Overbuilding yeast and yeast count

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For one of my most recent brews I over built the yeast (Fermentis Saflager W-34/70)

I used a calculator to over build by about 150bn cells.

I then swished it about and decanted to a few plastic vials.

It's been settled for a few weeks now.

Here are two photos exactly a month apart.

20211016_181500.jpg
20211115_134939.jpg


These are my questions to the great collective knowledge in the virtual multiverse:

1. I have no idea whether this is 150bn cells. Can someone with a reasonable level of certainty give me a rough idea what I have here please?

EDIT: To put this question in to perspective, I have some written notes that says "3bn/ml in clean settled top crop" So whilst I appreciate this is not not cropped, it's still clean, settled yeast. So this could be as little as (7x3)x3bn = 63bn or less. Or more.

2. Is the darker stuff on top viable yeast or crap from the starter process.

3. Comparing the two photos, it looks like the darker stuff is slowly creeping down from the top. Is this cause for concern?

I thought that overbuilding was likely to give you yeast that could be stored for a longer time.
 
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xozzx

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I usually overbuild starters and had exactly the same concerns as you... after a while I just gave up caring and now I just make a new starter from what I overbuilt and guess at the size to make. 1.050 and 3 month old yeast I do around 250ml starter to get it going then pitch that into 1L starter for brewing. 1.080 I do the same followed by an additional 2L starter and cold crash this to decant the "beer" from ontop. Add a "bit more" if you want to overbuild again.

I could be getting it very wrong so interested to hear if anyone has a more scientific answer. So far I havent had issues but it doesnt mean Im doing it right!
 

xozzx

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I have also started saving the slurry from some beers, particularly when using Kviek and this is even harder to judge cell count... few tablespoons in a 500ml starter, see how it reacts... slow then I build it more, goes like a rocket then should be good enough....
 

BlackRegent

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TBH thinking about this gives me a headache and I have tried to stop caring.

I overbuild by 100 billion cells, then decant part of my fully mixed starter into a 300ml or so jar, which I then use to make my next starter on the assumption that what is in the jar is roughly equivalent to one pack of shop bought liquid yeast as at the day it was made (with cell count decreasing thereafter). This rough and ready approach seems to work and so I don't worry about being more precise.

I appreciate that this doesn't answer your question, but might give you some reassurance that complete precision probably doesn't matter.
 

Galena

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I overbuild by 100bn cells because that is what is supposed to be in a new pack of liquid yeast (WLP at least), you have to believe the calculator for yeast count I guess and its hopefully a close proximity. I store mine in a Kilner type jar and label it with the date I made it which I then use as a manufacture date for the next time I use the calculator and build another starter also with 100bn cells overbuild.
With regards question 2) When I come to use the stored yeast I pour off the excess wort then shake it up to pour into the new starter, there is always a little darker stuff but a product of the DME boil I presume and I just ignore it. It would be a different matter if you were top or bottom cropping and some then stipulate yeast washing, but I have only ever overbuilt yeast so never needed to consider the long winded process of washing it.
3) No cause of concern as far as I am concerned.

So far as longevity is concerned as said, I assume 100bn cells when just made and use the calculator to work out its viability from my manufacture date.
 

foxbat

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I'll just reiterate what the others have said. I used to wonder whether I'd built what I expected but it worked out every time so I gave up thinking about it.

Now I just look at my supposed 100bn and think, yeah that looks about the same as I pour out of a Wyeast pack so I'm happy.

The dark stuff is DME trub and is completely normal.
 
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I'll just reiterate what the others have said. I used to wonder whether I'd built what I expected but it worked out every time so I gave up thinking about it.

Now I just look at my supposed 100bn and think, yeah that looks about the same as I pour out of a Wyeast pack so I'm happy.
I get all that, and I'm all for not worrying about stuff, but as this is my first overbuild, I can't actually say "yeah that looks about right" hence asking you lovely people :thumbsup:

Maybe, even if it is as 'low' as 60bn then I'm sure it will build up to 150/200bn in short order in a 2 litre starter.

The dark stuff is DME trub and is completely normal.
Good to know - thanks

Exciting isn't it doing things for the first time when you haven't got a clue what you're doing :D
 
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bobukbrewer

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I use all of the slurry from a 22 litre batch for the next batch, and so on, 4 times max, restart with sediment from one of the bottles in batch 1 and use the next 2 resultant slurries. Of course, in around 40 years, I will have to buy another packet of yeast.
 
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I use all of the slurry from a 22 litre batch for the next batch, and so on, 4 times max, restart with sediment from one of the bottles in batch 1 and use the next 2 resultant slurries. Of course, in around 40 years, I will have to buy another packet of yeast.
What?!
Buy another pack of yeast after only 40 years!
Your accountant will have a fit.
ps, I do very similar to you, and only do washing of the yeast slurry if pitching in to a seriously paler brew.
I must confess I have split the saved yeast, there being so much at times, that I've no idea now what generation it's on.
It was Wilko Gervin/Danstar Nottingham ale yeast originally.
It still ferments nicely and drops clear with no funny flavours evident.
Famous last words, my next brew will probably taste of a farmyard on a bad day!
🤢
🤮
🥴
😂
 
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To give a small update on this thread... and it's always good to explain exactly what you did and what happend.

In the end I had 5 small vials containing ~5ml of settled yeast

I used the lower reading of 3bn/ml which works out at 75bn cells (but may have been higher)

I used this in ~2.2litre starter to make ~250bn cells for a Marzen lager and ~100bn cells overbuild**.

It was a really healthy ferment and got to final gravity in about 4 days (W-34/70 at 17°c)

**This 100bn cells is currently settling in the fridge, that is currently looking like being 4 vials with 5ml of yeast which if we assume is actually 100nb cells would in theory work out to 5bn cells/ml
 

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