Red wine fermenting stuck

[KISA]

Hi,
I appreciate this is probably a common question, but this may have a slightly different twist to the norm.
I'm only new to wine making (I'm introduced myself in the new members forum) and have possibly dived into the deep end for a beginner wine maker.
For my first attempt at making wine I've chosen to try the Appassimento Technique, semi-drying the grapes before fermenting them.
I only have a few vines (3) and this year ended was able to fill a 10L bucket with the grapes I got. At the time of harvest they had a reading of about 23 Brix. I separated a couple of bunches, de-stemmed, crushed and started them fermenting separately, using the wild yeast. They fermented as hoped/expected.
The remaining grapes I semi-dried, then de-stemmed and crushed them, mixed in the pre-fermenting grapes and started the fermentation process. The Brix at that point was 27.
From there the grapes fermented away quite happily for a couple of weeks and them stopped, the Brix now at 18. I thought maybe it was because the temperature was getting too cold (around 15-17 degrees Celsius, 60F), so I put them into a temperature controlled fridge where it's sitting on about 22-23 degrees Celsius, 72F.
I've had it in the warmer condition for a couple of weeks and the Brix is still on 17, so it looks like the fermentation has stalled. That said, there is a strong smell of alcohol coming from the grapes.
From what I’ve read online, I should be expecting the Brix to get to roughly 0.
That said I tested a purchased bottle of wine and it read a Brix of 7. I’m assuming it’s probably had sugar added?
I also tested purchased Vodka, which had a Brix of 14, no idea why that is?
So I’m now unsure if I should be expecting a Brix of 0 for my fermenting grapes?
If the fermentation has stopped early, my first though is should I add a higher alcohol tolerant yeast? I am reluctant to go down that path as I’m concerned it will significantly affect the taste and ruin the affect I was after using the wild yeast.
Anyway, that’s my, possibly too long-winded, explanation, but hope it was useful and that there is a way forward with my little batch of wine (now down to about 3L).
Thanks!

 

[Ohio Bob]

Using a refractometer for measuring wines with alcohol will give incorrect results. That is why your vodka read so high. The proper technique is to use a hydrometer.

It’s possible your wine is fully finished to dryness. Given that you used wild yeast, it’s realy impossible to say for sure without a hydrometer reading. Wild yeast is a crap shoot, impossible to replicate. You never know if it’s robust enough to complete to dry. I never understood the allure with wild yeast, but it’s a wine makers decision.

 

[KISA]

Thanks for the reply. I do have a hydrometer, it there any benefit in pressing the grapes I have and checking it's specific gravity or it that pointless without a pre fermentation value to compare against? My objective to simply know if the fermentation is completed to dry?

 

[sour_grapes]

You don't need to press. You can just take some of the liquid out to test. I usuall put a kitchen strainer into the top of the must, and then use a wine thief to transfer some liquid out to a test cylinder for measuring the SG.

And yes, it is valuable! That should tell you if your fermentation is completed or not.

Your pre-fermentation reading of 27 Brix is probably accurate, because there was no alcohol at the time. So you can meaningfully compare your initial refractometer reading to your later hydrometer reading.

 

[KISA]

You don't need to press. You can just take some of the liquid out to test. I usuall put a kitchen strainer into the top of the must, and then use a wine thief to transfer some liquid out to a test cylinder for measuring the SG.

And yes, it is valuable! That should tell you if your fermentation is completed or not.

Your pre-fermentation reading of 27 Brix is probably accurate, because there was no alcohol at the time. So you can meaningfully compare your initial refractometer reading to your later hydrometer reading.

Thanks, I give that a try. How do you compare the brix value against a hydrometer value?

 

[ChuckD]

Thanks, I give that a try. How do you compare the brix value against a hydrometer value?

There are tables. I would post a link but I don’t know how.

 

[KISA]

No worries, I just did a search for brix to sg and found a conversion website
A 27 Brix converts to an SG of 1.1150.
I'll get a current SG and go from there.
Thanks again.

 

[KISA]

Ok, just checked the current SG and got 1.040.
Using the equation the ABV (alcohol by volume) = (OG - FG) * 131.25
ABV = (1.115 - 1.040) * 131.25
ABV = 9.84%
Based on the inital Brix of 27 I think I should be ending up with around 16%. Happy to be corrected on that?
Does that mean I probably need to add a yeast to kick it off again?

 

[ChuckD]

Get yourself some EC1118. It’s a real workhorse for stuck fermentations. Make a starter and introduce must in a few steps then add the starter and aerate the wine well.

 

[KISA]

Thank you

 

[winemaker81]

@KISA, all advice so far is solid.

Using EC-1118 is your best choice at this time. If the wine has been fermenting for weeks and the SG is at 1.040, it's a stuck fermentation. I agree with Bob, wild yeast is a wild card and ya never know which of the thousands of strains you'll get.

Something to consider is that some of the batch started at 23 brix while the remainder started at 27 brix, so the average is some where in the middle. That depends on how much juice you got from each, although you can approximate it by the pre-fermentation weight of each.

Regardless of the actual figure, I'm not surprised a wild yeast stopped, which happens when the yeast produces enough alcohol to poison its own environment. EC-1118 is rated for 18%, so it will do the job.

Once the wine is under airlock, do not pay much attention to activity in the airlock. It doesn't tell you anything useful, as it may be fermentation, active degassing, or changes in temperature/barometric pressure. Your hydrometer is your best friend -- it will tell you want is happening, e.g., if the SG is dropping, the wine is fermenting, or if the SG <= 0.998 and not changing, activity in the airlock is degassing.

Folks have said the yeast growing on the grapes is the best to use for that grape. I disagree, as the yeast is simply hungry, and it doesn't care what humans want. It's just eating sugar. Using a commercial yeast eliminates a variable, as you know the approximate ABV tolerance (how much sugar it can handle), and it's both sulfite resistant and likely to stomp out competitors (wild yeast and other microorganisms).

Yes, you jumped in the deep end for your first batch! I normally recommend kits as it's a friendlier situation, will normally produce a good result, and will give the winemaker a good feeling of accomplishment. You, OTOH, are facing adversity, but you're not giving up, so you'll feel even better when you're done.

 

[KISA]

@KISA, all advice so far is solid.

Using EC-1118 is your best choice at this time. If the wine has been fermenting for weeks and the SG is at 1.040, it's a stuck fermentation. I agree with Bob, wild yeast is a wild card and ya never know which of the thousands of strains you'll get.

Something to consider is that some of the batch started at 23 brix while the remainder started at 27 brix, so the average is some where in the middle. That depends on how much juice you got from each, although you can approximate it by the pre-fermentation weight of each.

Regardless of the actual figure, I'm not surprised a wild yeast stopped, which happens when the yeast produces enough alcohol to poison its own environment. EC-1118 is rated for 18%, so it will do the job.

Once the wine is under airlock, do not pay much attention to activity in the airlock. It doesn't tell you anything useful, as it may be fermentation, active degassing, or changes in temperature/barometric pressure. Your hydrometer is your best friend -- it will tell you want is happening, e.g., if the SG is dropping, the wine is fermenting, or if the SG <= 0.998 and not changing, activity in the airlock is degassing.

Folks have said the yeast growing on the grapes is the best to use for that grape. I disagree, as the yeast is simply hungry, and it doesn't care what humans want. It's just eating sugar. Using a commercial yeast eliminates a variable, as you know the approximate ABV tolerance (how much sugar it can handle), and it's both sulfite resistant and likely to stomp out competitors (wild yeast and other microorganisms).

Yes, you jumped in the deep end for your first batch! I normally recommend kits as it's a friendlier situation, will normally produce a good result, and will give the winemaker a good feeling of accomplishment. You, OTOH, are facing adversity, but you're not giving up, so you'll feel even better when you're done.

 

[KISA]

Thanks Winemaker81.
Just for clarification (no pun intended), the grapes were picked at a brix of 23 and after being semi-dried rose up to a brix of 27.
I went with the wild yeast option as there are vineyards near me using that method very successful, so I thought it worth a go. I'll have to give them a call and find out why they choose that option.
I know from my history of beer making that yeast and contributing factors like fermenting temperature can significantly affect the taste. So I was keen to avoid that and thought the wild yeast would have less of an impact in that regard. Though having now read up on EC1118, it appears it has minimal influence on the taste, handles the alcohol range and can ferment across a wide temperature range (I will have to read up on the best temperature to have the least effect on taste. If it's like beer yeast I assume it'll be at the lower end?)
I'll purchase some EC1118 tomorrow and try and restart the fermentation soon.

Thank you all for your help and quick support. I'm feeling a lot less worried about losing my batch now

 

[winemaker81]

Something to consider -- many wineries in Europe successfully use the indigenous yeast in their vineyards. But those vineyards have existed for decades, even centuries, so the winemakers know what the yeast is, and often fertilize their vines with the pomace, reinforcing a given strain's survival in the vineyard.

I have an idea that some of the best wineries in Europe are the best because they won the "yeast lottery" and have good strains living in their vineyards. There's far more to it than yeast strain, but it's an important factor.

OTOH, I buy grapes from California vineyards where I don't know the history. Plus last fall I purchased from a new vineyard in Virginia, which doesn't have much history. By using a known quantity, various cultured yeast strains, I reduce my risk in that area.

The wineries around you may have the type of history I mentioned above, or it may be a marketing gimmick. [Not a criticism, if I ran a commercial winery I'd do my best to make my wines stand out.]

While other factors have an effect, in your situation my first guess is that the indigenous yeast in your vineyard is not one you want. So you fix your current problem by adding EC-1118.

Next year, look at the list of available cultured strains and pick something that sounds good. You literally cannot go wrong.

 

[KISA]

Thanks again. Your reference to winning the lottery and the explanation behind that makes a lot of sense and I'll certainly head down the path of cultured strains starting with the EC-1118.
If I'm lucky enough in future to be able to make a few different batches out of one harvest, I might try a few different strains or maybe just different fermentation temperatures to see what difference it makes, if any.
You've all been very helpful, thank you .