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Pre-Pitch Yeast Culturing

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D-brewmeister

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So here's a technique I was mulling over this morning (sorry its a bit long, it must be the English major in me coming out!):

I have heard from several sources that you can perpetuate a yeast culture using the trub cake from your primary fermenter (i.e. by throwing a new batch of wort right on top of the old cake, or by shaking water with the trub to loosen and re-using [perhaps washing] that slurry). I am leery of this practice for two reasons: 1. I would be concerned about unpredictable hop/yeast/gunk flavors influencing subsequent batches, especialy if they were very different recipes. 2. Since I want to preserve the original characteristics of a given variety of yeast, I imagine that the fewer generations of yeast reproduction between the original smack pack and the current brew, the better (and the less chance for mutated strains to take hold). I am no micro-biologist, and have no idea how many generations occur during primary fermentation, but I bet it is a bunch.

So, I thought that a better way to stretch a given yeast culture over several batches would be through a process I would call "Starter Culture Continuation." And the process I would use for this would be as follows:

1. Shell out your hard earned dough for one of those Wyeast smack packs (Or any liquid yeast for that matter).

2. Smack it, warm it, whatever you do to prepare it (Soak it if it is dried yeast).

3. Boil up a pint or so of water and DME.

4. Put that mini-wort into a sterilized yeast starter jar (I use a 24 oz. Pomegranate jar w/ airlock) and cool to 75*.

5. When the Smack pack is bulging, pitch it into the starter jar.

6. Wait till the starter seems to be going pretty good.

7. Brew up your batch of beer, and prepare it for pitching (cool it to 75*).

8. Pitch about 2/3 of your starter into the main batch.

9. Now here you have a choice of actions, depending on if you want to use that same yeast culture for the next batch, or if you would prefer to save it for a later batch. If the former you would probably leave it in the starter jar as it is, and stick the whole thing in the fridge. And when you are ready to start your next batch, pull it out in advance, warm it to room temp, boil 12oz. of water and DME, cool it, and add it to the starter jar. Then you would start over with step 6 above.

If you wanted to save the yeast culture for a later batch, I would just pour the remaining 1/3 of the starter into a sterilized beer bottle, cap it, and stick it in your fridge. Then, when you want to brew with that yeast again, I would pull it in advance to warm to room temp, and start over with step 3 above, except you would only boil 12 oz of starter wort (since you should already have 4 oz. of starter from last batch), and at step 5 you would pitch the old starter from the bottle instead of a new yeast pack.

So there it is. You should get the benefits of pitching a larger, more active yeast starter than you would if you just pitched a smack pack, you don't have to blow 5-6 bucks on every batch, and you should be able to preserve the integrity and characteristics of the original yeast (for at least a few cycles).

But just a disclaimer -- I haven't tried this yet!! (I intend to with my next yeast purchase) And I would LOVE to hear what you think of the idea, wheather or not you have tried something similar in the past.

Thanks for your indulgence - D.
 

Janx

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Well, it seems a bit of overkill to me. That's why I just rack onto the old yeast. You don't use it forever, so generational changes are not something you'd notice. I throw it out after 3 or 4 batches. Also, you get the benefits of a massive starter, which your technique would not have.

Also, you need to *really* careful when working with yeast in such small quantities. I doubt you have a sterile lab, so that yeast, the containers, etc will never be sterile. Sanitized is the best you can do. Usually, yeast culturing like you're talking about requires carefully flaming bottle necks and using sterile glove boxes.

There's nothing wrong with the way you're talking about doing it. It's yeast culturing and you can read about it in a lot of the books. To me, it's way too much work for little or no gain. For my $5 pack, I get 36-50 gallons of beer. That works for me. And then I move on. Like I said, there is no flavor degradation of deviance in the yeast profile at that volume and that number of "generations". If there were, how could breweries ferment thousands of gallons at a time? The trub from old batches is totally not a factor in flavor either.

So it's really up to you, but with the time it will take vs. actual gain in quality, it better be something you're doing because it seems fun in and of itself ;)
 

Janx

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Oh, sorry, you asked if we had tried this in the past.

Yes. We had visions of owning a yeast library and tried doing basically exactly what you're thinking of doing. It definitely works if you are extremely careful. We did our culturing in a laminar flow hood with a HEPA filter. In the end, it was too much of a hassle.

One other thing to note. You still have "generational" issues with your technique. You're basically proposing a kind of sourdough starter approach where you bring the volume of the yeast back up to volume after using part of it each time. So you still have another "generation" for each batch you make, same as with the pitch-on-top method.

Lastly, be careful of step 4. You don't want to cool liquids in containers that have an airlock in them. It will pull liquid back in, and with something as sensitive as a yeast starter, that's bad news.

Good luck and let us know how it goes :)
 
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D-brewmeister

D-brewmeister

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Thanks for the reminder on the issues with cooling liquid in an airlocked container -- I might have forgotten that. So when you mention doing culturing in a hepa filter hood, where you doing cultures in open dishes? I just wondered if having various vesels (like the bottles, starter jars, etc.) open to the air for short periods of time poses a serious risk of contamination, because I am certainly not going to be able to replecate lab sterile environment. Thanks for the reply, and I will keep working on the process, perhaps study up a bit more on my propagation technology. D
 

Janx

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D-brewmeister said:
Thanks for the reminder on the issues with cooling liquid in an airlocked container -- I might have forgotten that. So when you mention doing culturing in a hepa filter hood, where you doing cultures in open dishes? I just wondered if having various vesels (like the bottles, starter jars, etc.) open to the air for short periods of time poses a serious risk of contamination, because I am certainly not going to be able to replecate lab sterile environment. Thanks for the reply, and I will keep working on the process, perhaps study up a bit more on my propagation technology. D
You're totally right that bottles help because they have much less exposure. I'm pretty sure that's what Papazian recommends in The Complete Joy... We used mason jars because they're easier to pour into. And we used the HEPA hood because we wanted to make a HEPA hood ;) You know how these things are...projects for projects' sake :D

In looking at my posts, I feel like I may be dissuading you or just ragging on the idea. Please forgive me if that's what it sounded like. My real point is that it should be a labor of love if you're going to undertake it, because it's somewhat involved and doesn't save you a ton of money or anything. But don't feel like it isn't doable. It definitely is...without a HEPA filter even. Just flame the lips of your bottles and be extra super duper careful with sanitation.

Also, you might want to consider dividing the smack pack in half right from the get go. That way you have two generational branches and can better achieve one of your primary goals (less generational iterations). Dump each half in a starter and then follow your course of action with one of them, holding the other in reserve for when you feel you have taken the first one far enough.

Anyway, I hope I didn't sound discouraging. I don't want to discourage anyone from adventures in homebrewing. It was too much work for me, but I'm lazy :D YMMV

Please do keep us posted on your project.
 

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I tried my own technqiue out. It goes basically like this.

1. At brew day, use 75% of the liquid yeast.
2. Fill the bottle back up with some strong DME+water mixture (boiled of course!).
3. Leave the lid slightly open so the air can get out, and keep warm for 4 days or so.
4. Throw it in the fridge until next usage. Start at step one again.

So far, I have done this about 4 times each with a Hefe yeast and a Belgian yeast. The second attempt with the Hefe may have actually turned out better than the original pack as far as banana flavors are concerned. After that, it was pretty much the same. I have noticed no issues with it at all so far, but I don't plan to keep it going forever...I just wanted it to go on long enough to lower the price of liquid yeast to below that of the cheap dry yeast.

Just try it out. If you're only brave enough to try it once, it's still pretty sweet. I use the white labs vials...
 
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D-brewmeister

D-brewmeister

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Janx said:
Also, you might want to consider dividing the smack pack in half right from the get go. That way you have two generational branches and can better achieve one of your primary goals (less generational iterations). Dump each half in a starter and then follow your course of action with one of them, holding the other in reserve for when you feel you have taken the first one far enough.
This is a good idea that set my wheels spinning again, so how about this idea:

I have a mini fermenter (actually a Mini MrBeer, with which I brewed my first homebrew! :D) that holds a gallon and a half or so. So I was thinking that I could take my active smack pack, pitch it into 4 or 5 quarts of boiled dme and water (perhaps a bit thin on the gravity), waiting till it is really rocking/ good krausen etc., then using the little spout at the bottom to draw off samples into bottles (leaving behind enough for a good pitch into the current batch), capping the bottles and sticking them in the fridge. When I want to use that variety of yeast in the future (or if I want to share it w/ friends), I would pull out my regular 24 oz. starter jar, boil up 4 oz of fairly dense DME wort, pitch the yeast bottle and the new wort into the starter jar (of course after flaming the bottle lips) and wait for it to get rolling enough to pitch.

This way I would only have 2 generations (initial step up in Mr. Beer, and step up in my starter jar) between smack pack and any given brew.

But I do have some uncertainties and questions:

1. Should I use a lighter wort for the initial step-up? I was worried that if the yeast still had too much sugar to work on once they where enclosed in bottles, I could have some bombs going off in my fridge.

2. How long should I allow the yeast to go at it in Mr. Beer? I would definitely pitch the yeast for the current brew when it was really rocking, but for the yeast to be bottled, should I let it calm down a bit? Again to avoid bombs.

3. Should I fill the bottles to the top, or leave a gap?

4. How cold, and how fast, should I chill the closed bottles?

5. How long can I expect the bottled yeast to be viable?

6. When restarting bottled yeast, should I warm it up in the bottle, or let it warm up in the starter jar?

Whew! I once again get a bit caried away with all the questions, and stretch this thread even longer. Ah well. So if anybody has any input, I would be jazzed to hear it!
 

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Whenever I make a batch I will bottle the yeast from the primary into 2-3 22 oz bottles. I fill them about 3/4 full. I put labels on them with the style and date I put it in the bottle.

I put an aluminum foil topper on them and let them sit for a couple of hours (in case of any activity). After no activity is witnessed I cap them and put them in the fridge.

Be sure to bring your older bottles to the front so you can use them first.
 
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D-brewmeister

D-brewmeister

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Would this technique work with Wyeast Activator packs? Sounds like you are re-using the packaging that the yeast came in to begin with?
 

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D-brewmeister said:
Would this technique work with Wyeast Activator packs? Sounds like you are re-using the packaging that the yeast came in to begin with?

It should work with any kind of yeast. Of course, you just need something for the yeast to live in...and the White Labs vials are a nice compact size.
 
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