Blueberry fermentation rate

[saccharomyces]

Making a blueberry wine for the first time, and I've read lots of articles both here and on other sites about various issues folks have had when fermenting blueberries.

I started mine about 10 days ago...starting brix was 24, and after moving along moderately for the first week, it's really slowed down. The brix reading was around 16.6 two days ago, and today it's only down to 16.

I'm using a variable volume fermentor, so it doesn't have your typical liquid-filled airlock. However, when I remove the lid to punch the cap down twice a day, there is a nice cap formed and the must bubbles and foams when I push the cap back into the must. So by all appearances, fermentation is going on, just super slow.

I've made plenty of wine from wine grapes, but this is my first foray into other fruit wine, so I am sort of at a loss here. I've had stuck fermentations before and you can definitely tell they are stuck (no airlock activity, no bubbling, cap doesn't form, etc.). This isn't showing any of the normal visible signs of a stuck fermentation, other than the brix levels moving at a glacial pace.

I ran across a tidbit on another web site that mentioned blueberries, during the natural course of fermentation, create potassium sorbate. Sorbate is a natural yeast inhibitor, and from what I have read, seems a natural explanation for what I am seeing. What I haven't been able to find is what to do about it?

Not sure if anyone else has run across this, but thought I'd post it and see if anyone has any suggestions.

Thanks!

 

[dangerdave]

I'll had to dig out my brix converter...

24 brix converts to SG 1.101, and my first thought was, "Thanks kind of high for a fruit wine, ain't it?" But that might just be your personal preference, so who am I to judge. Since your 10 days in and only down to 16 brix (SG 1.065), it is going pretty slow. If it were me, I'd dose it with some nutrient and energizer to keep it going. Have you added any yourself, and/or do you have any on hand. Are you following a recipe? How big is your batch?

 

[saccharomyces]

Hi..thanks for the quick reply!

Ok, so let's get some particulars out of the way.

I started with about 17 lbs of blueberries, added 9 lbs of sugar along with pectic enzyme and 50ppm of meta (verified with a Hanna titrator). Let it sit for a couple of days, then pitched the 71B yeast. In total, I started with about 6 gallons of must.

I agree the alcohol is a little hot..but I sort of threw this together by just following a recipe...

I actually added some Fermaid K a few days ago when the must measured 16.6 brix on my refractometer (I usually add it when the must ferments down about 1/3). I didn't notice any visible difference between the must before or after I added the nutrient (a cap was and is still forming, and it still fizzes and bubbles when I stir it back in). But I will say that the rate of fermentation appears to have actually *slowed* since I added the nutrient. Prior to adding it, it was moving down about 1 degree per day...now it's been two days since I added the nutrient and it's only moved a bit over 1/2 a degree since then. This is why I am stumped.

 

[dangerdave]

Well, at this point it looks like a learning experience in the making. I think you'll just have to sit back, continue as you're going, and wait until it's done it's thing. Sounds like it's still fermenting in there, so keep measuring, and see how long it takes. When are you planning to move it to secondary? At what brix?

 

[pjd]

I don't understand a variable volume fermenter but it sounds like you keep the lid on it and only remove it to punch down the cap. Leave the lid off of the fermenter, cover it with a towel and let some oxygen in there for the yeast. I am sure the fermentation will speed back up!

 

[dangerdave]

Phil makes a very good point. It does need O2 to keep it going in the primary. You can give it a good vigorous stirring when you punch down the cap to give it more oxygen, too.

 

[Deezil]

Yeah, with that much sugar left, it could still benefit a little from oxygen exposure

Amongst all this though, I've seen no mention of the temperature.. Is it a little low?

Sounds like most everything else is spot-on, but there's no mention of temp..

Oh, and its a benzoate that blueberries contain, not a sorbate.. Same sort of effect though..

 

[chris400]

the blueberry i did took 9 days in the primary to go from a starting sg of 1.085 to 1.000 and i used daves dragons blood recipe ...from what i read it seems blueberrys are a slow fermenter

 

[wpt-me]

I'm just pretty new to wine making. I thought you could't
use a refractometer to measure in a active ferment???

Bill

 

[wpt-me]

I am suprised there was no more discussion on this thread. As a
complete newbie, did I make a wrong assumption ??

Bill

 

[Stefani]

I made the assumption that the S.G. was being measured by a hydrometer. Are there those who measure it with a refractometer?