Author Topic: FG is finishing way too low, is it an infection?  (Read 2976 times)

Offline Slade7077

  • 1st Kit
  • *
  • Posts: 11
    • View Profile
FG is finishing way too low, is it an infection?
« on: January 03, 2016, 11:26:22 PM »
My last few AG batches have finished at least 10 points below the estimated final gravity. These were all APAs and IPAs.  The have no hop flavor or aroma. The beer has no malt character, and no real flavor.  It has more of a rubbing alcohol type burn to it, and a soapy type taste.  I don't understand what has caused this.  Is it an infection that is causing overattenuation, is it mash ph? somebody help.

Offline brewinhard

  • Official Poobah of No Life.
  • *
  • Posts: 3250
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #1 on: January 03, 2016, 11:29:34 PM »
Have you recently properly calibrated your thermometer you use for mashing?  This can really throw things off if your thermometer is 4-5 degrees out of whack.  Do you have temperature control for fermentation?

Offline Slade7077

  • 1st Kit
  • *
  • Posts: 11
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #2 on: January 03, 2016, 11:36:21 PM »
Yes, I have a fermentation chamber and a controller.

I calibrated my thermometer today and its right on the money. 

I am thinking I need to throw away my auto siphon and maybe a couple of fermenters.  I made several extract batches that were great and my all grain was good in the beginning.  4 out of last 6 batches have been basically undrinkable.

Offline HoosierBrew

  • Global Moderator
  • I must live here
  • *****
  • Posts: 13030
  • Indianapolis,IN
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #3 on: January 03, 2016, 11:38:46 PM »
Have you calibrated your hydrometer and corrected for temp? The paper slip inside a hydro can slip over time. One of mine reads ~ .004 high every time. Or if you use a refractometer do you use the correction for alcohol present?
Jon H.

Offline Slade7077

  • 1st Kit
  • *
  • Posts: 11
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #4 on: January 03, 2016, 11:43:11 PM »
Yes, I always correct for temp.  I was at 1.000 today in a glass of water.


Offline mainebrewer

  • Brewer
  • ****
  • Posts: 430
  • Palermo, Maine
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #5 on: January 04, 2016, 01:54:45 AM »
Since you've eliminated ferment temp and instrument calibration, I'm guessing the rubbing alcohol is due to bacterial contamination, likely pediococcus. That will create a solvent like flavor. It also will create a lot of diacelyl (butter/butterscotch or a slick feeling on the palate). Edit to add that a bacterial contamination will also result in the over attenuation that you noted.
« Last Edit: January 04, 2016, 02:15:35 AM by mainebrewer »
BJCP Certified

Offline Slade7077

  • 1st Kit
  • *
  • Posts: 11
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #6 on: January 04, 2016, 03:05:08 AM »
So what do I need to do?  How do I eliminate it?

Offline brewsumore

  • Brewmaster
  • *****
  • Posts: 623
  • Spokane, WA
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #7 on: January 04, 2016, 05:18:41 AM »
dial in your mashing temp and technique

cleanliness and sanitation of cold side equipment

proper yeast pitching rate (I recommend Mr. Malty pitching rate calculator - and I recommend stir plate starters if using yeast starters)

aerate wort immediately prior to pitching yeast ( I definitely prefer straight o2 via aeration stone)

pitch yeast within ~10 degrees of wort temp

pitch yeast below your initial desired ferment temp.  Avoid beer temp swings during the ferment

Ferment temp control (for most beers, keep beer temp <67F the first 72 hrs)

Ensure you have de-chlorinated / de-chloramined your brewing water (1 crushed campden tablet per 20 gal water stirred in first thing before heating strike water)
« Last Edit: January 04, 2016, 05:24:06 AM by brewsumore »

Offline brewsumore

  • Brewmaster
  • *****
  • Posts: 623
  • Spokane, WA
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #8 on: January 04, 2016, 05:29:52 AM »
And yes you might have an infection - you might want to change siphon / hose or at least soak in PBW followed by bleach solution, followed by rinse. rinse, rinse... and do same with fermenters.

Offline stevecrawshaw

  • Cellarman
  • **
  • Posts: 55
    • View Profile
    • My Recipes
Re: FG is finishing way too low, is it an infection?
« Reply #9 on: January 04, 2016, 10:53:55 AM »
I had similar issues a couple of years ago. Cold side sanitation. In brief i fixed it as follows.

  • stainless racking cane - blowtorch to sterilise
  • silicone transfer tubing. boil to sanitise (I autoclave but not everyone has one)
  • use a removable mouthpiece to create suction for siphon - suck on mouthpiece then remove when flow starts
  • with thin wall silicone tubing you can just compress the tube by hand to stop flow
  • use peracetic acid to sanitise FV after cleaning with PBW \ oxiclean
  • Store your FV with some peracetic in it and seal it
  • minimise exposure to air during chilling \ cold side process
  • ferment under airlock
  • don't keep opening the fermenter to look at it
  • ensure your starter flask \ equipment is boiled \ flamed. Use boiled and cooled water for starter \ rehydration

Some of this sounds excessive but if you want to eliminate all possible contamination (and stop throwing beer away) it works.

cheers
steve
I like to keep a bottle of stimulant handy in case I see a snake, which I also keep handy.

Offline Slade7077

  • 1st Kit
  • *
  • Posts: 11
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #10 on: January 04, 2016, 12:24:09 PM »
Thanks for the answers.

Makes me feel better that I am already doing alot of the things listed. I always use Mr Malty or another yeast pitching calculator. I always chill wort below pitching temp and let it free rise to fermentation temp. I think it is definitely somewhere in cold side sanitation. I have never used campden tablets but I am going to start immediately.

Could crushing my grain too fine cause any of these problems. I am using my barley crusher on factory setting. My drivers license will barely slide through the rollers.

Offline reverseapachemaster

  • Official Poobah of No Life.
  • *
  • Posts: 3195
    • View Profile
    • Brain Sparging on Brewing
Re: FG is finishing way too low, is it an infection?
« Reply #11 on: January 04, 2016, 04:36:15 PM »
Can you give us an example of one of these recipes and your process?

If you have an IPA or APA coming in ten points below expected FG then either the OG was way under, you are getting extreme mash efficiency, or you have a voracious infection that is eating your beer down to nearly 1.000. It's easy to always point to an infection as a source of problems but that doesn't make it necessarily the cause of your problematic beers.

Bacteria can be a cause of infection but most beer infecting bacteria do not cause significant drops in gravity even when producing significant volumes of acid or other flavor compounds. Pediococcus might be the exception but it is a slow moving bacteria and unlikely to be your culprit unless you are pitching a large volume of pedio into your beer or letting it sit for months and months. If you are getting off flavors plus a significant drop in gravity then bacteria is a likely culprit only if it is showing up to the party with other unwelcomed guests.

Most wild yeast are not so voracious that they can chew down gravity that far. Wild saccharomyces and related yeasts are as likely to stop fermenting at 1030 as they are at 1000. Oxidative yeast like brett are often the source of low FG but like pedio they are slow to grow and start fermenting unless you are pitching a large volume at the beginning of fermentation. Unless you are repitching slurry from a heavily infected batch this is unlikely. Another reason why you can likely eliminate brett from the possible candidates is that brett does a good job of consuming residual oxygen and leaving behind hop flavor. Brett will affect biotransformations on hop compounds to an extent but these are also slow processes that often take months to years.

All of that is not to say you definitely do not have an infection problem but there are many other culprits as likely or more likely.
Heck yeah I blog about homebrewing: Brain Sparging on Brewing

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 19858
  • Noti OR [1991.4, 287.6deg] AR
    • View Profile
    • Dennybrew
Re: FG is finishing way too low, is it an infection?
« Reply #12 on: January 04, 2016, 05:05:32 PM »
My last few AG batches have finished at least 10 points below the estimated final gravity. These were all APAs and IPAs.  The have no hop flavor or aroma. The beer has no malt character, and no real flavor.  It has more of a rubbing alcohol type burn to it, and a soapy type taste.  I don't understand what has caused this.  Is it an infection that is causing overattenuation, is it mash ph? somebody help.

Who's estimate are you using?  Most estimates of FG are nothing more than a WAG.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline Slade7077

  • 1st Kit
  • *
  • Posts: 11
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #13 on: January 04, 2016, 08:58:39 PM »
I over build my starters and repitch yeast. I guess this could also be the problem.

Denny, I get the estimate FG from the recipe I am using. My beers are all finishing at 1.006 or 1.008. Really thin, no flavor or aroma. My efficiency is usually between 75 and 80% 
« Last Edit: January 04, 2016, 09:17:29 PM by Slade7077 »

Offline brewsumore

  • Brewmaster
  • *****
  • Posts: 623
  • Spokane, WA
    • View Profile
Re: FG is finishing way too low, is it an infection?
« Reply #14 on: January 04, 2016, 09:30:00 PM »
I over build my starters and repitch yeast. I guess this could also be the problem.

Denny, I get the estimate FG from the recipe I am using. My beers are all finishing at 1.006 or 1.008. Really thin, no flavor or aroma. My efficiency is usually between 75 and 80%

As memory serves, overpitching can lead to:

1) early high ferment temps that can lead to higher (fusel) alcohol that often impart solvent-like flavor to the beer

2) higher-than-planned attenuation