Tips on separating dead yeast from fresh ?

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SanPancho

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got lazy and let the 4-5 yeasts i keep on hand get really old. probably 9 months, maybe bit more. ran them all through starters in past week. now going to run again and try and separate the dead. my technique had always been to do essentially what i just described. one starter to pull them out of hibernation, and then another within a few days to really build up healthy cells. once the second starter is on the plate for a few hours and starts getting creamy and opaque look to it, i stop the spin. then i let what should be the dead yeast fall quickly to the bottom, and then pour off the wort and the fresh live cells. go back to stirring and normal process.

anybody have a different/better/easier method they use?
 
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Maybe I shouldn't admit this, but I just pull old yeast slurry straight from the fridge, scoop the dead stuff off the top and then pitch it. I don't do it often, but when I do, it works fine.
 
Generally the healthy cells will form a white (ish) layer in the trub.

You can separate them by using a yeast washing procedure.

Allowing the starter to ferment out and then washing the yeast might be more productive as do you really know the health of the flocculated cells. (i.e. they're not all bad, might be more healthy cells than you think)

 
Maybe I shouldn't admit this, but I just pull old yeast slurry straight from the fridge, scoop the dead stuff off the top and then pitch it. I don't do it often, but when I do, it works fine.
not saying i've never done it. but the goal here isnt to pitch into a fresh brew, its to restore starter health so you get another 6mos or so before i have to do it again.
 
Generally the healthy cells will form a white (ish) layer in the trub.

You can separate them by using a yeast washing procedure.

Allowing the starter to ferment out and then washing the yeast might be more productive as do you really know the health of the flocculated cells. (i.e. they're not all bad, might be more healthy cells than you think)


that's way less productive than what i'm already doing. by taking only the yeast in active suspension and tossing what quickly sinks to the bottom im infinitely more likely to only pass on living cells. if the yeast is 100% flocced and/or inactive there's no way to know what you're keeping.
 
that's way less productive than what i'm already doing. by taking only the yeast in active suspension and tossing what quickly sinks to the bottom im infinitely more likely to only pass on living cells.

How quick is "quickly sinks to the bottom"? How much of the flocc'd yeast cells do you get when you pour off the wort?

if the yeast is 100% flocced and/or inactive there's no way to know what you're keeping.

There is and it's been explained but you skipped over it.
 
Maybe I shouldn't admit this, but I just pull old yeast slurry straight from the fridge, scoop the dead stuff off the top and then pitch it. I don't do it often, but when I do, it works fine.
I have done this...more than once...more than year old yeast...

now what I've started doing...

pull my yeast jar out and let start to warm up...during the middle of mash, I will draw about a pint of low gravity wort and cool it down...decant the yeast jar...mix yeast cake and wort and let it start up...finish brewing and rack to fermenter...once yeast is active, pitch into fermenter.

BUT...this does mean I pitch the whole saved yeast cake...If I let the starter settle out some and decant/pitch only the liquid I guess I would be getting most of the live yeast and leaving behind the dead yeast that did not "wake up".
 
not saying i've never done it. but the goal here isnt to pitch into a fresh brew, its to restore starter health so you get another 6mos or so before i have to do it again.

Why not just leave them till needed, then add the old slurry, estimating for a slight underpitch to promote new yeast growth? You can harvest the resulting yeast and you're good for another 6 months. Any time you do a starter, it's an opportunity for unwanted organisms to infect your yeast strain.
 
I have done this...more than once...more than year old yeast...

now what I've started doing...

pull my yeast jar out and let start to warm up...during the middle of mash, I will draw about a pint of low gravity wort and cool it down...decant the yeast jar...mix yeast cake and wort and let it start up...finish brewing and rack to fermenter...once yeast is active, pitch into fermenter.

BUT...this does mean I pitch the whole saved yeast cake...If I let the starter settle out some and decant/pitch only the liquid I guess I would be getting most of the live yeast and leaving behind the dead yeast that did not "wake up".

Do you (can you) do this with a fresh pack of dry/liquid yeast? Seems like a great way to reduce lag time.

On another note, from a previous thread, any of you guys ever had slurry that developed a grey or purple line in it? Is that just dead cells or an infection? I had this once, and I chucked the slurry.
 
not sure why this didnt post two weeks ago. been sitting as "draft"

How quick is "quickly sinks to the bottom"? How much of the flocc'd yeast cells do you get when you pour off the wort?



There is and it's been explained but you skipped over it.

for flocced yeast, we're talking a minute or two.

There is and it's been explained but you skipped over it.
no, it isnt. if it is, please post the part where its confirmed that you're separating active yeast from dead yeast.

also- this is not yeast washing. its yeast rinsing. not the same thing. and it sure as hell isnt going to get sleepy yeast into activity just by adding water. not to mention, you never ever add RO /DI water to yeast.
 
Why not just leave them till needed, then add the old slurry, estimating for a slight underpitch to promote new yeast growth? You can harvest the resulting yeast and you're good for another 6 months. Any time you do a starter, it's an opportunity for unwanted organisms to infect your yeast strain.
slurry harvest is not an option. brewing beer is also an opportunity for infection when you're harvesting.
 
I've had good success with pretty much your same method.
I take refrigerated yeast cake and decant off the beer, then add some
1.030 wort from either DME and nutrient, or left over last runnings from mashing.
(Both boiled and cooled.)
I'm a shaken-not-stirred starter, so that for about 12-18 hrs to high kraisen..
Then I just save what stays suspended and dump the rest.

It works great with 3522 Ardennes and 1056 American Ale. For whatever reason, I did not get good results from Whitbread 1099 or Imperial Stephon Weissber. Blended strains, or just old fashioned contamination.
 
Have you tried asking?
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In reality, the quantity of dead yeast in a pack is insignificant and would likely just serve as nutrients for the survivors.
 
Aren't yeast nutrients made with a large portion of dead yeast cells? For starters I let kit finish and only pour off the liquid if it's clear ,then pitch the whole thing. When saving a cake from a batch of beer I leave enough behind to swirl it up and pour into a beaker. Beakers are cylinders with a pour spout. Let it sit 10 min max and pour off the cleaned yeast.
 
Aren't yeast nutrients made with a large portion of dead yeast cells? For starters I let kit finish and only pour off the liquid if it's clear ,then pitch the whole thing. When saving a cake from a batch of beer I leave enough behind to swirl it up and pour into a beaker. Beakers are cylinders with a pour spout. Let it sit 10 min max and pour off the cleaned yeast.
Have you considered how many yeast cells are in that clear liquid?
 
The same amount that would be in a glass of beer most likely. Nobody wants to drink starter beer, unless the starter is a 5 gal batch of small beer intended to be a repitch.
 
On another note, from a previous thread, any of you guys ever had slurry that developed a grey or purple line in it? Is that just dead cells or an infection? I had this once, and I chucked the slurry.
yeah, I've had some jars of saved yeast get a little greyish...sniff test before you use it regardless of color.

if it doesn't look "clean" even if it smells ok...it gets tossed out...
 
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You cannot separate dead and healthy yeast cells from each other. Not by "washing" (which is everything but actually washing the yeast) and not by sedimenting layers. Also the colour of the layers does not say anything about the yeast health within the layer.

The only proven way I know of is to do a starter, get everything going and then remove a small portion from that starter. Use a multi step starter to get this small portion back to a proper size and you'll have mainly healthy yeast within the final volume.
 
Yes, homebrew yeast practice is all over the place! I have done a lot of different things over the years but I am trying to do things the right way now :)

To @SanPancho, I think your method it a good approach. It mirrors what is written in the "Yeast" book by Chris White. Yeast rinsing and or washing is homebrew lore imho. Keep them in beer and away from oxygen. Preferably in an oxygen purged brink. All you ever want is live, healthy active yeast. Pitching dead cells and saying they are food is just another form of hoping and is lazy! :)

Live cells want to eat so they will be in the liquid or at the top. Dead cells don't do anything, so they represent the bottom when food is presented. Give them some time to start eating and cull away the live ones. Not saying all flocced yeast is dead but when you are dealing with a 6+ month old slurry, what stays on the bottom when new wort is given is considered 'not wanted'.
 
Not saying all flocced yeast is dead but when you are dealing with a 6+ month old slurry, what stays on the bottom when new wort is given is considered 'not wanted'.
Yeast are non-motile. Trying to get the good stuff off the top of something that's relatively fresh is one thing, but when you are dealing with a 6+ month-old slurry, pretty much everything is going to be on the bottom.
 
Yeast are non-motile. Trying to get the good stuff off the top of something that's relatively fresh is one thing, but when you are dealing with a 6+ month-old slurry, pretty much everything is going to be on the bottom.
One has to keep context here. The OP is putting the old slurry on a stir plate with fresh wort. When he turns it on all of the potatoes go into suspension. He keeps the ones that start eating.
 
One has to keep context here. The OP is putting the old slurry on a stir plate with fresh wort. When he turns it on all of the potatoes go into suspension. He keeps the ones that start eating.
Sorry, but it doesn't work that way.
 
You will need to demonstrate how you are seeing it! When I have yeast in a slurry on the bottom of the starter vessel and I turn on the stir plate, they all get flown into suspension. Am I missing something?

The live cells start eating the wort. The dead ones are just that, dead. So live in the liquid, dead on the bottom if captured within 5-30 minutes.
 
The best way is to take the old cake,decant the liquid (all of it). I then take a sterilized (by flame) loop,dig in the whitest layer, add to a sterilized 15 ml tube with 1.020-1.030 wort. It takes about 3 days ( shake often) to see sediment on the bottom. That's your new yeast. Pitch into 150 ml 1.030-1.040 wort, then 1500 ml then into your 19L-20L batch. This is the only way I know to separate the live from the dead.
 
You will need to demonstrate how you are seeing it! When I have yeast in a slurry on the bottom of the starter vessel and I turn on the stir plate, they all get flown into suspension. Am I missing something?

The live cells start eating the wort. The dead ones are just that, dead. So live in the liquid, dead on the bottom if captured within 5-30 minutes.
Dead yeast and living yeast move the same amount. They do not move at all. Both. So you will have dead yeast and living yeast sedimenting and also floating around. If you remove the sediment and keep the liquid, you will only separate the part of the yeast that doesn't flocculate as well as the rest. So after some generations your yeast might lack flocculation in total.
 
I think some context is needed again. The OP is starting with a 6+ month old slurry. So everything is sitting at the bottom of the container. His goal is to find the live yeast and discard the dead yeast. The best way to do this is to remove any old supernatant and expose the yeast to fresh wort. The live cells will perk up and start being active and the dead cells will not. So the idea (mentioned in the Chris White "Yeast" book) is to shake up the container holding the fresh wort and old slurry, let it sit for 10+ minutes and then decant the liquid. The liquid would contain and relatively active cells and the not active and dead cells will flocc down and be left behind when the wort is decanted.

Not sure what you are arguing against here, but you would need to include Chris White if you think this method does not hold up to reality.
 
His goal is to find the live yeast and discard the dead yeast.
And the proposed solution is a pretty inefficient way of accomplishing this, even if it does come from Chris White. If you really want to get something close to 100% viable yeast, the best way to do that is to start with a small inoculum and step it up gradually, thereby diluting the dead cells into virtual non-existence. But of course the yeast will start dying again immediately if you put them back into the fridge. It's one thing to use this method to perk something up for pitching, but I'm not sure that doing it repeatedly is a great way of keeping a yeast bank long term.

And BTW, dead yeast really is yeast food. The most common laboratory growth media for yeast is yeast extract, hydrolyzed protein, and some glucose.
 
I think some context is needed again. The OP is starting with a 6+ month old slurry. So everything is sitting at the bottom of the container. His goal is to find the live yeast and discard the dead yeast. The best way to do this is to remove any old supernatant and expose the yeast to fresh wort. The live cells will perk up and start being active and the dead cells will not. So the idea (mentioned in the Chris White "Yeast" book) is to shake up the container holding the fresh wort and old slurry, let it sit for 10+ minutes and then decant the liquid. The liquid would contain and relatively active cells and the not active and dead cells will flocc down and be left behind when the wort is decanted.

Not sure what you are arguing against here, but you would need to include Chris White if you think this method does not hold up to reality.
Basically what he said:
And the proposed solution is a pretty inefficient way of accomplishing this, even if it does come from Chris White. If you really want to get something close to 100% viable yeast, the best way to do that is to start with a small inoculum and step it up gradually, thereby diluting the dead cells into virtual non-existence. But of course the yeast will start dying again immediately if you put them back into the fridge. It's one thing to use this method to perk something up for pitching, but I'm not sure that doing it repeatedly is a great way of keeping a yeast bank long term.

And BTW, dead yeast really is yeast food. The most common laboratory growth media for yeast is yeast extract, hydrolyzed protein, and some glucose.
And in addition, living yeast does not magically float and dead yeast does not magically flocculate and sink. Both are victim to escaping co2 and the currents it creates on it's way out. Both are everywhere in the liquid. You are only separating the better flocculating cells from the less flocculating ones, which is actually not desirable (at least not if you are after quick clearing beers).
 
living yeast does not magically float and dead yeast does not magically flocculate and sink
This is true, but dead cells are denser than live cells and so will sink somewhat faster once you stop stirring or shaking a culture. The problem is that it's just not a very clean or efficient separation method. Wait a little too long and you'll lose the better flocculating but viable cells; don't wait long enough and you'll keep too many dead cells.

Centrifugation through dense media is a very effective laboratory method of separating live cells from dead, but obviously beyond the reach of the average home brewer.
 
I think you guys need to take a chill pill! I don't disagree that Hotpepper's approach of getting a very small sample and letting the live cells outcompete by growing it up from there is perfectly viable. But the shake/stir then settle is just another form of that approach as you would then proceed to grow additional cells from the wort you just decanted. So a similar outcompete would take place.

If you take a sample off of the floor who knows what you will get (flocc or non-flocc, dead or half alive) so why not do a vitality test first to get 'the live ones'? The amount of live cells after 6+ months will be small, so probably a close approximation to a sample taken from sediment.

Again, working with 6+ month old slurries is obviously not SOP for a healthy yeast bank unless you have oxygen purged yeast brinks and that is pushing it.
 
This is true, but dead cells are denser than live cells and so will sink somewhat faster once you stop stirring or shaking a culture. The problem is that it's just not a very clean or efficient separation method. Wait a little too long and you'll lose the better flocculating but viable cells; don't wait long enough and you'll keep too many dead cells.

Centrifugation through dense media is a very effective laboratory method of separating live cells from dead, but obviously beyond the reach of the average home brewer.
I don't think that dead cells are denser m general. They brake apart, the pieces have different sizes, each part probably with different densities... We're talking cellular level here, these pieces are small. They float around with the slightest current occurring.

Just take a small portion from the sludge and let it grow. That's btw. The real beauty of slants. The portion is small and after multiple steps, the dead part of yeast is really small and neglactable.
 
I think you guys need to take a chill pill! I don't disagree that Hotpepper's approach of getting a very small sample and letting the live cells outcompete by growing it up from there is perfectly viable. But the shake/stir then settle is just another form of that approach as you would then proceed to grow additional cells from the wort you just decanted. So a similar outcompete would take place.

If you take a sample off of the floor who knows what you will get (flocc or non-flocc, dead or half alive) so why not do a vitality test first to get 'the live ones'? The amount of live cells after 6+ months will be small, so probably a close approximation to a sample taken from sediment.

Again, working with 6+ month old slurries is obviously not SOP for a healthy yeast bank unless you have oxygen purged yeast brinks and that is pushing it.
All good mate, no big feelings involved on my side. I just like to clarify things, either I learn something or the others learn something.
 
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