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Cpt_Kirks · 11-14-2009, 09:22 PM

Assuming I wash and properly store yeast, how many times can I reuse it?

So far, I have not reused yeast, but am about to start trying.

Bob · 11-14-2009, 10:28 PM

Even without washing, I've harvested and repitched slurry out to ten generations without ill effect.

Washing and proper storing is a pretty big reset button in terms of yeast quality, or so the theory tells us. I've never made a consistent practice of washing and storing, so someone else will have to weigh in on the practice's impact on generations.

**beerthirty** · 11-14-2009, 10:47 PM

I have washed and stored for 6 months before use with no ill effect, But so much time and fridge space is taken I prefer to pitch on the last cake. On the same cake I have pitched 4 times. After that I start worrying about trub buildup.

StAnthonyB · 11-14-2009, 11:19 PM

Quote:

Originally Posted by beerthirty

I have washed and stored for 6 months before use with no ill effect, But so much time and fridge space is taken I prefer to pitch on the last cake. On the same cake I have pitched 4 times. After that I start worrying about trub buildup.

How does that work?

You repitch new wort on the yeast at the bottom of the fermenter?

Donner · 11-15-2009, 12:18 AM

Quote:

Originally Posted by StAnthonyB

How does that work?

You repitch new wort on the yeast at the bottom of the fermenter?

Pretty much. You generally always want to pitch a darker beer or the same beer on to a yeast cake, though. It's hard to pitch a pale beer on to the yeast cake from a stout without the stout residue impacting the color of the pale. Get it?

StAnthonyB · 11-15-2009, 01:24 AM

I see.... There's a method I have heard about where most of the fermented wort is drawn off and some is left behind, and a new batch of wort is put onto the remainder.

There's a thought: Constantly making the same beer type. Why not? If you like it. I suppose, if one has a conical fermenter then they could draw off most of the trub and pitch new wort. If your sanitation is good then theoretically your yeast strain will adapt to that particular beer style and how you treat the fermentation. Is that right?

I mean it could never actually go too bad in there with the layer of CO2; that is, until you apply oxygen to the new wort.... Or, would you not do that?

Donner · 11-15-2009, 01:33 AM

When you rack your beer it's almost impossible to remove all the wort from the fermenter, so if you wanted to reuse that yeast cake you have a couple of options. One is to make a darker beer so as the color difference wont impact your beer that much. Two is to wash the yeast, which is just like it sounds. You can search for the process, but the idea is to separate the yeast from the trub and old wort.

The third option would be to use the same exact beer. If the beer you just brewed seems 'off' then you likely don't want to reuse the yeast cake. If the beer tasted fine then sanitation shouldn't be an issue if you practice a safe process. If the yeast fermented your beer then there should be plenty of good, healthy yeast in the cake. You'll basically just pour or rack the new wort onto the yeast cake and aerate the wort. You'll still want to introduce O2 since the yeast need it to work and since there isn't any the wort you just boiled.

Malticulous · 11-15-2009, 02:08 AM

I've gone ten generations without washing. Sanitation is key. If I was going to wash it would be with a acid wash, not watter.

chefmike · 11-15-2009, 02:29 AM

Quote:

Originally Posted by Donner

When you rack your beer it's almost impossible to remove all the wort from the fermenter, so if you wanted to reuse that yeast cake you have a couple of options. One is to make a darker beer so as the color difference wont impact your beer that much.

I am going to throw the experience/logic card on this one and say not true.

Logic first: You can siphon off 99% (or more)of the beer (it really isn't wort anymore, is it?). I personally leave less than 6 oz in the bottom (which would be 1% of a 5 gallon batch). How much color change is going to happen off of that 6 oz of stout in your new batch of 640 oz of pale ale?

Experience: I have been doing runs on the same yeast cake to be cheap and to use what I had. This fall was (on S-04) stout (SRM 24) to octoberfest ale (SRM 10) to Holiday Spice (SRM 17) to Pumpkin (SRM 12) to ESB (SRM 15?). This was a progression of siphon to keg (or secondary for the pumpkin), dump in new batch.

Not only was there no discernible effect on the color, there was no discernible carry through of any of the spices.

I have in gone from a stout on notty to a haus pale and found no significant effect.

Is this the best method? No. Does it work? Yes. I have taken to planning groups of beers around a yeast cake... it is efficient for my brewhouse. My consumers have zero complaints. And it is VERY cost effective.

I wash some yeast (water... no acid yet!), but I find my serial pitches very effective. I do ferment cool (low 60's) and I hit with some yeast nutrient on the 5th pitch (which DOUBLEd the size of the trub/cake that batch).

So I would encourage those who have the inclination to line up a few beers on a yeast cake and try this. It works.

EvilGnome6 · 11-15-2009, 11:51 AM

Quote:

Originally Posted by beerthirty

I have washed and stored for 6 months before use with no ill effect, But so much time and fridge space is taken I prefer to pitch on the last cake. On the same cake I have pitched 4 times. After that I start worrying about trub buildup.

I've taken a small twist to the method described in the Yeast Washing Illustrated thread. Instead of pouring the quart of washed yeast into pint jars, I set it in the fridge for a week. After a week, I decant the liquid on top and divide it into 4 oz. jelly jars. They take up far less fridge space.

So far it is working great. On Friday night I put a 4 month old jar of washed yeast in a 1 liter starter and ended up with this on Saturday morning: