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-   -   Splitting a yeast starter? (http://www.homebrewtalk.com/f163/splitting-yeast-starter-368714/)

Renard 11-19-2012 06:34 AM

Splitting a yeast starter?
 
Hi!

A have recently started brewing AG and and I only make 10 litre(2,64gal) batches to save some money and be able to brew more frequently.
But one thing I don't save money on is the yeast. :( I've started making starters but when reading about starters on Mr Malty I've noticed that you never should do a smaller starter then 1L, wich in my case i way to big for one batch.

So my questions are:
1. can I make a big starter and split it up between two batches even tho I brew one week apart?

2. How much yeast health will the other half loose in one week in the fridge?

3. Do I need to give the later half some extra wort to warm up with before pitch?

4. How big can a starter from one white labs vial be before I have to start stepping up my starters?

Thanks. :)

MalFet 11-19-2012 12:58 PM

1) Yep!
2) Not a ton
3) Sure, but it's not truly necessary.
4) No real limitation, but if you start going above 1.5L-2L for a single vial, the numbers get weird.

Good luck! :mug:

Renard 11-19-2012 02:44 PM

Thanks so much! :D

Michelob6 11-20-2012 03:17 AM

Same question here, I make 10 gallon batches, I make 1 2liter starter and split between the 2 carboys. Is there any harm in doing this? It always seems to ferment to desired FG.

MalFet 11-20-2012 03:20 AM

Quote:

Originally Posted by Michelob6 (Post 4605479)
Same question here, I make 10 gallon batches, I make 1 2liter starter and split between the 2 carboys. Is there any harm in doing this? It always seems to ferment to desired FG.

Make sure it's well mixed before pouring, but other than that no problem. Obviously you have fewer yeast cells, but if you're numbers check out it's fine.

Michelob6 11-20-2012 03:22 AM

It usually takes a little longer to start fermenting, but yes I get the numbers.I have never done this though on anything higher than 1.054 og

nevery 11-20-2012 03:51 AM

Very controversial... MANY respectable people say "cold pitching" (meaning not warming the yeast before pitching) leads to less lag time and more complete fermentations. Denny Conn is one of them and a quite a few microbiologists agree. Yeast are harmed by the "freeze" part of the freeze-thaw cycle, not the "thaw." Note: instead of flaming, please ask for citations and I'll post them. I don't want to flood the thread for something off topic.

Yes you can wait the week, but you can always just over-pitch which, within a reasonable quantity, won't hurt anything and probably only help.

UNDER-pitching, however, can lead to off-flavors and stuck fermentations. You'll wear out the yeast prematurely and you'll need a lot more aeration. (which, btw, for best yeast performance, one should aerate twice; once before pitching and again 12 hours after.)

Also, learn to wash or bank yeast man! You'll save hundreds. :)

Good luck man!

MalFet 11-20-2012 04:16 AM

Huh? Who said anything about cold pitching?

scubastan 11-20-2012 05:00 AM

my opinion on #4.

I recently had to figure something similar to this out, so I thought I would share.

Different Breweries / Brewers use different "Growth Factors". In searching the internet i've come across numbers from 3x to 10x. I see alot of mention of a 5x Growth factor.

White Lab vials contain 75-150Billion cells. So if you average that and say 100Billion cells.

The largest starter would be one that allowed you to go 100B x (10x) growth factor or 1 Trillion cells.

Using YeastCalc that works out to ~44Liters of starter or 11.6gallons.

So the simple answer would the max starter for a single vial would be about 11.6gallons.

However notice that if you follow the common growth factor of 5x you would end up somewhere around 5-6 gallons. Hence that is why White Labs and Wyeast pack that specific amount of yeast in the packs.

The higher the growth factor the higher your chances of altering the metabolism of your yeast. The lower the growth factor the smaller amount of cells will be grown.

But what if you make multiple steps? Then you will grow more and more cells. :)
The drawback however is every step you take increases the risk of contamination.

nevery 11-20-2012 11:16 PM

Quote:

Originally Posted by scubastan
White Lab vials contain 75-150Billion cells. So if you average that and say 100Billion cells.

Just a note: 3 months from it's manufacture date, it's at 50% viability according to Chris White. That's a month before its "use by" date on white labs labels.


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