Author Topic: Drop in FG after 10 days of stable readings  (Read 292 times)

Offline dmcohen1

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Drop in FG after 10 days of stable readings
« on: February 04, 2022, 04:16:57 am »
Hey folks, I brewed a Zombie Dust clone, all grain about 12 days ago.  I used 2 pkgs of Lallemend London ESB for a 6.25gal batch.  My OG was 1.070, with a target FG of 1.017.  I fermented in as Ss Brewtech conical.  The fermentation was robust, and arrived at 1.014 in 3 days.  A little low, but nothing that worried me. I added 2oz of citra dry hops at about 1.020.  Everything was great.  For 7 days, up until day 10, the gravity level stayed at 1.014 and the beer tasted juicy, with bright citrus aroma.  On day 10, I did a first dump to get rid of the trub and dry hops that had been in there for 7 days, and was planning to keg at 2 wks, to condition for a week before putting it on tap. 

Unfortunately, on day 12, I took another sample and reading and the gravity dropped to 1.009 and the juiciness in the beer was totally gone, as was some, but not all, of the aroma.  The beer doesn't taste 'off' in any way (no astringent or mediciney taste) but the fruitiness of the citra hops is largely gone and the beer is more bitter (I assume because it's dryer). 

My question is why the gravity would drop like that (a full bric from 9 to 8 on my reflectometer) after having been stable for a week?  Plus, this is not the first time this has happened to me, and with a range of different types of beers that may or may not have been dry hopped.  Is it the agitation of the yeast when dumping the trub?  Is it biotransformation, which I feel like if it was it should have happened sooner after adding the dry hops?  I guess theoretically it could be an infection, but I don't taste anything obvious and after sitting for 7 days with a 7.2% abv, I feel like it's unlikely to develop at that point.  Maybe my mash temp was off (reading off my bruzilla) but again, the gravity was stable for 7 days before it dropped again. 

So I'm out of ideas.  This beer was on track to be epic.  Juicy, amazing aroma, soft bitterness...etc.  Maybe it straightens itself back out again when it's cold and carbonated, but I don't even know if I'll get that far.  Is it going to keep fermenting more now?  Anyway, folks, please advise!

Offline ynotbrusum

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Re: Drop in FG after 10 days of stable readings
« Reply #1 on: February 04, 2022, 04:29:41 am »
Look into bio transformation. It involves the hops creating additional enzymes introducing amyloglucosidase into the fermented wort to further ferment it.

It might be that, or an infection….
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Offline neuse

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Re: Drop in FG after 10 days of stable readings
« Reply #2 on: February 04, 2022, 07:56:13 am »
It could be a wild yeast infection, which would be different from a bacterial infection. I'm not an infection expert, so all I can do is offer this as a suggestion.

Offline denny

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Re: Drop in FG after 10 days of stable readings
« Reply #3 on: February 04, 2022, 07:59:36 am »
Look into bio transformation. It involves the hops creating additional enzymes introducing amyloglucosidase into the fermented wort to further ferment it.

It might be that, or an infection….

I think you're confusing biotransformation with hop creep.
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Offline denny

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Re: Drop in FG after 10 days of stable readings
« Reply #4 on: February 04, 2022, 08:01:51 am »
Hey folks, I brewed a Zombie Dust clone, all grain about 12 days ago.  I used 2 pkgs of Lallemend London ESB for a 6.25gal batch.  My OG was 1.070, with a target FG of 1.017.  I fermented in as Ss Brewtech conical.  The fermentation was robust, and arrived at 1.014 in 3 days.  A little low, but nothing that worried me. I added 2oz of citra dry hops at about 1.020.  Everything was great.  For 7 days, up until day 10, the gravity level stayed at 1.014 and the beer tasted juicy, with bright citrus aroma.  On day 10, I did a first dump to get rid of the trub and dry hops that had been in there for 7 days, and was planning to keg at 2 wks, to condition for a week before putting it on tap. 

Unfortunately, on day 12, I took another sample and reading and the gravity dropped to 1.009 and the juiciness in the beer was totally gone, as was some, but not all, of the aroma.  The beer doesn't taste 'off' in any way (no astringent or mediciney taste) but the fruitiness of the citra hops is largely gone and the beer is more bitter (I assume because it's dryer). 

My question is why the gravity would drop like that (a full bric from 9 to 8 on my reflectometer) after having been stable for a week?  Plus, this is not the first time this has happened to me, and with a range of different types of beers that may or may not have been dry hopped.  Is it the agitation of the yeast when dumping the trub?  Is it biotransformation, which I feel like if it was it should have happened sooner after adding the dry hops?  I guess theoretically it could be an infection, but I don't taste anything obvious and after sitting for 7 days with a 7.2% abv, I feel like it's unlikely to develop at that point.  Maybe my mash temp was off (reading off my bruzilla) but again, the gravity was stable for 7 days before it dropped again. 

So I'm out of ideas.  This beer was on track to be epic.  Juicy, amazing aroma, soft bitterness...etc.  Maybe it straightens itself back out again when it's cold and carbonated, but I don't even know if I'll get that far.  Is it going to keep fermenting more now?  Anyway, folks, please advise!

A lot of people will tell you you're experienci. bbg "hop creep".  While I can't say that's not it, in my experience I think it's unlikely.  It's more likely a reading error, continued fermentation, or infection.  If you read what you thought was yiur FG at 3 days, it's possible that it actually hadn't hit FG.
Life begins at 60.....1.060, that is!

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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 ynotbrusum

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Re: Drop in FG after 10 days of stable readings
« Reply #5 on: February 04, 2022, 12:41:24 pm »
Yea, Denny.  I errantly described hop creep, but the biotransformation is what I intended to say could have been the cause of the change in the taste in the beer for the OP - just that it is yeast interaction with hops in changing the beer's profile over time - the actual chemical reaction not being fully known (glucoside cleaving is one such example).
Hodge Garage Brewing: "Brew with a glad heart!"