Low floculation when reusing yeast.

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bja

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I've been reusing yeast for about 6 months and this problem has gotten progressively worse. It's to the point where 4 weeks after pitching it's still cloudy, even cold crashing for a week won't drop the yeast out.

To make sure it wasn't an issue elsewhere, I used new yeast for the last brew and it is perfectly clear 7 days after pitching.
 
Yeah, I noticed that too. My flocculation problems get worse already on second or third generation of yeast. I'm not sure how breweries can still use the same yeast from 100 years ago.
 
At what point are you harvesting the yeast (primary/secondary) and are you keeping all of it? Commercial breweries save the middle third of the yeast cake, I believe so that they are selecting yeast with the desired floculation. Unless you use conical though, that would be rather hard to do at home. My suggestion would be to reuse it until you start having problems and then start fresh again. Or, grow up a bunch of it from the start and freeze it so that you are always using first generation yeast.
 
Some of it will depend on what yeast you're reusing. For instance, if you transfer to a secondary and use that yeast, it will naturally be less flocculant than what was originally pitched.

Even if you don't secondary, perhaps the less flocculent yeast, since its been dormant for a shorter period of time, has a higher viability and therefore ends up dominating future fermentations.

Anyways, if you're seeing lower flocculation, its because somehow you are selecting less flocculent yeast at each propagation step.
 
You are viewing natural selection in action, or i guess it's artificial selection since you are the one choosing the trait. In this case flocculation properties. As I understand it a yeast flocculates based on proteins present on the surface of the cell. As time goes by, and cell reproduction occurs, there are random mutations, some of those mutations might cause a change in those surface proteins, and change the how effective the individual cells are at falling out of solution. So when you take the yeast that are left at the bottom of your secondary, you are harvesting the yeast that are the poorest flocculators, and throwing out all the ones that drop out of solution quickly. Do that a few times and you are left with a whole colony of yeast that are not as good at flocculating as the original strain.

The breweries that are using the same strain are growing them up from single colonies that they grow up through bigger and bigger starters, and like was said before, they are harvesting the yeast for the next batch from the ones that floc out like they expect from that strain.
 
So when you take the yeast that are left at the bottom of your secondary, you are harvesting the yeast that are the poorest flocculators, and throwing out all the ones that drop out of solution quickly.

I don't use a secondary.
 
Even if you don't secondary, perhaps the less flocculent yeast, since its been dormant for a shorter period of time, has a higher viability and therefore ends up dominating future fermentations.

Possible, i just don't know how to prove something like this.
 
At what point are you harvesting the yeast (primary/secondary) and are you keeping all of it? Commercial breweries save the middle third of the yeast cake, I believe so that they are selecting yeast with the desired floculation. Unless you use conical though, that would be rather hard to do at home. My suggestion would be to reuse it until you start having problems and then start fresh again. Or, grow up a bunch of it from the start and freeze it so that you are always using first generation yeast.

I do keep all the yeast, split into 4 jars. I have no way of selecting the middle layer.
 
Do you rinse the yeast at all when you're harvesting it? That would select for less flocculent yeast as well.
 
I do keep all the yeast, split into 4 jars. I have no way of selecting the middle layer.

Do you wash it? Perhaps you could weed out some of the low floccers while you wash? Or, make a starter witht the saved yeast and decant while there is still some activity in the starter so that the low floccers get tossed and just save what has already settled and make a fresh starter from that. There must be a way to make it work if you are determined.
 
Do you rinse the yeast at all when you're harvesting it? That would select for less flocculent yeast as well.

I pour off all of the beer, add ~1 gallon of boiled and cooled water then pour into the jars.

Why would rinsing select less flocculant yeast?
 
I pour off all of the beer, add ~1 gallon of boiled and cooled water then pour into the jars.

Why would rinsing select less flocculant yeast?

Well, if you end up with everything that was in your fermenter in the jars, then you aren't really rinsing, you're just making it easier to move, and then I wouldn't think you wouldn't impact the flocculation much.

By rinsing, I meant adding water, shaking the heck out of it, then letting the trub settle for a bit before pouring the liquid into your jars. By leaving behind the trub, you're also going to leave beind the most flocculent yeast, which would have settled out with the trub.

In summary, if everything that was in your fermenter ends up in your jars, there shouldn't be much selection pressure there. If anything gets left behind, you are directionally selecting less flocculent yeast.
 
Well, if you end up with everything that was in your fermenter in the jars, then you aren't really rinsing, you're just making it easier to move, and then I wouldn't think you wouldn't impact the flocculation much.

Exactly. I keep everything. Actually I only transfer clear wort into the fermentor so there almost no trub.
 
Exactly. I keep everything. Actually I only transfer clear wort into the fermentor so there almost no trub.

Well then I'm back to your high floccing yeast must just be more viable and therefore dominate future generations. :p
 
I would recommend you purchase the new book "Yeast", there is a chapter that addresses this very issue and the mutations and natural selections that occur and why and how to minimize them.

In short and being mobile, every time you re-use yeast even with washing there is a lot of dead cell, mutated cells high floc and low floc that is in the yeast and over time and re-use certain cells become les desirable and others more but you have no control as a homebrewer's without a conical.

The conical allows you to drain off the the fast flocculating yeast at the bottom, save the middle layer and then discard the slowest flocculating on the top due to the shape of the vessel and the valve.
 
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