Over Pitching?

[Filby]

Hi!

From a previous brew I have collected the yeast and washed it a few times. I'm looking at doing another brew on Sunday and was wondering how much of the washed yeast I should use? I reckon ive got around 200ml of pure yeast sitting at the bottom of the yar but I assume there is such a thing as overpitching? Also is there some technique to overcome any bacteria that may be in with the yeast, such as a starter that has a lot of yeast cells in it?

Cheers for any help!


Fil

 

[Cube]

250 mls is ample mate. Just biff it all in and stir it. Better still biff it into a half full fermenter then top up with water using the water to aerate and mix it.

 

[Fourstar]

if its unwashed slurry my rule of thumb is:

1/2 cup for ale @ 1.050~ @ 23L
1 cup for lager @ 1.050~ @ 23L

as for washed yeast solids:

assume 4.5 billion cells per ml of compacted yeast solids, using that we perform the following:

750,000 cells required per ml of wort * ml of total wort * deg plato of beer

750,000 * 23000 * 12.5 (1.050 OG) = 215.63 billion cells required to ferment the beer at ample pitching rate and cell growth etc.

so, 215.63/4.5 cells per ml of yeast solids = 47.91ml of yeast solids required to pitch into said beer. Double 750,000 in the equation or double the final figure for that of whats required for a lager of equal volume and deg plato.

hope this helps.

 

[Filby]

Cheers for the info. Screwtop also sent me a link to a nice calculator which came out with the same result.

If I chucked in 100ml is there any penalty?

Also, by pouring off the water on top of the washed yeast, does that reduce the chance of infection?

 

[Fourstar]

generalised penalty = minimal cell growth = minimal yeast derived flavours.

tip the water, it has no place in your beer. if i ever wash yeast (which is almost never) i dump the water, rouse it in some of the wort and dump that into the fermenter.

cheers.

 

[Ian Gommers]

DO IT!!!!!! ......................and learn from the results.....good or bad it's the learn'in that counts.

 

[Lecterfan]

DO IT!!!!!! ......................and learn from the results.....good or bad it's the learn'in that counts.

How true - pity I have to keep learning it all the hard way haha.