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General Category => Yeast and Fermentation => Topic started by: noodle on May 21, 2011, 11:51:50 PM

Title: Missing FG???
Post by: noodle on May 21, 2011, 11:51:50 PM
Fresh pitch from starter. Correct amount of yeast for target/actual OG. Missed FG by 5 points.

OG - 1.051
FG - 1.018 - supposed to be 1.013

Why?

thanks,

noodle
Title: Re: Missing FG???
Post by: Hokerer on May 21, 2011, 11:58:53 PM
Fresh pitch from starter. Correct amount of yeast for target/actual OG. Missed FG by 5 points.

OG - 1.051
FG - 1.018 - supposed to be 1.013

Why?

thanks,

noodle

how 'bout a recipe?  could be the extract or the mash schedule if all grain, the yeast, the fermentation, etc.
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 12:11:23 AM
All grain

Primary for 7 days

Mash @ 152

We will run a new yeast then rack to secondary and add new wort to the fermentor.

Seems that our first batch will not finish as expected.

Additional batches will come out as expected.

thanks,
Title: Re: Missing FG???
Post by: tubercle on May 22, 2011, 12:13:39 AM
All grain

Primary for 7 days

Mash @ 152

We will run a new yeast then rack to secondary and add new wort to the fermentor.

Seems that our first batch will not finish as expected.

Additional batches will come out as expected.

thanks,

Not sure what ' run a new yeast " means but if you mean pitching more yeast it won't matter if there are no more fermentables. Skip the secondary unless you nees the room.
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 12:16:49 AM
We brew every week and will reuse the yeast for a period of time. Our issue with not hitting FG seems to be with the first/original pitch of our starter.

thanks,
Title: Re: Missing FG???
Post by: narcout on May 22, 2011, 12:47:25 AM
What was the recipe?

Did you aerate or oxygenate the wort?

What yeast did you use? At what temperature did you pitch? At what temperature did you ferment?

Sometimes fermentation isn't finished after only 7 days, are you sure it has already reached terminal gravity?
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 01:59:02 AM
narcout -

Beersmith software - It shows an expexted OG and FG based on the recipe. We hit OG but miss FG on initital pitch only.

Wort is fully oxyginated via inline stone.

Issue is with first pitch verse second, third, fourth and so on.

I faill to see the relevance of the recipe or yeast type.

Terminal gravity is usually reached within three to four days.

thanks,


Title: Re: Missing FG???
Post by: a10t2 on May 22, 2011, 02:12:47 AM
I faill to see the relevance of the recipe or yeast type.

Do you have any experience brewing? Different recipes will have different FGs, and even fermenting the same recipe with a different yeast will alter the FG.

Regardless, somewhere along the line you input an expected attenuation into BeerSmith, which it is using to calculate the expected FG. It doesn't "know" anything about your beer, so it can't make a prediction.

There are some pretty experienced brewers on this forum, on the other hand, so if you'd tell us the recipe we *could* make a prediction.
Title: Re: Missing FG???
Post by: bluesman on May 22, 2011, 02:27:30 AM
Detailed recipe please. This will help us get to the bottom of your potential issue.

Thanks.
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 10:34:57 AM
This is why I ask -

We will run the same yeast for four batches starting as follows - Pub Ale, ESB, ESB, Brown Ale

Pub - Missing FG
ESB - Hit numbers as expected
ESB - Hit numbers as expected
Brown - Hit numbers as expected

Second run as follows - Brown, ESB, ESB, Pub
Brown - Missing FG
ESB - Hit numbers as expected
ESB - Hit numbers as expected
Pub - Hit numbers as expected.

In both cases, the first beer of the run doesn't finish as expected.

Any ideas?

Thanks,
Title: Re: Missing FG???
Post by: stlaleman on May 22, 2011, 11:45:23 AM
I'll take a shot at this. If I understand correctly, you are repitching the yeast three more times, each of those times you hit the expected FG, but never the first time. Therefore the starter is to blame, either too small or you somehow stressed the yeast. Revisit that aspect of your brewing.
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 01:24:21 PM
stlaleman -

Thanks, this is what I need to figure out. I make the starter 1-2 days prior to brewing and everything looks good with it.

Any advise as to what I'm looking for?

Thanks for your help and direction.
Title: Re: Missing FG???
Post by: Hokerer on May 22, 2011, 03:30:34 PM
stlaleman -

Thanks, this is what I need to figure out. I make the starter 1-2 days prior to brewing and everything looks good with it.

Any advise as to what I'm looking for?

Thanks for your help and direction.


Try messing around with the Pitching Rate Calculator here...

http://www.mrmalty.com/calc/calc.html (http://www.mrmalty.com/calc/calc.html)

and see if your starter is big enough.  A re-pitch is going to be a much higher pitching rate than a 1-2 day starter so it makes sense that you're getting full attenuation on batches 2, 3, 4.
Title: Re: Missing FG???
Post by: denny on May 22, 2011, 04:01:52 PM
Beersmith software - It shows an expexted OG and FG based on the recipe. We hit OG but miss FG on initital pitch only.

Beware of ANY software that does this...it's a guess and it's bogus.  The software is using the attenuation rating of the yeast, which is actually meant only as a method of comparing one yeast to another, NOT as a way of predicting FG.  Wort composition is actually much more important to FG and any yeast can yield a wide range of attenuation depending on the wort you pitch it into.
Title: Re: Missing FG???
Post by: Pawtucket Patriot on May 22, 2011, 04:30:09 PM
Wort composition is actually much more important to FG and any yeast can yield a wide range of attenuation depending on the wort you pitch it into.

Which is why other posters have been asking for detailed recipe info.  I don't know why the OP is so reluctant to provide this -- we're only trying to help!  It's sort of SOP on this forum to provide your recipe if you want a proper diagnosis of a problem.
Title: Re: Missing FG???
Post by: narvin on May 22, 2011, 06:50:58 PM
First generation of yeast is often slower.

 I wouldn't rack after 7 days in the primary... it may drop another 3 points if you give it an extra week.
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 08:35:18 PM
stlaleman - I use Mr Malty to compute the required yeast.

Narvin - 7 days for fermentation? How do commercial breweries do it? They aren't waiting that long.

Pawtucket Patriot - If I was having this issue with one particular yeast and recipe over and over then I could see the relevance but this is not the issue. The problems lies with the initial pitch.

Thanks,
Title: Re: Missing FG???
Post by: sandy on May 22, 2011, 09:36:18 PM
Well, if you insist that it's not your pitching rate or oxygenation or time, that only leaves your recipe or mash...

Since you obviously don't want to provide that, for whatever reason...we'll (and you'll) just have to assume you have a lot of non-fermentables in there...either due to mash temp, or grains...
Title: Re: Missing FG???
Post by: narcout on May 22, 2011, 10:05:36 PM
Like Narvin said, the first generation can sometimes ferment more slowly - especially with certain strains.  Which strain are you using?

Have you at least tried leaving the beer on the yeast for a few extra days? 

When you repitch, are you pitching significantly more cells than on the first pitch?
Title: Re: Missing FG???
Post by: noodle on May 22, 2011, 11:09:38 PM
Same strain for both examples. It's always the first pitch that doesn't finish as expected.

When re-pitching, we just add fresh wort to the carboys. We rack to secondary then just add wort to whats left.

thanks for your help.
Title: Re: Missing FG???
Post by: tubercle on May 22, 2011, 11:13:06 PM
Same strain for both examples. It's always the first pitch that doesn't finish as expected.

When re-pitching, we just add fresh wort to the carboys. We rack to secondary then just add wort to whats left.

thanks for your help.

 With you refusing to help with a recipe I can only conclude this:


1. You are underpitching the first batch.

  2.  "When re-pitching, we just add fresh wort to the carboys"...you are over pitching the others.
Title: Re: Missing FG???
Post by: nateo on May 22, 2011, 11:15:00 PM
You are underpitching the first batch.

  2.  "When re-pitching, we just add fresh wort to the carboys"...you are over pitching the others.

+1 to that. Tubercle hit the noodle on the head with that one.
Title: Re: Missing FG???
Post by: narvin on May 23, 2011, 02:50:46 AM
You are underpitching the first batch.

  2.  "When re-pitching, we just add fresh wort to the carboys"...you are over pitching the others.

+1 to that. Tubercle hit the noodle on the head with that one.

Definitely agree with this as well.  Yeast growth during fermentation means that you'll have significantly more yeast for the second batch, and unless it's a very high gravity beer you won't need all of it.

If your FG is 1.013 even when overpitching, I'd look at your recipe or your mash temperature to try to make a more fermentable beer.  Calibrate your thermometer against a lab grade model or quality certified digital thermometer to make sure you are mashing at the temperature you think you are.
Title: Re: Missing FG???
Post by: noodle on May 23, 2011, 11:24:42 AM
Thanks for the info. This is why I'm using the Mr Malty calculator to make sure we pitch enough but it seems we're still off a bit. Using Blichman kettles and we calibrated the thermometers.
Title: Re: Missing FG???
Post by: denny on May 23, 2011, 04:14:13 PM
we calibrated the thermometers.

Hopefully with a certified lab thermometer and not the freezing/boiling method.