Yeast Cultures – Non Definitive

[evanvine]

I must stress that the following method has been developed by me with very little knowledge of harvesting yeast.

Oblivious did a how to guide a while ago Clicky from which I got some of my ideas.

The only Lab facilities I have are those for measuring acid and SO2 levels.

To begin, the brew is siphoned into a secondary fermenter (4” cap and bubbler) after two days of full head ferment, this gets rid of lot of rubbish.
After the ferment is finished there is normally 0.25 -0.5 ltrs left in the bottom + the yeast pancake.
This is agitated until all the yeast is in suspension and poured into a 1 ltr PET, which is topped up with boiled and filtered rain water (cheepo demin).
After about 20-30 mins a layer of heavy stuff (rubbish) is formed, with the required yeast forming a layer on top.
A piece of paper is stuck onto the bottle and the top of the heavy layer marked.
The bottle is agitated and left to begin settling again, when the marked level is reached, all above it is poured into a second PET, topped up with the water and put into the fridge for 24 hrs, the remaining trub is discarded.
A new layer forms, the wanted yeast, and all above is poured off and discarded.
3X the volume of Phosphoric acid at pH 2.0-2.5 is added and the bottle placed back into the fridge, it is agitated at regular intervals over the next 48 hrs and then left to settle out.
The clear fluid is poured off and discarded, the bottle topped up with the water, agitated and allowed to settle again.
This is repeated 3X.
After the third time, enough of the water is poured off to leave a fluid mixture, this is then put into wide top specimen bottles (normally about 70ml of yeast) leaving about 10mm expansion room at the top and then frozen.

When the yeast is needed it is placed into the fridge for 24 hrs and then poured directly into the brew.
Normally it takes about 36 hrs to form a yeast head.

That’s what I do Tony, it may be completely wrong, but it works.

 

[BigYin]

Can you edit your clicky link please - I'm pretty sure it's not pointing to the right thread :thumb:

 

[evanvine]

Thanks BY, clicky edited!

 

[BigYin]

OK, maybe I'm being bloody obtuse here, but is it the liquid above the sediment that is being preserved in each of the steps, or the sediment..? :wha:

 

[evanvine]

OK, maybe I'm being bloody obtuse here

Not at all BY!
Having re-read my my text, it was a bit confusing.
Hope I have made it clearer. :pray:

 

[BigYin]

well, I'm making my first stab at this...

I've taken the most liquid part off the top of the trub from my latest brew and bottled it, to let it settle out. I did use isinglass finings in this brew, so I'm hoping that isn't a blocker to capturing the yeast for re-use :wha:

Looking forward to seeing how well this works :mrgreen:

 

[evanvine]

Looking forward to seeing how well this works

Best of luck BY, I can't see finings making much difference as you rinse them all away.

 

[Moley]

Jim, what's the business with the phosphoric acid about?

 

[luckyeddie]

Jim, what's the business with the phosphoric acid about?

It's to kill off the weaklings and any bacteria that may have found their way in - 'thinning the herd', so to speak. It can be any acid, but be careful of the concentration - you want to reduce the pH to around 2 to 2.2 for a couple of hours then wash it out again. Healthy, viable yeasts can withstand that comfortably. I have used citric acid 2% w/v and that seemed about right.

 

[Moley]

Thanks for that :thumb:

Is this just an optional refinement then?



So do I use Citric or just wash them in Coca Cola? :hmm:

 

[luckyeddie]

It's something I've only done a couple of times so far, and that was with a second-generation WLP550 sample.

 

[evanvine]

Sorry Ade, Net access been down since mid day Mon, just come back; God bless BT!

LE is correct, acid washing just gets rid of the unwanted ****!
I do it as a matter of course.

Phosphoric - Ales etc.
Citric - Cider etc.
Malic - wines etc.