Author Topic: Starter size impact on estimated ABV  (Read 1975 times)

Offline amadest

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Starter size impact on estimated ABV
« on: April 09, 2019, 06:36:05 AM »
Hello,

It seams that there is no option for adjustment of estimated ABV if using starter.
For example I have 18l batch, 1,072OG, 1,005FG and 3l 1.036 starter. No matter if I check checkbox "Add starter to bottling vol" final ABV does not change.
But actually difference with or without starter is over 0.7% in my case:
18l with estABV of 9.0% makes 1.62l of pure alcohol (FG 1.005)
3l 1.036 starter with estABV of 4.07% makes 0.122g of pure alcohol (FG 1.005)
So final ABV is 8.3% (1.62+0.122)/(18+3)
Am I wrong in my calculation?

Offline BOB357

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Re: Starter size impact on estimated ABV
« Reply #1 on: April 09, 2019, 08:06:28 AM »
Yes, it does impact bigger beers quite a lot if you pitch the whole starter volume. I decant off the liquid, leaving just enough to swirl up the yeast. This greatly reduces the impact.


Bob

Offline dtapke

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Re: Starter size impact on estimated ABV
« Reply #2 on: April 09, 2019, 10:39:49 AM »
Could this be easily mitigated by using the SG of the wort in the fermenter AFTER the starter wort has been added?

I also only pitch slurry so I've never worried about it myself... and honestly I'm a bit curious as to how/why the starter volume would be added to the bottling volume and not the batch volume as it would be more reflective of the process in some ways.

It would seem there would be issues in determining your BHE using either method.

For me, only pitching the slurry eliminates adding any wretched off flavors that my starter would add to a beer, so It's a huge non-issue as I would never pitch the starter "beer"
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Secondary/Lagering:
Next Brew: RIS

Offline Oginme

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Re: Starter size impact on estimated ABV
« Reply #3 on: April 09, 2019, 11:15:23 AM »
I also decant and pitch just the slurry. 

For the OP, 18 liters in a batch plus 3 liters in a starter ends up with 21 liters in the fermenter, with 3 / 18 or 14.3% of what you are brewing is not what you designed in your recipe. 

When I decant my starter and measure out to the cell count that I need in my beer, I end up pitching less than 200 ml into a 10 liter batch in a high gravity ale or lagers which would be around 2% dilution of the beer I want.  For the majority of the recipes that I brew, it is less than 1%. 

I do fully understand the OP's question and agree that the program does not reflect the affect of the starter on the ABV calculation. 
Recycle your grains, feed them to a goat!

Offline dtapke

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Re: Starter size impact on estimated ABV
« Reply #4 on: April 09, 2019, 12:14:16 PM »

I do fully understand the OP's question and agree that the program does not reflect the affect of the starter on the ABV calculation.


Yep I should've stated that as well. I just feel it's bad practice to pitch the "beer" anyways so I'd never have thought of it.
32g eHERMS
Drinking: Dopplebock, NEIPA, Pils
Primary: empty
Secondary/Lagering:
Next Brew: RIS

Offline Oginme

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Re: Starter size impact on estimated ABV
« Reply #5 on: April 09, 2019, 12:33:49 PM »

Yep I should've stated that as well. I just feel it's bad practice to pitch the "beer" anyways so I'd never have thought of it.

Agreed!
Recycle your grains, feed them to a goat!

Offline amadest

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Re: Starter size impact on estimated ABV
« Reply #6 on: April 10, 2019, 12:07:01 AM »
Thanks for opinions! I will go for dacanting.
But I think Bred can add this option in new version of soft.

 

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