Author Topic: Yeast fresh vs yeast repitch  (Read 978 times)

Offline klickitat jim

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Yeast fresh vs yeast repitch
« on: February 26, 2016, 07:48:14 PM »
I was thinking lately about the debate over the blind triangle test being the best if not only way to determine difference. Some say that every detail must be the same, but for the one issue being tested. Cool, I get that idea.

How would we apply that to comparing a fresh pitch to a subsequent generation repitch? For a 1st gen vs 2nd gen you would be compairing beers brewed several weeks apart with different wort, or you would have to split a batch of wort and use a different 1st gen pitch to compare to a 2nd gen from a different batch of yeast.

Wouldn't we have to stipulate that using a different lot of 1st gen yeast would be acceptable, or stipulate that its OK to store the 1st gen beer until the 2nd gen beer was ready? There's a lot of techy brewers that would invalidate either idea.

Where I'm going with this is that there are times when personal opinion based on memory comparison should be acceptible, and/or... we need to recognize that we don't have prove everything scientifically.

Offline Wort-H.O.G.

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Re: Yeast fresh vs yeast repitch
« Reply #1 on: February 26, 2016, 07:53:34 PM »
i would think you make a batch , harvest the slurry. then make the batch to be tested, split it, use slurry in 1/2 and new yeast/starter in 1/2. then compare the split batch 2nd generation pitch vs new yeast/starter pitch?

edit: first batch and test batch identical recipes, process, etc.
« Last Edit: February 26, 2016, 07:55:18 PM by Wort-H.O.G. »
Ken- Chagrin Falls, OH
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Offline The Professor

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Re: Yeast fresh vs yeast repitch
« Reply #2 on: February 26, 2016, 08:00:06 PM »
i would think you make a batch , harvest the slurry. then make the batch to be tested, split it, use slurry in 1/2 and new yeast/starter in 1/2. then compare the split batch 2nd generation pitch vs new yeast/starter pitch?

edit: first batch and test batch identical recipes, process, etc.

I've done that with a few of my 'standard' brews.
And as far as I could tell, the repitched yeast made better beer every time.
I still routinely repitch through a minimum of 8 generations these days.   In the past I've gone far beyond that as well.
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Offline Wort-H.O.G.

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Re: Yeast fresh vs yeast repitch
« Reply #3 on: February 26, 2016, 08:09:36 PM »
i would think you make a batch , harvest the slurry. then make the batch to be tested, split it, use slurry in 1/2 and new yeast/starter in 1/2. then compare the split batch 2nd generation pitch vs new yeast/starter pitch?

edit: first batch and test batch identical recipes, process, etc.

I've done that with a few of my 'standard' brews.
And as far as I could tell, the repitched yeast made better beer every time.
I still routinely repitch through a minimum of 8 generations these days.   In the past I've gone far beyond that as well.

yeah-it just would seem to me too many variables could be introduced between wort from 1st batch and the 2nd batch, vs splitting wort from a single batch and then using new yeast and slurry for blind test.
Ken- Chagrin Falls, OH
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Offline dannyjed

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Re: Yeast fresh vs yeast repitch
« Reply #4 on: February 26, 2016, 10:22:23 PM »
A fellow homebrew friend offered many different samples of the same Pale Ale recipe with different generation yeast at a club meeting. The yeast used was US-05 from 1st pitch up to 10th generation repitch. I could not tell a difference among them. We did not do a triangle test and there were 5 different samples, but I couldn't tell a difference at all. Maybe a different yeast strain with less of a neutral profile would be more suitable for an experiment.
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Offline klickitat jim

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Re: Yeast fresh vs yeast repitch
« Reply #5 on: February 26, 2016, 10:37:02 PM »
The argument though is going to be that the new fresh pitch will not be guaranteed to be the same as the fresh pitch that then created the slury

Offline Wort-H.O.G.

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Re: Yeast fresh vs yeast repitch
« Reply #6 on: February 26, 2016, 10:41:26 PM »
The argument though is going to be that the new fresh pitch will not be guaranteed to be the same as the fresh pitch that then created the slury

id argue that's the lesser concern or problem for me. IMO two different wort's have a higher probability of being unequal or different for testing purposes vs. same yeast strain used from two different vials/packs.
Ken- Chagrin Falls, OH
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Offline bierview

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Re: Yeast fresh vs yeast repitch
« Reply #7 on: February 26, 2016, 10:44:37 PM »
Eight  generations?  I rarely go beyond four. I think the more you reuse yeast, the more chance of infection through the handling process. Having said that I just dumped a new brew on top of a yeast cake that I just racked to secondary. It took off like a rocket for 48 hours then dies down. I've noticed that pattern with dumping on top instead of harvesting, washing and starting on a stir plate.

Offline Stevie

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Re: Yeast fresh vs yeast repitch
« Reply #8 on: February 26, 2016, 10:45:55 PM »
It would need to be two stage. Stage one - fresh pitch. Stage two - fresh pitch and slurry. Compare the two fresh pitch to see if there is a difference, then compare the slurry to fresh pitch.

Offline Wort-H.O.G.

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Re: Yeast fresh vs yeast repitch
« Reply #9 on: February 26, 2016, 10:56:52 PM »
Eight  generations?  I rarely go beyond four. I think the more you reuse yeast, the more chance of infection through the handling process. Having said that I just dumped a new brew on top of a yeast cake that I just racked to secondary. It took off like a rocket for 48 hours then dies down. I've noticed that pattern with dumping on top instead of harvesting, washing and starting on a stir plate.

well your risk may go up....but not linear to repitch I think.  Many of us have gone much further than 4 without issue, and I'm sure some have gone 1 or 2 and had a problem with infection or other.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

http://braukaiser.com/wiki/index.php?title=The_Science_of_Mashing

Serving:        In Process:
Vienna IPA          O'Fest
Dort
Mead                 
Cider                         
Ger'merican Blonde
Amber Ale
Next:
Ger Pils
O'Fest