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Author Topic: Dumping new Wort on Previous Batch's Yeast  (Read 1789 times)

Offline aleman1949

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Dumping new Wort on Previous Batch's Yeast
« on: January 23, 2017, 04:05:15 pm »
Later this week, I'm planning on kegging the pale ale that's currently in my fermenter, then brewing an oatmeal stout and dumping the wort on top of the yeast cake that's left behind from the ale. I've never done this before, but I know It's a common practice among homebrewers. I was thinking about kegging one day, then brewing the next. This means the yeast would be sitting for about 24 hours. My fermenter is a Sabco converted keg. I have a closed system that uses CO2 to push the beer into my kegs. When this is done, the fermenter would remain closed to the outside. I'm thinking the yeast would remain safe during this time. Any thoughts on this, or any other considerations for adding wort to then prior batch's yeast? Thanks. Brew On!

Offline brewinhard

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Re: Dumping new Wort on Previous Batch's Yeast
« Reply #1 on: January 23, 2017, 04:34:01 pm »
Reptiching onto a full yeast cake is not always the best bet as you do not achieve a lot of yeast growth in this fashion which is not the best bet for a healthy fermentation, especially if you are just doing a moderate gravity beer.
Why not just leave a bit of beer on top of the yeast, swirl it all up to get the yeast in solution, sanitize the lip/openeing of your fermenter, and pour some of the slurry into a sanitized mason jar. With beer on top of the settled yeast layer, this will be good to repitch for up to about 1 week with no starter needed. Best if used within a couple days which sounds like you have already planned to do. You can even check out a yeast calculator (Mr. Malty) to see how many mL's you might need to save (and pitch) into your next batch.

If you do plan on reusing the whole yeast cake it is still wise to leave a bit of beer on top of the yeast to keep it safe and healthier.

Offline SilverZero

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Re: Dumping new Wort on Previous Batch's Yeast
« Reply #2 on: January 23, 2017, 08:22:12 pm »
I agree with the above. I pitched on a yeast cake a few weeks ago, same as your setup, I had a closed fermentation (spunding valve) and pushed to kegs with CO2. Racked the new batch onto it the next day. It was a bad recipe to begin with but it didn't come out very good, and I don't think the yeast cake helped. I'd harvest the slurry and keep it in solution in the fridge with some of the first batch of beer.