Just a quick question on reusing yeast.

I am about to bottle a 40 pints of St-Peters cream stout this weekend I was going to save the yeast and use it again. I'm going to do a small 1 gallon batch of some dark beer very soon.

  1. Question is how much of the liquid reused yeast do i put in to 1 gallon??
  2. Is it worth doing is the second question.
  3. Does it take the same amount of time to ferment or is it faster as it is already liquid?

I know I said a question ended up being three . Thanks John

2 Answers 2


The generally specified amount is about 1/3 of a cup of yeast slurry into a 20 litre/5 gallon batch - so maybe 25ml, more?. This is all very rough, because you can never be sure of the concentration or viability of the yeast without putting it under a microscope. It's difficult to pitch too much yeast at the home brew level though, so I'd err on the side of more yeast.

If a "St-Peters cream" stout is a high-alcohol and therefore hard-work environment for the yeast, it may not be very healthy after fermentation. So if you just fermented a super-double-mega-imperial-table-beer, then maybe don't re-use the yeast.

As long as you can maintain a sanitary environment, there's no reason not to re-pitch healthy yeast. If your cream stout tastes weird at all, I would certainly not re-use the yeast then. Taste the beer before pitching its yeast.

I believe the "amount of time" you are referring to, is the post-pitch "lag phase" where the yeast is initially multiplying (and creating the bulk of the esters/flavours), before fermentation becomes noticeably vigorous. Pitching a good amount of healthy yeast will reduce this time.

  • Hi.Thanks for the reply i thought it would have been a lot more than that im so glad i asked and not just gone a head and put the whole lot in. i will give it a go and let you know how i got on. Thanks again. John
    – John.C
    Apr 23, 2020 at 7:49

Years ago I got a growler (1/2 gallon?) of yeast from a local craft brewery when their fermentation was done. I pitched it in my 5 gal carboy and the beer came out great.

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