Reusing yeast for my next batch

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BlackRock

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Three days ago I kegged my third batch of IPA. I left the yeast cake in the primary, sealed it back up and tossed the container back into my ferment chamber (aka the downstairs bathroom).

I want to start another batch later this week and reuse the yeast from the last batch if possible. I'm just not clear on a few things.

How long can the yeast cake be left in the fermenter before I pull it to wash or make a starter?

Can I simply swirl the yeast cake and pour some into a starter solution or do I need to "wash" the yeast by adding water and letting things settle and decanting a few times. I just don't know the do's and don'ts of working with the yeast.

I'd like to make a starter that's around 300B cells for the next batch of the same IPA and since I just pulled the beer off the cake there has to be a fast track to making a starter from it.
 
First, you really won't need to make a starter when re-using a yeast cake. The point of a starter is to grow the yeast population from a purchased pack or vial up to the point where you have 'enough' cells to starte a healthy ferment. You could say that your previous batch was just a really big starter in itself, you have plenty of cells already. What most people do in this case is just brew up a new batch of similar beer and then rack the new wort right on top of the old yeast cake.

A rule of thumb here, you always want to do this with either the same recipe as your yeast consumed originally, or a generally bigger/darker/stronger recipe to mask any flavors that might transfer over from the yeast trub. So using the yeast from one IPA for another is great. You could use the yeast from a bock style beer for an amber, but you wouldn't want to use the yeast from an amber for a pale.. for example.

If you do this, I'd suggest trying to brew the new batch and get it on top of the old yeast cake on the same day. It sounds like your yeast should be fine to try this with tough even on the third or fourth day. Some people will intentionally leave a few inches of beer on top of the cake to keep it hydrated for a day or two be fore doing this. When you are ready, just pour off any remaining beer from the previous batch and rack your new wort in.

The other method I think you were eluding to is harvesting and washing your yeast. This is when you take a small sample of your yeast cake and 'wash it' save it for later. I've done this a few times with small mason jars when I had a unique strain of yeast I wanted to save. It works well but is a lot of effort. You can read up on this method here https://www.homebrewtalk.com/f163/yeast-washing-illustrated-41768/

Best of luck!
 
Excellent info! This is exactly what I was looking for. My plan is to remake the same IPA using the same yeast. I was just missing how to use the yeast cake easily and most effectively from one batch to the next.

Anything to watch out for when dumping a new batch on the entire yeast cake? Will it affect the taste much with all that trub on the bottom?
 
BlackRock said:
Excellent info! This is exactly what I was looking for. My plan is to remake the same IPA using the same yeast. I was just missing how to use the yeast cake easily and most effectively from one batch to the next.

Anything to watch out for when dumping a new batch on the entire yeast cake? Will it affect the taste much with all that trub on the bottom?

I'd go the yeast rinsing route before I'd rack a new wort onto a yeast cake. There's a lot more than just good yeast in there, and it's generally stuff you don't want in your next beer (dead yeast, hops, break material, etc.). People do it and it'll make beer, but I've been much happier with the results when rinsing. It's a little bit more work, but you don't have to spend a ton of money (a few bucks for some mason jars, or polypropylene bottles).
 
Just an FYI I've made 3 beers in a row racking onto the yeast cake, an oktkberfest ale, an IPA and an amber ale and they all tasted great
 
Another thing to think about, I was faced with this same question last week when I brewed. I had a yeast cake from bottling the night before and I was going to brew 2 brews the next day. I could have racked onto the yeast cake but instead I swirled the cake around, let it settle for a couple min then poured it into some mason jars leaving behind the majority of the heavy chunks at the bottom. I pitched a mason jar in each brew the next day and a very healthy fermentation started up within 18 hours. With this method you could stock up some yeast to prolong the life of your yeast regarding the number of generations you want to re-pitch.

Im certainly no expert but this is what worked for me.
 
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