Fusel's and too low final gravity

Hi,

Contamination, left beer on trub too long, or just worrying to much?


We just moved a chocolate stout to secondary after 7 weeks on the trub. Thing is, this one never completely stopped bubbling which concerned me. I have this fear a bug or something got into it and was eating all beer's character away. When we stopped it was bubbling about once every two minutes. The beer is scheduled to be on secondary for a week or two, and be kegged.

Three of us did a taste test.

3 of 3 detected definite fusel warmness.
2 of 3 sensed a sour edge. For me it was reminiscent of Guinness.

Both of these characteristics have developed in the last month. We did a gravity pull and taste test on 4/11 without any problems. This coupled with the unexpected final gravity (81% attenuation) makes me wonder if the beer is sick.

3/29 Brew OG = 1.076 - Bubbling in ~ 12 hours
4/11 Gravity 1.024 @ 70º <= 1 point away from where I expected it
5/17 Gravity 1.014 @ 76º <= Way low, 81% attenuation for a yeast rated at 70%

Recipe:


1002a Sweet Chocolatte Brown Ale
10-C American Brown Ale
Author: Internet
Date: 9/7/08

Size: 11.0 gal
Efficiency: 88.92%
Attenuation: 70%
Calories: 256.59 kcal per 12.0 fl oz

Original Gravity: 1.076 (1.045 - 1.060)
Terminal Gravity: 1.023 (1.010 - 1.016)
Color: 21.98 (18.0 - 35.0)
Alcohol: 7.03% (4.3% - 6.2%)
Bitterness: 21.8 (20.0 - 40.0)

Ingredients:
20.0 lb 2-Row Brewers Malt
1.2 lb Crystal Malt 60°L
1.5 lb Chocolate Malt
24.0 oz Lactose
16.0 oz Invert Sugar: Corn Syrup
8.0 oz White Table Sugar (Sucrose)
5.0 oz Cocoa Powder - added during boil, boiled 60 min
8.0 oz Bakers Chocolate (Bar) - added during boil, boiled 60 min
2.6 oz Fuggle (4.8%) - added during boil, boiled 60 min
0.5 oz Goldings (5.0%) - added during boil, boiled 15 min
2.0 ea Whirlfloc Tablets (Irish moss) - added during boil, boiled 10 min
1.0 tsp Yeast Nutrient (AKA Fermax) - added dry to primary fermenter
2.0 ea White Labs WLP002 English Ale
2.0 ea Yeast Starter - added dry to primary fermenter
7.0 oz Priming Sugar
18.0 gal Water: Deer Park Spring Water - added during mash
0.7 oz Chocolate Extract - added dry to secondary fermenter
85.0 ea Bottling: Caps & Lables
1.0 ea Propane

Schedule:
Ambient Air: 70.0 °F
Source Water: 68 °F
Elevation: 0.0 m

00:03:00 Mash-in - Liquor: 7.0 gal; Strike: 165.92 °F; Target: 153 °F
01:03:00 Rest - Rest: 60 min; Final: 153.0 °F
02:03:00 Fly Sparge - Sparge Volume: 11.35 gal; Sparge Temperature:
176.0 °F; Runoff: 13.0 gal

Results generated by BeerTools Pro 1.5.3

Sounds like worrying too much with the information present.

The 81% isnt an indicator of a bug, a bug isn't going to "over ferment" and and produce additional alcohols. The warm fusel taste is common in a green beer. Your OG is pretty high considering that mash temp. I would say you may have had a few false readings in there to calculate 81% attenuation.

I wouldn't fret it..bottle/keg and drink...

I tend to agree with MNBugeater. My first thought was an error in your mash temp reading. Is it possible that you were mashing a few degrees cooler? That would definitely drive your FG down further than expected.

bull8042 said:

I tend to agree with MNBugeater. My first thought was an error in your mash temp reading. Is it possible that you were mashing a few degrees cooler? That would definitely drive your FG down further than expected.

Click to expand...

It is very possible I mashed at a lower temperature - maybe even 150. This was my "first" all grain batch (which is why I overshot the gravity so much) and had thermometer problems. Pretty sure the gravity is right, we used a refractometer, that had been properly zeroed out, and because it was new, compared converted readings to a hydrometer.

MNBugeater said:

Sounds like worrying too much with the information present.

The 81% isnt an indicator of a bug, a bug isn't going to "over ferment" and and produce additional alcohols. The warm fusel taste is common in a green beer. Your OG is pretty high considering that mash temp. I would say you may have had a few false readings in there to calculate 81% attenuation.

I wouldn't fret it..bottle/keg and drink...

Click to expand...

I agree that it sounds mostly like too much worrying and it's fine, just green and a bit dryer than expected. however, 'bugs' (bacteria or wild yeast) can 'over ferment' and produce additional alcohols; many of them can ferment dextrins, etc - the more complex sugars that normal brewers yeast can't ferment.

ericm said:

. . . however, 'bugs' (bacteria or wild yeast) can 'over ferment' and produce additional alcohols; many of them can ferment dextrins, etc - the more complex sugars that normal brewers yeast can't ferment.

Click to expand...

This is actually what I'm concerned about. I walked past the carboy's just in time to see one bubble so there is still pressure there. These will be in a glass secondary and off of the trub for a minimum 1 week maybe 2 waiting for the kegerator to be finished. If the gravity continues dropping, I think I'm going to officially worry.


Thanks, everyone for the feedback - its helpful knowing we aren't in this thing all alone.