Why does harvested yeast need to be used quicker than a pitch you get from wyeast or white labs. I've heard you want to use harvested yeast within 2 weeks for best results and viability decreases rapidly. Why is this different than fresh yeast?
Why does harvested yeast need to be used quicker?
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Pie_Man
Well-Known Member
My guess is sanitization. The yeast companies have better processes to sanitize their final product than the average homebrewer.
I don't think that it has to be used any quicker. I have used harvested yeast much later than two weeks after harvest without I'll effects. I would guess my average use time is 5 to 6 weeks later and I usually do not make a starter.
william_shakes_beer
Well-Known Member
I regularly harvest yeast from split starters and use it up to 8 months later with no ill effects. Who told you you need to use it within 2 weeks?
william_shakes_beer
Well-Known Member
I would think it would store just fine for longer than 2 weeks, provided you washed it.
stratslinger
Well-Known Member
Are we talking simply harvesting yeast cake, or washing yeast?
I just used month-old washed yeast, and have two more mason jars in the fridge washed and harvested from the same fermenter that I figure on using sometime in the next 5 months or so.
I just used month-old washed yeast, and have two more mason jars in the fridge washed and harvested from the same fermenter that I figure on using sometime in the next 5 months or so.
william_shakes_beer
Well-Known Member
Not clear from the OP, which is why I was more specific in my posts. Perhaps the guidance comes from saving a cake. Can anyone who is listening that recycles cake provide guidance?
yeast from wyeast or white labs have been put in sanitary containers, in ideal conditions - but even they die off with time. because homebrewers can't re-create those ideal lab conditions like the pros, our yeast dies off faster.
so it's not that you NEED to use it after 2 weeks, it's that the cells are dying off - so you want to use it while there are still enough left.
for an ideal of how quickly cells die, and how much saved yeast to pitch, use mrmalty.com (for example, it says that after 2 weeks only 71% of the cells are still viable). so while you might have needed 200 ml of fresh yeast when 100% viable, you now need 280 ml)
so it's not that you NEED to use it after 2 weeks, it's that the cells are dying off - so you want to use it while there are still enough left.
for an ideal of how quickly cells die, and how much saved yeast to pitch, use mrmalty.com (for example, it says that after 2 weeks only 71% of the cells are still viable). so while you might have needed 200 ml of fresh yeast when 100% viable, you now need 280 ml)
Zacher
Well-Known Member
+1. It's also in how the yeast are prepared to go dormant. In the lab, the conditions are ideal for them to store up on nutrients and hibernate. In homebrewing, we either crash cool or rack right after primary fermentation as the yeast are still building up their reserves.
Dave
Dave
Zacher
Well-Known Member
I remember reading it from the Yeast book as well and being surprised because I have had the same results. However I think they are talking about ideal conditions and the hidden desire to sell more yeast.....
Dave
in the end it's not the age that counts, but the number of viable cells. the longer you wait, the fewer cells you have. if you saved enough slurry you can probably wait a long time because 10% of of 2 liters will be enough... then again you'll also be adding in 1.8 liters of dead cells and other crap (slurry isn't 100% yeast, there is trub in there too). also, yeast calculators provide estimates based on assumptions, and your storage conditions might not match the assumptions of the calculations. the farther out you go, the higher the chances are that the numbers won't align (i.e. you may be pitching a different number of cells than what the calculators say you are).
so the longer you wait, the more crap you'll be pitching and the less certainty you'll have about viability. we all have different comfort levels with uncertainty & potential contamination.
so the longer you wait, the more crap you'll be pitching and the less certainty you'll have about viability. we all have different comfort levels with uncertainty & potential contamination.
ReverseApacheMaster
Well-Known Member
If you look at the homebrew vs. commercial sides of WY/WL websites you'll see that difference that homebrewers shouldn't use strains more than 5 times but commercial brewers can go up to 10. No explanation there.
As far as washed yeast, it doesn't have to be used that quickly but sanitation is an issue as is the viability of your washed yeast.
Me too
I've used stuff that was a couple years old and it was fine. If 45 million year old yeast that was preserved in amber could be grown into a starter and beer made from it, really would you worry over a few months...or years?
I've done yeast that was at least 3 years old, maybe more since it wasn't dated and it was fine. It took some babying to grow it to a useful size, but it did work.
I don't know if you know the story of Charlie Papazian's yeast (White Labs "Cry Havoc") or not. He talked about it on basic brewing. The recipes in both Papazian's books, The Complete Joy of Homebrewing and The Homebrewers Companion, were originally developed and brewed with this yeast. Papazian had "Cry Havoc" in his yeast stable since 1983.
He has used it nearly continuously since 83, sometimes pitching multiple batches on top of a cake, sometimes washing or not washing, etc. In a basic brewing podcast iirc last year he talked about how a batch of the yeast after a lot of uses picked up a wild mutation, and he noticed an off flavor in a couple batches.
Now most of us would prolly dump that yeast. Instead he washed it, slanted or jarred it (I can't recall which,)marked it, and cold stored it, and pretty much forgot about it for 10-15 years. He had plenty other slants of the yeast strain, so he left it alone.
Well evidently he came across that container of yeast, and for sh!ts and giggles made a beer with it. Evidently after all those years in storage, the wild or mutated yeast died out leaving behind a few viable cells of the "pure" culture, which he grew back into a pretty hardy strain...which iirc is the culture that White Labs actually used for their cry havoc...because of it's tenacity and survivability.
He's been using his yeast constantly for decades, in various strains.....
Yeast is hardier than you might think.
If you've made/are making a starter the age of the yeast is irrevelant- When you make a starter, and grow it, you're replicating more yeast to make up for any loss. You're making new, fresh yeast.
Bobby M did a test on year old stored yeast here; https://www.homebrewtalk.com/f13/testing-limits-yeast-viability-126707/
And my LHBS cells outdated tubes and packs of yeast dirt cheap 2-3 dollars each and I usually grab a couple tubes of belgian or other interesting yeast when I am there and shove it in my fridge. and I have never had a problem with one of those tubes.
I usually make a starter but I once pitched a year old tube of Belgian High Gravity yeast directly into a 2.5 gallon batch of a Belgian Dark Strong, and after about 4 days it took off beautifully.
The purpose of a starter is to reproduce any viable cells in a batch of yeast....that;s how we can grow a starter form the dregs in a bottle of beer incrementally...and that beer may be months old.
Even if you have a few still living cells, you can grow them....That's how we can harvest a huge starter (incrementally) from the dregs in a bottle of some commercial beers. You take those few living cells and grow them into more.
I've done yeast that was at least 3 years old, maybe more since it wasn't dated and it was fine. It took some babying to grow it to a useful size, but it did work.
I don't know if you know the story of Charlie Papazian's yeast (White Labs "Cry Havoc") or not. He talked about it on basic brewing. The recipes in both Papazian's books, The Complete Joy of Homebrewing and The Homebrewers Companion, were originally developed and brewed with this yeast. Papazian had "Cry Havoc" in his yeast stable since 1983.
He has used it nearly continuously since 83, sometimes pitching multiple batches on top of a cake, sometimes washing or not washing, etc. In a basic brewing podcast iirc last year he talked about how a batch of the yeast after a lot of uses picked up a wild mutation, and he noticed an off flavor in a couple batches.
Now most of us would prolly dump that yeast. Instead he washed it, slanted or jarred it (I can't recall which,)marked it, and cold stored it, and pretty much forgot about it for 10-15 years. He had plenty other slants of the yeast strain, so he left it alone.
Well evidently he came across that container of yeast, and for sh!ts and giggles made a beer with it. Evidently after all those years in storage, the wild or mutated yeast died out leaving behind a few viable cells of the "pure" culture, which he grew back into a pretty hardy strain...which iirc is the culture that White Labs actually used for their cry havoc...because of it's tenacity and survivability.
He's been using his yeast constantly for decades, in various strains.....
Yeast is hardier than you might think.
If you've made/are making a starter the age of the yeast is irrevelant- When you make a starter, and grow it, you're replicating more yeast to make up for any loss. You're making new, fresh yeast.
Bobby M did a test on year old stored yeast here; https://www.homebrewtalk.com/f13/testing-limits-yeast-viability-126707/
And my LHBS cells outdated tubes and packs of yeast dirt cheap 2-3 dollars each and I usually grab a couple tubes of belgian or other interesting yeast when I am there and shove it in my fridge. and I have never had a problem with one of those tubes.
I usually make a starter but I once pitched a year old tube of Belgian High Gravity yeast directly into a 2.5 gallon batch of a Belgian Dark Strong, and after about 4 days it took off beautifully.
The purpose of a starter is to reproduce any viable cells in a batch of yeast....that;s how we can grow a starter form the dregs in a bottle of beer incrementally...and that beer may be months old.
Even if you have a few still living cells, you can grow them....That's how we can harvest a huge starter (incrementally) from the dregs in a bottle of some commercial beers. You take those few living cells and grow them into more.
cheezydemon3
Well-Known Member
Have used 4 month old yeast cake with good results.
I think like anything, a mysticism surrounds the big commercial producers that makes it seem far more magical than actuality.
I have used dried out 4 month old whole cake, no problems. Might have been overpitching, but who can say how many cells were viable?
I think like anything, a mysticism surrounds the big commercial producers that makes it seem far more magical than actuality.
I have used dried out 4 month old whole cake, no problems. Might have been overpitching, but who can say how many cells were viable?
ReverseApacheMaster
Well-Known Member
Probably a lot more than you would imagine. Before liquid yeast or lyophilized yeast was available to brewers the most common source of yeast was a big dried block. Just break off a chunk and add to your wort. Bread yeast can still sometimes be found in that format but since lyophilization is cost effective at the bread yeast manufacturers, it's cheap enough to get a higher quality product in the market that way.
Sanitization is part of the issue. Someone like white labs is growing their yeast from pure stocks in sterile, not just sanitized, conditions. Consequently, there is a lower probability of contamination. Another issue is that cells stored for long periods are still metabolizing at a slow rate and are stressed. Some cells die but others just accumulate problems. Cells that accumulate problems can mutate when refrozen and introduce variation in your population. Both of these considerations also explain only using a limited number of times. Problems, whether contaminants or variants accumulate with use and stress. High gravity beers stress cells more.
If you are interested there is a thread on freezing yeast and I have used the information there to write an article that is posted in the articles section. That should allow you to store yeast in a pretty inert state for months to years depending on your conditions. It is particularly good if you have a yeast that you don't use often but want to have on hand.
If you are interested there is a thread on freezing yeast and I have used the information there to write an article that is posted in the articles section. That should allow you to store yeast in a pretty inert state for months to years depending on your conditions. It is particularly good if you have a yeast that you don't use often but want to have on hand.
cheezydemon3
Well-Known Member
Pure stocks. from whence did these magical stocks come? and how does whitelabs keep them pure and happy?
Not saying that you are wrong, it just sounds like mysticism.
Given the cost and viability or dry yeast, maybe drying is the ultimate storage method?
indeed, my assumption in this thread is that we're talking about directly pitching saved slurry from a mason jar. make a starter and the age doesn't matter nearly as much. in matter in so far as you want to know how many cells you're starting with, so you can estimate how many you'll end with (and consequently if you need to step up).
another very good consideration. over time the yeast will be dying out but bacteria could be growing (or at least not dying off as quickly).
ReverseApacheMaster
Well-Known Member
Pure stocks. from whence did these magical stocks come? and how does whitelabs keep them pure and happy?
Not saying that you are wrong, it just sounds like mysticism.
Given the cost and viability or dry yeast, maybe drying is the ultimate storage method?
All yeast banks isolate pure cells, grown in sterile conditions and lyophilize them for long term storage. They can then remove very tiny samples and grow them up in sterile conditions.
shadows69
Well-Known Member
I just fired up 11 month old lager yeast with no problems. It 's all in the process and conditions.
Pure stocks. from whence did these magical stocks come? and how does whitelabs keep them pure and happy?
Not saying that you are wrong, it just sounds like mysticism.
Given the cost and viability or dry yeast, maybe drying is the ultimate storage method?
There is nothing magical about pure yeast stocks. Microbiologists usually store stocks of microorganisms by isolating clones of a single cell so that the culture is without genetic variation. That is how you get a strain like WLP001 and know that it is not multiple strains or contaminated in some way. Of course some brewing yeast strains are actually blends and then you can maintain them separately and blend them in the right ratios when you desire.
The method is to take a small amount of yeast and spread it out on a petri dish so that single cells are separated in space. Those cells then grow up into colonies (populations) derived from a single cell (they are clones). If you then pick one colony and grow it up, you have a pure population of a single strain of yeast. Of course you have to not cross contaminate strains and you have to maintain sterility.
I hope that helps you understand the mysticism of microbiology.
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