Quantcast

Viability of yeast in re pitching multiple generations

HomeBrewTalk.com - Beer, Wine, Mead, & Cider Brewing Discussion Community.

Help Support Homebrew Talk:

catalanotte

Well-Known Member
Joined
Jul 30, 2014
Messages
197
Reaction score
65
Perhaps I am overthinking this, but do you need to consider reduced viability in subsequent generations of re-pitched yeast, to account for the nonviable portion of yeast that was pitched in the prior batch? Or is the volume of new viable yeast produced in the fermentation enough to make this insignificant, so we can start over with the ~97% slurry viability for each generation (default in Mr. Malty). Unfortunately, I do not have a conical, and while I do separate the slurry from the visible trub, I don't have the ability to harvest the middle of the yeast cone, which I read is often done with a conical. If this has been asked and answered, please share a thread. I did search first and didn't see this.
 

bracconiere

Jolly Alcoholic
HBT Supporter
Joined
Jan 19, 2018
Messages
9,259
Reaction score
3,902
Location
S.AZ
i'm not sure about 'viability'....but i repitch my yeast cake for a couple years, and it keeps making beer? and i brew once a week.....so like 52-100 repitches, and it usually still kicks off after a couple hours of pitching.....


this is not an example of 'best practices' just what i do....
 
OP
C

catalanotte

Well-Known Member
Joined
Jul 30, 2014
Messages
197
Reaction score
65
i'm not sure about 'viability'....but i repitch my yeast cake for a couple years, and it keeps making beer? and i brew once a week.....so like 52-100 repitches, and it usually still kicks off after a couple hours of pitching.....


this is not an example of 'best practices' just what i do....
Do you do any pitch rate calculations, or at this point do you just have it dialed in enough to repeat what works?
 

bracconiere

Jolly Alcoholic
HBT Supporter
Joined
Jan 19, 2018
Messages
9,259
Reaction score
3,902
Location
S.AZ
Do you do any pitch rate calculations, or at this point do you just have it dialed in enough to repeat what works?

no i don't do any calculations....i just scoop the cake into a tupperware container, and keep in the fridge till next batch...throw the whole thing in.....i'm not a pro brewer, but i know it 'works'.... :mug:

i assume the yeast don't morph too much. because they still flocculate fine after so many repitches.....
 

BruceH

Mostly Retired
HBT Supporter
Joined
Nov 2, 2017
Messages
3,150
Reaction score
2,088
Location
30 miles north of Seattle
Pretty much the same thing here except I usually go 5x and then start over. No reason why, it's just my limit.

IMO my best brews come from the second use onward. I don't do any calculations and don't wash the yeast. My thought process is that the dead yeast acts as nutrient for the live ones once fermentation starts. Second brew uses the whole cake, the third batch onward I just pour some beer and yeast slurry into the next batch.

Like bracconiere I don't claim this to be a best practice, lol.
 
OP
C

catalanotte

Well-Known Member
Joined
Jul 30, 2014
Messages
197
Reaction score
65
@BruceH and @bracconiere Thanks for the feedback. Nice to hear what has worked well for you, I value experience over theory. I got into the weeds on calculating pitch rates, which some will say is essential, but I have brewed for many years with a similar approach to what you all are doing, with tasty results. I have made a few lagers over the last month, but now want to revive a jar of ale yeast slurry that is about 6 weeks old, and am building starters to bring it back to life. I suspect this to be only 50-60% live yeast, so thinking through this one a bit more closely.
 

Immocles

Supporting Member
HBT Supporter
Joined
Jan 9, 2019
Messages
1,567
Reaction score
4,327
Location
Minnesota
Yeah, add me to the "not the best practices but brews by the seat of the pants" category. I don't have a huge brew fridge, so I generally use a fresh pack. That cake gets split into 3-4 jars, and I just use those one time and ditch the cakes after that unless I have a massive beer for that third generation. I tried keeping things for several generations but I got way too overwhelmed with too many jars.

@BruceH and @bracconiere Thanks for the feedback. Nice to hear what has worked well for you, I value experience over theory. I got into the weeds on calculating pitch rates, which some will say is essential, but I have brewed for many years with a similar approach to what you all are doing, with tasty results. I have made a few lagers over the last month, but now want to revive a jar of ale yeast slurry that is about 6 weeks old, and am building starters to bring it back to life. I suspect this to be only 50-60% live yeast, so thinking through this one a bit more closely.
I regularly direct pitch said jars after 2-3 months without a starter. I've only once come across an off flavor in doing so, and I blame that on a severe under pitch (grabbed the wrong jar that was saved for a 1G batch). Building a starter up is a good idea, though. If I had the gumption and planning, I would probably do the same.
I like to think that the jars of slurry are just a massive drunken overkill blitzkrieg attack on the wort, while the starter is a bit more of a refined, focused attack. Both seem to get the job done, though. Maybe the latter has less collateral damage.
 

eric19312

Supporting Member
HBT Supporter
Joined
Dec 5, 2012
Messages
3,141
Reaction score
1,595
Location
Long Island
I repitch almost every batch too. I monitor the fermentation and will switch to fresh yeast if something seems off. My typical brew cycle is to soft crash the yeast on day 6-7 and harvest 2 days later. I then dry hop, cold crash, dump dry hops and carbonate and finally end up kegging and rebrewing on about day 14, 21 or 28. So the yeast will be anywhere from 7 to 21 days old on brewday and I have opportunity to taste and test the finished, cold and carbonated beer that was brewed with the yeast before I re-pitch.

I use the yeast starter calculator in Beersmith to estimate quantity to use. I created a custom yeast called Harvested US-05 and estimated that when "packaged" it has 2 billion cells per mL. This is for clean yeast harvested from after dumping initial pint of trub/yeast and before dry hopping the beer. My guess is the first bit that I dump has bulk of the older yeast that were dead when pitched.

It doesn't really matter to me if the 2 billion estimate is accurate, it is just an assumption that makes the rest of the calculation consistent (the other inputs being age of the yeast, volume and starting gravity of the wort.
 
OP
C

catalanotte

Well-Known Member
Joined
Jul 30, 2014
Messages
197
Reaction score
65
Guess I have no worries with this 6 week old starter. Mr Malty says 27% viability but my 2L starters are 2 hrs old and going full bore. I think I over thunk this. Time for beer.
 

bracconiere

Jolly Alcoholic
HBT Supporter
Joined
Jan 19, 2018
Messages
9,259
Reaction score
3,902
Location
S.AZ
Brewers yeast is a nutritional supplement.

i know, i add active dry yeast to my rice bran smoothies...for the folate and niacin....not to mention the nutritional benefits of sprouted grains from the malt!

edit: and in case my comment sounded like a negative, it was a compliment, can't think straight if you're starving!
 

couchsending

Supporting Member
HBT Supporter
Joined
Jun 21, 2016
Messages
2,567
Reaction score
1,563
Technically yes you should be concerned with viability. Certain yeasts will lose viability rather quickly and others won’t at all. Also depends on how they’re stored and what ABV/Hopping rate they were pulled from.

Only way to truly know is a microscope. Everything else is pure conjecture. Just cause something makes “beer” doesn’t mean it’s good beer...

You could document and weigh everything and maybe come up with a set protocol if you were using one yeast strain constantly but again unless you’re looking at it under a microscope you’ll truly never know.
 

Moose_MI

Well-Known Member
Joined
Dec 30, 2013
Messages
971
Reaction score
476
Location
SW Michigan
I do 15G batches and brew every 4-6 weeks. I use Notty for 80% of my beers. I combined and rinse the slurry from every 3rd batch or so and get 3 jars with about 1cup each of pretty clean yeast. I use 1 in a 4.5L starter for each new batch...usually around 1.065 OG. By the time I get to the 3rd jar Im using slurry around 5 months old and I’ll reset by rinsing yeast into 3 jars again.
I’d love to not have to mess with starters but they’re necessary for what I’m doing. Probably save maybe $8 a batch but I do it more for the results as I also think reused yeast is better then fresh.
 
OP
C

catalanotte

Well-Known Member
Joined
Jul 30, 2014
Messages
197
Reaction score
65
Probably save maybe $8 a batch but I do it more for the results as I also think reused yeast is better then fresh.
Agreed. I notice more predictable attenuation and steadier fermentation (less blow off) with subsequent generations. Glad to hear I’m not the only one that is using slurry that is a few months old. Might try some cell counts someday if I can bum a microscope, but for now I like the simplicity of repeating what is working.
 

Moose_MI

Well-Known Member
Joined
Dec 30, 2013
Messages
971
Reaction score
476
Location
SW Michigan
To be honest I’m not sure if it’s as much about subsequent generations or the fact the yeast is fresh off a healthy starter. I think with 5G batches you can probably get away with pitching a large amount of saved slurry that’s got a month or so of age w/o a starter. Ive not done it but Ive read of several folks doing it that are happy with results.
At 15G I really dont want to “hope” my yeast are OK and I’m not really excited about storing that much slurry. I’ve never had a problem when 1st doing a 4.5L starter.

One of these days I’m going to try reserving some yeast from the starter so I can skip the yeast rinsing but when something works I try not to fix it. :)
 
Top