[Iliff Ave]

I have some old slurry that was harvested back around the middle of August. How much should I use to make a starter for a 5 gallon batch of 1.064 IPA? I normally just repitch slurry but since this is so old I would like to make sure I am getting enough healthy yeast. I was planning on a 1L starter if that's realistic.

[Bob357]

How long is a string?
 If you age the  slurry at the same rate as liquid yeast, the viability would be about 35 to 40%. Estimating the cell count of a slurry is making an educated guess based primarily on thickness, volume and % of trub/hop matter it contains.

[Iliff Ave]

How long is a string?
 If you age the  slurry at the same rate as liquid yeast, the viability would be about 35 to 40%. Estimating the cell count of a slurry is making an educated guess based primarily on thickness, volume and % of trub/hop matter it contains.

So just throw some random amount of slurry in and hope for the best?

[denny]

How long is a string?
 If you age the  slurry at the same rate as liquid yeast, the viability would be about 35 to 40%. Estimating the cell count of a slurry is making an educated guess based primarily on thickness, volume and % of trub/hop matter it contains.

So just throw some random amount of slurry in and hope for the best?

That's pretty much what I do.  Never failed me.  I shoot for around a couple Tbsp.

[Robert]

Wait, I think I hear Denny coming... what will he say?  I'll proactively agree with him here.  Take about a third of what you normally would pitch, make a 1L vitality starter, and pitch the whole thing at high kräusen.   You should be able to repitch as usual for the next batch.

(Ahh, Denny got here while I was typing...)

[denny]

Wait, I think I hear Denny coming... what will he say?  I'll proactively agree with him here.  Take about a third of what you normally would pitch, make a 1L vitality starter, and pitch the whole thing at high kräusen.   You should be able to repitch as usual for the next batch.

Beat ya.....just barely!

[Iliff Ave]

Thanks guys.

[EnkAMania]

I have my doubts about those doom and gloom yeast death projections.  I have my mason jar of slurry, do a vitality starter 4-5 hours prior to pitch.  I haven't had issues and have used year old or more slurry.

[Iliff Ave]

I have my doubts about those doom and gloom yeast death projections.  I have my mason jar of slurry, do a vitality starter 4-5 hours prior to pitch.  I haven't had issues and have used year old or more slurry.

Good to hear. I don't normally make starters. I will give the vitality starter a go.

[Robert]

I have my doubts about those doom and gloom yeast death projections.  I have my mason jar of slurry, do a vitality starter 4-5 hours prior to pitch.  I haven't had issues and have used year old or more slurry.

Good to hear. I don't normally make starters. I will give the vitality starter a go.

I don't normally make starters either, except for the first generation, then just repitch slurry.  But when it's been sitting long enough that it makes you nervous, the vitality starter is a good piece of insurance.

[a10t2]

I'll second the general consensus here so far... I routinely re-pitch yeast in this way, since I've rarely had time to brew lately and no LHBS.

In my experience the "doom-and-gloom" has been accurate. I can't say to have much or any experience outside of a few strains, but broadly speaking I think viability of relatively small amounts of slurry stored under beer drop into the 80s relatively quickly (a few weeks) but then decline more slowly. I've seen 55% in a 19-month old slurry of 1272, though methylene blue staining is known to be inconsistent below 75%-ish (and even in general) so take that for what it's worth.

Long story short, take a couple tablespoons of packed slurry (30 mL), that would be about equivalent to a fresh smack pack or vial or whatnot when harvested, so even if viability is down to 50% you're in the ballpark. Give them oxygen and nutrients and yeast will reproduce until they run out of substrate, and a 1 L starter at 8°P will net something like 100-150 billion fresh cells in my (again, strain-limited) experience. (And for my brewing practices would be slightly underpitching in a high-gravity beer, but take that for what it's worth.)

[Iliff Ave]

I'll second the general consensus here so far... I routinely re-pitch yeast in this way, since I've rarely had time to brew lately and no LHBS.

In my experience the "doom-and-gloom" has been accurate. I can't say to have much or any experience outside of a few strains, but broadly speaking I think viability of relatively small amounts of slurry stored under beer drop into the 80s relatively quickly (a few weeks) but then decline more slowly. I've seen 55% in a 19-month old slurry of 1272, though methylene blue staining is known to be inconsistent below 75%-ish (and even in general) so take that for what it's worth.

Long story short, take a couple tablespoons of packed slurry (30 mL), that would be about equivalent to a fresh smack pack or vial or whatnot when harvested, so even if viability is down to 50% you're in the ballpark. Give them oxygen and nutrients and yeast will reproduce until they run out of substrate, and a 1 L starter at 8°P will net something like 100-150 billion fresh cells in my (again, strain-limited) experience. (And for my brewing practices would be slightly underpitching in a high-gravity beer, but take that for what it's worth.)

Very helpful thanks. I was mainly worried because the mr malty calc was saying that my yeast only has 10% viability if harvested back in mid august. I may consider a slightly larger volume to get more healthy cells.

[Iliff Ave]

Well I made a regular starter about 36 hours before brewday. Everything seemed to be good but when I went to smell the starter I was getting some notes of nail polish remover (acetone?). Obviously I decided not to use it and luckily had a back up pack of dry yeast. I assume the acetone odor is related to an infection?

[Slowbrew]

Well I made a regular starter about 36 hours before brewday. Everything seemed to be good but when I went to smell the starter I was getting some notes of nail polish remover (acetone?). Obviously I decided not to use it and luckily had a back up pack of dry yeast. I assume the acetone odor is related to an infection?

This is purely anecdotal and the beer is still fermenting so take this as is please...

I used a slurry of WY1010 American Wheat to make a starter last week.  When I went to pitch it smelled gawd awful.  I had no backup so I decided, since starters never smell exactly 'right" anyway, I pitched it in the wort. 

So far the bubbles coming through the air lock smell great.  I may be greeted by an ugly mess when I go to keg it but for now it seems to be working fine.

Fingers crossed...

Paul

[denny]

Well I made a regular starter about 36 hours before brewday. Everything seemed to be good but when I went to smell the starter I was getting some notes of nail polish remover (acetone?). Obviously I decided not to use it and luckily had a back up pack of dry yeast. I assume the acetone odor is related to an infection?

This is purely anecdotal and the beer is still fermenting so take this as is please...

I used a slurry of WY1010 American Wheat to make a starter last week.  When I went to pitch it smelled gawd awful.  I had no backup so I decided, since starters never smell exactly 'right" anyway, I pitched it in the wort. 

So far the bubbles coming through the air lock smell great.  I may be greeted by an ugly mess when I go to keg it but for now it seems to be working fine.

Fingers crossed...

Paul

My experience is the same, Paul.