After months of trying and failing, now we have the following conclusion.

The yeast needs to be propagated every batch! If we use freshly propagated yeast, the fermentation can be done in 10 days with good precipitation. (lager yeast, 13 P down to 2-3 P at 12C, D-rest at 14 C). Even the first generation cone to cone pitching at 20 mil/ml still didn't do the job -- slow fermentation and heavy yeast suspension. However, the freshly propagated yeast works well even when it is pitched at 12 mil/ml rate.

Hope someone can tell me why.

[Gregg]

After months of trying and failing, now we have the following conclusion.

The yeast needs to be propagated every batch!Cannot tell you why, but I can make a recommendation. Spank that naughty yeast right out of your brewery, and get a better-behaved new strain in.

[liammckenna]

You might try propagating on a glucose basal medium (don't know your current propagation regime) and stepping up into non-maltose media. Last propagation step into wort and then pitch.

An old professor of mine suggested this for a particularly sluggish ale yeast strain. It revived immensely. His explanation was that wort fermentation actually stressed the heck out of yeast after a few generations. Can't recall the details.

Pax.

Liam

[gitchegumee]

Look at your oxygenation techniques and mineral profile. Sounds like the yeast isn't happy. Select the middle third of the yeast for repitching. The last third will select for non-flocculant yeast. Make sure you have a single strain of yeast. Some of the strains available are mixed and difficult to repitch. You should be able to get multiple generations without a problem if you do everything right. Good luck!

[chaosmaster]

Thanks Gregg, I have had that spanking section done! :D

[chaosmaster]

I will try that too. As I have said, (without seeing you two's posts), I have used a new strain. However, the old one is still sitting there and I will be more than happy to find out why they behave badly in case we run into the same issue again.

[meister]

After months of trying and failing, now we have the following conclusion.

The yeast needs to be propagated every batch! If we use freshly propagated yeast, the fermentation can be done in 10 days with good precipitation. (lager yeast, 13 P down to 2-3 P at 12C, D-rest at 14 C). Even the first generation cone to cone pitching at 20 mil/ml still didn't do the job -- slow fermentation and heavy yeast suspension. However, the freshly propagated yeast works well even when it is pitched at 12 mil/ml rate.

Hope someone can tell me why.


I suspect you have a yeast viability or vitality problem. A 13°P lager @ 12°C should be completely fermented out in 6 days even with a pitching temp of 9°C or lower. Maybe you have a wort aeration issue. not enough air or too much oxygen if you are using pure O2.

[grassrootsvt]

A few things come to mind:
1. You don't the know origin of your yeast? Generation?
2. How are you cropping your yeast? Sounds as if you may be doing cone to cone transfer? Without selectivity?

[simon]

We have encountered the same issues with Wyeast 1056, and I believe that the problem is not related to yeast generations - we have had similar issues with highly vigorous ferments, and sluggish ones, and with first and fifth generation cultures. I believe that the real issue is different temperature zones within the tank, the "layering" that has been touched on. We have at times racked back to unitank to draw off more yeast, but that has only partly solved the problem.

Once again, it flocs out nicely in the bottle or keg, but we would rather minimise yeast in the package, without having to filter. Our sample taps on our bright tanks are below the jackets, as is the thermowell for the probe, and we have demonstrated (by putting the same sterilized probe into the product down the prv) that there is a significant difference in temperature (about 6 deg C) within the tank. My current theory is that the beer taken from the sample tap (next to the manway) is not indicative of either the clarity or the temperature of the entire tank. I have talked to other brewers who don't have this problem, and they have single skinned tanks in coolrooms, which is a very different refrigeration scenario.

My next best guess is to raise glycol temperature to about - 1/-2 deg C to make the cooling a bit slower, and more uniform throughout the tank.

Chaosmaster, what is your glycol temp? Could this be the problem?

[chaosmaster]

Hey Simon, thanks for your reply. Our ferm tank is only 2.5 ton and we had the beer sitting there for a month. So, i figure the temp should be quite uniform after so long. Our glycol temp is -3/-4 C.

PS: i don't think it is an areation problem as the other strains of yeast used the same amount of O2.