Author Topic: Can you over pitch a lager?  (Read 2289 times)

Offline gmac

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Can you over pitch a lager?
« on: March 28, 2013, 07:57:26 PM »
I've got a 5 gal amber lager with WLP833 sitting out for a D-rest right now. 
I'm going to do another lager right away, probably a 1.060ish bock of some sort.  Should I just re-pitch the entire yeast cake?  Mr. Malty says I should pitch about 230 ml of yeast from a re-pitch but I have no idea how to factor in how "clean" my re-pitch is.  I wasn't planning on trying to wash it or anything.  I would expect that there are maybe 2 cups of slurry in the bottom of the bucket, depending on how much liquid I have to use to get it re-suspended to pour.

So, long way to get to my question.  Is there any downside to just re-pitching the entire yeast cake?  I was going to chill to about 45 or so and then pitch.
Thanks

Offline klickitat jim

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Re: Can you over pitch a lager?
« Reply #1 on: March 28, 2013, 10:44:17 PM »
Autolysis? Maybe... I'll tune in for the pro responses

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Offline davidgzach

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Re: Can you over pitch a lager?
« Reply #2 on: March 29, 2013, 04:59:56 AM »
If you are increasing the OG that is preferable, however I've pitched on top with an identical OG with no ill effects at all.  And it was a Pils so it would have been detected.  I'd say go for it and RDWHAHB.

Dave
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Offline kylekohlmorgen

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Re: Can you over pitch a lager?
« Reply #3 on: March 29, 2013, 05:52:43 AM »
After racking off the cake, just swirl it to mix and measure out your needed volume. You can adjust the Yeast Concentration to the low end (try 2) on the calculator.

You'll find you have much more yeast than you need. I've heard JZ mention several times that over-pitching is detrimental to beer flavor.

Also - if you plan on continue using the yeast in future pitches, over-pitching greatly increases the average cell age of the slurry. More yeast = less growth = fewer new cells in subsequent pitches.
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Offline blatz

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Re: Can you over pitch a lager?
« Reply #4 on: March 29, 2013, 06:51:09 AM »
yes, you can.  i've done it 2 times in the past, both resulting in acetylaldehyde, even after a 4 week primary with 1 week at diacetyl rest temps. 

both because I observed the viability factor on Mr. Malty and pitched almost 1500mL of loose slurry in 10gal.

I was able to rescue the beers by letting them sit at room temp (acetylaldehyde has a low boiling point - like 60s or 70s) and bubbling Co2 periodically from the bottom to degas the kegs, thanks to some advice from posters here.

As for your situation - 230mL is a little more than a cup - I would pitch a cup and a half and you will be in the ballpark and be fine.
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Offline gmac

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Re: Can you over pitch a lager?
« Reply #5 on: March 29, 2013, 09:02:55 AM »
yes, you can.  i've done it 2 times in the past, both resulting in acetylaldehyde, even after a 4 week primary with 1 week at diacetyl rest temps. 

both because I observed the viability factor on Mr. Malty and pitched almost 1500mL of loose slurry in 10gal.

I was able to rescue the beers by letting them sit at room temp (acetylaldehyde has a low boiling point - like 60s or 70s) and bubbling Co2 periodically from the bottom to degas the kegs, thanks to some advice from posters here.

As for your situation - 230mL is a little more than a cup - I would pitch a cup and a half and you will be in the ballpark and be fine.
Thanks. I will do a cup and a half and see how it goes. Maybe 375 to 400 ml.

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Re: Can you over pitch a lager?
« Reply #6 on: March 30, 2013, 04:13:23 AM »
I don't like repitching in general due to autolysis and acetaldehyde concerns. Not that this technique can't be done successfully- but see it as a source of problems for the average homebrewer.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline ynotbrusum

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Re: Can you over pitch a lager?
« Reply #7 on: March 31, 2013, 05:15:35 AM »
I just hit 20 batches of repitched WLP 800.  No problems with reuse - the first use was in 2011!  But I am ending there - pushing my luck further is not worth it.  I use Yeast nutrient each time, I am meticulous on sanitation and I repitch about 700-800 ml for a ten gallon batch. I've never overpitched a lager, but I did so with an ale - a lot of esters (cloves mostly) from US-05.  Use the Mr. malty calculator to get the amount of slurry and you will be fine.
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Offline klickitat jim

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Re: Can you over pitch a lager?
« Reply #8 on: March 31, 2013, 01:24:31 PM »
I'm learning,  guessed autolysis

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Offline kylekohlmorgen

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Re: Can you over pitch a lager?
« Reply #9 on: April 01, 2013, 06:42:22 AM »
Not that this technique can't be done successfully- but see it as a source of problems for the average homebrewer.

I see fermentation issues stemming from low cell counts or low viability as the main source of problems for homebrewers at every level.

Making a starter for EVERY batch is difficult to accomplish, even if you're really dedicated. With good sanitation and storing practices, harvesting and repitching yeast can significantly increase the quality of your beer.

The keys are sanitation, storage, and repitching the correct amounts. Dumping fresh wort on an entire yeast cake creates almost (just?) as many problems as under-pitching.
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Offline davidgzach

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Re: Can you over pitch a lager?
« Reply #10 on: April 01, 2013, 10:13:07 AM »
I only did it once as I like to save slurry and stick with Mr Malty calculations.  I guess after this thread I will not do it again unless it's to a much bigger beer!

Dave
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Offline blatz

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Re: Can you over pitch a lager?
« Reply #11 on: April 01, 2013, 10:24:38 AM »
I only did it once as I like to save slurry and stick with Mr Malty calculations.  I guess after this thread I will not do it again unless it's to a much bigger beer!

Dave

I think that's taking it too extreme.  I repitch A LOT and most pros do 20+ generations as well, so I have no issue with repitching as a practice.  I think the issue I found is that the viability calculations for harvested yeast are inaccurate, which I previously treated as gospel.  I try to reuse my yeast within a month (hopefully less than 2 weeks) and just do 20-30% more than what a freshly harvested pitch is recommended according to MrMalty.com. 
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Offline davidgzach

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Re: Can you over pitch a lager?
« Reply #12 on: April 01, 2013, 11:16:50 AM »
I only did it once as I like to save slurry and stick with Mr Malty calculations.  I guess after this thread I will not do it again unless it's to a much bigger beer!

Dave

I think that's taking it too extreme.  I repitch A LOT and most pros do 20+ generations as well, so I have no issue with repitching as a practice.  I think the issue I found is that the viability calculations for harvested yeast are inaccurate, which I previously treated as gospel.  I try to reuse my yeast within a month (hopefully less than 2 weeks) and just do 20-30% more than what a freshly harvested pitch is recommended according to MrMalty.com.

Paul, I meant pitching on top of a previous cake, not saving and re-pitching at all......
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Offline kylekohlmorgen

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Re: Can you over pitch a lager?
« Reply #13 on: April 01, 2013, 11:24:01 AM »
I think the issue I found is that the viability calculations for harvested yeast are inaccurate, which I previously treated as gospel.  I try to reuse my yeast within a month (hopefully less than 2 weeks) and just do 20-30% more than what a freshly harvested pitch is recommended according to MrMalty.com.

I've heard JZ recommend using harvested slurry within 2 weeks, if stored properly. I'd assume the viability calcs are for slurry that's less than 2 weeks old.
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Offline blatz

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Re: Can you over pitch a lager?
« Reply #14 on: April 01, 2013, 11:29:16 AM »
Paul, I meant pitching on top of a previous cake, not saving and re-pitching at all......

oops - my bad - misread!

kyle - if you use a date 4 weeks prior to the current, the recommendation is over double the amount as if harvested today - that's what got me in trouble with acetylaldehyde - I pitched that double sized amount, and the primary was finished in 5-7 days (wasn't monitoring it close since most of my lagers take at least 10 days) and then if flocced and i guess didn't clean up after themselves.  I just find that to be too steep of a decline. 

if its over a month, though, I rebuild the colony. 
The happiest people don’t necessarily have the best of everything; they just make the best of everything they have.

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