Adding DME to starter in progress

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t^3

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I mostly use dry yeast or slurry to avoid the whole starter mess. I say mess because I always seem to have an overflow from the flask on the stir plate. I only have a 2l flask and brew 5 gallon batches of ~1.070 wort. I don't think my stir plate can handle a 5l flask so I don't really want to go there. To combat the overflow I start many days in advance and do 2 step starters with cold crash and decant. Looking for a way to simplify/speed up the process. When the krausen starts to fall can I just add more DME into the flask? The stir bar ought to mix it up well enough. Anyone do this or have other ideas?
 

JohnSand

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I haven't done it in a starter. I have added sugars to fermenting beers, feeding Belgian ales. So I believe you can. I make pretty simple starters when necessary, generally using a growler and just shaking it occasionally.
 

RufusBrewer

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If I was convinced I needed lots of yeast. Make a starter, grow the yeast, decant new yeast and dump that new yeast into a fresh starter wort. The second starter would be larger than the first.

At some point the second starter looks like a batch of beer. So why not brew a beer in place of the starter?
 

TBA

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Make a starter, grow the yeast, decant new yeast and dump that new yeast into a fresh starter wort. The second starter would be larger than the first.

This is what I currently do. I guess I should say the reason for needing so much yeast is to save some for next batch. I do try to harvest after kegging or top cropping but sometimes it doesn’t work out. I like to have the backup yeast.

More I think about it, I guess you can only have so much yeast in a given volume. So no way around the 2 step starter. Adding more DME would just start to make more alcohol and that isn’t what i’m after here.
 

IslandLizard

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To combat the overflow I start many days in advance and do 2 step starters with cold crash and decant.
Are you using a yeast calculator to estimate volume, growth and cell numbers?
BrewUnited's Yeast Calculator

Make a starter, grow the yeast, decant new yeast and dump that new yeast into a fresh starter wort. The second starter would be larger than the first.
If you don't use a larger volume of starter wort for the second step, growth rate will be severely stunted. See that yeast calculator I linked to, above.

An alternative to using larger starter vessels, you could save out 80-90% of the slurry from the first step, to use in your upcoming brew, then make a new starter with the leftover 10-20%. That will give you more growth due to a smaller inoculation rate. It's like making a double batch.
If you want to save some time, letting the first round starter crash while propagating the 2nd round, use 10-20% of your 1st starter volume (uncrashed but well homogenized).
If the 2nd round starter contains 10% spent starter wort (= starter beer) from the first round, due to omit crashing, make your new starter a little stronger, say 1.045 to come out at 1.037-1.040 for round #2.

If in a pinch yes you could add some extra DME to your spent starter. I would dissolve it and give it a quick boil to pasteurize, then chill, before adding. A stainless kitchen pot with a well fitting lid works wonders for that. Chills fast too in a tub or sink with cold water.

I find using 2 liter starter vessels working well for me, using propagation schedules as in the example above. I can't easily place a 3 or 5 liter flask in my fridge, I would have to remove a shelf to get the required headspace which is not very practical.
 
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t^3

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Thanks @IslandLizard! I see the problem with not increasing the volume. I don't often start out with a new liquid yeast, mostly dry or slurry. I usually wake a slurry up on brew day with a vitality starter for 4-6 hours. For the occasions when I do get a new liquid yeast I like to overbuild and save some.
 
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