Author Topic: Reusing 34/70 dry lager yeast  (Read 2289 times)

Offline petermmitchell

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Reusing 34/70 dry lager yeast
« on: August 13, 2017, 09:29:33 AM »
I read somewhere that reusing dry yeast was not recommended, but wanted to see if others had any experience with reusing 34/70.  I have a 5 gal batch of pilsner fermented with 34/70 that I would like to repitch into a larger 10gal batch of Oktoberfest.  I was planning to pitch half of the yeast cake into each 5 gallon batch of the Oktoberfest. I am using 2 buckets for the 10 gal batch.  Any issues with doing this?

Offline denny

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Re: Reusing 34/70 dry lager yeast
« Reply #1 on: August 13, 2017, 09:35:55 AM »
Never had a problem reusing any dry yeast.
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Offline BrewBama

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Reusing 34/70 dry lager yeast
« Reply #2 on: August 13, 2017, 10:54:46 AM »
I read on one of the dry yeast mfrs sites that they recommend it not be reused.

Here it is: http://www.fermentis.com/brewing/homebrewing/frequently-asked-questions/

Can I re-use the yeast?
Due to the risks of infection and the inability to check yeast cell counts of yeast slurries it is not recommended as the risk of failure is increased and outweighs the cost of new yeast.

Edit: But the Danstar tech data sheet for London ESB says "When using Lallemand Brewing Yeasts, you may repitch the yeast just as you would any other type of yeast according to your brewery’s SOP for yeast handling."  LOL

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« Last Edit: August 20, 2017, 01:43:35 PM by BrewBama »
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Offline denny

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Re: Reusing 34/70 dry lager yeast
« Reply #3 on: August 13, 2017, 11:01:34 AM »
I read on one of the dry yeast mfrs sites that they recommend it not be reused.

Here it is: http://www.fermentis.com/brewing/homebrewing/frequently-asked-questions/

Can I re-use the yeast?
Due to the risks of infection and the inability to check yeast cell counts of yeast slurries it is not recommended as the risk of failure is increased and outweighs the cost of new yeast.

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which are exactly the same concerns with reusing any yeast, liquid or dry.  Dry yeast is not more prone to those issues than liquid, yet we reuse liquid yeast all the time.
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Offline natebrews

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Re: Reusing 34/70 dry lager yeast
« Reply #4 on: August 13, 2017, 11:11:13 AM »
Wasn't it, once upon a time, that dry cultures weren't pure cultures (something to do with the drying method) and so they weren't suitable for use over many propagations?  I don't imagine this is the case anymore, but I'm wondering if this is some bit of knowledge that has lasted beyond its relevancy. 
Risk of failure should be no deterrent to trying.

Offline BrewBama

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Re: Reusing 34/70 dry lager yeast
« Reply #5 on: August 13, 2017, 11:27:33 AM »
I read on one of the dry yeast mfrs sites that they recommend it not be reused.

Here it is: http://www.fermentis.com/brewing/homebrewing/frequently-asked-questions/

Can I re-use the yeast?
Due to the risks of infection and the inability to check yeast cell counts of yeast slurries it is not recommended as the risk of failure is increased and outweighs the cost of new yeast.

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which are exactly the same concerns with reusing any yeast, liquid or dry.  Dry yeast is not more prone to those issues than liquid, yet we reuse liquid yeast all the time.

I even read lager yeast shouldn't be reused because it absorbs DMS in the fermentation D rest so when reused could increase the chance of DMS in the new brew. If it's on the internet it has to be true right?  (I read '6 myths' on AHA by Denny last night.)


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Offline denny

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Re: Reusing 34/70 dry lager yeast
« Reply #6 on: August 13, 2017, 11:55:08 AM »
I read on one of the dry yeast mfrs sites that they recommend it not be reused.

Here it is: http://www.fermentis.com/brewing/homebrewing/frequently-asked-questions/

Can I re-use the yeast?
Due to the risks of infection and the inability to check yeast cell counts of yeast slurries it is not recommended as the risk of failure is increased and outweighs the cost of new yeast.

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which are exactly the same concerns with reusing any yeast, liquid or dry.  Dry yeast is not more prone to those issues than liquid, yet we reuse liquid yeast all the time.

I even read lager yeast shouldn't be reused because it absorbs DMS in the fermentation D rest so when reused could increase the chance of DMS in the new brew. If it's on the internet it has to be true right?  (I read '6 myths' on AHA by Denny last night.)


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well, I don't do a d rest, so I guess I'm OK!  ;)
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Offline petermmitchell

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Re: Reusing 34/70 dry lager yeast
« Reply #7 on: August 13, 2017, 12:41:43 PM »
Hey that's why this forum is needed.  We can learn and change our misconceptions :)  Thanks for your advice!

Offline Bob357

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Re: Reusing 34/70 dry lager yeast
« Reply #8 on: August 13, 2017, 05:29:08 PM »
I generally keep a pack or 2 of US-05 in my yeast fridge just in case. I recently found myself with only that for ale yeast and one packet was dated. Didn't have any reason to use it for quite some time. The second packet was getting close to 2 years old, so I rehydrated it and then pitched it into a starter to produce a couple of 100B cell vials. I used these vials as I would fresh liquid yeast and they performed well. While I use mostly English ale yeasts for my APAs and IPAs, I haven't found a dry English ale yeast that I prefer over the liquid offerings.

Not sure if first rehydrating is necessary when making a starter from dry yeast, but I prefer to err on the side of caution. IMHO, today's dry yeasts are of a quality comparable to liquids. As for re-use, US-05 is reputed to perform much better when re-using than on the first pitch. 
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Offline GolfBum

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Re: Reusing 34/70 dry lager yeast
« Reply #9 on: August 14, 2017, 06:13:27 AM »
I have started using 34/70 for my lagers this summer and have saved the yeast and it is going on it's 4th batch. I don't see any negatives to saving it and reusing. In fact I think the fermentation has gotten stronger as the generations move forward. The first batch fermented well but the second and third batches had shorter lag times, and seemed to ferment well. The beers tasted amazing too. I only plan to use a couple more times before I start over with some new packs though.

Offline MerlinWerks

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Re: Reusing 34/70 dry lager yeast
« Reply #10 on: August 14, 2017, 07:27:02 AM »
I just pitched an 8th generation slurry from two packs of 34/70 that I re-hydrated at the beginning of the year. I'll probably go two more and start over.

Offline reverseapachemaster

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Re: Reusing 34/70 dry lager yeast
« Reply #11 on: August 14, 2017, 08:18:32 AM »
I've repitched slurry from both US-05 and 34/70 with no problems.

Fermentis's position is one part an unspecific statement of fact (repitching yeast always invites risk of infection) and one part straight marketing (it's cheaper to buy new yeast). Put them together it's just advising you to buy more of their product.
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Offline Brew Cat

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Re: Reusing 34/70 dry lager yeast
« Reply #12 on: August 14, 2017, 07:06:20 PM »
Of course the manufacturer says don't repitch.  I've actually found 34/70 works better when repitching. I'll start my lager series in November and keep repitching until March. I've done this for 3 seasons and haven't noticed any difference pitch to pitch

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Offline el_capitan

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Re: Reusing 34/70 dry lager yeast
« Reply #13 on: August 17, 2017, 09:44:53 PM »
Man, I'm always amazed at how this forum supports my brewing.  Right now I'm cold-crashing an O-fest, with plans to repitch the 34/70 into a Munich Dunkel tomorrow.  I think that as long as the initial fermentation was clean and healthy, the slurry should be in better shape than the original dry pack.  Maybe I'm vastly oversimplifying things here. 

One thing that I recently picked up here was the idea of overbuilding starters in order to maintain a cleaner yeast culture.  I've been using that method a lot in my brewing, and I like it a lot.  So, the downside with repitching is the gamble of contamination.  I plan to reserve a clean portion of my yeast slurry from the Ofest as my "pure" culture, and then build that through starters for future lagers. 

However, a whole batch worth of lager slurry is way to valuable to just dump, so I see myself overbuilding a starter, brewing a batch, then using the slurry for a second batch or two.  I don't brew lagers that often, but I'm definitely going to keep moving forward with this method as a way to simplify lager production. 

PS - doesn't dry yeast pretty much turn to liquid once you use it?   ;)

Offline ynotbrusum

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Re: Reusing 34/70 dry lager yeast
« Reply #14 on: August 23, 2017, 05:14:07 PM »
I have gone to using dry yeast in the summer months and not repitching during the summer due to a concern that there is just a higher degree of airborne contaminants during the warm months, so any collection and repitching is more perilous in the summer. Probably overkill, though, because if you pitch enough yeast it should outcompete a minor infection, right?  I just try to minimize the chances of an infection.  Also I have found that I really like S-189, so it is pretty easy peasy to use that for my lagers without needing to repitch.
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