Author Topic: Reusing 34/70 dry lager yeast  (Read 8459 times)

Offline doc280

  • 1st Kit
  • *
  • Posts: 2
Re: Reusing 34/70 dry lager yeast
« Reply #15 on: November 06, 2020, 11:47:14 pm »
I know this is an old thread, however it almost had all the information I required. When harvesting 34/70 and then when it is time to pitch, does one use half or the entire amount of the harvested yeast. I know ale yeast it is about half, just not sure about lager yeast.

Offline HopDen

  • Brewmaster
  • *****
  • Posts: 628
Re: Reusing 34/70 dry lager yeast
« Reply #16 on: November 07, 2020, 01:15:22 pm »
I know this is an old thread, however it almost had all the information I required. When harvesting 34/70 and then when it is time to pitch, does one use half or the entire amount of the harvested yeast. I know ale yeast it is about half, just not sure about lager yeast.

That depends on what you are making. 34/70 is a lager yeast so I will comment on using it for a lager recipe. Use all of it, making sure you have the proper pitch rate. I personally don't worry about that when repitching. Pour most of the beer off, swirl the remaining and pitch. I have gone, if I remember correctly, 6-7 generations with 34/70 without any perceptual difference. I also will pitch straight from the cooler. No need to let it warm up.

Online Saccharomyces

  • Senior Brewmaster
  • ******
  • Posts: 1026
  • Deus ex machina
Re: Reusing 34/70 dry lager yeast
« Reply #17 on: November 07, 2020, 09:33:54 pm »
You want to pitch around 150ml of settled, thick slurry per five gallons of wort, especially if you plan to serially repitch a culture.  Underpitching is okay.  Overpitching leads to insufficient new cell growth to sustain a culture over multiple repitches.
« Last Edit: November 07, 2020, 09:41:48 pm by Saccharomyces »

Offline majorvices

  • Global Moderator
  • I must live here
  • *****
  • Posts: 10879
  • Polka. If its too loud you're too young.
Re: Reusing 34/70 dry lager yeast
« Reply #18 on: November 08, 2020, 11:23:24 am »
I know this is an old thread, however it almost had all the information I required. When harvesting 34/70 and then when it is time to pitch, does one use half or the entire amount of the harvested yeast. I know ale yeast it is about half, just not sure about lager yeast.

I find the yeast picthing calculators handy and convenient. Gives you an idea how much yeast you need for every batch. http://www.mrmalty.com/calc/calc.html

I have counted counted cells with a microscope and hemocytometer and matched it very closely with these results.

Online Saccharomyces

  • Senior Brewmaster
  • ******
  • Posts: 1026
  • Deus ex machina
Re: Reusing 34/70 dry lager yeast
« Reply #19 on: November 08, 2020, 01:58:37 pm »
I find the yeast picthing calculators handy and convenient. Gives you an idea how much yeast you need for every batch. http://www.mrmalty.com/calc/calc.html

I have counted counted cells with a microscope and hemocytometer and matched it very closely with these results.

I have also counted stained yeast cells using an hemocytometer and a microscope. It is an interesting exercise and necessary for commercial brewing, but has limited use at home.  At this point, I really do not find yeast calculators to be all that useful.  I find rules of thumb combined with my experience with a culture to be more useful.  That being said, what is interesting is that Mr. Malty's standard re-pitch suggestion is 173ml, which is basically a 1L starter at maximum cell density. His ale pitching rate is 500ml at maximum cell density, which solidifies my assertion that underpitching by as much as 50% makes no difference in fermentation outcome while providing enough new cell growth that a culture can be serially re-pitched more than a couple of times without worrying about a huge loss in viability, that is, as long as one's wort is well aerated.   I have always re-pitched between 150 and 175ml of settled slurry per 5.25 gallons.  That is based in the rule of thumb that 1ml of settled, thick slurry contains approximately 1.2 billion cells as well as the accepted average maximum cell density of a 1L starter, which is 200 billion cells.  If we divide 200 / 1.2, we get 167ml; therefore, pitching anywhere between 150 and 175ml of settled, thick slurry will yield approximately an equal number of cells as a 1L starter at high krausen. Pitching less less slurry will yield more new cell growth in well-aerated wort while pitching more slurry will increase the average age of the cells in the culture due to suppressed new cell growth.  That is why overpitching is a poor practice in a serially re-pitched brewery.  It is better to improve brewery hygiene than overpitch to avoid contamination from wild microflora.  For most part, we do not base pitch rates based a fermentation reaching projected terminal gravity.  That is function of genetics and dissolved O2 demand.  We can seriously underpitch if there is enough dissolved O2 to support the number of replication cycles necessary to reach maximum cell density and our brewery hygiene is impeccable.  Suggested pitching rates are for commercial brewing, which accounts for the difficulty encountered in keeping a commercial brewery and brewing equipment spotless.  Pitching rates are primarily about outcompeting competitors.
« Last Edit: November 20, 2020, 06:14:26 am by Saccharomyces »

Offline TXFlyGuy

  • Brewmaster
  • *****
  • Posts: 742
Re: Reusing 34/70 dry lager yeast
« Reply #20 on: November 18, 2020, 05:35:20 pm »
You want to pitch around 150ml of settled, thick slurry per five gallons of wort, especially if you plan to serially repitch a culture.  Underpitching is okay.  Overpitching leads to insufficient new cell growth to sustain a culture over multiple repitches.

Hmmmmm...I pitch 475 ml, or 1 pint per 5 gallons. We always over pitch for lagers. With good results. Little or no lag time.
Bluebonnet Brewoff 2021 Winner:
Munich Helles - 1st Place
Oktoberfest   - 1st Place
English Porter - 3rd Place

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 24594
  • Noti OR [1991.4, 287.6deg] AR
    • Dennybrew
Re: Reusing 34/70 dry lager yeast
« Reply #21 on: November 18, 2020, 06:35:15 pm »
You want to pitch around 150ml of settled, thick slurry per five gallons of wort, especially if you plan to serially repitch a culture.  Underpitching is okay.  Overpitching leads to insufficient new cell growth to sustain a culture over multiple repitches.

Hmmmmm...I pitch 475 ml, or 1 pint per 5 gallons. We always over pitch for lagers. With good results. Little or no lag time.

Lag time is a canard.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline majorvices

  • Global Moderator
  • I must live here
  • *****
  • Posts: 10879
  • Polka. If its too loud you're too young.
Re: Reusing 34/70 dry lager yeast
« Reply #22 on: November 18, 2020, 08:00:40 pm »
I find the yeast picthing calculators handy and convenient. Gives you an idea how much yeast you need for every batch. http://www.mrmalty.com/calc/calc.html

I have counted counted cells with a microscope and hemocytometer and matched it very closely with these results.

I have also counted stained yeast cells using an hemocytometer and a microscope. It is an interesting exercise and necessary for commercial brewing, but has limited use at home.  At this point, I really do not find yeast calculators to be all that useful.  I find rules of thumb combined with my experience with a culture to be more useful.  That being said, what it interesting is that Mr. Malty's standard re-pitch suggestion is 173ml, which is basically a 1L starter at maximum cell density. His ale pitching rate is 500ml at maximum cell density, which solidifies my assertion that underpitching by as much as 50% makes no difference in fermentation outcome while providing enough new cell growth that a culture can be serially re-pitched more than a couple of times without worrying about a huge loss in viability, that is, as long as one's wort is well aerated.   I have always re-pitched between 150 and 175ml of settled slurry per 5.25 gallons.  That is based in the rule of thumb that 1ml of settled, thick slurry contains approximately 1.2 billion cells as well as the accepted average maximum cell density of a 1L starter, which is 200 billion cells.  If we divide 200 / 1.2, we get 167ml; therefore, pitching anywhere between 150 and 175ml of settled, thick slurry will yield approximately an equal number of cells as a 1L starter at high krausen. Pitching less less slurry will yield more new cell growth in well-aerated wort while pitching more slurry will increase the average age of the cells in the culture due to suppressed new cell growth.  That is why overpitching is a poor practice in a serially re-pitched brewery.  It is better to improve brewery hygiene than overpitch to avoid contamination from wild microflora.  For most part, we do not base pitch rates based a fermentation reaching projected terminal gravity.  That is function of genetics and dissolved O2 demand.  We can seriously underpitch if there is enough dissolved O2 to support the number of replication cycles necessary to reach maximum cell density and our brewery hygiene is impeccable.  Suggested pitching rates are for commercial brewing, which accounts for the difficulty encountered in keeping a commercial brewery and brewing equipment spotless.  Pitching rates are primarily about outcompeting competitors.

My only point is that, for chronic underpitchers and new brewers, looking at how much yeast they actually should be pitching is helpful. And the yeast pitching calculators can give them an idea. I'm not sure why a lot of brewers seem to have moved on from recommending them especially when underpitching is a far bigger problem in homebrewing that overpitching.

Offline BrewBama

  • Official Poobah of No Life. (I Got Ban Hammered by Drew)
  • *********
  • Posts: 4796
Reusing 34/70 dry lager yeast
« Reply #23 on: November 18, 2020, 08:02:22 pm »
Lag time is a canard.

We agree to disagree. I believe lag time is one of a few indications of health and viability.

I agree with this:

... the yeast pitching calculators can give them an idea. I'm not sure why a lot of brewers seem to have moved on from recommending them especially when underpitching is a far bigger problem in homebrewing that overpitching.

...and this:

“It is also important that the lag phase not last too long, ... Although most worts will remain stable for at least 24 h, it is best to err on the side of caution and aim for active fermentation within 15 h.” — Chris White from the The Oxford Companion to Beer definition of lag phase.

Sent from my iPad using Tapatalk
« Last Edit: November 18, 2020, 09:52:34 pm by BrewBama »
wisdom is proved right by her deeds

Brewed in the Tennessee Valley. Rocket City — Huntsville AL

Online Saccharomyces

  • Senior Brewmaster
  • ******
  • Posts: 1026
  • Deus ex machina
Re: Reusing 34/70 dry lager yeast
« Reply #24 on: November 20, 2020, 06:15:40 am »
Hmmmmm...I pitch 475 ml, or 1 pint per 5 gallons. We always over pitch for lagers. With good results. Little or no lag time.

And a progressively less variable culture with every repitch

Online Saccharomyces

  • Senior Brewmaster
  • ******
  • Posts: 1026
  • Deus ex machina
Re: Reusing 34/70 dry lager yeast
« Reply #25 on: November 20, 2020, 06:20:34 am »
My only point is that, for chronic underpitchers and new brewers, looking at how much yeast they actually should be pitching is helpful. And the yeast pitching calculators can give them an idea. I'm not sure why a lot of brewers seem to have moved on from recommending them especially when underpitching is a far bigger problem in homebrewing that overpitching.

Underpitching was a serious problem when I first started to brew because commercial cultures were tiny compared to today.  The average White Labs culture doubles at most two times in a 1L starter.  I am finding that modern amateur brewers who repitch are overpitching, often seriously overpitching. Bragging about having little to no lag time demonstrates a fundamental lack of understanding about yeast culture management.

Online Saccharomyces

  • Senior Brewmaster
  • ******
  • Posts: 1026
  • Deus ex machina
Re: Reusing 34/70 dry lager yeast
« Reply #26 on: November 20, 2020, 06:31:45 am »
We agree to disagree. I believe lag time is one of a few indications of health and viability.

Well, I have to respectively disagree with you and agree with Denny.  There is a difference between a lag time of 15 hours and little to no lag time. Lag time is critical to yeast culture viability.  A lag time of over 24 hours is definitely a sign that one pitched too few viable cells.  One of the biggest problems in amateur brewing today is the overuse of attemperation.  I do not know where the dogma of pitching at a lower temperature than the fermentation temperature originated, but it is a recipe for long lag periods.  The optimal replication temperature for most brewing ale cultures is 30C/86F.  The replication period grows larger as we reduce temperature.  In my humble opinion, it is better to pitch a few degrees higher and allow the fermentation to come down to target fermentation than vice versa, but dogma almost always trumps science in amateur brewing.  The largest determiner of higher alcohol and ester production is not temperature.  It is wort composition, specifically carbon-to-nitrogen ratio.
« Last Edit: November 20, 2020, 06:39:14 am by Saccharomyces »

Offline ynotbrusum

  • Official Poobah of No Life. (I Got Ban Hammered by Drew)
  • *********
  • Posts: 4235
Re: Reusing 34/70 dry lager yeast
« Reply #27 on: November 20, 2020, 11:12:29 am »
A friend of mine who went to Siebel would pitch his lagers a bit warm and allow them to cool over the first 24-36 hours to fermentation range, going from 64F down to 52-54F.  He won many comps before going pro
« Last Edit: November 20, 2020, 04:40:03 pm by ynotbrusum »
Hodge Garage Brewing: "Brew with a glad heart!"

Offline BrewBama

  • Official Poobah of No Life. (I Got Ban Hammered by Drew)
  • *********
  • Posts: 4796
Reusing 34/70 dry lager yeast
« Reply #28 on: November 20, 2020, 01:10:34 pm »
We agree to disagree. I believe lag time is one of a few indications of health and viability.

...  There is a difference between a lag time of 15 hours and little to no lag time. Lag time is critical to yeast culture viability.  A lag time of over 24 hours is definitely a sign that one pitched too few viable cells.  ...

I may be confusing my terms. I agree with everything you said here. ...which is what I thought I said or at least intended.  I believe 12-18 hrs is about right.

I believe a cpl other indications of healthy and viable yeast pitched at the proper amount are the rate the fermentation is taking place and a complete finish — both based on expectations for the strain. 

Sluggish fermentation and lower than expected attenuation can be attributed to yeast pitch rate and health (among other things).

Sent from my iPad using Tapatalk
« Last Edit: November 20, 2020, 01:27:41 pm by BrewBama »
wisdom is proved right by her deeds

Brewed in the Tennessee Valley. Rocket City — Huntsville AL

Offline doc280

  • 1st Kit
  • *
  • Posts: 2
Re: Reusing 34/70 dry lager yeast
« Reply #29 on: November 20, 2020, 04:47:22 pm »
I made my transfer from fermenter to keg and had two pints of yeast cake and beer mixture remaining in the fermenter. I just went with one pint of this mixture into my fresh batch, pitched at 59 F,  fermentation temp 56 F, it took off with in 12 hours.