Testing the limits of yeast viability

I'm a lazy brewer and while I muster enough energy up to collect mason jars or 12oz bottles full of slurry from my primaries, I hardly ever wash the yeast. I usually don't get around to brewing something that can use that yeast in the next month or so and I'm likely scared to pitch it. It got me thinking though, really how long is too long and how can you tell on the fly if you've still got viable yeast in there.

Yesterday I brewed 11 gallons of Belgian Wit and had prepared a 1.5 liter starter from a fresh Wyeast 3944 activator pack. I was pretty confident that would have been enough to split between the two carboys but I also have about a pint of WLP-400 slurry from last August in the fridge. Yes, that's 11 months old.

I decanted off all the beer and smelled and tasted it. It wasn't delicious but it wasn't foul either. It smelled like witbier. I transfered it to a growler, added 500ml of wort and oxygenated the hell out of it. It bubbled in about an hour.

Into one carboy, I pitched the fresh yeast in 1.5L starter, in the other I pitched the awoken and fed year old slurry. They both started fermenting in about 6 hours and are blowing off like nuts. Let's see what happens.

This has me curious as well. I have yet to save any yeast and use it although I did pour out some of the last cake into a bottle and put it in the fridge.

I'm very interested in how this turns out.

I have a couple strains (Pacman from a bottle of Rogue something or other, and a WLP029 starter that I ended up not using) that have been hanging out in my refrigerator for several months.

I think I'll let them hang around a while longer and see how your current batches turn out.

Thanks for posting. Looking forward to the results.

I'm sure there's a lot of biology involved in what makes a healthy yeast cell but I was working off of what I'd call the puke test. I've sniffed a few slurries that obviously went south and it literally makes you want to puke. I figured, if the beer layer smelled and tasted okay, at the worst, it just wouldn't ferment all the way.

I have some preliminary results.

After 15 days of fermenting, the year old WLP400 slurry pitched batch is down to 1.010 and is showing no more activity. The flavor is clean and I'll be racking it to keg tonight. The batch with the new 3944 in a 1.5 liter starter is still at 1.024 and still chugging along.

Unwashed slurry can only be used within a couple weeks? Busted.

Obviously the slurry collection method and handling is important and I really do recommend the sniff and taste test. Boil the mason jar and lid and keep the slurry in the fridge.

I had come upon something that said if the yeast band in the mason jar looks gray, and no longer "creamy off white" then the yeast cells have kicked the dust.

You didn't happen to note how the yeast band looked did you?

I have a lot of year old harvested yeast in my fridge, I never get around to use.

Good thread!!!

I've regularly resurrected jars over a year old. Just treat 'em like a bottle harvest and gradually build up the starter.

jkarp said:

I've regularly resurrected jars over a year old. Just treat 'em like a bottle harvest and gradually build up the starter.

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Yeah I figured as much...I guess Bobby's puke test is probably the standard test for these puppies.

I use one gallon glass jars (maraschino cherry jars from work) to save whole cakes or I will siphon the cake into flip top bottles and store in the keg fridge. It works fine for me. No problems yet.

I had one grey looking jar (harvested and washed that batch), but it smelled fine and it worked fine.

If it smells like yeast and bubbles like yeast....

I gotta say, the words "Bobby M" and "Lazy Brewer" are NOT two sets of words I would have ever equated with one another. If Bobby is a lazy brewer than I must be a;

No seriously, I really am lazy and scatterbrained. That's why it still takes me like 6+ hours to brew.

I should have taken a picture of the jar before messing with it as I don't recall what it looked like. I also smelled it after I gave it some time with that half liter of starter wort. I figure if things are funky, it would be somewhat obvious by then.

Bobby_M said:

I have some preliminary results.

After 15 days of fermenting, the year old WLP400 slurry pitched batch is down to 1.010 and is showing no more activity. The flavor is clean and I'll be racking it to keg tonight. The batch with the new 3944 in a 1.5 liter starter is still at 1.024 and still chugging along.

Unwashed slurry can only be used within a couple weeks? Busted.

Obviously the slurry collection method and handling is important and I really do recommend the sniff and taste test. Boil the mason jar and lid and keep the slurry in the fridge.

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just curious if i missed something......but if your not washing, why boil the mason jar instead of starsan? or do both work equally as good for this?

I think boiling give you the satisfaction of knowing that you made the jar an extreme environment not livable for most fungus or spores. Beyond that I don't know why you wouldn't wash the yeast

Pure laziness.

so starsan is just as good as boiling for this?

One idea behind boiling the water is to remove the oxygen (but I guess that doesn't matter if you aren't washing the beasties)

wow, resurrected thread, but i'll chime in:

how to tell on the fly? other than i microscope, i don't know any tell-tale signs. a starter is the only definite test i can perform.

i'm no expert, but i had an 10oz jar of wlp400 wit slurry hanging out in my fridge for at least 6 months. pitched it into a wit and had busy fermentation within 12hrs. it didn't smell like puke, but had the same pungent odor i get when i brew my wit with wlp400. that jar was the oldest slurry i've ever tried. i usually use them within 2 months.

a while back, i had tried splitting some white labs tubes into 4 12oz bottles filled with refrigerated sterile wort and stuck them directly back into the fridge with plans of step culturing when needed. looking back at my notes, i see that had a wlp400 (1st generation portion of a yeast tube) from may 08 that was in my fridge up until july 09 that cultured up with no problem. 14 months. thank you mr. chris white.

you mileage may vary, but i'll vote that wlp400 slurry can hang around for at least 6 months with no problem. other strains may differ.

btw, i've never boiled my slurry bottles/jars. just soaked them in a strong solution of iodaphor...probably 4-5x recommended strength

lately, i've been washing my yeast. i boil my water to remove the oxygen, but i still just sanitize in strong iodaphor. no problems as of yet with 4 batches of yeast.

FWIW...

I heard a podcast (http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2007 scroll to March 22, 2007) with Murl Landman of National Chemicals Idophor. He said at no rinse strength idophor is not toxic to yeast. He did say stronger than no rinse can be toxic to yeast. Don't recall how strong toxic is though.

Obviously this hasn't been your experience.

I freeze yeast. I would guess they last indefinitely that way, on glycerine. I stepped up a starter this week with a 6 month old frozen vial without any problem.

Inspired by this thread I pulled a 1-gallon jug of WLP940 (Mexican Lager) out of the fridge. It's from a Vienna Lager that was transferred from the fermenter to keg in September of last year. I can't remember whether I washed it or or just poured off a slurry. There was a thick layer of clean yeast without any obvious trub under the gallon of clear amber liquid, so I probably washed it. Smelled like beer when I gave it the sniff test, though. There weren't any obvious off odors. I didn't taste the liquid. The yeast layer was darker than the usual creamy beige but wasn't anywhere near peanut butter. There was a little slick of darker material that swirled up when I pulled the jug from the fridge.

I made a 2L starter wort with 200g (about 7oz) of light DME boiled for 15 minutes. Boiled off a little more than expected and came in at 1.042. Cooled the wort to 75° before pitching the yeast. The obligatory ******* moment came when decanting the liquid off the top of the yeast. I poured off most of the liquid, but most of a gallon jug still leaves quite a bit. Doh! I had about a quart of slurry after swirling the yeast back into suspension. After pitching I ended up with about 3L of 1.028 wort (according to the Beersmith dilution calculation). Perhaps the yeast will appreciate the slightly weaker wort as they try to recover.

I've got it on a stir plate and will let it go for three or four days and see what happens. I'll post back here with results. With any luck I'll have a decent harvest of this yeast, which I really liked in my Señor Misterioso, Negra Modelo-style Vienna. I'd like to make this my house lager yeast. I'm annoyed that I've waited this long to reculture it. Thanks, Bobby, for the jump-start.

Chad

yesterday i washed a 1L starter of 1187 ringwood i made in may (i split the smack into 2 1Ls). half the cake was light cream brown tint. the other half is nice cream white. i was only tryin to save pure cells to start a frozen bank. now it seems slanting is more user friendly. and especially now that i hear a year with trub and dead brothren a year is no problem, slants should last waaaaay longer and you can take from them and put em back. you cant freeze and thaw and freeze.

Ah well, it was worth a shot. After three days on the stir plate the wort had a pretty bad smell and the OG hadn't dropped by so much as a point. My fault for letting the original slurry go as long as I did. I really liked that yeast and should have done something like this much sooner.

Chad

passedpawn said:

I freeze yeast. I would guess they last indefinitely that way, on glycerine. I stepped up a starter this week with a 6 month old frozen vial without any problem.

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What do you do? Make little yeast starters in test tubes and pour glycerin over the top of the starter inside the tube, shove in a cooler and stick them in deep freeze?

Found an excellent pic worth sharing



http://braukaiser.com/wiki/index.php?title=Making_Plates_and_Slants

I made up a 1.5 litre starter for my brew last Saturday. I used some washed 1056 from an IPA i brewed in Jan-Feb, so it was around 9 months old . The yeast passed the very scientific sniff test and after around 8-10 hours on the stirplate was doing quite well. Pitched the entire starter and its been fermenting like mad for a couple days now. I have to say i am pretty impressed that it took off like it did.

StAnthonyB said:

What do you do? Make little yeast starters in test tubes and pour glycerin over the top of the starter inside the tube, shove in a cooler and stick them in deep freeze?

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woops... missed this. Yes, that is about how I do it. There is a good tutorial from FlyGuy regarding frozen yeast banking. I don't have/use a pressure canner though, just starsan.

I do wash my yeast but I go further and use potable aqua tablets. I follow all the normal steps but when I get to the quart stage I mix in a potable aqua tablet and let it do it's thing. So far... so good.

It's always been my assumption that if you keep washing yeast over several beer generations you will eventually end up with low-flocculating yeast. However, that is just my unchecked assumption.

This year I've waited 3-4 months to pitch washed Pacman and Wyeast 3655 (Schalde) and they both fermented just fine. I plan on doing a belgian Jan. using the 3655. By that time it'll have been 5 months w/o use. The three jars I have look pretty bad, not very creamy anymore. I'll update to let everyone know of the results.

I use this method all the time now. Have my fridge fillede up with bottles with different yeast strains.

I don’t wash the yeast either, simply swirl up the sediment from my carboy and transfer to bottles and cap, and since I started using this method (8 months ago) I haven’t had an infection or a bad vial either.

thanks bobby for another very helpful thread-- subscribed.

Bonde said:

I use this method all the time now. Have my fridge fillede up with bottles with different yeast strains.

I don’t wash the yeast either, simply swirl up the sediment from my carboy and transfer to bottles and cap, and since I started using this method (8 months ago) I haven’t had an infection or a bad vial either.

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I do this as well. I just swirl and dump the yeast into sanatized mason jars, no washing. I must say I don't even boil them for short term storage. I just sanatize and dump the yeast. I just did 2 beers with some saved 1028 for a bitter I made. One was a Barleywine started OG 1.103 and in 6 days hit the expected FG of 1.022. If I am going to store the yeast for longer I will boil the mason jars but I usually only hold on to them for a month or so and have had no problems with the swirl and dump method.

jlpred55 said:

I usually only hold on to them for a month or so and have had no problems with the swirl and dump method.

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My assumption is that you're collecting trub along with the yeast cake using this method. Is there any noticeable effect from this?

I bought a flat of small mason jam jars and boiled them in some water, then let the lids seal on them while they cool. Now, when I have a primary transfered I just pop two open and dump the water into my pirmary, swish it around and pour it back into two jars. When I brew, I will use one jar to make a starter with and save the second as a back up in case I forget to catch a primary down the road. easy and quick way to save money per batch!

wow this thread has been going for a while.

Let me get this right, I don't have to wash the yeast I can save some trub in a mason jar for 6+ months and make a starter with it?

I am going to have to rethink some things.

i was about to ask the same thing!

Don't get me wrong, this isn't something I'd recommend or do on a regular basis. I'll collect yeast cake in a sanitary jar in the most sanitary way I can and put it in the fridge. If I find the time to go through a yeast rinsing process, I will. In either case, I'll go ahead and direct pitch that sucker within say a month. If it's been sitting for over a month, I'll make a starter (don't forget to label the jar with strain, generation, and collection date. I guess the main point I wanted to make with the original post is that it's a myth that all the yeast is going to die or get infected in a couple months of sitting around.

Add another name to the list of people who do this. I started off re-using yeast by brewing on racking day and pitching right onto the cake. I decided after a few batches that this was TOO much yeast for the new batch. Now I just fill a sanitized mason jar with some trub and re-use it pretty much like Bobby does.

Me three.

What temps are you storing the mason jars?