Extremely Slow Fermentation

[raelynn]

I am making my 6th batch using the Dragon Blood recipe, and the first time with blueberries. The first 5 batches all behaved similar, including the time to finish fermenting, and all ended at 0.990.

The blueberry DB started similar until it reached 1.026 SG, and since then, it's been going extremely slow - 0.001-0.002 per day. I am used to DB batches reaching the finish line quickly, even at 18-20C. The temp on this batch has been steady at 23C. I've given it extra vigorous stirs to get oxygen in there too.

It's not stuck so I'm not worried (yet), but wanted to ask here, since I haven't had a batch slow down like this before.

 

[ChuckD]

Yep. I’m fermenting a maple wine right now, which like skeeter pee, is mostly flavored sugar water but even less fruit solids. I’m past the three-week mark and still haven’t hit 1.020! PH is near 4.0 and I have followed TONSA protocols for nutrients…

Yeast is gonna do what yeast wants to do I guess.

 

[cmason1957]

There are at least two things that often cause problems, blueberries with ferments and Merlot with MLF. I am guessing your ph is within a reasonable range, since it got to here and that your started your SG at something like 1.080-1.095. You might give it a shot of some yeast nutrient, but not much, it might be to late for the yeast to make good use of it. You could also consider mixing up a nice starter of EC-1118 yeast and let it go over night, then slowly add must to it, doubling size each addition to see if that helps. or just let it go. Take your pick, throw your dice.

 

[raelynn]

There are at least two things that often cause problems, blueberries with ferments and Merlot with MLF. I am guessing your ph is within a reasonable range, since it got to here and that your started your SG at something like 1.080-1.095. You might give it a shot of some yeast nutrient, but not much, it might be to late for the yeast to make good use of it. You could also consider mixing up a nice starter of EC-1118 yeast and let it go over night, then slowly add must to it, doubling size each addition to see if that helps. or just let it go. Take your pick, throw your dice.

Thank you! How much yeast nutrient would you suggest? You are correct, my starting SG was 1.090, and it quickly dropped down to 1.022, then I step fed it +0.020, and it acted as expected, until it ground to a snail's pace at 1.026. I have a batch of cherry DB going as well, started on the same day, same start SG, same step feed, etc, and it carried on and is nearly dry.

What is it about blueberries that cause problems?

 

[cmason1957]

I don't know what it is about blueberries that can cause fermentation problems. I have seen several folks having issues over the years. Perhaps it is the Acids that are present in blueberries, perhaps it's that there are both fructose and glucose present. I am not much on making fruit wines. Have made some and even less on making the Dragons blood, not my style of wine, but I know lots of folks seem to like it.

How much nutrient to add. I would add at least 1/4 of the recommended amount on your yeast nutrient, maybe even a half. I'd also probably go the make a yeast starter and be ready to try to acclimate it to your wine. What are you out, some yeast, yeast nutrient, sugar. Get it going really good and healthy. Best of Luck.

https://washingtonwinemaker.com/blog/2013/04/12/blueberry-wine-high-maintenance/

 

[winemaker81]

If all of the above doesn't spur the fermentation, give it time. Yeast is a living organism, and while fermentation normally proceeds as expected, occasionally it does not. If all else fails, rack into a carboy and airlock it. Give it 2 or 3 weeks, then the SG.

 

[Jim Welch]

From what I've read yeast use neither oxygen nor nutrients once ABV gets to 10% and from your SG readings its about 9% now so I wouldn't add nutrients at this point. If it were my batch I'd rack it first as has been suggested, and when I rack I'd intentionally try to take the lees too then hit it with EC-1118 as has also been suggested.

 

[Rice_Guy]

I agree with Jim.

View attachment 96883
Main phases of wine fermentation. Evolution of the main fermentation parameters during wine fermentation on a synthetic medium containing 200 g/L-1 glucose/fructose and 330 mg/L-1 assimilable nitrogen, with the commercial wine strain EC1118 at 24°C. Dark blue: fermentation rate; light blue: ethanol; red: cell number; green: nitrogen; and purple: sugars.

Marsit, Souhir & Dequin, Sylvie. (2015). Diversity and adaptive evolution of Saccharomyces wine yeast: A review. FEMS yeast research. 15. 10.1093/femsyr/fov067.

In a normal fermentation, Yeast cell division basically stops after 1/3 sugar reduction, so there isn’t much gain in adding more nutrient. See inflection on red line and purple at about 1/3 sugar. The situation where we can grow more yeast is in a ferment which reinoculates with a high alcohol tolerant selection like 1118. ,,,, Wine is toxic to yeast.

 

[raelynn]

Thank you! If the SG is still going down slowly, should I wait it out and see if it gets there, before racking and adding EC-1118? The SG is dropping 0.002/day and is at 1.012 as of this morning. Because I step-fed it, the abv is about 13% right now.

 

[ChuckD]

Thank you! If the SG is still going down slowly, should I wait it out and see if it gets there, before racking and adding EC-1118? The SG is dropping 0.002/day and is at 1.012 as of this morning. Because I step-fed it, the abv is about 13% right now.

I would add the EC1118 starter right away. The lower the SG, the more inhospitable the must will be for the new yeast

 

[winemaker81]

Thank you! If the SG is still going down slowly, should I wait it out and see if it gets there, before racking and adding EC-1118? The SG is dropping 0.002/day and is at 1.012 as of this morning. Because I step-fed it, the abv is about 13% right now.

What yeast did you start with? If it was a lower potency yeast (alcohol tolerance < 15%) then add the starter.

If the SG is dropping 0.002/day, the yeast is doing its thing. Slower than you like, but let's be honest, the yeast doesn't care one bit what you do or don't like.

IMO, relax. Fermentation is proceeding and you have a good plan.

 

[raelynn]

What yeast did you start with? If it was a lower potency yeast (alcohol tolerance < 15%) then add the starter.

If the SG is dropping 0.002/day, the yeast is doing its thing. Slower than you like, but let's be honest, the yeast doesn't care one bit what you do or don't like.

IMO, relax. Fermentation is proceeding and you have a good plan.

I used Latvin K1-V1116, and if this batch were to finish at 0.990 like all the other DB batches I've done, I'll end up at 16.3% abv (we like it strong lol). I'm good with slow, as long as it gets there.

 

[winemaker81]

I used Latvin K1-V1116, and if this batch were to finish at 0.990 like all the other DB batches I've done, I'll end up at 16.3% abv (we like it strong lol). I'm good with slow, as long as it gets there.

K1-V1116 is rated at 18% alcohol tolerance, so you shouldn't need to add EC-1118, especially as the fermentation is proceeding.

That said, adding EC-1118 will not hurt anything, so there's also no reason to not add it.