How much yeast to pitch?

[Ckilner]

I brew 5 gallon batches and if I'm using a new liquid yeast I make a starter of 10% DME and add one pack of yeast.
After the brew I harvest the yeast and then for the next brew, I make another starter but I can't decide how much harvested yeast should I add? The volume of harvested yeast I have available is much more than the original new yeast pack so I have lots of it available.
I've read that too little yeast causes flavour trouble with a slow starting ferment but also too much yeast causes flavour problems too.

 

[Yob]

Check out Mr malty

The yeast pitching calculator is a good place to start


How much to pitch depends on a few factors

 

[Ckilner]

So when pitching from slurry (I assume this means harvested yeast), it's a matter of judging how thick the slurry is (thin to thick) and estimating how much active yeast is in it?
Guesswork and experience?

 

[Yob]

thick yeast, is yeast that has settled out, Ive always found this to be the best guide. 1 cup of slurry has (everything else being equal) usually enough for a pitch if not a bit more than, Id always rather have a bit much than not enough.

 

[Ckilner]

so do you make a starter with the slurry and then pitch that?

 

[Yob]

depends on the age.. if its more than about a month old, its a good idea, if you have taken it right from a previous ferment, its likely good to go..

when I say a cup, I also mean this to be for an ale of not more than OG ~1.055.. you will obviously need more for higher gravities / lagers

 

[mofox1]

Sounds about right... I did my first repitch the other night using about two cups worth of unwashed slurry and it went absolutely apeshit.

The slurry was after pretty much completely emptying all beer from the fermenter (maybe 250 - 500ml remaining), and adding 500ml cooled boiled water to the fermenter. Gave it a swirl, let it settle a couple of mins and poured back into 500 ml jug.

So for what it's worth, whatever that adds up to in yeast is, is too much!

 

[Ckilner]

ok, so I think I'm not too far off the mark with what I've been doing. The only thing I can't work out is how much slurry to add to a starter of say 1L. Let's say I have 200ml of slurry that is 1 month old so viability is probably 50%. If I need 250billion cells for my brew then how much do I add to 1L of DME for a 1.046 OG brew.

 

[Matplat]

I was under the impression (perhaps incorrectly) that the volume of the starter determines the final cell count. i.e. the yeast reproduces as far as it can, so if you have fewer yeasts to begin with your starter will simply take a bit longer to finish but you will have the same amount at the end.

It is highly possible that I'm completely wrong though...

 

[sponge]

Having less yeast also puts more stress on the yeast and as a consequence, produces undesirable esters (along with fermentation issues).

If in doubt, over-pitch. Happy yeast makes happy beer

 

[mofox1]

Having less yeast also puts more stress on the yeast and as a consequence, produces undesirable esters (along with fermentation issues).

If in doubt, over-pitch. Happy yeast makes happy beer

Although possibly a mess in the fridge... even at 17*C my two cup pitch of WLP001 slurry has resulted in krausen blowing through the airlock. Fun times.

 

[Ckilner]

I was under the impression (perhaps incorrectly) that the volume of the starter determines the final cell count. i.e. the yeast reproduces as far as it can, so if you have fewer yeasts to begin with your starter will simply take a bit longer to finish but you will have the same amount at the end.

It is highly possible that I'm completely wrong though...

That was my impression too but I could be wrong too. It would seem reasonable that it would be the case. If you want more cells then you add a bigger starter, however if I add a large volume of yeast to a starter , say 500 billion cells then they'll soon munch through the DME and not increase their number too much. If I then add that starter to the brew it would (according to what I've read elsewhere) be too many cells for the size of brew. Perhaps I should get a microscope and count them

 

[sponge]

Although possibly a mess in the fridge... even at 17*C my two cup pitch of WLP001 slurry has resulted in krausen blowing through the airlock. Fun times.

You need a bigger fermenter

 

[mofox1]

You need a bigger fermenter

Oh no, because that will start that whole head space thing again.

I do reckon it's probably about time to brew bigger batches, do maybes a 60 is the way to go.

So much brew crap collected over so few short years....

 

[sponge]

As long as you rehydrate your yeast first then head space doesn't matter

h34r:

 

[Topher]

Won't someone pleeeaassee think of the poor kittens.

 

[big78sam]

As long as you rehydrate your yeast first then head space doesn't matter

h34r:

I thought you could get botulism from rehydrating yeast h34r:

 

[sponge]

Lets not derail the thread by bringing cubes into this.

 

[Ducatiboy stu]

Or no-chill

 

[Danscraftbeer]

I use MrMalty http://www.mrmalty.com/calc/calc.html
Comparing with Beersmiths yeast calculator as well. Beersmith seems to recomend almost twice what Mrmalty recomends but
Mrmalty calculations seem like Plenty! Ales brew out in 2 to 3 days for the main part. I usually go a touch over thecalcs. I'm quite sure I'm always overpitching.
The time and thought doing this gets you into the ball park of correct balance at least.

Another thing to consider is how many brewers out there just put their new beer wort onto the entire yeast cake of the last brew.
That would be extremely over pitching (possibly 6 times as much as needed!) but many swear that it works fine.