Reused Yeast on over 150 batches

[winnph]

If you were to want to harvest yeast and have it truly be random, I would think you would have to mark your fermenter with an X,Y,Z coordinate system and use a random number generator to determine which point in your brew to pull yeast from.

So, from a practical homebrewer's perspective, what about waiting until fermentation is finished and the beer has cleared, then decanting the beer (i.e., bottling/kegging) and mixing the yeast slurry so that it's a relatively homogenous blend of the yeasts that flocc'd at various points in the fermentation. If you use a jar of this "mixed" slurry, would you be avoiding selective pressures more so than if you're top-cropping or pulling the cake after a few days?

 

[Reno_eNVy]

This is true JayBullen! But I was under the impression that the vast majority of Petites occur in the non-coding section of the genome and thus would have any expression.

And your last statement is definitely the truth-fact: a mutation doesn't mean that a yeast cell is going to have a faux-hawk or be like a super-yeast that can ferment an entire batch by itself. Mutations are simply a change in DNA nucleotides, most of the time just ONE nucleotide, and 75% of the time that nucleotide is substituted for the exact same one or another that will cause the translation of the same amino acid (i.e. no change.) In fact, every single one of us is born with on average 3 point-mutations (single nucleotide substitution, deletion or insertion) that our parents do not have.

 

[Reno_eNVy]

So, from a practical homebrewer's perspective, what about waiting until fermentation is finished and the beer has cleared, then decanting the beer (i.e., bottling/kegging) and mixing the yeast slurry so that it's a relatively homogenous blend of the yeasts that flocc'd at various points in the fermentation. If you use a jar of this "mixed" slurry, would you be avoiding selective pressures more so than if you're top-cropping or pulling the cake after a few days?

To some degree, yes this is random. But if one were to nit-pick (and I guarantee someone would mention this; there are nit-pickers in the scientific community that would make you want to kill yourself) you could say that you have selected for more highly-flocculant yeast as you have racked off all the yeast that is still in suspension.

EDIT: But from the practical homebrewer perspective, to answer your question: yes.

 

[Misplaced_Canuck]

I'm sure some breweries go this route:

Yeast from Batch #1 -> Yeast from Batch #2 -> #3 -> #4 (etc)

And I'm sure that others (including my homebrewery!) go this route:



Batch #1 -> Batch #2
Batch #1 -> Batch #3
(...)
Batch #1 -> Batch # X -> Batch # X + 1
(...........)-> Batch # X -> Batch # X + 2

And so on.

I always divide my new yeasts into 3 to 10 for future use. The ones I don't use too often, I only divide in 3-5.

M_C

 

[winnph]

To some degree, yes this is random. But if one were to nit-pick (and I guarantee someone would mention this; there are nit-pickers in the scientific community that would make you want to kill yourself) you could say that you have selected for more highly-flocculant yeast as you have racked off all the yeast that is still in suspension.

True, though if a yeast cell can remain in suspension for 1-3 months after fermentation is finished (about how long I usually leave my beers in primary), I'd guess I'm probably better off not selecting that yeast for anything other than a wheat beer or similar style where cloudiness is desirable.

 

[winnph]

I always divide my new yeasts into 3 to 10 for future use. The ones I don't use too often, I only divide in 3-5.

M_C

Yeah, same here. I usually do about 3-4 jars of washed yeast or slurry from each batch. Then, after drinking the batch, I decide (based on the batch I just drank) whether that's the batch I want to use as my next generation of yeast once I run out of the current generation of that strain. Never really have "off" tastes, but sometimes there's more or less yeast character, and depending on the strain I might prefer either more or less.

 

[Reno_eNVy]

True, though if a yeast cell can remain in suspension for 1-3 months after fermentation is finished (about how long I usually leave my beers in primary), I'd guess I'm probably better off not selecting that yeast for anything other than a wheat beer or similar style where cloudiness is desirable.

This, too, is the truth-fact.

 

[Misplaced_Canuck]

I don't reuse yeast from the primary... I split the yeast prior to pitching. I trust my starter techniques better than my brewing techniques


M_C

Yeah, same here. I usually do about 3-4 jars of washed yeast or slurry from each batch. Then, after drinking the batch, I decide (based on the batch I just drank) whether that's the batch I want to use as my next generation of yeast once I run out of the current generation of that strain. Never really have "off" tastes, but sometimes there's more or less yeast character, and depending on the strain I might prefer either more or less.

 

[winnph]

I don't reuse yeast from the primary... I split the yeast prior to pitching. I trust my starter techniques better than my brewing techniques


M_C

Ahh, see I feel the opposite. My starters are warmer than ideal (ambient plus heat from stir plate), under constant oxygenation (stir plate), and are usually just DME and nutrient (rather than all-grain wort), so I feel like I'd rather collect yeast that has brewed a beer than one that has been in an artificial rapid growth chamber.

 

[Misplaced_Canuck]

Well if you collect from the starter, and that the beer you made from that same starter turns out fine, you're pretty likely to have a healthy starter! If the downwards product is good, that means that the upwards product is good too... I'd think

M_C

Ahh, see I feel the opposite. My starters are warmer than ideal (ambient plus heat from stir plate), under constant oxygenation (stir plate), and are usually just DME and nutrient (rather than all-grain wort), so I feel like I'd rather collect yeast that has brewed a beer than one that has been in an artificial rapid growth chamber.

 

[winnph]

Well if you collect from the starter, and that the beer you made from that same starter turns out fine, you're pretty likely to have a healthy starter! If the downwards product is good, that means that the upwards product is good too... I'd think

M_C

I mean, I see what you're saying, I just don't like the idea of using yeast that has only lived, for generations, in starters. I'd rather yeast that has lived in starters, fermenters, starters, fermenters, etc., so that I know the yeast does well in both situations. If I have yeast that has for, let's say, 10 generations lived only in 78F, 1.035 wort, under constant agitation/oxygenation, it just seems like I'm starting to select for a particular environment that's different from the one I want my yeast operating in. If, on the other hand, I subject the yeast to that environment from time to time for growth purposes, but let it do most of its life cycle under optimal fermentation conditions, I'm selecting for yeast that can withstand and grow rapidly in a starter, but also grow, live, and produce beer under more ideal conditions.

But, I really do see what you mean about minimizing possible contamination and stress, and I agree that your process could very well be the wiser choice. I just like being able to label yeast slurry and select my next generation from four choices, based on the actual performance of each choice.