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Brews & Views Bulletin Board Service * Brews and Views Archive 2004 * Archive through December 21, 2004 * Ever tried this?? -- LT Yeast Storage < Previous Next >

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Richard Nye
Intermediate Member
Username: Yeasty_boy

Post Number: 349
Registered: 01-2004
Posted on Sunday, December 12, 2004 - 02:55 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I read with interest Bill Pierce's recent article in BYO on yeast storage. Bill very clearly wrote about two methods to store yeast. The first in on agar plates stored in the refrigerator for a few months, and the second is frozen in a glycerin solution for a year or more. Each method has it's pros and cons the way I see it.

During my holiday time off I want to get my yeast in order, and set up many strains for long term storage. Bill's article reminded me of a method I read about in "First Steps in Yeast Culture" by Pierre Rajotte.

Pierre talks about a method we brewers can use to store yeast for the rest of our lives in the basement!!

Basically you make a 10% sterile sucrose solution and pour 10ml into test tubes with screw on caps. You take an inoculation loop full of actively fermenting wort and put it in the test tube sucrose solution and cap it tight.

When you're ready to make a starter, scrape some of the yeast cells off the wall of the test tube and add a loop full of sucrose/yeast solution to 10ml of wort. Then grow your starter up like normal.

Pierre said the drawback to this method is you must keep the test tubes vertical, and the 10ml starters can take 4 days the get active.

Does anybody use this method? I've been storing my yeast on slants, but I'd like a longer term storage solution.
 

Richard Nye
Intermediate Member
Username: Yeasty_boy

Post Number: 354
Registered: 01-2004
Posted on Monday, December 13, 2004 - 02:00 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I want to bring this thread (if you call one post a thread) up to the top again. What do you all think of this yeast storage method? Do you think it will work (Fredrik?)? Apparently it's used in Europe by commercial brewers more than the US.
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 1434
Registered: 01-2002
Posted on Monday, December 13, 2004 - 02:24 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I don't have any experience with that particular method. However, I don't see any reason not to try it if it interests you.
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 1837
Registered: 03-2003
Posted on Monday, December 13, 2004 - 03:53 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I have just started my yeast storage testing myself so can't offer much sensible input...

But I suspect though that enough cells can survive for a really long time with a range of different storage methods, probably longer than one may think! But the fewer viable cells you have, the harder is it to revive it, and the greater chance of reviving bacterial contaminations too. My frozen yeast got going after a few days, which got me gladly suprised. I had prepared myself to wait much longer if necessary. Even after moderate storage the viability may suck as compared to what we are used to but that is not an issue as long as we have a few cells that survives.

I am not sure what the method you mention suggests, cap tubes tight while the yeast is fermenting and add sucrose?? Anyway, my guess is that you can do it in many ways more than a year. I think some good things except for beeing anal about sterilization, is to make sure the yeast is in top shape before storing it, add yeast nutritions, and make sure it's not exhausted just cominig from a long fermentation and take precautions to not expose the yeast to oxygen during storage or prior to storage without in the presence of wort. It clearly doesn't make much sense to store yeast that's already crappy at the point of entering storage. They need all the health they can get to stay alive for years without food.

I hope to some more fridge tests eventuelly and then I would make sure to have no headspace, or at least make sure there is no oxygen in the headspace. Also I would prepare the yeast in a very low gravity culture, with extra additions of nutritions, to make sure it's stuffed with everything good before entering long term storage.

About which method is "best" I don't even have any speculations at this point. I think there are many methods that are probably "good enough", all you want is to be able to revive the population and stay away from bacteria, wether the viability is 10% or 0.01% hardly matters from a functional point of view, except it may be more or less difficult to revive it and any bacteria contaminations may become relatively more important.

If you try it report the results.

/Fredrik
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 1838
Registered: 03-2003
Posted on Monday, December 13, 2004 - 04:20 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I think there may be different strategies depending on the target storage time and how you intend to store it. If you can slowly feed the yeast during the storage, it will no run out of energy which is good (it will keep the viability up longer), on the other hand, deeply dormant cells are supposed to be more resistant to various shocks, an actively fermenting cell may more easily die from a heat shock as compare to a dormant cell. Dormant cells are more "rugged". I don't know what the preferrable tradeoff is, more testing may be needed.

/Fredrik
 

Richard Nye
Intermediate Member
Username: Yeasty_boy

Post Number: 355
Registered: 01-2004
Posted on Monday, December 13, 2004 - 05:18 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I will be trying this method because it seems simple and yeast can be stored under various storage conditions for decades. I'll report my results in a few months. Keeping the solution sterile is probably the biggest difficulty.

Wouldn't it be great to have a bank of 15 or 20 strains of yeast that will last decades? WOW!
 

davidw
Advanced Member
Username: Davidw

Post Number: 771
Registered: 03-2001
Posted on Monday, December 13, 2004 - 05:41 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Richard: I purchased Rajotte's book several years ago and have used this method of storing yeast sucessfully.

That said I don't find myself doing it much anymore. What I found was that the time it takes to build up a population of yeast from such a small sample added to the cost of DME to make the starter really doesn't make it any more economical than simply purchasing a pitchable tube or smack pack and pitching either of those into a half a gallon starter. A couple days later I've got a good, viable, pitchable quantity of yeast. That verses a week to ten days building up a population from a small number of cells, making a 10 ml starter, then a pint, a quart, then half gallon. Again, it's a considerable amount of time and money spent.

Economics aside, if your goal is to simply have a variety of yeast strains on hand in storage then this is a good option vs. messing with slants or glycerin.

When I started doing this I desired having several strains on hand. I'd get a new strain, make a starter, then using this method would innoculate 3 or 4 tubes and put them in the fridge. I built up quite the collection. But as mentioned above I found that it was much easier to simply purchase new yeast and go from there. I actually still have a couple vials of Wyeast 1028 in the fridge that must be (at least) 3 years old. I keep telling myself when I find the time I need to pull one out and see if it is still viable.

Again, it goes back to if you're interested in doing it, go for it. You don't really save yourself any money or time for your effort. But it is fun to have a large number of strains available.
 

Craig Johnson
Intermediate Member
Username: Californiacraig

Post Number: 294
Registered: 03-2003
Posted on Monday, December 13, 2004 - 08:31 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Richard,

I use the sucrose solution for my yeast. It works very well for me. I twill take a week and a half to get a proper starter going. The biggest problem is that on occasion I have streaked a plate and nothing grew and I had to restreak and wait another weekfor results.
 

Vance Barnes
Senior Member
Username: Vancebarnes

Post Number: 1250
Registered: 03-2003
Posted on Monday, December 13, 2004 - 08:44 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

David pretty much nailed my thoughts. I used to use nothing but yeast slants from the YCK in Michigan. Seemed the natural thing to do after years of working in labs during college and after. Then things got busy and WL came out with their so-called "pitchable tubes" and I've never brewed from a slant since. Seems like I can never plan my brewing schedule 2 weeks out. If I can get to the LHBS by Wed and get a starter going for a Fri or Sat brewday I'm doing good.
 

Denny Conn
Senior Member
Username: Denny

Post Number: 3933
Registered: 01-2001
Posted on Monday, December 13, 2004 - 08:49 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

SAme here...I used to have a really large yeast ranch. Now, the only thing on slant is CL50, because that's the only way I can get it. If I run across other strains I like that are slant only, I'll do the same with them. But anything I can buy in a tube, I will.
LIfe begins at 60...1.060, that is.
 

danno
Advanced Member
Username: Danno

Post Number: 573
Registered: 03-2002
Posted on Monday, December 13, 2004 - 09:39 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

After trying a number of methods, my preference is for the Rajotte method but with wort. I'm left with about 3ml of spent wort with a thin film of yeast on the bottom. I shake up the yeast, use a pipette to remove most of it and then add back fresh, oxygenated, wort.
 

Richard Nye
Intermediate Member
Username: Yeasty_boy

Post Number: 357
Registered: 01-2004
Posted on Monday, December 13, 2004 - 11:14 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

danno, how long with the yeast last that way? Also, do you leave the cap on loose? What size container is the 3ml of wort in?

My LHBS doen't stock that much yeast so many times I'll have to order it from him in advance. I also find yeast from a slant gives me faster starts than from a smack pack given the same size starter.
 

Craig Johnson
Intermediate Member
Username: Californiacraig

Post Number: 295
Registered: 03-2003
Posted on Tuesday, December 14, 2004 - 06:49 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

If I go from a fresh slant I can step up pretty quickly and have a decent starter (1.5 liter) in three days.

A few times when I have been delayed a week or two I crash cooled my starter. On brew day I decant the liquid off of the starter and replace with fresh wort. By the time I am ready to pitch, my starter is already very active. My lag times are generaly under six hours.
 

danno
Advanced Member
Username: Danno

Post Number: 574
Registered: 03-2002
Posted on Tuesday, December 14, 2004 - 01:58 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I haven't tested the longevity beyond 6 months. ABout every 6 months, I drain the spent wort and refill each with fresh, oxygenated wort. I let them sit out at 65F for about three days with the cap screwed tight. I burp them (loosen the caap to relieve the pressure) and them put the m back in the fridge for another 6 months.

I have used the snap on caps but the pressures blows that seal too often. I've been using a plastic vial with screw on caps.
 

Vance Barnes
Senior Member
Username: Vancebarnes

Post Number: 1254
Registered: 03-2003
Posted on Tuesday, December 14, 2004 - 04:25 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

danno, when you drain the spent wort, the fresh wort just gets inoculated from the yeast left in the vial?
 

Rob Farrell
Member
Username: Robf

Post Number: 200
Registered: 02-2003
Posted on Tuesday, December 14, 2004 - 06:44 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Fredrik, this one's for you:

http://mic.sgmjournals.org/cgi/content/full/146/5/1023

Any scientific types will appreciate this presentation of data on yeast aging and longevity. Google Scholar is pretty cool for us geeky types. Based on this article I will consider harvesting yeast from the secondary rather than the primary. As I read it, the last to settle are the youngest, with more life cycles left in them.
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 1854
Registered: 03-2003
Posted on Wednesday, December 15, 2004 - 06:52 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Rob, that's a very good article :-) I've seen that before. I don't remember if it is in that article but though there is a kind of rough genetic limit how many cell divitions a single cell can live through, in a beer fermentation there is so much stress that the cells typically doesn't get near this limit. If you want to see a cell live as long or near this limit I suspect you probably have to set up a controlled low stress fermentation in some lab setup.

In brewing I think they die from stress and irreparale cell damage rather than hitting the age limit as such.

Apart from possibly getting rid of some trub and junk, I'd personally prefer a mixed sample with a representative age distribution.

At any point the nature of the age distribution means that if you take a typical representative mixed sample 90% of all cells are either virgins, or have budded at most 2 times. These are young. The really old cells are very small % of the population anyway, and I think there are greater risks than benefits with selecting the yeast in a certain ways. I would be worried about for example flocculation selection if I repeatadle selected secondary yeast.



As I understand, due to the nature of age distribution in yeast, there is a relation between typical actual maximum lifetime and viability of a continous culture ay any time. Once can conclude that if the yeast lived even near the theoretical maximum limit, the viability would be 99.99% or something like that @ EOF. I am quite sure this is not the case. I measured the viability once and though I can't give you decimals I'd say even accounting for my errors the viability was absolutely not higher than say 99% (it was less! though >95%). This directly sets the single cell average lifetime before death to around 5-6 generations, whil the theoretical limit is expected to be maybe around 30.

/Fredrik
 

Rob Farrell
Member
Username: Robf

Post Number: 202
Registered: 02-2003
Posted on Wednesday, December 15, 2004 - 02:07 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Good point. When reading these type of articles one has to keep in mind that these studies are done in ideal laboratory conditions, while our brewing in certainly less than ideal. If the yeast are not surviving past 5 cycles in my basement, harvesting for youth is not as compelling. I've never harvested from the secondary because I'm a bottler and flocculation is important to me. Are the yeast in the secondary less flocculent or just the offspring of yeast that were younger and smaller (and thus suspended) at the time of racking?
 

Fredrik
Senior Member
Username: Fredrik

Post Number: 1857
Registered: 03-2003
Posted on Wednesday, December 15, 2004 - 02:55 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

> Are the yeast in the secondary less flocculent
> or just the offspring of yeast that were
> younger and smaller (and thus suspended) at the
> time of racking?

I would think that in general it may be both, depending on when you rack, and the strain etc. Also I suspect that some of that very last settlers are also some dead cells. Dead cells are bound to have a disfunct flocc mechanism. I read a test when clearing time is related to viability. More dead cells require slightly longer clearingtime as they dead cells doesn't flocc properly. I am not sure exactly what is happening but the potential hazard for selecting less flocculant strans if you consistent resuse only secondary yeast is I think clear. I think the age profile is good enough as is, and there is not much point in trying to manipulated it. The only point I see is removing trub and junk.

/Fredrik
 

Rob Farrell
Member
Username: Robf

Post Number: 203
Registered: 02-2003
Posted on Wednesday, December 15, 2004 - 05:57 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

So it seems that racking early, such as just upon the kreuzen falling, would separate the trub and junk while capturing flocculent cells. I'll aim for that next brew, although I'll have to break my habit of doing all my brewing tasks on weekends.
 

Chris Bodley
New Member
Username: Cincichris

Post Number: 6
Registered: 12-2004
Posted on Wednesday, December 15, 2004 - 06:14 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Pardon my ignorance but I don't understand why one couldn't merely have a number of yeast starters that you would keep in a cool / dark place. I usually use the same strain at least a few times. I take the yeast from the secondary and introduce it to a small amt of sterile wort - put it in a beaker w/ an airlock. I've had great success so far & I've done this for a few years. However, I've never used the same strain more than 5 or so times.

My experiences have resulted in good beer - do you think this is a bad practice?
 

Rob Farrell
Member
Username: Robf

Post Number: 205
Registered: 02-2003
Posted on Wednesday, December 15, 2004 - 06:22 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Anything that results in good beer is good practice. Practices can be improved, leading to geeky discussions about an article in a microbiology journal. For some, brewing good beer is enough, others have to delve into science and engineering.
 

Vance Barnes
Senior Member
Username: Vancebarnes

Post Number: 1270
Registered: 03-2003
Posted on Thursday, December 16, 2004 - 04:14 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Chris, not a bad practice and similar to what many here do. I don't always do the same thing when re-using yeast. Sometimes I pitch on a yeast cake, sometimes collect the yeast to a sanitized jar and put in the fridge, sometimes pitch that directly, or if its more than 2 weeks old make a starter or sometimes 2 starters if it's a 10 gal batch.

All of that would be considered short term storage though. Slants or the method discussed here with the tubes would be considered long term storage. > a month and up to a year or more.

Useing the yeast no more than 5 times should be fine unless a brew is high gravity which stresses the yeasties.