Yeast re-pitching

[Merkur]

I am making two back to back 10 gallon batchs of beer in my CF10 conical and would like some advice about re-pitching the yeast. While I have harvested yeast before, I have never re-pitched it. The yeast I am using is Imperial's A09 Pub Yeast which is the Fuller's strain.

The first batch finished fermenting and I dumped 1 L/2.5 pints of clean yeast before dry-hopping. I put that in a sanitized mason jar in the fridge and after flocculating, drained off the beer and topped it up with sanitized, (boiled) RO water at 60F. I have just drained off that liquid after 4-5 days of rest and the yeast looks clean and homegeneous. The resulting quantity is about 0.7 L/1.25 pints.

I am brewing the second batch of the same beer this week. What do I need to do to prepare that yeast for re-pitching? I was going to pull it out of the fridge the day before pitching to allow it to warm and put it in an Erlenmeyer flask on the stir plate. When I have some first runnings of the wort, I propose to add this to the flask and start to 'wake up' the yeast.

Does this sound like a good approach? Should I make up a starter wort with DME as normal? How do I ensure that I am not over or under-pitching?

 

[hottpeper13]

First- yeast does better in storage with degassed beer on top ,not water,so don't do that! Second- it should be fine to pitch as is ,but I would take some wort after 10 min of boiling and chill it then add to yeast(vitality starter). I set mine next to the fermenter until they are at pitching temps.

 

[Merkur]

Thanks. I‘ll try this with a cup or so of boiled wort while I am brewing.

I’m apprehensive about this first yeast re-pitch. My fall-back is to just open the other pack of A09 I have, but I would like to perfect the re-pitch technique.

 

[Miraculix]

I had very mixed results with re-pitching pub. This yeast handles being stored as sludge poorly and dies quickly. Best would be a starter to build up the numbers again. Your water/beer exchange probably worsened the situation a bit.

The longer the sludge is being stored the lower the cell count, I wouldn't use anything directly which has been stored for more than 7 days personally.

 

[Merkur]

Thanks for the input. I decided to not risk re-pitching. It wasn’t worth the risks and I had another packet of A09 on hand. This is an important batch as I am brewing four kegs for my son’s wedding. I will experiment with re-pitching and work out the process on a less time critical and important batch.

 

[Miraculix]

Thanks for the input. I decided to not risk re-pitching. It wasn’t worth the risks and I had another packet of A09 on hand. This is an important batch as I am brewing four kegs for my son’s wedding. I will experiment with re-pitching and work out the process on a less time critical and important batch.

Better make a starter...

 

[Merkur]

Done. I love A09! This was 90 minutes after pitching the yeast into the starter.