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Really stuck fermentation

TresK3

NewBee
Registered Member
Feb 5, 2012
23
3
3
Cincinnati, OH
Started a batch of traditional back in November 2020. The fermentation seems to have been stuck for quite some time, no matter what I do (and I've tried quite a lot).

Initial Recipe:

3 lbs local wildflower honey
2 pkg. Red Star Premier Blanc Yeast
LD Carlson "Yeast Nutrient" (from beer brewing)

11/25/20 Made yeast starter with ~16 oz boiled, cooled water and 1-2 Tbsp honey. Capped and shook vigorously. Uncapped and sprinkled yeast on top. Allowed to hydrate 10 min. Capped and shook again. Loosened cap and left at room temp overnight. Evidence of yeast activity from kraeusen forming.

11/26/2020 Sanitized 3 G carboy & triple-rinsed. Poured 1 G of bottled, purified water into carboy. Added 3 lbs honey and shook vigorously to dissolve. Added 2nd gallon of water, capped and shook very well. Saved sample to measure gravity. Pitched yeast starter into carboy. Added 1 tsp Yeast Nutrient. Fitted carboy with blow-off tube and left at room temp (63-66 F), wrapped in towel.

OG = 1.043 (borrowed, calibrated refractometer) and 1.037 (borrowed hydrometer)

11/27/2020 Added 1 tsp Yeast Nutrient and agitated briefly to mix.

11/28/2020 Mead looked very white - almost as if it were a bacterial infection. Moved carboy to basement and fitted with airlock.

11/30/2020 Panicked about cool basement temp and moved carboy back up to kitchen, near heater.

12/1/2020 Bubbles coming from airlock.

12/3/2020 Bubbles slowed to 1 X per 15-20 seconds

12/27/2020 Moved carboy to garage to cold crash for a month. Temp 35-45 F.

1/24/2021 Moved carboy from garage to basement and racked to second carboy. Slight haze still in must, but much clearer. About 1/2" layer of yeast sediment in bottom of carboy. Mixed to make uniform in second carboy, then split between two, 1G glass jugs. Added 3-4" of toasted French oak curl to one jug; left the other plain. Fitted air locks on jugs.
S.G. = 1.015 (new, calibrated refractometer). Tasted smooth, very slightly sweet. Hints of citrus.

1/30/2021 Measured S.G. Oaked = 1.017. Plain = 1.014 pH 3.0 on both. Added ~1/8 teaspoon Yeast Nutrient to each jug.

2/5/2021 Measured S.G. Oaked = 1.015. Plain = 1.015. Taste was similar in each. Maybe a slight bit tarter than last month.
Made new yeast nutrient by microwaving baker's yeast and cooling. Added about 1/4 teaspoon to each jug.

3/1/2021 Measured S.G. Oaked = 1.015. Plain = 1.015
Taste was fine on both. Not much different in oaked sample.
Poured each jug into a sanitized 3 G carboy (removed oak from "oaked" sample). Sprinkled ~ 1/2 packet of Lalvin EC-1118 on top of each. Added 1 tsp Yeast Nutrient. Let yeast hydrate then shook each carboy very well and fitted airlock. Kept at 63 - 66 F

3/7/2021 No evidence of fermentation. Moved must back to jugs, by pouring through funnel, which oxygenated must.
S.G. Oaked = 1.017 Plain = 1.016 Taste was good on both, but not much different.

4/12/2021 S.G. Oaked = 1.017 Plain = 1.016
Taste was fine on both. Very smooth & neutral. Slight vanilla aroma on oaked and maybe slight tart. Plain had very faint sweetness.

So basically there's been no change in the SG in 3 months. It tastes and smells fine, it's just not reading dry. My plan had been to ferment to an SG of around 1.000 then add a bit of corn sugar or honey to condition, and bottle into beer bottles.

Am I done fermenting? Why is my SG still above 1.000? Is there anyway to get a sparkling mead at this point, or should I just put it into wine bottles and call it a "success?" The taste is fine, it's just not what I was going for. Any other ideas on what to do with this.

Thanks!
 

sdlehr

NewBee
Registered Member
Mar 21, 2021
6
0
1
Boca Raton, FL
Have you double-checked your refractometer readings against hydrometer readings? Doing a little reading here it seems that refractometer readings become less accurate the further along you get in the fermentation. You might actually be at 1.000 or less.
 

TresK3

NewBee
Registered Member
Feb 5, 2012
23
3
3
Cincinnati, OH
I have not checked against a hydrometer, mostly because I dropped mine about a year ago (which necessitated buying the refractometer). I have, however, checked the calibration on the refractometer and set pure water to 1.000. It probably drifts a bit, as do all scientific measuring devices, but I expect it's reasonable close.
 

sdlehr

NewBee
Registered Member
Mar 21, 2021
6
0
1
Boca Raton, FL
"Once fermentation has begun, the alcohol present in the beer will skew the results" from https://brucrafter.com/refractometer-vs-hydrometer/

Refractometers work by measuring how much a ray of light is refracted (bent). Sugars in solution change the angle of refraction (compared to distilled water). So, apparently, does ethanol. I'm still suspicious that your apparent difficulty is a result of the ethanol not behaving like either sugar or water, which it shouldn't. If distilled water reads 1.000 on your refractometer, and you add ethanol, the reading is going to change. It makes no sense that distilled water (1.000) will refract light to the same degree that a 5-15% ethanol solution might, and we know that when we've finished our fermentation hydrometer SG readings will be around the 1.000 mark. It's probably unreasonable to expect an instrument to work equally well measuring a solution in which sugars are converted to ethanol. You can get a reading from an ethanol solution (as you did), but there's going to be an error introduced as sugars diminish and ethanol increases.

So while a refractometer may be valuable in measuring the SG of a sugar solution, it may not work as well for an ethanol solution. I'd be tempted to make up a series of 3-5 ethanol solutions and compare refractometer results from one to the other, but that could be considered a waste of ethanol. Unless you put it to good use afterward.

I'd bet real money that your fermentation is complete, and that's why your "apparent SG from refractometer readings" has remained steady, even if it isn't the actual number (<1.000) that you are looking for.
 

EricHartman

Lifetime GotMead Patron
Lifetime GotMead Patron
Mar 4, 2019
378
62
28
Indiana
Getting a hydrometer is a good idea but I'd be surprised for a refractometer to be that far off. I've no experience with them but it seems that refractometers would be rather inaccurate if their error rate was so severe. I'd check your must with the original refractometer, to ensure there's no significant difference between the two, and with a hydrometer.

Potential issues:
  1. what is the alcohol tolerance of your yeast? I'd be surprised if you maxed them out already but it can be a reason for a halt
  2. what is the pH of your must? again unlikely to be the issue but possible if your must is less than 3.0 (sodium bicarbonate can increase the pH)
Comments:
  • there's a goferm yeast rehydration protocol that is much kinder to yeast than your starter was. the scotts lab fermenters handbook has the protocol within it.
  • don't rack your must until the primary fermentation is completed. stir gently every so often don't rack. Racking leaves yeast behind and gives the remaining yeast more work to get things done
Bottling now is a potential solution. Your ABV is low enough that you'd have a nice drink that you can work through a good number without rapidly becoming hammered. I'd probably still use sulfates/sorbate otherwise you're asking for the fermentation to restart and making a carbonated bottle bomb.

Alternatively you could rehydrate another yeast, following goferm protocol, and try to take things to completion. Scott's lab handbook has a protocol for restarting stuck fermentations that might get the job done... it all depends on what you're looking for out of the mead.
 
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sdlehr

NewBee
Registered Member
Mar 21, 2021
6
0
1
Boca Raton, FL
but it seems that refractometers would be rather inaccurate if their error rate was so severe
It's entirely possible that the refractometer is truly measuring the index of refraction correctly and reproducibly and the problem is the alcohol in the solution changing that value, hence the statement about refractometers becoming less useful the further the fermentation proceeds. I don't have a refractometer to test this. But, if you take distilled water (1.000) and add just about anything else to it I'd expect the index of refraction to change. To expect an alcohol solution to measure close to or less than 1.000 just doesn't sound realistic to me. It would require that the alcohol have an index of refraction almost the same as water.... and in reality, it is 1.361, not very close.
 

EricHartman

Lifetime GotMead Patron
Lifetime GotMead Patron
Mar 4, 2019
378
62
28
Indiana
oh I don't expect water and ethanol to have the same refraction... and I'm definitely not saying you're incorrect. Its just that for a refractometer to be 0.017 off, at his relatively low ABV, is such a staggering inaccuracy as to conceivably make the tool useless for what we would ask for out of it. Makes me think of a tape measure that only has measurements by the foot rather than fractions of the inch... a rather blunt tool for sure :ROFLMAO:! Ethanol also effects the SG of water making it lower than the remaining sugars and water would be in the absence of the alcohol... However, the error is so small that it can be ignored without significant inaccuracies in the process; thus the tool remains useful. I'm not planning on switching to a refractometer so its a mute point to me, but I'm glad I went with a hydrometer if their error rate is really that severe.
 

TresK3

NewBee
Registered Member
Feb 5, 2012
23
3
3
Cincinnati, OH
Thanks EricHartman and sdlehr for your thoughts on the refractometer. Since they are sold for brewing purposes, I assume them to be sufficiently accurate. (Basically, I agree that being off by 0.017 would be a lot). I'll dive more into that issue when I get the time. Probably I'll go ahead and buy yet another hydrometer and compare readings. My main issue there is the sample size required - I have two, 1-gallon batches going and I don't want to waste half of them taking a series of readings. (They are in dark glass jugs, so floating the hydrometer in the secondary isn't really an option).

The pH is just above 3 (via pH paper) and the first yeast was champagne yeast, so the alcohol tolerance and pH should be fine. I won't have time to play with it for several weeks; I may try adding some fresh honey and new yeast (using the goferm hydration protocol) when I get back to it, to see if I can kick start the fermentation. I also may combine the two batches, to decrease loss to hydrometer readings.

Does anyone put their hydrometer sample back into the secondary? I would be hesitant to, but if I used very good sanitation techniques, I wonder if the alcohol present by now would kill any nasties?

Thanks again...
 

Dan O

Got Mead? Patron
GotMead Patron
Registered Member
Oct 12, 2020
66
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18
New Hampshire, USA
Thanks EricHartman and sdlehr for your thoughts on the refractometer. Since they are sold for brewing purposes, I assume them to be sufficiently accurate. (Basically, I agree that being off by 0.017 would be a lot). I'll dive more into that issue when I get the time. Probably I'll go ahead and buy yet another hydrometer and compare readings. My main issue there is the sample size required - I have two, 1-gallon batches going and I don't want to waste half of them taking a series of readings. (They are in dark glass jugs, so floating the hydrometer in the secondary isn't really an option).

The pH is just above 3 (via pH paper) and the first yeast was champagne yeast, so the alcohol tolerance and pH should be fine. I won't have time to play with it for several weeks; I may try adding some fresh honey and new yeast (using the goferm hydration protocol) when I get back to it, to see if I can kick start the fermentation. I also may combine the two batches, to decrease loss to hydrometer readings.

Does anyone put their hydrometer sample back into the secondary? I would be hesitant to, but if I used very good sanitation techniques, I wonder if the alcohol present by now would kill any nasties?

Thanks again...
I always put my samples back in. As long as your sanitizing habits are sound, you should be fine.
 

EricHartman

Lifetime GotMead Patron
Lifetime GotMead Patron
Mar 4, 2019
378
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Indiana
I'm spoiled with my tilt2 hydrometer but prior to using that I never hesitated with returning the sample to the fermenter so long as nothing dumb happened to threaten the sanitation protocol.
 
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Crispy

Grumpy Old Drone
Lifetime GotMead Patron
Apr 28, 2016
81
19
8
Burlingame, California
>> But, if you take distilled water (1.000) and add just about anything else to it I'd expect the index of refraction to change. To expect an alcohol solution to measure close to or less than 1.000 just doesn't sound realistic to me. It would require that the alcohol have an index of refraction almost the same as water.... and in reality, it is 1.361, not very close.

It seems to me that you are trying to compare apples to oranges here. What does the number 1.000 stands for in your post ? You did not provide any indication what is really is, but from your wording it looks like you assume that the index of refraction for water is 1.000. That is not true, refraction index of water is 1.333

I think you are confusing Specific Gravity with refraction index. The numbers on your refractometer are showing you Specific Gravity (SG for short) not the refraction index. SG of water is very close to 1.000 and Specific Gravity of alcohol (ethanol) is 0.787. As you can see, SG of water is higher than SG of alcohol and you cannot measure solution of alcohol in water accurately solely by using a refractometer. What you need is to correct refractometer reading with a correction value. That can be done using online Refractometer Calculator or manual calculation. You can read more about this here.

Edit:
I just calculated your corrected Final Gravity using the Refractometer Calculator from the link above. I used the values from your initial post: OG = 1.043; FG = 1.015 (3.8 Brix). The resulting corrected FG = 0.999
 
Last edited:

EricHartman

Lifetime GotMead Patron
Lifetime GotMead Patron
Mar 4, 2019
378
62
28
Indiana
Crispy coming in for the win lol! You clearly have the experience with refractometers that we have been distinctly lacking thus far. This was really bugging me as I didn't think sdlehr was incorrect but I also didn't think that the tool could be that terrible given how common they are used. Thanks for the insight
 
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sdlehr

NewBee
Registered Member
Mar 21, 2021
6
0
1
Boca Raton, FL
it looks like you assume that the index of refraction for water is 1.000. That is not true, refraction index of water is 1.333

I think you are confusing Specific Gravity with refraction index.
Indeed I was, thank you for coming in to clarify what is happening. I've got to sit down and think about this some more, and I have to look at the links you provided.
 

Crispy

Grumpy Old Drone
Lifetime GotMead Patron
Apr 28, 2016
81
19
8
Burlingame, California
Speaking of confusion... it looks like my thinking got cloudy late last night :)
For some reason I have mistaken @sdlehr identity with the original poster @TresK3 and the "edit" in my last post should have been directed at @TresK3.
Anyway, with the corrected SG reading we can assume that there is no stuck fermentation here and there is no need to do a restart.
 
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TresK3

NewBee
Registered Member
Feb 5, 2012
23
3
3
Cincinnati, OH
@Crispy -

THANKS!! Based on my beer and wine experience, everything "seemed" fine. There had been good yeast activity for a reasonable amount of time; there was a nice layer of spent yeast in the bottom of the carboy; and it tasted fine (no detectable sweetness).

The refractometer I have is scaled for SG, not RI (it's sold for wine making).

Thanks for the links, too. I owe you one!
 

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