Month old slurry. Vitality starter or nah?

[tyrub42]

I usually pitch slurry directly if it's 2-3 weeks old, but make a starter if it's over a month. In this case it'll be exactly 1 month since I've harvested. Normally I'd make a big vitality starter for two jars to split between two batches, but I'm trying to simplify everything as much as possible lately (malt bills, hops schedules, yeast practices, etc etc). I've read wildly conflicting info on how quickly slurry looses it's cell count, so not really sure which way to go on this one. What do you all think?

Thanks!

P.S. the slurry came from a 5.3 abv beer with low IBU and no dry hops if that influences your vote

 

[Miraculix]

It highly depends on the yeast strain. I had half a year old kveik behave like day one and Imperial pub being literally dead after two months. Both stored under same conditions in the same fridge.

 

[jtratcliff]

Tough call... This one is right on the edge... But most likely your cell count was way high from the collected slurry...

I'd probably chance or myself but wouldn't council anyone else to do so

 

[TheBluePhantom]

I just repitched into a cheap experiment batch (another thread...). The yeast had sat under the beer, refrigerated for at least 4 or 5 months. It fired up in less than a day and is banging away now. I think that was US-05. With 5.3 abv at one month, I would say pitch a little more slurry if you are worried about it, but it should be pretty good.

@Miraculix how high was the abv on that imperial pub? Could that have killed it?

 

[IslandLizard]

One month in the fridge?
Use it as is, no starter needed. Just estimate your cell count to pitch.
And oxygenate that wort well, or at least aerate it.

 

[Miraculix]

I just repitched into a cheap experiment batch (another thread...). The yeast had sat under the beer, refrigerated for at least 4 or 5 months. It fired up in less than a day and is banging away now. I think that was US-05. With 5.3 abv at one month, I would say pitch a little more slurry if you are worried about it, but it should be pretty good.

@Miraculix how high was the abv on that imperial pub? Could that have killed it?

Nope, it was around 4%.

 

[tyrub42]

Ok seems like I should be ok without but if I have time I could always fire one up for a quicker liftoff. Thanks everyone!

Btw what cell density per ml do you usually use if calculating for the jars in the fridge where the slurry settles down and compacts under the beer? (This includes hot break but no hop matter). The jars are 450ml but the yeast has compacted down to about 200-250 with the beer on top. What's a safe bil/ml count for just the compacted yeast cake?

 

[IslandLizard]

Ok seems like I should be ok without but if I have time I could always fire one up for a quicker liftoff. Thanks everyone!

Btw what cell density per ml do you usually use if calculating for the jars in the fridge where the slurry settles down and compacts under the beer? (This includes hot break but no hop matter). The jars are 450ml but the yeast has compacted down to about 200-250 with the beer on top. What's a safe bil/ml count for just the compacted yeast cake?

Mr. Malty has always been my preferred calculator for the "pitching from slurries" tab. Sadly, it's defunct now, since Flash Player got axed late last year.

Here's the help/instruction page for it, alas without interactive sliders:
http://www.mrmalty.com/calc/repitch.htmlIt still gives you a decent insight into estimating yeast content in saved out slurries containing non-yeast content (trub).

For calculating pitches I use:
BrewUnited's Yeast Calculator

 

[monkeymath]

It highly depends on the yeast strain. I had half a year old kveik behave like day one and Imperial pub being literally dead after two months. Both stored under same conditions in the same fridge.

I second that. And I feel that things can go down south very quickly:

I had brewed a beer (with WY 1469) and stored top-cropped yeast in a jar in the fridge.
Two weeks later, made a starter using just some of the yeast for my next brew: the starter went nuts after just a few hours. I certainly could've pitched the yeast straight.
Again, I top-cropped, another four weeks later I made a starter using all of the yeast: it took roughly 60 hours to show signs of life, and I ended up pitching a starter made from a fresh pack instead.

By the way: the first beer was actually stronger than the second one (about 6.5% and 4.7%), so the alcohol content is not to blame here.

 

[tyrub42]

Mr. Malty has always been my preferred calculator for the "pitching from slurries" tab. Sadly, it's defunct now, since Flash Player got axed late last year.

Here's the help/instruction page for it, alas without interactive sliders:
http://www.mrmalty.com/calc/repitch.htmlIt still gives you a decent insight into estimating yeast content in saved out slurries containing non-yeast content (trub).

For calculating pitches I use:
BrewUnited's Yeast Calculator

Oh I totally forgot they used flash. That's a bummer. Idk about their timelines, though. They said slurry would be dead within a crazy short time. I've never had slurry die on me at all, and it's always gone well in starters even if it's 6-12 months.

Now that I'm reading about these stories of slurry being dead in a matter of weeks, though, I guess it's just super strain specific.

 

[tyrub42]

I second that. And I feel that things can go down south very quickly:

I had brewed a beer (with WY 1469) and stored top-cropped yeast in a jar in the fridge.
Two weeks later, made a starter using just some of the yeast for my next brew: the starter went nuts after just a few hours. I certainly could've pitched the yeast straight.
Again, I top-cropped, another four weeks later I made a starter using all of the yeast: it took roughly 60 hours to show signs of life, and I ended up pitching a starter made from a fresh pack instead.

By the way: the first beer was actually stronger than the second one (about 6.5% and 4.7%), so the alcohol content is not to blame here.

These stories are wild to read. I've never had slurry die on me even in 6-12 months, and it's really good to know that is a possibility. Maybe a starter is a good idea after all just to make sure it's alive. Familiar with the overall strain London iii but this is my first time using the dried version

 

[IslandLizard]

They said slurry would be dead within a crazy short time.

That's not true. Although it looked miserable when moving that age slider, it may picture a conservative worst case scenario.
Yeast loses viability with age, there's no denying that. When refrigerated, under beer, a rule of thumb viability loss is about 10% per month, or 50% per 6 months. Some fare better, others worse, also dependent on how it was handled and stored.

I've woken slurries that were over 3 years old. Kept in the back of the fridge, in a small 8x10x5" box with others small jars of slurries.

 

[tyrub42]

That's not true. Although it looked miserable when moving that age slider, it may picture a conservative worst case scenario.
Yeast loses viability with age, there's no denying that. When refrigerated, under beer, a rule of thumb viability loss is about 10% per month, or 50% per 6 months. Some fare better, others worse, also dependent on how it was handled and stored.

I've woken slurries that were over 3 years old. Kept in the back of the fridge, in a small 8x10x5" box with others small jars of slurries.

Yeah my experience is similar to yours (never gone over a year though, that's pretty badass), but the Mr Malty calc listed viability decreasing much faster than 10 percent per month for slurry, at least when I used it. I think it was closer to 50 percent and by something like 3 months it was basically just dead. I wish I could go check to confirm, but since the calculator is no longer around, all I can say is maybe there was a setting to change that I messed up and I was using it incorrectly.

Once I read 10 percent/month I felt much better, although I don't know if that number is actually accurate or if I just want it to be. Hopefully it is, though, as that makes slurry way more viable long term

 

[IslandLizard]

Once I read 10 percent/month I felt much better, although I don't know if that number is actually accurate or if I just want it to be. Hopefully it is, though, as that makes slurry way more viable long term

BrewUnited uses a decline of 10%/month. Other calcs may well use a similar attrition rate.
It's been working for me for many years.

Even with a 10% decrease in viability per month, (~50% decrease over 6 months), that doesn't mean it's dead after 12 months (1 year). Viability would still be around 25%. After 18 months around 12%, etc. YMMV

 

[odie]

My last couple beers were some slurries almost a year old. Yeast woke up just fine. Have not tapped the kegs yet to taste...but they fermented as normal.

 

[tyrub42]

My last couple beers were some slurries almost a year old. Yeast woke up just fine. Have not tapped the kegs yet to taste...but they fermented as normal.

Wow you did those without starters? Definitely the longest I've heard of. Glad they turned out well!

I ended up doing a small vitality starter. Probably wasn't necessary, but after the talk of not knowing for sure whether the yeast was still viable, it seemed like a good bet. Woke up in the vitality starter right away and is now happily fermenting in some beers

 

[CascadesBrewer]

I ended up doing a small vitality starter. Probably wasn't necessary, but after the talk of not knowing for sure whether the yeast was still viable, it seemed like a good bet. Woke up in the vitality starter right away and is now happily fermenting in some beers

That was probably the best option. I find that if there is every anything that I question doing, any flaws in the beer I will blame on my shortcut...or I will even search for flaws that don't exist and blame them on my shortcut. ("I just know there are some musty flavors from that 2 year old crystal malt...it must be in there somewhere!") It is a downside of being the brewer. You know every ingredient in the beer and every mistake made in the process.