Yeast Experiment

Ever been told “You can’t do that!”… and in the back of your mind say: well maybe you can’t, but I will…

That seems to happen a lot with homebrewing…

You can’t leave the beer in the primary or you’ll get autolysis…

You can’t aerate hot wort or you’ll get hot side aeration…

You can’t ___________ …

Well… sometimes this is true, but not always…

… and I’ve been wanting to find out when those exceptions are so I can better understand the brewing process and hopefully find better ways to brew beer…

… today, I’m going to tackle the yeast storage debate…

It’s pretty much the same as leaving beer in the primary… brewer’s say the yeast will die after a few weeks… others say the yeast can keep much longer than that…

This will obviously be a long term experiment, but here’s the short of it…

I just brewed a Milk Stout

… and I re-used yeast from the Brown Porter

I basically collected yeast and used half of it to ferment the Milk Stout and I’m going to save the rest so I can brew a batch 6 months from now and if that goes well, I’ll use the remaining yeast a year from now…

Here’s the thinking behind that…

If you look at your yeast vials coming from the lab, they have shelf lives of about 4 to 5 months…

… and then supposedly yeast goes bad (or it’s not optimum would be more correct)…

… but then you hear stories of brewers who successfully used yeast from a bottle that was aged for years…

Hmmm…

Well… some say you can’t store the yeast longer than a month or two without drying it out and freezing it and some say you can…

… and with all the conflicting information, there’s only one way to find out…

Do it!

Well, I am…

I want to find out how long can you really store yeast for and get an idea of when autolysis does start to happen…

… and if you have any experience with storing yeast that could help me I would love to hear about it… simply leave a comment below

21 Comments

  • Sid

    Reply Reply November 30, 2012

    George I have harvested yeast my first time in September and just brewed a batch a couple of days ago (nov 28) so essentially it is 2 months old i did up a starter of 500 ml on a stir plate 24 hours and pitched at 65° 2 hours later air lock activity like crazy. Now i am a bit concerned about autolisys how can i detect if this is occurring?

    • Jorge

      Reply Reply November 30, 2012

      @Sid 2 months, I would move the beer to a secondary if you don’t want to bottle or keg yet (get the beer off the yeast)…

      A starter is not really needed when you re-use yeast… it’s easy to overpitch when you re-use yeast… you can see in my video I have a lot of activity even without a yeast starter… (that’s the power of good yeast ;P )

      I’ll be focusing on this for the next few months so stay tuned because I plan on making tons of mistakes so we can all learn…

  • michael

    Reply Reply November 30, 2012

    Great minds think alike… I’ve been wanting to save a few bucks per batch by splitting a starter vial (before I use it rather than washing and reusing the yeast). I briefly detailed what I did on our new homebrew club’s website (see: http://brewthervillelabs.com/yeast-experment/).

    Essentially all I did was:
    1) made a yeast starter with fresh WLP001
    2) used about 3/4 of the starter for my brown ale and saved the remaining 1/3
    3) added some more cooled, pre-boiled wort to the starter to reactive reproduction
    4) chilled the starter, dumped the beer and divided the yeast slurry into three slants/sterile tubes
    5) i added a glycerol solution (10%, if memory serves) so i could freeze the slant tubes
    6) stored the slants in the fridge for a few days then moved them to the freezer (didn’t want to “shock” the yeast or create “sharp” ice crystals)

    Next time I want to use WLP001 I’ll pull one slant from the freezer, create a starter and pitch.

    (wish me luck)

    • Jorge

      Reply Reply November 30, 2012

      @Michael That’s great! Keep in touch, because I do want to also test the difference between storing at fridge temperatures VS freezing… it’s hard to come around reliable information like this…

      Cheers!

  • Jon Jefferson

    Reply Reply November 30, 2012

    I haven’t gone as long as you are planning to go, but lately I have been saving from batch to batch and repitching. The time between pitches has been 3 weeks at times, depending the beers. The standard reasoning I have heard has been that the yeast will be no good after as little as two weeks. I have had no issues with the fermentations and no off flavors associated with fermentation.

    I have not been making starters for these repitches. There has been ample amounts of yeast for the fermentation just based on the previous batch growth.

    • Jorge

      Reply Reply November 30, 2012

      @Jon Right… I don’t think two weeks would make the yeast bad… 6 months probably, but who’s actually tried it?

  • Sid

    Reply Reply November 30, 2012

    sorry Jorge the yeast was 2 months old refrigerated, not the brew. But I still don’t understand pitching rates. Like when I harvest yeast i have 4 jars of yeast do i use all 4 vials or 2?

    • Jorge

      Reply Reply November 30, 2012

      @Sid gotcha… Depends on the size of your beer… 1 vial should be enough… 2 can be too much (that’s what I did on this batch to experiment a bit)… I would use 1 for most ales except high gravity and 2 vials for lagers…

  • Martin

    Reply Reply November 30, 2012

    I have been reusing White Labs 500 Trappist. Each time it has been reused it has started quicker and has finished faster than the previous batch. Excellent attenuation and the results are excellent so far. None of the reused yeast has been older than 2 weeks old when pitched. I still have some of the first generation and will try that next to see what effect age has on the new batch.
    I do use a starter.
    I am just finishing a Wyeast 1056 on a high gravity IPA which will be more appropriate as I make 4 beers using it and will give me a wider range of results. I would be interested in hearing other peoples results with their experiments. I will post notes as I get results.
    Martin

    • Jorge

      Reply Reply November 30, 2012

      @Martin i’ve enjoyed the results of reusing yeast so far too…

  • KEVLAR

    Reply Reply December 1, 2012

    The yeast should be fine. I have used it a year later.( stored in plastic bottles) you should make a starter, then activate it.
    Fresher is always better. But in a pinch…

    • Jorge

      Reply Reply December 3, 2012

      @Kevlar – good to hear… did you dry the yeast or keep it in water/wort?

  • Old_Grumps

    Reply Reply December 3, 2012

    I brewed a batch of Premium American Lager a few weeks ago, using yeast harvested from a batch of Dark American Lager brewed in July (harvest date was 07/28/12, so almost 5 months in storage). I created a step up starter using 2 of the pint jars I had stored in the fridge (no freezing here), using 1 liter of starter wort for each step. After brewing and pitching the yeast, I attached a blowoff hose to my airlock setup, and the next morning, it was plugging away, just as I expected. Brew was fermented @ ~54 deg along with a Dopplebock in a temp controlled freezer. Gravity began @ 1.056, and a check after 2.5 weeks showed the gravity was down to 1.010, so it has been moved to room temp for a couple of days. I’ve done this in the past as well, using yeast after storing it at fridge temps for several months, and have always had good results. I guess the ‘experts’ aren’t always right, lol.

    • Jorge

      Reply Reply December 3, 2012

      @Old_Grumps – Nothing like actually doing things to find out regardless of what the ‘experts’ say… Cheers!

  • Sid

    Reply Reply December 3, 2012

    I can not find any info on how to dry yeast for storage. Jorge can you enlighten us on some procedure? I will be brewing the exact same recipe for a long while and willing to try different approaches to yeast handling and sharing my findings.

    • Jorge

      Reply Reply December 6, 2012

      @Sid – I’ll try to fit something in throughout the winter…

  • KEVLAR

    Reply Reply December 3, 2012

    Jorge, I kept it in wort. It can be hard to get good yeast here. Sometimes you find a straggler in the ” kegatron” and go for it. Always seems to work. It would be interesting to do 2 side by side, to see the difference with old and new. There are always so many factors.

  • Nick

    Reply Reply December 14, 2012

    I’ve been reusing yeast for the last few batches of lagers I have been brewing in the last month. Had a White Labs German Bock Lager (WLP833) (Jan 8,2013) where I made a 2 litre starter and used a home made stir plate. Poured the contents after active fermentation into 4 small mason jars and put those jars in the fridge. Added more wort using DME to bring the 2L starter back up to 2L in volume. Back on stir plate, pitched on brew day.

    Used one of the mason jars to make a new 2L starter, used dme, boiled water, cool and back on stir plate. Pitched on brew day, active fermentation within 6 hours, at 54F.

    Will continue to use remaining mason jars to make 2L starter for new batches over the coming months. I decant the wort of the yeast slurry in the mason jar and use the slurry for my starter. Use dme boiled with water, cool, pitch slurry into flask, on to stir plate for active fermentation.

    I usually put a little bit of CO2 gas in to the mason jar before sealing the lid.

    While I have harvested yeast from the primary, and with success, I find using the original strain easier for me then going through the decanting off the trub process.

    If I can stretch a vial to 4 batches I’m happy.

    • Jorge

      Reply Reply December 14, 2012

      @Nick – Great info! I cap out at 5 or 6 myself, though depends on what I’m brewing… What do you use to pump CO2 into the jars?

  • michael

    Reply Reply February 4, 2013

    Jorge,

    Here’s a weird follow up to my earlier comment (scroll up… I was the second to comment on this thread), I pulled my first slant from the freezer, defrosted it and made up a new starter from the defrosted slurry and then brewed my favorite Irish Red and pitched the yeast on Saturday morning. The fermentor sat in my basement where my wife accidentally left the exterior door ajar on Saturday night (it was cold outside, so the basement temp dropped to about 62). Needless to say, there was no visible fermentation (i.e., no bubbles in the blow off tube bottle) on Sunday morning (24 hours post pitching). I closed the door, bringing basement temp to 68 and by Superbowl time last night (hurray Ravens!) the blow off was chugging along, but very gently (usually I get a pretty vigorous bubbling in about 12 hours). This morning (48 hours post pitching) no more bubbles. I gently agitated the fermentor and got no additional activity. I know not to worship the bubbles, so I checked the gravity tonight and this is what I got:

    Original Gravity using a refractometer was 14.1 (1.057). “Final” Gravity tonight was 6.5 (1.006 with correction calculator). I guess it’s possible the yeast went crazy last night when I was sleeping, but there’s not even evidence of krausen.

    What happened? Did I just get a very rapid and highly attenduated yet very gentle fermentation? Any thoughts?

    michael

    • Jorge

      Reply Reply February 4, 2013

      Interesting… well, it’s hard to know without actually seeing it myself, but if you’ve brewed this beer before you know what to expect from it… When re-using yeast, I’ve had pretty quick fermentation’s like this so I wouldn’t worry so much from that stand point. Now, adding glycerol and freezing is something I have yet to try, so I wouldn’t know what to expect.

      There’s really only two things that can happen with a fast fermentation like that… either you got very rapid, highly attenuated fermentation as you describe, or you may have wild yeast. (1.006 is a bit low for an Irish red and I would assume you usually end up at ~1.010?) Check again in a couple of days and if it gets closer to 1.000, then your overattenuation may be from wild yeast…

      I hope not… I’ll cross my fingers, but let me know…

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