Re-using yeast

I've got it in my head from somewhere on this forum that re-using yeast is a) possible and b) good. Something I read was about just pitching the new batch of wort on top of the yeast cake in the FV.

I have a stout in the FV right now, and have a bitter lined up for my next brew. At the moment I'm just brewing with pre hopped extract of the no-boil variety. Planning to move on to adding hops etc and doing other extract brews once I'm a bit more comfortable and have some more equipment.

Can I try this out using the stout yeast for the bitter? How would I go about it?

I have never pitched on top of the yeast cake before, but I know that some of the flavors from the first beer can be passed on to the second. Because of this, most people go from a lighter style to a darker one.

In your case, some of the roastiness from your stout may be transferred to your bitter. Which could be unwanted.

Someone else will have to chime in about the actual yeast differences in flavor seperate from the beer. I think most stouts use an Irish yeast, and most Bitters use english so that could cause some unwanted flavors as well.

IMO you should pitch some new yeast for your bitter.

Either way you should read up on washing the yeast cake. You could also just sanitive a glass jar or measuring cup, and scoop some of the yeast off of the bottom after you rack your beer off of it. That would give you a chance to clean your fermenter (ridding it of the stout flavors), you would be less likely to pitch on top of some of the stout that was left, and would also keep you from over pitching.

Reusing yeast IS a good thing and many many brewers do it as a matter of standard practice. Look for the washing yeast sticky on this forum as a starting point.

You will read a number of things from a number of different sources in regards to just dumping your wort onto the entire yeast cake from a previous batch and its benefits and detriments (but I don't wish to further that debate here). However, one thing that is nearly "universally" accepted is doing that if the first beer was a lower gravity beer like a session and the next one is a huge imperial this-or-that due to yeast cell counts etc (but again there are exceptions to this "rule").

You don't mention what yeast strain you used in the stout, but I'm guessing you have a Mr. Beer since you mention pre-hopped extract? If that's the case, most would recommend against using the Mr. Beer yeast and buying a high quality yeast (probably dry would be easier to get started with). In either case, most yeasts appropriate for stouts would also be acceptable in bitters.

Personally I'm a big fan of minimizing the number of strains of yeast and pretty much use London Ale yeast as my house ale yeast, similar to what Great Lakes does. However, spend some time on the wyeast and white labs pages and you'll see the huge variety they have.

And have fun.

Interesting discussion. I would assume that you would want to dump onto a secondary to avoid even more trub and old hops. I am planning a stout soon, and now am wondering if I should just dump the wort onto the secondary from a wyeast 1056 batch.

Thanks- its not exactly mr beer, I don't think we get that here in the uk. It is a youngs harvest stout tin- like the coopers tins. Heat water, add extract and sugar of some kind, top up to required volume ( my first was 5 uk gal. And this stout was 3.75 uk gal) pitch unbranded pack of dry yeast. Instructions say bottle after 7 days or so- did that with #1 and won't ever do that again!

I just thought that having a bit of "stoutiness" in my bitter might be cool and this might be a cool experiment for a technique for a noob.

Would love to hear advice from the experts- I know there are a few that know a lot about extract on here.

Cheers

badbrew said:

Interesting discussion. I would assume that you would want to dump onto a secondary to avoid even more trub and old hops. I am planning a stout soon, and now am wondering if I should just dump the wort onto the secondary from a wyeast 1056 batch.

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I'm only doing primaries and then straight to bottle. Might this be a stumbling block in my half-formulated plan?

There's not much trub- 1/4 to 1/2 inch. And no hops or the like due to only using pre hopped extract from a can so far. Thanks for the info.

OP: Since your going from a dark beer to a light one, I'd wash the yeast first per the sticky Bmore mentioned. It's really easy and you wind up with enough yeast to do three more batches with.

badbrew: Since your second beer is a stout you can just dump your wort directly onto the yeast cake.

Ravenshead said:

OP: Since your going from a dark beer to a light one, I'd wash the yeast first per the sticky Bmore mentioned. It's really easy and you wind up with enough yeast to do three more batches with.

badbrew: Since your second beer is a stout you can just dump your wort directly onto the yeast cake.

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I will get on with reading the sticky. I'm not too worried about the bitter being "how it should be" if I learn from the experiment and get a beer which is good whether it's a "bitter" or not.

All thoughts greatly appreciated and over the next week or so while the stout is sitting on the cake I will come to some sort of plan.

To address a couple of issues...

Many of the flavors produced by yeast come during yeast growth. If you repitch onto an entire yeast cake, there will be very little yeast growth (since they already reproduced a lot). How important this is depends on how much flavor your particular beer gets from the yeast. So a bigger deal on something like a belgian beer where yeast adds a lot of character vs a clean fermenting eyast.

Pitching onto a secondary cake does result in a cleaner yeast cake, because you left most of the trub in primary. However, you are pitching onto a yeast cake made up of less flocculant yeast. This is because the moer flocculant yeast flocculated out in primary. So your next beer may take longer to clear and have more yeast make it to bottling because of the selective pressure you put on your yeast population by only using what made it to secondary.

If you pitch onto the entire yeast cake, vs pitching only a portion, you will have a larger percentage of dead cells in your next ferment. This ties back to the lack of significant cell reproduction when you repitch on an entire cake. As an example, lets say you pitch a 100 billion cells in your initial ferment, and they reproduce to where you have 800 billion cells in your yeast cake at the end of the ferment (i don't actually remember how much multiplication occurs in a 5 gal ferment). So now you have 800 billion cells in your cake. and lets say you haev 90% viability, so 80 billion of those are dead. If you repitch on that yeast cake, you're starting with 80 billion dead cells which will continue to be dead. If you take a quarter of your yeast cake, 200 billion cells, 20 billion of those will be dead. Pitch that, it reproduces to about 800 billion cells, so you end up with the same final amount of yeast to do your work, but a much smaller percentage of them are dead.

I'm actually in the middle of listening to an interview with chris white of white labs, so all this is kinda fresh in my head.