Repitching on Yeast Cake (Twice)

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Skipper74

Well-Known Member
Joined
Apr 14, 2011
Messages
205
Reaction score
3
Location
Franklin
This weekend, I brewed a repeat batch of the same beer that I bottled earlier in the day, so I just dumped the new wort on the old yeast cake (Safale 05). The airlock on the new beer began showing activity within hours and fermentation was rolling along within 12 hours.

This was the first time I re-used a yeast cake and I was impressed with the time it saved me. (I didn't even have to wash the fermenter from the first batch. For my next batch, I will be brewing a darker, stronger beer, so I believe that I can again re-use the yeast cake. Since it will now be two generations in, however, I am wondering if I should scoop out some of the trub/yeast from the bottom before adding the new wort (using a sanitized measuring cup). Has anyone ever done this?
 
Personally, i would wash the yeast. Essentially, you could move you beer to the bottling bucket, wash the yeast, and by the time you bottle the first batch and brew the new one, you could have "clean" yeast to pitch. This way you are using just the healthy yeast cells.
And when i wash, i end up with enough yeast to pitch into three more batches...and if you use a starter you can stretch it even further.
 
I would also wash the yeast, then make a starter. This ensures you're not overpitching (which you are when pitching directly onto a yeast cake, unless the next batch is significantly larger than the previous ie. several times larger) and using only healthy yeast cells without any trub/undesireables.

It's pretty easy to wash yeast and make a starter, so I say why not? Your beer will benefit.
 
If I wash the yeast can I pitch it without using a starter? I have never used a starter before when pitching dry yeast into the cooled wort and always had great fermentations. Having to make a starter to reuse washed yeast just seems like an additional step I'd like to avoid if possible.
 
Yes, you can pitch the washed yeast without making a starter.

Mr. Malty has a calculator for figuring that out. Use the "yeast slurry" function.

Also, from Mr. Malty regarding repitching yeast:

There are about 4.5 billion yeast cells in 1 milliliter of yeast solids (solids with no excess liquid). According to Fix, in a slurry, only about 25% of the mass is yeast solids. Of course, if there is a lot of trub in there, you have an even lower percentage of yeast solids. The bad thing is that you can't tell how viable that yeast is, unless you have the equipment to properly test and count it. So this is where it gets a little bit like black magic. There are a number of factors that affect the viability of a given pitch of yeast. How old is the yeast? How stressful was their last fermentation? Have they had the proper environment and nutrients for successful reproduction or are they too scarred and tired to go on?

When the yeast is fresh and healthy off an previous batch, viability is maybe around 90%+. It goes down from there fairly quickly without proper storage and it also really depends on the strain of yeast. Unless you're going to get into testing viability, you're going to need to make some educated guesses and keep good notes on the results. This is where being a yeast psychic really helps. Start in a range of 80 to 90% viability and you probably won't be too far off. Use the Pitching Rate CalculatorTM to help figure out how much of that yeast you need. If your yeast viability is much lower than 90%, you should probably toss the yeast. If you really want to use it, you might consider pitching it in some starter wort to get the still viable cells active. When they're in solution, decant that active part of the starter into another vessel, hopefully leaving the dead cells behind.

Making a starter with the washed yeast, IMO, is the best assurance of yeast health and a good start.
 
I don't wash yeast, but I do limit the amount of slurry to a quart or so. At 25% cells, that's over a trillion.
 
I don't wash yeast, but I do limit the amount of slurry to a quart or so. At 25% cells, that's over a trillion.

I also never wash yeast. I know that many brewers swear by it but I never have seen a good reason to do it. I just save about 8 oz of good trub yeast from the bottom of my primary in a "clean jar". I usually use it within a few weeks so I know it's still alive. Anyway I have reused the same yeast over 20 times and still it works like a champ. :mug:
 
I've done it! I have simply pitched atop a yeast cake for a third fermentation. I didn't "wash" the yeast or anything.

It was awesome!
 
I'm pretty sure this is a micro evolution problem I did in biology. By washing and using a starter, you always ensure, at least the best homebrewers can, that you are getting the best yeast cells (survival of the fittest, or in this case decanting off the fittest). Therefore you get the best fermentation. Some yeasts that are more forgiving to less than optimal fermentation conditions will result in having an expected result from just pitching on the yeast cake over and over again. But I'd guess (since I've never done this) that a less forgiving yeast like 3068 would end up giving an unsatisfactory result if you just repitched on the same yeast cake over and over.

Starter is so key in taking beer to the next level, aside from maybe temperature control. And it's so easy, I'd recommend doing one. We go through a lot of trouble on brew day and bottle day, an extra 30 minutes for a starter to ensure good fermentation just makes sense.

Anyways, just my 2 cents.
 
I apologize if this is a stupid question (and maybe it shows that I do't really understand the process of making a starter), but if I am going to reduce down my yeast/trub cake to a 1 liter (or thereabouts) slurry anyway, instead of making a starter to ensure enough healthy yeast cells, couldn't I just dump 2 liters of slurry (presumably doubling the number of cells that were in 1 liter)?

Thanks for humoring my curiousity.
 
2 years ago I did a series of 3 beers in my conical without ever opening it. I started with a 1.060 ESB, then went to a 1.070 rye pale and finished with a big robust porter. Each beer was in primary 3-4 weeks. After the porter I cleaned the conical and found a very small circle of mold forming around the thermowell opening. It never affected the beer but it did teach me how long I can go before I need to clean up after myself. I used Nottingham FWIW.
I usually only dump trub once during fermentation, about the second or third day just to get any stray hops out.
 
Generally, you should wash yeast and not just pitch onto a yeast cake. From what I understand, somme of the flavor that yeast impart to beer comes from the reproduction process that precedes fermentation. Also, after every batch there are a good number of cells that are about to die and that will contribute off-flavors to the beer. That's certainly the case if you're like me and leave your beer on the cake for four weeks or so before bottling.
 
Skipper74 said:
I apologize if this is a stupid question (and maybe it shows that I do't really understand the process of making a starter), but if I am going to reduce down my yeast/trub cake to a 1 liter (or thereabouts) slurry anyway, instead of making a starter to ensure enough healthy yeast cells, couldn't I just dump 2 liters of slurry (presumably doubling the number of cells that were in 1 liter)?

Thanks for humoring my curiousity.

It's not so much cell count as quality of yeast cells. Washing and using a starter ensures you have the right amount of cells AND that they are healthy and ready to go. This ensures that you will have a good fermentation every time that will yield consistent results. Whereas with trub/yeast cake, you don't really know what you are getting. Therefore you may get more or less esters from pitch rate variation, of flavors from dead yeasts, or contamination do to accumulation over time of foreign material... Although the last one can happen with washed yeast used for many generations without good sanitation.

Anyways, a starter is just so easy, just you tube it and you'll see what I mean. I'm making one this week. I'll search the forum to see if there is a good thread with step by step and pics, if not, I'll document mine an post it and you can see how simple it is.
 
Generally, you should wash yeast and not just pitch onto a yeast cake. From what I understand, somme of the flavor that yeast impart to beer comes from the reproduction process that precedes fermentation. Also, after every batch there are a good number of cells that are about to die and that will contribute off-flavors to the beer. That's certainly the case if you're like me and leave your beer on the cake for four weeks or so before bottling.

Correct.

Another one from Mr. Malty:

Of course, you don't want to reuse the whole thing. I know a number of people dump a new batch on top of the yeast cake, but you're not going to get the best beer that way. Yeast do need some growth to result in the right kind of ester profile, etc. While too big a pitch is better than too little, it is pretty easy to figure out how much you need and pitch just that.
 
Anyways, a starter is just so easy, just you tube it and you'll see what I mean. I'm making one this week. I'll search the forum to see if there is a good thread with step by step and pics, if not, I'll document mine an post it and you can see how simple it is.


Thanks I appreciate that.
 
I also never wash yeast. I know that many brewers swear by it but I never have seen a good reason to do it.

- Anyway I have reused the same yeast over 20 times and still it works like a champ. :mug:

Years ago I did the yeast 'rinsing' thing and never saw a good reason to keep doing it. But then again I brew alot:mug:

I transfer and save the correct amount and repitch into the new wort, I go 3-5 batchs.


BTW whats always posted as "yeast washing" is not really correct but lets not allow facts to get in the way.


http://www.whitelabs.com/beer/acid_wash.html

and here is another effective method
http://www.brewingscience.com/yeast_care.htm
 
Years ago I did the yeast 'rinsing' thing and never saw a good reason to keep doing it. But then again I brew alot:mug:

I transfer and save the correct amount and repitch into the new wort, I go 3-5 batchs.


BTW whats always posted as "yeast washing" is not really correct but lets not allow facts to get in the way.


http://www.whitelabs.com/beer/acid_wash.html

and here is another effective method
http://www.brewingscience.com/yeast_care.htm

Good info in the links posted.
I now realize that I really have been doing everything wrong. Please don't tell my yeast. They may decide to stop producing good beer. Cheers :mug:
 
Back
Top