London III

Discussion in 'Homebrewing' started by jburke06, Apr 9, 2016.

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  1. SFACRKnight

    SFACRKnight Grand Pooh-Bah (3,274) Jan 20, 2012 Colorado
    Pooh-Bah Society Trader

    @honkey brought it up and can probably answer better than I ever could.
     
  2. erway

    erway Crusader (454) Jul 28, 2006 New Mexico


    Not sure exactly what the question is, but I usually answer the whole pitching discussion with an question: What is under-pitching? My belief is that the amount that you are pitching should result in:
    1) lag phase of less than 8 hours
    2) A complete fermentation with attenuation occurring in a predictable and reasonable time period
    3) A desirable fermentation profile and maturation that occurs in a predictable and reasonable time period

    Anything more than this amount has the potential to result in:
    1) An overall lack of yeast nutrients.
    2) Loss of yield to yeast sediment
    3) Loss of iso-alpha acids through excess krausen
    4) Loss of iso-alpha acids through excess yeast flocculation
    5) An extended sedimentation time

    So we are currently pitching 10 million cells/ml to our IPAs. Some in the US would say that is under-pitching, some in the UK would say that is over-pitching.

    As far as NEIPA, I find the phenomena of them fascinating. We brewed 1 batch of Dank with more fruit-forward hops than we normally have, didn't bitter to nearly as high a level, and used no auxiliary finings so the beer would remain at least somewhat cloudy. It is currently on tap. Some of our die-hard hop heads here absolutely love it and want us to brew it forever. Some think it was a stupid thing to do and look forward to this batch being gone. I will admit that it is not as murky as some of the NEIPAs that I have seen. Cloudy like our hefeweizen, but not muddy per se.
     
  3. Brew_Betty

    Brew_Betty Initiate (0) Jan 5, 2015 Wisconsin

    10M cells/ml is considered a normal pitch rate for a medium gravity beer. Maybe even an over pitch. Definitely not an under pitch. Using the phrase over or under pitching doesn't imply the wrong amount of yeast was pitched, IF the result is good. It just means more or less yeast than the textbook recommended pitch rate.
     
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  4. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    We under pitch at a rate of .6 million/ml/degree plato. Part of the reason is because a vigorous fermentation has a tendency to blow off more of the volatile hop compounds resulting in less hop aroma. This is a fairly common practice for commercial brewers. The other aspect of it is, as you mention, increased ester production. 1056 can give off subtle (in comparison to flavorful strains like London III) fruit esters. It is so widely used because of its adaptability, not just because it is "clean."
     
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  5. erway

    erway Crusader (454) Jul 28, 2006 New Mexico

    Textbook would be 1*10^6 cells/ml/°P, which would put pitch rate at ~1.7*10^7cells/ml.
     
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  6. erway

    erway Crusader (454) Jul 28, 2006 New Mexico

    110% agree with this sentiment. There is a limit to how low one should go with it as there can be issues, though rare. We pitch 5*10^6 cells/ml to our 15°P ESB and I actually love the fermentation profile of that beer. Once went under that.... Once.:grimacing:
     
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  7. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    Yeah... I went down to about that rate on our Amber Ale about a year ago and fermented at 60F... Diacetyl bomb. Dumped the batch, haven't tried again.
     
  8. Brew_Betty

    Brew_Betty Initiate (0) Jan 5, 2015 Wisconsin

    There is more than one textbook.
     
  9. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
    Pooh-Bah Society

    From an article on the Brewers Friend website:

    “A popular study done by George Fix concluded a rate of 0.75 million cells / ml / degree Plato is appropriate for ales, and double that for lagers. Other popular brewing tools use this number, though some opt for 1.0 instead of 0.75.”

    It would be prudent to keep in mind that the above pitch rates assume the yeast was previously used to brew a batch of beer; the yeast is being re-pitched.

    Yeast from a fresh smack-pack, vial, or pouch will have much better viability/vitality than yeast that was previously used to brew a batch of beer.

    Cheers!
     
  10. SFACRKnight

    SFACRKnight Grand Pooh-Bah (3,274) Jan 20, 2012 Colorado
    Pooh-Bah Society Trader

    Do you mind sharing your impressions of the differences between the hazy dank and clear dank?
     
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  11. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    This is what we were taught at school, except for high gravity ales we were taught to go to 1 million and high gravity lagers to 2 million. Many German brewers mentioned that they decrease the ale pitching rate for hefeweizens to about 2/3rds of the normal pitching rate. If you are harvesting yeast well, I would argue that the yeast from a previous batch would be healthier than yeast directly from a smack pack. That would mean that yeast is harvested right after the beer reaches terminal gravity. That is difficult for most homebrewers unless they have conicals. When we harvest, we never use yeast that is less than 95% viable yeast and normally our second generation yeast has a smaller lag phase than the first. Using 95% as our minimum, we can easily get up to 8 generations of yeast and each generation can be split into 3 direct pitches for subsequent batches.
     
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  12. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
    Pooh-Bah Society

    Weedy, I suppose the critical aspect is the difference between commercial brewing and homebrewing?

    Below is what John Palmer stated in an article he wrote for BYO magazine concerning the George Fix pitching rate:

    “What is often not mentioned is that this recommendation is for re-pitched yeast — such as you would get from the bottom of the fermenter from a previous batch. That yeast is not at peak vitality (i.e., health) and viability (i.e., % alive), depending on age in the fermenter, previous original gravity, etc.”

    As homebrewers we typically do not know what the values are for vitality/viability of yeast we used to ferment a previous batch.

    How exactly do you assess viability/vitality at your commercial brewery? When you arrive at a value what are the error bars associated with that value (i.e., how accurately are you able to assess these values)?

    Cheers!
     
  13. honkey

    honkey Maven (1,326) Aug 28, 2010 Arizona
    Trader

    I feel like I'm missing a few sentences before this paragraph, but I think that the last part of that is "depending on age in the fermenter, previous original gravity". When I harvest yeast, I do it the day after I reach terminal gravity and only from beers lower than 1.060 and not hoppy beers. When I homebrew and I reuse the yeast, I transfer the beer right after reaching terminal gravity into a purged secondary. I wouldn't do so if I had a conical... I think those Fast-Ferments look pretty nice in that regard. and harvest the yeast into mason jars and stick it in the fridge for storage for no more than a week. If I'm not brewing with in the week, I dump it.

    I don't regularly check vitality, but I always check viability when I'm doing my cell counts. I just stain with methylene violet. It is very rare that I see any dead cells at all... maybe 1 or 2 out of several hundred. If the yeast has been stored for a while, I start to see dead cells. I have been told before that when you get below 75% viability that the test is no longer accurate at all, but that there is no reason to question viability when you see consistent counts like we do. That is just what I was told by BSI, so I am not sure how they came up with that statistic. If I see less than 95% I just don't brew with it and I'll pull another yeast keg and check that one. That only normally happens if I didn't dump enough to start.
     
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  14. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,181) Dec 15, 2005 Pennsylvania
    Pooh-Bah Society

    http://www.wyeastlab.com/hb_pitchrates.cfm

    "Accurately re-pitching yeast is a difficult task for a home-brewer. Due to stresses from fermentation conditions, harvested slurry is typically in a less healthy condition than laboratory grade culture Pitch rates when using harvested slurry should be 1.5-2 times the rate of laboratory grade culture"

    Cheers!
     
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  15. erway

    erway Crusader (454) Jul 28, 2006 New Mexico

    We ferment that beer at 70°F for the first 24 hours and then let it rise to 72... Surprisingly characterful fermentation profile, and still very clean.
     
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