Rinsing for repitching

[cannon]

I more or less understand this process,but its the last part that is still confusing me a little.

Here's how i have understood the process.

Step 1.Mix the yeast cake back into suspension with around 1L of beer left in FV,decant to sterile 2L container.
Step 2.Place in fridge to let beer settle on top.
Step 3.Decant beer from solution,then add 4x the amount of slurry with sterile water.
Step 4.Wait for seperation of 3 layers,trub and dead cells bottom layer,viable yeast middle layer, and lighter cells,protien and other matter top layer
Step 4.Decant top layer,then decant yeast layer to another sterile container,discard bottom layer.

This is where i start to get confused as to what happens next.I am assuming that you are now left with somewhere in the region of a litre or so of slurry/sterile water,with around 5 billion cells in solution,way to much to pitch directly to next batch.

How do you work out how much of the solution you need,to be pitching at correct rates for a 23L batch.ie 200 million cells as stated on mr malty.Do have to measure 100mls out of the solution ,or do you just pitch a 1/3 of the slurry solution assuming you had around 5/6 million cells in the yeast cake from a healthy fermentation.
If any of my assumption on yeast cells are out i stand corrected,its just what i have been reading the last month.
Any help much appreciated Graham. :?

 

[battwave]

This may not help you at all, and I've never done the whole harvesting thing (I'm as confused as you are by the instructions Graham), but if you can arrange to move your donor beer to the secondary fermenter on brew day, you can pitch your new cooled wort straight onto the lees of the donor beer (introducing oxygen as you do it).

I was worried about trub and dead yeast cells messing-up my new brew, but I've done it twice and it works fine; the fermentation really gets moving quickly.

If you do suss the recovery and manage to store the recovered yeast, I'd be keen to hear how well it works when you come to re-pitch.

Tim

 

[luckyeddie]

I believe that the yeast may degrade a little (i.e. some unwanted characteristics may be introduced, and also the risk of infection) each time you re-pitch, but that degradation will only become significant after a number of repeats (5 or 6 generations?).

I'm sure that aleman will have the definitive answer on what's good and what's bad - he is the yeasties guru (microbiologist) and has already increased my knowledge of the little blighters by around 500% (although 0 x 5 is still 0)

 

[Aleman]

This is where i start to get confused as to what happens next.I am assuming that you are now left with somewhere in the region of a litre or so of slurry/sterile water,with around 5 billion cells in solution,way to much to pitch directly to next batch.

How do you work out how much of the solution you need,to be pitching at correct rates for a 23L batch.ie 200 million cells as stated on mr malty.Do have to measure 100mls out of the solution ,or do you just pitch a 1/3 of the slurry solution assuming you had around 5/6 million cells in the yeast cake from a healthy fermentation.
If any of my assumption on yeast cells are out i stand corrected,its just what i have been reading the last month.
Any help much appreciated Graham. :?

In an ideal perfect world, we would suspend the yeast in sterile distilled water, take a sample and serially dilute it 6 times, before doing cell counts using a haemocytometer slide and a microscope. In the real world we just make some assumptions (as does Jamil on Mr Malty ). Personally I tend to pitch 100ml of thick slurry into a 5 gallon batch . . . When I have checked the cell counts doing this it appears to be close to the 1 million cells/ml that we are looking for. Bigger beers and lagers pitched cold get more yeast.

 

[battwave]

I would like to thank Aleman and luckyeddie for the information imparted here. I managed to recover Nottingham from a brew in early May, store in the fridge, and now it's alive and working again after pitching yesterday.

From the experience, I've bought a turkey baster, as a means to remove the liquid above the yeast sediment, and I have two further questions please:

Is it normal for the yeast to continue to ferment slowly in the fridge (bottles were under pressure)?

How do I go about freezing it, and will it keep better this way?

 

[evanvine]

How do I go about freezing it, and will it keep better this way?

Although I do it a great deal, I think freezing liquid yeast is frowned upon as the freezing action destroys a percentage of the cells.

 

[luckyeddie]

I would like to thank Aleman and luckyeddie for the information imparted here. I managed to recover Nottingham from a brew in early May, store in the fridge, and now it's alive and working again after pitching yesterday.

From the experience, I've bought a turkey baster, as a means to remove the liquid above the yeast sediment, and I have two further questions please:

Is it normal for the yeast to continue to ferment slowly in the fridge (bottles were under pressure)?

How do I go about freezing it, and will it keep better this way?

There will be a little fermentation in the fridge unless you really crank the temperature down. Lager yeasts especially will work away at 8C very happily, but when you get the temperature down to just above freezing they will pretty well stop (I'm not sure if there will still be a touch of activity).

I bottle my reclaimed yeasts in Grolsch bottles, and there's always a satisfying 'pop' when I come to open one to make a starter, and that fridge is at 5C. Unlike Evanvine, I don't freeze my yeasts, but that's not to say that I'm right or wrong. We all have methods that work - for us.

 

[battwave]

Thanks both evanvine and luckyeddie; even more valuable advice.

 

[Kev888]

This is really interesting; I guess freezing yeast will kill some of it, but presumably it'll then reduce in viability more slowly than unfrozen yeast. I wonder if its possible to say 'very' roughly what loss in viability freezing slurry causes and so work out when its the better option?

Cheers
Kev