I am just finishing up fermenting an american hefe with a kolsch yeast. I was thinking about doing a kolsch next and reusing the yeast.
How do i go about it? Can i just rack on to the slurry?
While that may work OK, you’re probably better off going to mrmalty.com or using some other yeast calculator to determine the actual volume of slurry that you need for the beer you’re going to brew. Using the full cake will probably be a big overpitch for a Kolsch.
Should be fine. You won’t over pitch
It’s easy enough to just harvest the yeast (trub and all) in a gallon ziplock bag and then pitch about half of it, if pitching within 2 weeks of harvest. That way you can clean the fermenter. Now, whether the yeast is appropriate for a Kolsch is another question entirely…but it started as a Kolsch yeast, so it should be good to go.
If you’ve never done it and you’re worried about sanitation or think it’s too complicated, go ahead and pitch onto the cake. It should be fine although you are most likely over-pitching.
However, ynot is correct that you’re better off pouring it out into a sanitized container and pitching only a portion of the cake. I use Rubbermaid plastic beverage containers, but a gallon zip lock sounds like it should work fine.
If you want to pour it into a jar or tupperware you can also try your hand at washing it.
Better to ferment in a clean carboy (or bucket) than one that has all the residue of the past batch.
Never thought of using a Ziploc bag. Is it sanitary right out of the box or do you need to rinse?
Pitching onto the entire cake is WAY over pitching. It’s better to start off with a small amount of healthy yeast thanhaving allot of tired/half-spent yeasties. Use Mr Malty. If you are going to reuse the carboy, first spray the stopper/airlock area with some sanitizer or Grain alcohol and dump 2/3 or 3/4ths of the slurry out.
Reusing yeast is pretty easy. You just need to get over the hump!
Find a suitable storage container. Boiled Mason Jars are a common pick. I use Iced Tea containers. I bleach the crap out of them and then rinse VERY well with hot water. Give the fermenter a swirl after racking to stir up the cake and pour in to the container. Place in the fridge and let everything settle out over night. I’ll then decant off the beer and add distilled water. You can also wash the yeast at this point by transferring to a new container. I find this tedious and overly burdensome for my purposes.
Anyway, I would add 1/3-1/2 container to the new beer depending upon how long the slurry has been in the fridge. Check the mrmalty viability calulator and go from there with 1/3 being 90-100% viability.
Dave
I would add, make sure to put a piece of tape on the container with date and strain.
Otherwise, you might wind up with a whole bunch of mystery yeast.
+100! I also include the previous style so I know what the gravity was and IBUs.
Dave
Like Joe said, you may try washing the yeast. I just started doing this and have had great results. Here’s a link I used to get me going: http://billybrew.com/yeast-washing
+1 on the billybrew.com!
Interesting method to let it settle in the fermenter before transferring. I may have to try that.
They’re sanitary (for our purposes, anyway) right out of the box.
I read the link and it mentions that washed yeast can be used a few weeks up to maybe a few months after washing. Is this a reasonable estimate? I’m going to bottling a belgian golden strong in the next week or two, and probably won’t make another Belgian until next January/February. Would I be better off just getting a fresh vial after that long?
I’ve reused yeast 3-4 months plus with no problems. Just make a starter.
Dave
After a couple weeks, it’s good practice to make a starter. I’d make a good sized starter or step it up after it’s been sitting for a couple months. You’re gonna lose viability after a while so a 2L starter would be wise. Watch the starter and see how it goes. If it takes off fast, it’s probably enough but if it takes a few days to get to krausen and seems sluggish, you may want to step it once more to make sure you’ve got enough fresh new yeast.
There’s nothing wrong with the yeast after a couple months (assuming good sanitation) but you may not have enough to go right into a new beer.
Me, too. But be aware that you don’t really have a pure culture anymore.
I’ve not noted any significant flavor changes in re-using yeast, but I have on occasion noted that after a generation or two the yeast does not flocc out as well. YMMV.
How does that follow? Are you saying that there will be some (minimal, hopefully) contamination? Obviously that’s true, but it’s also true when pitching from the initial pack/vial.
I think that’s most likely due to harvesting process, getting the least flocculent top layer of sedimented yeast.
FWIW, I’ve built up 12-18 month old slurries on several occasions.
When making a starter from old yeast, my recommendation is to take a sample (1 tsp, for example) and step it up from there. First ~200 - 300 ml then 1000 ml for ale and 2000 ml or more for lager.
The reasoning behind this is that there is a lot of dead yeast stuff in that old slurry that you don’t want in your beer. You want healthy young cells.
This will not clean up any infection. For that you would have to plate the yeast, pick a single growth colony and step up from there.
Kai
Yes. Hopefully minimal contamination. Whatever mutation there may be (probably more on later generations). You’re correct that it’s also true with the initial pitch, but there are more intermediary steps once you’re re-using yeast. Nothing I’m worried about, but others may be. I think the only way you’d have a pure culture is using slants, correct?
I agree with this also, as the logic seems airtight. My only conundrum is the Ardennes I repitched where I used the entire amount of slurry I harvested and it simply would not drop out without fining. Typically, I swirl the carboy to get everything mixed up and pour out the slurry into containers. This would seem to mix it well, but maybe I did not agitate enough. Who knows?