Author Topic: What is the shelf life of a yeast starter?  (Read 8245 times)

Offline Wildrover

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 480
What is the shelf life of a yeast starter?
« on: November 24, 2011, 07:51:14 AM »
I'm thinking if the yeast are kept cool and protected with a layer of starter wort it should last indefinitely?

Thoughts?   

Offline Johnnyv42

  • BeerSmith Brewer
  • ***
  • Posts: 34
Re: What is the shelf life of a yeast starter?
« Reply #1 on: November 30, 2011, 07:04:31 AM »
I don't have any thoughts, but I do have a recommendation, a book:

"Yeast: The Practical Guide to Beer Fermentation"
http://www.amazon.com/Yeast-Practical-Fermentation-Brewing-Elements/dp/0937381969/ref=sr_1_1?s=books&ie=UTF8&qid=1322661467&sr=1-1

I just finished reading it and I know the answer to the question you are asking is in there. I don't think "indefinitely" is the answer, but I don't want to misquote the book. I just did an experiment where I brewed 2 5 gallon batches of 1.065 OG Stout, in one batch I pitched the starter at high kraeusen, in the other batch I pitched the yeast from a starter that I had let completely ferment (ferment to dryness) and then put in the refrigerator for 3 days before pitching. Both batched of beer are actively fermenting, I see no difference at this point (but I only pitched the 2nd batch 2 days ago). So I'm thinking 3 days in the fridge are fine, but that's way short of "indefinitely". The book is great!

Primary: Wit, Red

Secondary:

Bottled: Brown, Coffee Stout, Stout, Wee heavy, 60 Shilling, Brown Ale, Smoked Black IPA, American Pale Ale, Vanilla Porter, Wit

Offline Wildrover

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 480
Re: What is the shelf life of a yeast starter?
« Reply #2 on: November 30, 2011, 09:47:35 PM »
Yeah I'm not talking days, I'm talking weeks (almost two months in one case).  I have three starters that I made with the intention of brewing a while back but then got swamped and probably won't be able to anytime soon (a couple of weeks if I'm lucky).  I have them being kept just above freezing in my fridge in my garage (North Dakota Winter is setting in so keeping the garage and of course the fridge that's there cold, isn't much of an issue)

Having said that, if you look around the web you'll see clones for two-hearted ale (great beer by the way) where people recommend cultivating the yeast from the bottle.  My guess is that the yeast in that bottle isn't all that fresh and has seen a bump or two but you can still grow a decent starter from those bottles. 

I also heard a story about a shipwreck that had some preserved beer in some bottles for more than a couple of hundred years.  As I understand it, some experts took the yeast, cultivated it and now there is a commercial beer made with it (not sure how much, if any of that is true, just something I heard). 

I recently started to decant all the starter wort and pitching some wort from the batch to see if that makes a difference.  I'll wait until that little bit (approx 2-3 liters or so) gets to high krausen and then I'll pitch all of it into the wort.  I'm not sure if it makes a difference or not but it does seem to get the fermentation off quicker. 

I guess what I'm after is will my yeast that's been sitting in the fridge for a few weeks still make good beer when I get around to it.  I can't really think of any reason why not and I was wondering if any one else could? 

Offline Bootlegbrewer

  • BeerSmith Brewer
  • ***
  • Posts: 42
Re: What is the shelf life of a yeast starter?
« Reply #3 on: December 01, 2011, 09:56:03 PM »
A yeast starter is usually considered "Active" for about 2 weeks stored in a standard fridge. By active we are saying that you could pitch this directly into batch of wort without re-energizing the yeast. The problem as I understand it is viability. After about a month I think the yeast have about an 85% viability rate or something close to that. So if yoru starter originally had about 700billion cells then after 1 month  15% of the cells would have expired. This would leave you with 595billion cells. You would simply need  to reactive the yeast with fresh wort to get the cell count back up.

Check out the book referenced by the previous poster, I have that and it is an excellent resource. I have been successfully culturing yeast or over 10 years and can say that is the book I wish existed when I first started.

Offline MaltLicker

  • Global Moderator
  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 2004
    • Blue Ribbon Brews
Re: What is the shelf life of a yeast starter?
« Reply #4 on: December 02, 2011, 08:29:45 PM »
..................I'm talking weeks (almost two months in one case)............... 


I just went 2.5 months as a non-brewer and had a starter that I re-started three times, hoping I'd brew.  I noticed it changed color and I finally tossed it.  It might've worked fine, but time and labor far 'out costs' a new smack pack if it had not. 

I made a starter today for Monday and used olive oil for the first time; curious to see if it acts any differently.

Offline ghwren

  • BeerSmith Master Brewer
  • ****
  • Posts: 83
Re: What is the shelf life of a yeast starter?
« Reply #5 on: December 03, 2011, 06:43:07 AM »
..................I'm talking weeks (almost two months in one case)............... 


 

I made a starter today for Monday and used olive oil for the first time; curious to see if it acts any differently.

I've found Pixie Dust is much more reliable than olive oil.

Offline Johnnyv42

  • BeerSmith Brewer
  • ***
  • Posts: 34
Re: What is the shelf life of a yeast starter?
« Reply #6 on: December 04, 2011, 05:15:28 PM »
Interestingly, olive oil is not "pixie dust". Once again, the frequently quoted "Yeast" book talks about New Belgium experimenting with using olive oil instead of adding O2 to the wort. Apparently the O2 helps the yeast build cell walls which have a strong component of saturated fats. Apparently if olive oil, aka saturated fats, are readily available the yeast take advantage of it and use them. The book did not decisively indicate that olive oil could indeed replace O2 though and never mentions it except for the one section, whereas it mentions O2 addition repeatedly. Even though New Belgium experimented with the olive oil they never used it for a production product. Please give us an update when the results of your olive oil experiment are done. I'm very curious!
Primary: Wit, Red

Secondary:

Bottled: Brown, Coffee Stout, Stout, Wee heavy, 60 Shilling, Brown Ale, Smoked Black IPA, American Pale Ale, Vanilla Porter, Wit

Offline ghwren

  • BeerSmith Master Brewer
  • ****
  • Posts: 83
Re: What is the shelf life of a yeast starter?
« Reply #7 on: December 05, 2011, 06:39:07 AM »
Here's the research paper on the experiment at New Belgium: http://brewcrazy.com/hull-olive-oil-thesis.pdf
The attempt was to provide yeast cells with an unsaturated fatty acid during the dormant stage for later growth and cell membrane health because of concerns that normally used oxygenation could reduce stability of the final product. It sort of worked with regards to stability, but increased esters and fermentation times.
I would consider an experiment to increase storage time and viability of rinsed yeast and slurries, but will continue to use the more reliable "Pixie Dust."

Offline Johnnyv42

  • BeerSmith Brewer
  • ***
  • Posts: 34
Re: What is the shelf life of a yeast starter?
« Reply #8 on: December 05, 2011, 09:10:02 AM »
Thanks for the link to the detailed article, very, very interesting! Also, thanks for the correction regarding unsaturated fatty acids, also much appreciated. I gotta ask though, what's "pixie dust"?
Primary: Wit, Red

Secondary:

Bottled: Brown, Coffee Stout, Stout, Wee heavy, 60 Shilling, Brown Ale, Smoked Black IPA, American Pale Ale, Vanilla Porter, Wit

Offline ghwren

  • BeerSmith Master Brewer
  • ****
  • Posts: 83
Re: What is the shelf life of a yeast starter?
« Reply #9 on: December 05, 2011, 01:44:20 PM »
Pixie Dust is great, if you can get hold of it. It will guarantee perfect water for the style, maximum utilization of your grains, perfect fermentation, and negates the need for dry hopping. My LHBS never has it in stock.

Offline MaltLicker

  • Global Moderator
  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 2004
    • Blue Ribbon Brews
Re: What is the shelf life of a yeast starter?
« Reply #10 on: December 05, 2011, 02:15:18 PM »
I don't know if it was referencing the same New Belgium experiment or other more substantial data, but I first read about olive oil in either BYO or Zymurgy a while back. 

I didn't brew today as planned, so we'll see if it helps the starter stay "game ready" for a week. 

 

modification