Pitching

[eclipse]

I have been hearing a lot of people on here talking about over and under pitching. How do I work out how much yeast to use? I am, planning to clean and reuse the yeast from a previous batch then make a starter....makes things a little different when you aren't using the standard whitelabs tube.

Is there a way of working out how much to use per litre?

[Kev888]

The Mr Malty calculator can help - make sure you select your preferred units in 'preferences' and then set your perameters in the 'repitching from 'slurry' tab. It depends both on the quality and age of the slurry as to how many viable cells remain, though its quite a simple calculator so must make assumptions about how well you looked after it and so on.

Cheers
kev

[eclipse]

Thanks for the link.....but I am so confussed!!


In the pitch from slurry bit, does the ml of yeast needed mean the actual amount of cleaned slurry, which is normally a think clay thickness? Or is it more like the liquid that you get in the vitals?

Can I keep reusing the slurry or does it have a limit?

What happens if I over/ under pitch?


Thanks for the help

[guypettigrew]

Hi eclipse

If you're thinking of using the yeast from one brew to pitch into another brew, then you can't do better than read Wolfy's post on yeast rinsing.

Here it is.

Easy to do, and gives you 5 or 6 bottles of yeast from just one fermentation. These store really well in the 'fridge.

Guy

[Kev888]

In the pitch from slurry bit, does the ml of yeast needed mean the actual amount of cleaned slurry, which is normally a think clay thickness?

Yes, I believe so; you can adjust the slider below to tell it how thick your yeast is. Its all very much an estimate, but I don't believe its massively critical.

If you greatly under-pitch, then the yeast will spend much more time initially reproducing, before they begin to settle down and concentrate on fermenting; apart from the slow start, I believe you can get some unpleasant tasting by-products from this excessive reproduction.

With serious over-pitching there is very little reproduction as there are already enough yeast, it may make fermentation start sooner but clearly it wastes yeast and I believe its undesirable to have little or no reproduction. To be honest I'm no yeast expert and am a bit hazy as to exactly why but I 'think' its related to the desirability of the initial reproduction causing the rejuvenation and selection of fresh, young healthy yeast cells. Hopefully someone with more knowledge will be able to answer this with a bit more confidence..

Cheers
Kev