Yeast slurry

[Michael Burnley]

It has finally occurred to me that I don't need to buy fresh liquid yeast for every brew I make. I have now started to collect the slurry and I'm keeping it in sterilised kilner jars in the fridge, I'm filling a 1 litre jar.

So when using the slurry next time, how much of this should I pitch?

And is it as simple as draining off any liquid/beer leftovers, bringing it up to room temp and then pitching it into the wort?

How long can I store it in a fridge?

Mick

 

[The Baron]

i Think there are some calculators on brewing engine sites but just as a laymans way I would use about 1 third in a standard 20 to 23ltr brew, I am sure you will get better and more accurate advice as there are some members who are more scientific than me when it comes to cell counts and pitching I would not keep my slurry more than 4 weeks but again that is not cast in stone

 

[Linalmeemow]

I would not keep my slurry more than 4 weeks but again that is not cast in stone

In a pinch I've used slurry that was over 6 months old with no starter. Beer came out at least as good as usual. Don't waste good yeast!

 

[terrym]

Try these
https://www.thehomebrewforum.co.uk/threads/yeast-slurry-storage-reuse-advice.90227https://www.thehomebrewforum.co.uk/...mount-of-harvest-yeast-into-next-batch.88343/https://www.thehomebrewforum.co.uk/threads/trub-yeast-re-use.85651/
If its any help I recover trub from a brew into a sanitised pint glass which is then kept in the fridge for usually no longer than two weeks, after which I will dump it. When I use it I take about three tablespoons off the top of the settled out trub and use that in brews of about 20 litres. I will not re-use trub past three generations. And that's about as scientific as it gets, but it works for me.

 

[DocAnna]

My favourite pitch calculator is the one at brewers friend - the problem for yeast slurry is knowing how many billion cells there are in your slurry. This will depend on what it's been harvested from so whether it contains trub and how much, and whether you've rinsed the yeast to purify it.. oh and how long you have kept it and at what temperature.... so I guess not that much help after all .

There is this from Wyeast which I like Yeast Harvesting / Re-Pitching | Wyeast Laboratories that quotes:

Estimates of cell counts can be made using percent yeast solids of the slurry. Percentage of yeast solids per volume of slurry can be estimated by allowing a sample to sediment under refrigeration and estimating the percent solids. Generally 40-60% yeast solids will correlate to 1.2 billion cells per mL.​

so the precipitated yeast solids would by this rule have 2-3 Billion cells per ml. This allows you to work out how much to use in the cells per ml pitch calculator. I'm not sure how to work out the age effect for slurry since it depends on how it's stored. You should store it ideally close to zero but not frozen and under a layer of water - I use bottled water for this for convenience of not having to boil it.

Anna