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Old 04-17-2009, 01:59 AM   #1
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Default Yeast Propagation

I want to step-up a starter (2 days on a stir plate with 1 liter of wort and a Wyeast smack pack);

Now I want to step it up to 2 liters, adding a fresh liter of wort. Do you recommend

a) decanting the existing wort before adding fresh wort or

b) adding the new wort on top of the old?

Regardless of answer: Why?

I've read lots of brewing books, but don't see any clear answer to this simple question.

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Old 04-17-2009, 02:14 AM   #2
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It doesn't really matter, per se, BUT... you'd have to crash cool it for 24-48 hours before decanting starter beer or you'll lose a lot of yeast still in suspension. You'll get more yeast growth if you decant also... that is, if you started with 1 liter, crash cooled it, decanted the starter beer off, then added 2 liters more of wort (so, that's effectively a 3 liter starter).

However, there is nothing wrong with adding new wort onto starter beer. The standard definition of a "2 liter Starter" that's stepped up would be to start with 1 liter and add a liter of new wort to the fermenting(-ed) starter beer (no decanting).

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Old 04-17-2009, 02:21 AM   #3
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Originally Posted by menschmaschine View Post
The standard definition of a "2 liter Starter" that's stepped up would be to start with 1 liter and add a liter of new wort to the fermenting(-ed) starter beer (no decanting).

What is the advantage of doing it this way? Why not just put 2 liters in to begin with?
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Old 04-17-2009, 04:05 AM   #4
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IMHO and experience I would just pitch a smack pack or vial into a 2L starter. Remember this pack(vial) is supposed to be enough for 5 gallons per the respective lab.

Now, when I'm stepping up a starter, they way I treat it is dependent on the timeline involved and the activity of the yeast. If the yeast is past high kreusen and starting to drop, I'll crash cool it, let it drop out, decant the liquid and add fresh wort about 24 hours prior to when I'll need it. This should bring is back to high kreusen for pitch into the wort.

If the starter is at high kreusen and I'll need to pitch it in 24 hours, I'd add the additional wort without decanting or crashing.

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Old 04-17-2009, 07:53 AM   #5
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What is the advantage of doing it this way? Why not just put 2 liters in to begin with?
When yeast have too much wort, rich in various sugars, they pick simple sugars first and they quicky forget how to digest more complex sugars. Yeast grown that way will produce under-attenuated beer.
Step-up rate should not be bigger than 1:10 (others say 1:4). However, whole vial in 2 liters - I think it will be OK.
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Old 04-17-2009, 03:27 PM   #6
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What is the advantage of doing it this way? Why not just put 2 liters in to begin with?
I think there is more yeast growth with multiple additions of wort than there is just adding it all at once. I believe this is because the yeast go through the growth phase twice in a stepped up starter than just once in a non-stepped up starter. Someone can correct me if I'm wrong.
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Old 04-18-2009, 04:41 AM   #7
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Default Why not 2 liter to start with?

Quote:
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What is the advantage of doing it this way? Why not just put 2 liters in to begin with?
Actually my practice is to usually pitch into a two liter wort for propagation. However, I then pitch half of it and have another half to either:

1. Save and use on another batch
2. Freeze with glycerine so I have a number of 30ml vials already for use later.
3. Step-up for another growth and split-off again.

In this case the left over half had sat in the fridge for a month. Thus the need to revitalize it with some fresh wort and get it back to 2 liters.

Thanks for all your help folks.
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Old 02-01-2011, 09:14 PM   #8
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I just bought a 5L erlenmeyer flask. I'd like to propogate a single pack of wyeast to get as many batches out of the pack as possible. Anyone do this very often? Should I just keep adding fresh wort and decanting? About how many "step ups" can I get away with? In total I'd like to get about enough yeast for 4-5 different 5 gallon batches. Just like yeast washing I would probably decant the final volume, add enough sterile water to fill 5 small mason jars, swirl and then fill the jars.

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Old 02-04-2011, 12:04 PM   #9
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Quote:
Originally Posted by steinsato View Post
I just bought a 5L erlenmeyer flask. I'd like to propogate a single pack of wyeast to get as many batches out of the pack as possible. Anyone do this very often? Should I just keep adding fresh wort and decanting? About how many "step ups" can I get away with? In total I'd like to get about enough yeast for 4-5 different 5 gallon batches. Just like yeast washing I would probably decant the final volume, add enough sterile water to fill 5 small mason jars, swirl and then fill the jars.
You can step up as many times as you want. In theory, you could start with a tiny colony of cells and grow it into trillions and trillions of cells. This is essentially what White Labs and Wyeast do professionally. That said, knowing how to hit your expected numbers is more complicated.

To my knowledge, comprehensive research on yeast population dynamics in beer has yet to be done. There is a bit of info scattered about; check out the Wyeast and MrMalty calculators and the data on page 140 of Chris White's yeast book, but all of it is pretty rudimentary.

There are plenty of people on here who yeast ranch, including several good threads about it. What you describe is certainly possible, but I would recommend doing some research first. The Yeast book I mentioned is a good place to start. If you are just looking for an easy way to get cheaper yeast, I think you'd be better off harvesting and washing.
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Old 02-04-2011, 02:07 PM   #10
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Quote:
Originally Posted by steinsato View Post
I just bought a 5L erlenmeyer flask. I'd like to propogate a single pack of wyeast to get as many batches out of the pack as possible. Anyone do this very often? Should I just keep adding fresh wort and decanting? About how many "step ups" can I get away with? In total I'd like to get about enough yeast for 4-5 different 5 gallon batches. Just like yeast washing I would probably decant the final volume, add enough sterile water to fill 5 small mason jars, swirl and then fill the jars.
In the Mr Malty 14 Essential Questions About Yeast Starters it says the following:
Quote:
Q: I’ve heard that too small or too large a starter can be bad for the yeast. How is that possible?

Parker says putting a fresh vial of yeast into 500 ml of wort and letting such a small starter go to completion can actually leave the yeast less ready to ferment a batch of beer. The yeast do not rebuild their reserves and have very little increase in cell mass.

The minimum starter size for significant yeast growth from a vial or pack of yeast is 1 liter. One vial or pack into 1 liter results in approximately a 50% increase in cell mass.

Some brewers make a small starter volume (500 ml or less) with the sole intent of “waking” the yeast. When making small starters, it is best to pitch the entire volume at the height of activity.
So according to this, you don't want to 'overpitch' the starter too much or you could be doing more harm than good.

So to me it seems that if you keep stepping-up, at some point you'll be overpitching the starter, not getting very much increase in cell mass and yielding less healthy yeast than before. Doesn't mean the yeast won't ferment the batch (disclaimer for those thinking; "I've done that and the beer came out fine."...you can screw a lot of things up and still make beer).

Another disclaimer: I think that quote above applies to a fresh vial/smackpack. If you have an old-ish vial/smackpack then the smallest starter you should use would be smaller as well (since you're starting with less viable yeast). The point is that you don't want to grossly overpitch (or underpitch) yeast starters. Yeast HEALTH should be priority #1.
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