starter FG

Its going on 2 days on my starter and krausen is falling back in. I would like to know what should be the FG for it? Never made a srarter so im new to this. The OG was 1.035-1.040 ish. Just trying yo get an idea how long it'll be. I want to cold crash it when ready. Thanks

If you allow the starter to finish the yeast will build up glycogen reserves which will help them ferment the beer. If you crash it now you will have 90% of your cell count. It all depends on how much time you have. You could let it wait for a week with no I'll effect. Assuming 100 billion cells in a 1 or 2 litter starter 3 or 4 days is pretty much ideal.

Like with beer a stable final gravity would indicate that 100% of the cell count / fermentation has been achieved.

I plan on letting it finish. I just dont know what a good FG is for it.

The final gravity will depend on several factors. In addition to original gravity it depends on the yeast strain, pitch rate, temperature and sugar make up of the malt extract.

Good point. I will take a sample and check gravity and see it changes the following day. However its a 3 liter starter, 10.6oz extra light dme with wyeast 1272 london ale yeast fermenting at 67°

Wyeast 1272 says attenuation of 72-76%, to give a rough idea of about what you'd expect for FG. Wyeast seems to call 1272 "American Ale II" though, not London Ale??

whoaru99 said:

Wyeast 1272 says attenuation of 72-76%, to give a rough idea of about what you'd expect for FG. Wyeast seems to call 1272 "American Ale II" though, not London Ale??

Click to expand...

My bad you are right!

Hows the 72-76% equate to a gravity reading?

Jman_01 said:

Hows the 72-76% equate to a gravity reading?

Click to expand...

(Og - fg)/(og - 1) = apparent attenuation

Thanks thats good to know!

I was searching for a thread like this a week or so ago. I'm not confident that the FG of a starter will fall in-line with the final gravity of a typical beer; then again, why wouldn't it??? Anyway, I intend on recording the FGs of my next several starters (OGs too) just so I can create a baseline for those instances when I'm worried a starter isn't moving along like it should. I guess my assumption is that when propogating a starter we are actually aiming for maximum yeast cell reproduction which should be counter to alcohol production (I think), and how all of that affects the FG is questionable.

As of now, using a stirplate, I'm primarily interested in seeing a creaminess change in the starter. It usually starts off like very dirty dishwater; coffee with a little milk as creamer; or normal colored caramel with some translucency. I aim for a finished product that resembles a very creamy, too light caramel color with not a lot of translucency. Of course, if I had numbers to work with then I could forgo the silly verbal descriptions

Jman_01 said:

Hows the 72-76% equate to a gravity reading?

Click to expand...

What I'd do is this...

1-0.72 = 0.28
1-0.76 = 0.24

Assuming OG = 1.040

40 x 0.28 = 11.2
40 x 0.24 = 9.6

FG = ~1.011-1.010

whoaru99 said:

What I'd do is this...

1-0.72 = 0.28
1-0.76 = 0.24

Assuming OG = 1.040

40 x 0.28 = 11.2
40 x 0.24 = 9.6

FG = ~1.011-1.010

Click to expand...

That's some good stuff!

My blog has a few posts on starters. On of them has an equation for attenuation based on pitch rate and gravity. It was the last of a four part series that I did about a year ago. My book has more information.

Or, maybe a little easier...

OG = 1.040

OG points - (OG points x attenuation) = FG points

40 - (40 x 0.72) = 11.2

FG = 1.0112