Another Stab at Rhubarb Wine

[gitano]

I recently found it necessary to make room in my freezer, and doing so, found 26 lb of rhubarb. Since this was last year's production, and we have plenty from this year's production, I decided that the best use for it was to try my hand at rhubarb wine again. (See here for the first attempt: https://www.homebrewtalk.com/forum/...issues-with-fermentation.585999/#post-8609432)

I found a new, considerably less 'exotic' recipe than the first, 'keeping it simple'. The recipe consists simply of rhubarb juice, sugar, grape juice, and yeast. Campden tablets were optional. Per the "experts" on the internet, I crushed 6 campden tablets for 6+ gallons of must. But I'm getting a little ahead of myself.

Without the addition of any water, the 26 lb of rhubarb produced 3 gallons of rhubarb juice. The specific gravity of the juice alone - no sugar or water added - was 1.016. While it is reasonable to assume that some of that "extra gravity" (0.016) was some form of sugar, I do not believe all of it was. Rhubarb isn't that 'sweet'. It is not fruit. After adding 10 lb of sugar and sufficient water to produce a specific gravity of 1.085, I had about 6.25 gallons of must in the primary fermentor. (To which I added the 6 tablets of campden.) After waiting 48h, I pitched a packet (5 grams I think), of Lalvin 71B yeast. Fermentation was vigorous in another 48h.

A local brewing supply house suggested the Lalvin 71b yeast because, according to them, it is supposed to stop fermentation at around 9% ABV, which is about what I want. Furthermore, the initial specific gravity of 1.085 would mean that at 1.000 or slightly less, "all" of the sugar would be gone at about the same time as the yeast reached its max alcohol tolerance.

Here's what I'm wondering:

Assuming that the fermentation does stop at 1.000 or less, I will assume that all of the sugar has been fermented, AND, based on what the "experts" say, the yeast is not going to continue to ferment if I add more sugar to sweeten the wine. Is that a realistic expectation?

Assuming, (as I do), that the yeast will IN FACT continue to ferment above an ABV of ~9%, (say all the way to ~14%), and that given that the ABV will only be about 9%, the more likely outcome of adding sugar to sweeten the wine will be to (re)start the fermentation. Therefore, the 'best' way to stop the fermentation at about ~9% ABV and sweeten the wine, is to add a "Wine conditioner" containing potassium sorbate?

Just FYI: The specific gravity after 48h of fermentation was 1.048, down 0.037 from 1.085.

To make my intentions with this wine as unambiguous as possible: What I want in a finished product is a sweet/dessert/fruit wine with an ABV < 9%.

Thanks,
Paul

 

[Seamonkey84]

71B will go beyond 9%, advertised to go to 14% and can be pushed to 16% with proper nutrient additions and degassing.
For your situation, starting gravity of 1.075, let it ferment dry. Allow it to clear, then stabilize by adding potassium Sorbate and sulfite, both are needed to keep fermentation from restarting. After stabilizing, add more sugar. Or you can use non fermentable sugars, that’s what the conditioners are.

 

[gitano]

71B will go beyond 9%, advertised to go to 14% and can be pushed to 16% with proper nutrient additions and degassing. Yeah, I suspected that.
For your situation, starting gravity of 1.075, (1085) let it ferment dry. Allow it to clear, then stabilize by adding potassium Sorbate and sulfite, both are needed to keep fermentation from restarting. After stabilizing, add more sugar. Or you can use non fermentable sugars, that’s what the conditioners are.

Thanks. That's what I suspected.

I still wonder about the 0.016 of "extra" specific gravity. As I said, I do not believe that is all sugar, (but I could be wrong, I suppose). If it was not sugar or some other fermentable compound, then, when the fermentation stops, the final specific gravity may be above 1.000. In which case, the ABV will be even lower. (<8.5%). I don't care if it's lower, just thinking about how to decide when fermentation "stops".

Paul

 

[Seamonkey84]

When the gravity is stable for at least two weeks.

 

[gitano]

The fermentation has 'stopped'. Obviously, not absolutely in a biological sense, but there is no activity in the lock for more than 5 minutes. (I didn't watch it longer.)

The specific gravity now is 1.018, which happens to be exactly what the juice alone was before the addition of the sugar and water. I would not say there is any 'sweet' left to the taste. I have no expectation that the specific gravity will go down by any significant, or even measurable, amount from this value. Therefore, ABV should end up between about 6.7% and 7%.

I'll let this set for a week or so before transferring to a carboy-with-lock.

Paul

 

[Seamonkey84]

If it’s In a bucket and basically done, transfer it all (lees and all) into a carboy now. The yeast still has some cleaning up to do as it clears. You want to reduce the headspace now that it’s not actively producing CO2, let it clear in the carboy before doing another racking.

 

[gitano]

"Reduce the headspace..." is a good idea.

Paul