Stuck fermentation

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Peterpasha
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Stuck fermentation

Post by Peterpasha » Sun Feb 03, 2019 4:30 pm

About 2 weeks ago, I brewed my own recipe of Mexican Hot Chocolate Stout. It had, among other things like lactose, maltodextrin and cumin, about a pound of actual melted chocolate. The original gravity was 1.061, I pitched 2 packets of dry yeast (Safale)and after a week of pretty intense activity the gravity had dropped to 1.040. I let another week go by and figured that the time had come to keg it. There was a lot of trub still floating on the surface, so I dumped the ball of trub and drained the keg to a sanitized keg. I tested it and to my surprise, I was still at 1.040. I cleaned and sanitized the fast ferment and transfered the beer back to it with an empty ball and a fresh airlock. There was some activity overnight, so something is happening.
I was wondering if that was enough to reactivate the yeast still present in the beer, or should I add another packet? My original recipe had predicted an FG of 1.014 to give me just over 6%. I'd still like to hit that, or at least, slightly better than 2.75% this being a 'winter warmer' recipe.
On Tap:
Ginger Ale (non-alcoholic)
Blackstrap Stout
On Deck:
The Cities of the Plain - American Pale Ale
Fermenting
Planning
Blackstrap Stout Mk II
Hop To It - American Pale Ale with unknown hops

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John G
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Re: Stuck fermentation

Post by John G » Sun Feb 03, 2019 5:19 pm

Share your recipe and process, that may help to diagnose. The two ingredients that signal a potential reason for the high FG are lactose and maltodextrin. Both are not fermentable by yeast, so depending on the % of your grain bill that were made up of these two ingredients, you may have reached your FG. However, hard to say without more info.

Peterpasha
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Re: Stuck fermentation

Post by Peterpasha » Sat Feb 09, 2019 10:50 am

My recipe is:

Title: Mexican Hot Chocolate Stout
Author: Wharf Works

Brew Method: All Grain
Style Name: American Stout
Boil Time: 90 min
Batch Size: 5 gallons (fermentor volume)
Boil Size: 7 gallons
Boil Gravity: 1.043
Efficiency: 50% (brew house)


STATS:
Original Gravity: 1.061
Final Gravity: 1.014
ABV (standard): 6.09%
IBU (tinseth): 36.28
SRM (mosher): 40
Mash pH: 5.38

FERMENTABLES:
10 lb - American - Pale 2-Row (57.1%)
3 lb - Rolled Oats (17.1%)
2.25 lb - American - Chocolate (12.9%)
2.25 lb - American - Roasted Barley (12.9%)

HOPS:
1 oz - Brewer's Gold, Type: Pellet, AA: 9, Use: Boil for 60 min, IBU: 36.28

MASH GUIDELINES:
1) Infusion, Temp: 152 F, Time: 60 min, Amount: 5.4 gal
2) Temperature, Temp: 170 F, Time: 20 min
3) Sparge, Temp: 170 F, Time: 20 min, Amount: 2 gal
Starting Mash Thickness: 1.25 qt/lb

OTHER INGREDIENTS:
1 lb - chocolate, Time: 60 min, Type: Spice, Use: Boil
14 g - Habanero Chilies (dried), Time: 90 min, Type: Flavor, Use: Boil
2 each - cinnamon, Time: 15 min, Type: Flavor, Use: Whirlpool
4 tbsp - cumin, Time: 15 min, Type: Flavor, Use: Whirlpool
1 lb - lactose, Time: 15 min, Type: Other, Use: Whirlpool
0.5 lb - maltodextrin, Time: 15 min, Type: Other, Use: Whirlpool
2 each - vanilla, Time: 15 min, Type: Flavor, Use: Whirlpool

YEAST:
Fermentis / Safale - English Ale Yeast S-04 (2 packets)
Starter: No


TARGET WATER PROFILE:
Lake Major with Campden

I've been brewing for about 2 years, almost always my own recipes and most of it has been quite successful. This is a departure using some really out there ingredients. I wouldn't use the chocolate again, since I've read that it can be a yeast inhibiter, which may explain the stuck fermentation. I've done other milk stouts with the same amount of lactose and maltodextrin and never had any problems. I'm really starting to think that the mistake this time was using actual chocolate instead of cacao nibs but I really wanted to emphasize the chocolate flavour.
I had a vigorous airlock bubbling for almost the first week which was far longer than I had ever seen before and was thinking that with the high amount of adjuncts that I may have just stressed out the yeast and it gave up before the fermentation was finished.
And then yesterday I opened it to get a gravity reading and saw this, which I have never seen before. It doesn't smell bad or moldy. What do you think?
Image
On Tap:
Ginger Ale (non-alcoholic)
Blackstrap Stout
On Deck:
The Cities of the Plain - American Pale Ale
Fermenting
Planning
Blackstrap Stout Mk II
Hop To It - American Pale Ale with unknown hops

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GAM
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Re: Stuck fermentation

Post by GAM » Sat Feb 09, 2019 5:23 pm

Photo Bucket!!

May be ok but if you bottle be careful.

S

Peterpasha
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Re: Stuck fermentation

Post by Peterpasha » Sat Feb 09, 2019 5:46 pm

GAM wrote:
Sat Feb 09, 2019 5:23 pm
Photo Bucket!!

May be ok but if you bottle be careful.

S
nothing else would work for adding a photo, I tried to attach a jpg and it said it was an invalid format.
On Tap:
Ginger Ale (non-alcoholic)
Blackstrap Stout
On Deck:
The Cities of the Plain - American Pale Ale
Fermenting
Planning
Blackstrap Stout Mk II
Hop To It - American Pale Ale with unknown hops

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BBrianBoogie
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Re: Stuck fermentation

Post by BBrianBoogie » Sat Feb 09, 2019 8:07 pm

Hate to say it, but I think you've got yourself an infection there.

saosborne
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Re: Stuck fermentation

Post by saosborne » Sat Feb 09, 2019 9:19 pm

looks to me like pellicle or a bio film. It could be an infection or exposure to oxygen. I've had it on a similar beer recipe with lactose,maltodextrine and cocoa. not sure if the ingredients are a coincidence or not. With mine I had forgotten to reinstall a airlock for a couple of hrs and assume it was because of oxygen most likey some sort of bacterial growth occurring. With mine I kegged it being careful not to disturb the film as much as possible or to draw any into the keg. beer turned out fine, didnt seem to affect the flavor at all.
my suggestion would be take a gravity reading and taste it (if it tastes bad, well not much you can do but dump it or store it to see if something interesting comes of it) if its anywhere close to finished keg it and purge really well with gas chill it to stop anymore growth, hopefully you don't end up with off flavors.
if your bottling transfer to a new carboy with out disturbing the film and leave it sit for a while to see if it regrows then bottle carefully.

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GAM
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Re: Stuck fermentation

Post by GAM » Sun Feb 10, 2019 11:05 am

Photo Bucket!!
Photo of a bucket. My humour is twisted.

S

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John G
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Re: Stuck fermentation

Post by John G » Sun Feb 10, 2019 9:23 pm

GAM wrote:
Sun Feb 10, 2019 11:05 am
Photo Bucket!!
Photo of a bucket. My humour is twisted.

S
I got it Sandy. Good one. :cheers2:

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