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Double-volume starter vs. Starter-Decant-Starter?

Post #1 made 13 years ago
by UncleBuckO
I'm curious if anyone can help with this question. In the past, when making a yeast starter for a large batch I have:
1) made a 2L starter
2) let it go for a few days
3) cooled it
4) decant
5) made another 2L starter & poured into original 2L slurry
Given the lack of larger flasks, this was how I could effectively make a 4L starter.

QUESTION:
Will simply making a double-volume (4L) starter produce the same or similar result? I have access to a 5L flask now....

Cheers!
My girlfriend told me she would leave me if I brewed today.....

I sure am going to miss her.

Post #3 made 13 years ago
by UncleBuckO
I've used this yeast pitching rate calculator....Also have used the yeastcalc site, as well.

It is for a single batch.
My girlfriend told me she would leave me if I brewed today.....

I sure am going to miss her.

Post #4 made 13 years ago
by mally
Are you using a stir plate?

If so I would make a "guess" that what you are doing (2x2L) will be similar to 1x4L. Logic tells me that the yeast are seeing a similar concentration of sugar in the wort, and they are not receiving any "it's cramped in here" signals! They should keep budding & eating sugar until its gone.

If you are not stirring/agitating then I would guess there may be a difference between them? Wouldn't like to guess about quantifying it though.

YMMV

By the way, you could always try both methods & report back (if you fancy doing an experiment that is)?
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Double-volume starter vs. Starter-Decant-Starter?

Post #6 made 13 years ago
by Lars
I'm pretty sure the 2 smaller starters will not achieve the same level of growth. If I remember rightly( from Yeast book) the 1st 2l starter will have a max return so when the slurry goes into the second starter the volume of cells will be close to max'd out so there will very little return from the final step. You would get more yeast by splitting the slurry after the 1st step and creating a new 2l starter with 1/2 the slurry

Post #7 made 13 years ago
by mally
Lars - I would be interested to read any more information you have about that. Logically I cannot see why it would make a difference, but I am by no means a zymurgist (hence my piqued interest).

I have read that stirring Vs not stirring can give up to 15-fold yeast growth yield.
I understood this to be due to (amongst other things) the "it's cramped in here" signals not being triggered,as well as oxygen availability. Hence my theory that it wouldn't matter whether you had 2 small volumes or one (equal) large one.

Put simply, with stirring; the yeast are fooled into thinking there is an abundabce of sugar, nutrients, and oxygen which to them means "get budding".
When they get cramped, or there is no/less oxygen, they reduce growth & concentrate more on sugar consumption.
Last edited by mally on 18 Apr 2013, 04:59, edited 2 times in total.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Post #9 made 13 years ago
by mally
Thanks Lars, very interesting.
Does it mention anywhere what method was used? Stirring, oxygenation etc.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Post #11 made 13 years ago
by mally
Thanks Lars,
If i understand correctly, those values are based on not stirring/mixing/agitating.
If so, you will likely find different growth rates/curves if you do.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Post #12 made 13 years ago
by mally
For info;
The guys at HBT had a similar discussion here

If anybody wants to delve a little deeper, the link in post #7 (maltosefalcons) is interesting too.
Last edited by mally on 18 Apr 2013, 20:37, edited 2 times in total.
G B
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
    • SVA Brewer With Over 100 Brews From Great Britain

Double-volume starter vs. Starter-Decant-Starter?

Post #13 made 13 years ago
by Lars
mally wrote:Thanks Lars,
If i understand correctly, those values are based on not stirring/mixing/agitating.
If so, you will likely find different growth rates/curves if you do.
I wouldn't expect the curve shape to be different, would you? I would only have expected to improve the yield in each instance
Last edited by Lars on 18 Apr 2013, 23:32, edited 2 times in total.
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