Proper temperature to store..., ... harvested lager yeast Options

[kenlenard]

Gang: I used to save yeast and reuse it but I was having an issue with my stored lager yeast. It appears (after much troubleshooting) that I wasn't storing it cool enough and the yeast wasn't really shutting down. I was getting some funky off-flavors in my lagers (where I reused the stored yeast) and I stopped storing yeast for awhile. But I'd like to get back into saving some of my favorite strains like 2124, 2206, 2112, WLP800, WLP830, WLP802 and WLP840. Have any of you lager brewers (who save your yeast) concluded that saved lager yeast should be stored at a certain temp to assure that the yeast has gone dormant? I'm thinking that anywhere from 34° to maybe 38° would be cool enough. I was storing it warmer than that when I was actively storing yeast. Thoughts?

[blksabbath]

I'd say as cold as you can go without freezing it. What were the off flavors? If it's funky...are you sure you aren't storing something else along with the yeast? Just a thought.

One more thing, I assume your talking saved slurry, not slants or frozen stocks right?
dan g

[tag]

I'd say as cold as you can go without freezing it.

Ditto!

[kenlenard]

Yes, stored slurry. I don't really want to get into slants.

The off-flavors were well documented on this board and no one could really help me troubleshoot it. But it was a wine-like flavor that I would only get in lagers where I used previously stored lager yeast. I was storing the slurry in 22-ounce bottles with airlocks in them (with a #2 stopper) in my spare fridge. But this fridge would also be used for primary fermentation of lagers which means I would have the fridge set to 45-50°. This is certainly too warm to store lager yeast because it would wake up. I never got the off-flavor in any other batch except for lagers where stored yeast was used. I have used the same blob of yeast over & over in successive batches (but never stored the yeast) and those lagers were fine. I no longer do my primary lager ferments in this spare fridge and it's now set to about 34° full time. I'm thinking that this is cool enough to store them "dormant" and then I can wake them up later by taking the yeast out of the fridge making a starter with it. Sound reasonable?

Ps. This is not as big an issue with ale yeast because I would assume that anything in the 40s would be enough to make them sleep.

This post has been edited by kenlenard: Mar 31 2008, 12:29 PM

[dagomike]

Hey Ken,

Yes, cold as possible. Like 32. There was a write up about this in Zymurgy I think not too long ago. There are pros and cons of storying both under beer and sterile water, and then temps, over time.

Maybe another possibility is some TLC if your yeast. Maybe some feeding every few weeks, or maybe even just oxygenate the slurry before storage. Just some ideas.

[blksabbath]

How long are you storing the slurry for? Are the beers that you've made with slurries finishing, sluggish to start, etc?

[kenlenard]

The slurries had been stored for anywhere from 1 to 6 months. They always started without a problem and they always finished up with good FGs. The problem came when I went to bottle or keg these beers. I would taste a very pronouced wine-like flavor in the beer. If I bottled the beer with corn sugar, it seemed like the yeast metabolizing the priming sugar actually helped make the wine-like flavor disappear. But if I kegged the beer, the wine-like flavor would remain. I exhausted every resource I could including the Szamatulskis (Clonebrews) and Greg Noonan. It has to be that my lager yeasts were stored too warm or in fluctuating temps (in a spare fridge set to 45-50° for primary lager fermenting and then colder for lager secondaries). Again, all of my lagers made with "new" or "just-harvested" yeast have all come out great. I will try storing them as close to 32° as I can & see what happens. Thanks guys, good stuff.

This post has been edited by kenlenard: Mar 31 2008, 03:12 PM

[dagomike]

I would taste a very pronouced wine-like flavor in the beer.

Just wondering, how are you oxygenating?

[kenlenard]

After my wort is racked from brewpot to primary, I use an oxygenating stone (attached to tubing that is connected to a pure O2 cannister) and oxygenate the wort for about 60 seconds. I do this for every batch whether I am just using an Activator pack, yeast that was just harvested from a previous primary or stored yeast. I oxygenate the wort and then pitch the yeast into the wort. All of the batches I do this with come out fine. The red flag only comes up when I used this improperly stored lager yeast. When I stopped saving yeast, I went to a schedule where I just made consecutive batches with the same slurry... I would brew a new batch on the same day that I was moving a previous batch from primary to secondary, carefully take the yeast and put it into a sanitized flask or growler, throw it into the fridge for an hour or 2 while the new batch is boiling, cooling, etc., oxygenate and pitch the slurry. All of those batches have come out great... except then I have a bunch of batches that were all made with the same yeast. Not a bad thing, but sometimes you want to mix it up! (IMG:style_emoticons/brewboard/biggrin.gif)

[dagomike]

In my blog below I'm working on O2 issues with lagers. I picked up a dissolved O2 meter and finding some interesting things. I've got a post I'm working on where I did some tests tests in full size volumes of water and found it actually takes longer to get 10-12ppm of O2 when I used higher pressure O2. When I lowered the pressure way down, the bubble size was smaller and saw faster oxygenation. It's very likely I haven't been getting the O2 I thought I was getting, even with 2+ minutes.

I'm not seeing it and I can't remember whether you're doing starters with this stored yeast? If so, how's that happening?

Here's a theory for you... The yeast from a fresh starter and successively from another batch should have good glycogens reserves. The yeast that you are storing obviously is greatly depleted. Now, if you're not getting as much O2 as you think into your wort, it may be fine with fresh yeast, but not enough for these depleted yeast. I'm finding that many lager strains can be touchy. The result may be these excessive wine-like esters and/or alcohols.

Just an idea.

[kenlenard]

I read somewhere that adding the oxygen slowly is best, so that is what I do. On the stored yeast, I probably used the stored slurry as is... no starter. This may very well be the problem as I was very anti-starter there for awhile (I simply don't like making them). But my new strategy is to take some lager yeast (I have some 2124 Bohemian finishing up an Oktober right now) and store it in my fridge at 34° for a few months. Then take it out, warm it up a bit, make a starter for it and brew something over the summer. If it comes out okay, this will be my new routine. If it doesn't, I'll consider that batch an experiment and I'll just go back to brewing with the same yeast in consecutive batches.