Reusing yeast that has hit its alcohol tolerance

[Groover McTuber]

Just started a one gallon BOMM using Wyeast 1388. Original gravity was 1.135, which according to Bray should finish around 1.015. So, some residual sweetness, indicating the yeast has hit its alcohol tolerance. Considering reusing this yeast in a Belgian ale in a couple of weeks. Is this wise? Does the yeast die when it hits it's alcohol tolerance, or is it still viable?

 

[GoodTruble]

The general rule is to re-use yeast from lower abv batches to higher abv batches because it allegedly stresses the yeast less over time. But I don't know if there is an abv limit after which the yeast would no longer even work. The taste may be negatively effected, but I doubt the yeast would entirely die off. -You could do a yeast starter and see, them just re-use part of the starter.

 

[Dan O]

You could look up how to wash yeast & use your washed yeast to make your starter with.

 

[McMullan]

High levels of ethanol cause irreparable damage to yeast cells, especially nucleic acids and proteins. They're knackered so start over with a fresh culture. Repitching yeast is quite unique to brewers, but there are limits.

 

[Miraculix]

Second best option would be to make a multi step starter from s small amount of slurry. That way, there should be more new cells than the old ones, potentially being more healthy than the damaged ones.

 

[McMullan]

Second best option would be to make a multi step starter from s small amount of slurry. That way, there should be more new cells than the old ones, potentially being more healthy than the damaged ones.

Problem with that is there's a good chance of promoting genetic drift away from the strain's expected behaviour/profile. It is possible to isolate healthy-looking yeast colonies from an old bottle of imperial strength beer, but we're needing to do some microbiology to get there. From what I've observed, the proportion of 'petit' mutants increases significantly. Even if starting from a little slurry (which I highly recommend under more favourable circumstances) then serially stepping up, there's a good chance of under pitching in the brewery wort. These cells aren't small, the colonies are, because their metabolism is knackered. If they make up a large proportion of the yeast population (and they probably do) selecting for healthy cells is likely too inefficient over our time frame to pitching. A good way to promote a sluggish fermentation and risk of stalling before expected FG. By chance you might succeed, but, if you want to maintain predictability, consistency and meet your expectations, it's better to start over or, as pros do, repitch yeast held back from a previous lower gravity beer. After all the extra effort and cost to make an imperial strength wort, is it worth taking a punt on knackered yeast?

 

[Groover McTuber]

High levels of ethanol cause irreparable damage to yeast cells, especially nucleic acids and proteins. They're knackered so start over with a fresh culture. Repitching yeast is quite unique to brewers, but there are limits.

Thanks, this was my concern.

 

[Dan O]

Problem with that is there's a good chance of promoting genetic drift away from the strain's expected behaviour/profile. It is possible to isolate healthy-looking yeast colonies from an old bottle of imperial strength beer, but we're needing to do some microbiology to get there. From what I've observed, the proportion of 'petit' mutants increases significantly. Even if starting from a little slurry (which I highly recommend under more favourable circumstances) then serially stepping up, there's a good chance of under pitching in the brewery wort. These cells aren't small, the colonies are, because their metabolism is knackered. If they make up a large proportion of the yeast population (and they probably do) selecting for healthy cells is likely too inefficient over our time frame to pitching. A good way to promote a sluggish fermentation and risk of stalling before expected FG. By chance you might succeed, but, if you want to maintain predictability, consistency and meet your expectations, it's better to start over or, as pros do, repitch yeast held back from a previous lower gravity beer. After all the extra effort and cost to make an imperial strength wort, is it worth taking a punt on knackered yeast?

It is my understanding that the drift away from a particular strain of yeast, (consistent taste & results) doesn't really have a noticeable variance until you've reused the yeast 5 or 6 times. I use BOMM yeast a lot & @ 8$/packet, I try to stretch it out over as many batches as I can, without sacrificing flavor, quality or yeast integrity. But, my palate may not be as refined as other people's.

 

[McMullan]

It is my understanding that the drift away from a particular strain of yeast, (consistent taste & results) doesn't really have a noticeable variance until you've reused the yeast 5 or 6 times. I use BOMM yeast a lot & @ 8$/packet, I try to stretch it out over as many batches as I can, without sacrificing flavor, quality or yeast integrity. But, my palate may not be as refined as other people's.

High levels of ethanol are going to increase the risk of drift, due to the impact on nucleic acids. Chiefly DNA. Contrarians are free to believe otherwise. It's a free world.

 

[GoodTruble]

High levels of ethanol are going to increase the risk of drift, due to the impact on nucleic acids. Chiefly DNA. Contrarians are free to believe otherwise. It's a free world.

I heard nothings free!