Stalled fermentation, any chance to resurrect?

[igrlk]

Hi, fellow brewers,

Disclaimer: I'm a newbie and made a ton of mistakes while making my first wine. This post is my only chance to get advice and possibly resurrect my brew.

I wanted to make 2 gallons of brew.
1. First was a homemade raspberry jam wine, starting gravity - 1.11
2. The second was a blueberry mead, starting gravity - 1.1

I've mixed the ingredients together and added half a teaspoon of Fermaid-O and a pack of 71B yeast to each carboy.
Then it went to my storage room which is not the warmest place in the flat. I should've added Fermaid-O on days 2, 3, and 4, but I didn't know about it.

During the next month, I took the readings for every brew. Here are the results:

1. Raspberry jam wine:
   • 21 March: start, sg: 1.11
   • 31 March: check, fg: 1.085
   • 14 Apr: check, fg: 1.055
   • 17 Apr: check, fg: 1.05 (bubbles almost stopped)
   • 24 Apr: check, fg: 1.05 (stalled, bubbles stopped)
2. Blueberry mead:
   1. 27 March: start, sg: 1.1
   2. 31 March: check, sg: 1.0
   3. 14 Apr: check, sg: 1.07
   4. 17 Apr: check, sg: 1.06 (bubbles almost stopped)
   5. 24 Apr: check, sg: 1.06 (stalled, bubbles stopped)

I didn't know what to do, so I decided to add more yeast with fermaid-o to each carboy, but it did absolutely nothing—the fermentation didn't start at all.

I decided to "start from the beginning (or the middle)" a couple of days ago. Pasteurised both brews, waited for the sentiment to fall, and racked them into the same gallon. The starting gravity in the mix was 1.055
Then, I made a yeast/honey/fermaid-o mixture and waited a day for it to "start". After it started bubbling, I poured it into the carboy. I also put my carboy into a warmer place in the flat, where other jugs are now fermenting.

It's been 2 days, and... there is no activity whatsoever. Even though the yeast mixture was active, after I poured it in to the combined mix of 2 wines, and added more fermaid-o, it just stopped doing anything. If I add fermaid-o to the carboy, there are no bubbles.

My hypothesis is that the yeast dies after it gets added to the carboy. However, the alcohol content in the carboy should be at least 2 times less than the yeast tolerance. The dead yeast would probably explain why nothing reacts with fermaid-o.

Dead forum readers, I would appreciate any advice on how can I resurrect this brew (if there are any options), as well as some suggestions on how not to get to this situation ever again (besides not skipping fermaid-o feeding and keeping brews in a warmer place)

Thank you all!

 

[IslandLizard]

Welcome to HBT!

What instrument did you use for your gravity readings?

 

[igrlk]

Welcome to HBT!

What instrument did you use for your gravity readings?

Just a standard hydrometer. I've got a couple of them, and they both show "expected" gravity (expected meaning the other brews that done fermenting have 1.0 fg according to the hydrometer)

 

[IslandLizard]

Just a standard hydrometer. I've got a couple of them, and they both show "expected" gravity (expected meaning the other brews that done fermenting have 1.0 fg according to the hydrometer)

That's good, your measured gravity should be as accurate as can be with a hydrometer.
It's not bottoming out, right?

I asked, because we often have "homebrewers" use a refractometer, especially with small(er) batches. With a refractometer, when alcohol is present, the gravity readings will be off (showing much too high), by badly skewing the refraction index. A correction formula would need to be used to correct for that.

Your high gravity readings could have to do with the lack of nutrients upon pitching, the yeast not being strong enough to metabolize all the sugars to finish the fermentation. Or larger amounts of unfermentables are present in the (fruit) source.

At what temperature are they being kept? Have you tried placing them in a higher temperature environment? That may help resume them.
Steadiness of temps during fermentation is also important. While alcohol percentages are increasing, a temp drop, such as overnight, could stall actively fermenting batches midway.

 

[igrlk]

Thank you for the explanation, @IslandLizard!

> It's not bottoming out, right?
Correct. Also on the taste, I can sense some alcohol but it's super sweet so feels like exactly somewhere midway.

> At what temperature are they being kept?
It's around 18 degrees Celsius.

I have a sous vide at home, so I can potentially try to create the ideal temperature just for this batch of brew. If I were to do this, I would probably need a new separate mixture of yeast/honey. Does it all sound reasonable?

Are there any other "emergency" manipulations besides the temp control you would do to make the chances of resurrecting the brew higher?

 

[Johnny2]

Maybe your yeast is bad. Did you buy it from Amazon?

 

[IslandLizard]

It's around 18 degrees Celsius.

If you can, put them in a warmer area, and see if fermentation resumes/continues. It may take a few days.
Yet, it's quite difficult to resurrect stalled fermentations. The alcohol % being present is one of the factors.

I have a sous vide at home, so I can potentially try to create the ideal temperature just for this batch of brew.

To provide a warmer environment? Just don't cook them.

A good strategy to prevent fermentations from stalling (partly due to rising alcohol levels) is to raise the temps somewhat toward the end of the fermentation, by ramping up a few degrees over a few days.

Although it depends on the yeast strain, warmer fermentation temps tend to produce more fusel alcohols ("rocket fuel)" and another unwanted flavor and aroma byproducts. Low and slow is best, don't start out high. There are some exceptions.
https://winemakermag.com/resource/yeast-strains-chart

If I were to do this, I would probably need a new separate mixture of yeast/honey. Does it all sound reasonable?

That's one way to try to resurrect a stalled fermentation. By adding some of your stalled batch to a new, very actively fermenting batch.

 

[Raptor99]

An OG (original SG) of 1.111 gives a potential ABV of 16%. The alcohol tolerance of 71B yeast is 14%, depending on conditions. Your hydrometer reading of 1.005, given your OG of 1.111, shows ABV of 14.5%. So your yeast are done and probably dead.

If you want ABV above 14% you need to use a different yeast. Right now your best options are:
* Stabilize and bottle it as it, for a slightly sweet wine, OR
* Add a different yeast with a higher alcohol tolerance so that it can finish the fermentation, EC-1118 would work well for this.

The morale of the story is, always read the data sheet for the yeast that you are thinking of using.

 

[Bobby_M]

I decided to "start from the beginning (or the middle)" a couple of days ago. Pasteurised both brews, waited for the sentiment to fall, and racked them into the same gallon. The starting gravity in the mix was 1.055

I'm not sure why you felt the need to pasteurise. You had likely a tasty sweet wine there and should have just enjoyed it. You'll do better next time with staggered nutrient additions and don't forget to shake in some oxygen at first yeast pitch.

 

[igrlk]

I'm not sure why you felt the need to pasteurise

In this case it was done at the end when the fermentation stalled. I did it to make sure that there will be no yeast activity whatsoever and the brew can clear in a couple of days so that I can rack into a new vessel and start the fermentation process again.

Your hydrometer reading of 1.005

Not quite that. My reading was 1.05, not 1.005

State of things as of today
After not doing anything with it for a week, I decided to try to revive it again. Yesterday, I mixed some honey with yeast and fermaid-o. Today, I added the bubbly mixture to the carboy with stalled fermentation and put the carboy into sous vide bath at 26 degrees Celsius. D-47's upper range is 30 degrees, so setting it to 26 should feel like a "warm" environment (my assumption). I also tried to aerate the mixture by shaking it and using a milk mixer to get more air into it.

I'll monitor how it goes today. Hopefully, it will continue the fermentation tomorrow. I'll keep folks updated!

That's one way to try to resurrect a stalled fermentation. By adding some of your stalled batch to a new, very actively fermenting batch.

I decided to be a bit greedy and use the whole stalled batch instead of some of it. Worst case, it won't work, and I can try with some of it instead (If I don't drop the ball on that idea before)

 

[igrlk]

Update: The combination of yeast/honey/fermaid-o mixture and sous vide bath at 26 degrees Celcius restarted the fermentation.

Yesterday's gravity was 1.045
Today's gravity is 1.042

So it's slowly fermenting. I will post an update for future readers when the fermentation finishes.