Slow Meyer Lemon Wine

[Angelic Alchemist]

12/23/09:
2 gallons meyer lemon juice
2 gallons spring water (SpG of juice+water without any sugar was 1.02)
16lbs sugar
1 packet K1V yeast, rehydrated in water, then tempered with must to avoid osmotic shock
4oz K2CO3 (to adjust pH: original pH ~2, adjusted pH 4.0)
pitched at 70F degrees in a bucket, stirring 2X daily
OG = 1.16

5T super ferment post lag

01/02/10: SpG = 1.09, pH = 3.2 - added 7T K2CO3 to raise the pH to 4.0

01/09/10: SpG= 1.08, added 5t super ferment

01/16/10: SpG = 1.05, pH ~4.0

This seems a little sluggish to me. Since it's my first time making citrus wine, I need a little advice or perhaps just some reassurance. I would have pitched 2 packets of yeast at the top of the project but I did not have that much on hand. The must seems to be fermenting just fine and smells great. It's just taking its sweet time. Thoughts?

 

[akueck]

Hmm. 1.16 is a pretty darn high OG, so you're already at 14% abv, give or take a little. Yes, that's below the rated tolerance of K1V but you gave it quite a challenge.

You might try adding some yeast hulls (aka ghosts) in case there are some yeast toxins floating around in there (besides alcohol). I'd also recommend keeping the yeast suspended by gentle stirring or swirling, which might coax a little more bit of work out of them.

I have no sense of what 7 or so tbsp of your yeast nutrient ends up being as a nitrogen concentration, but if you could figure that out it could give us a clue about the amount of YAN you started with. High gravity musts need a lot more nitrogen, you'd probably be shooting for >300 ppm.

 

[Angelic Alchemist]

I'll pick up some more yeast hulls at the LHBS tomorrow. I'm a little hesitant to add more nutrient so late in the game (we're way past the 1/3 depletion), though I've never been entirely clear as to why this is considered a good rule of thumb. We've been stirring gently too -- I know oxidation is a concern but given the benefits of keeping the yeast suspended, we decided to take our chances. Plus, this batch has enough vitamin C in it to stun a moose.

 

[Medsen Fey]

Hi Angelic,
Another thing in addition to the yeast hulls is to give it 1 gram of MgSO4 (Epsom salts). That will sometimes help it eek out a tad more. If you've been fermenting it at 70, you can let it warm up to about 75 F and that may get you a bit more out of the yeast.

Although it is too late for this batch, for future high gravity batches remember that pitching a larger biomass of yeast does make a difference. If you only have one packet of yeast, build up a big starter and then acclimate that starter.

If that 5T was 5 tablespoons and the other 5t was 5 teaspoons, then it should have had enough nitrogen. It becomes very difficult for the yeast to assimilate nitrogen in any form late in fermentation. The build up of alcohol is very disruptive to the cell membrane transport systems.

If you do stall at 14+% ABV with a load of residual sugar, there isn't a lot that can be done. Restarting such a batch even using Uvaferm 43 is hit or miss at best, though you can try slowly acclimating it and might be able to get it to work. One of the encapsulated Pro-Restart yeast might work, but they are expensive as you have to buy them in bulk.

One other note for future batches is that you don't have to raise the pH to 4.0 to have them work. Getting it to 3.4-3.6 works fine and will leave you with a more-stable final product.

Endeavor to persevere!

Medsen

 

[wayneb]

I'll pick up some more yeast hulls at the LHBS tomorrow. I'm a little hesitant to add more nutrient so late in the game (we're way past the 1/3 depletion), though I've never been entirely clear as to why this is considered a good rule of thumb.

Although there's no absolute way to know when the majority of your yeast population is past the point of reproduction, at about the time that happens (the 1/3 break point is a reasonable rule of thumb approximation), the yeast then can no longer utilize nitrogen from inorganic sources (such as DAP). Unless you are feeding a nutrient that contains only amino nitrogen past that point in time (yeast hulls have some amino nitrogen; commercial preparations such as Fermaid-O are higher in concentration), then you are essentially adding inorganic nitrogen compounds that will remain when fermentation is complete -- and if they are present in high enough concentration, they'll act as flavoring agents in your mead.

 

[Angelic Alchemist]

01/23/10: SpG = 1.04. Added 10g yeast hulls (by boiling Red Star champagne yeast in a bit purified water, then cooling it with a little more water) plus 1g Epsom Salts. We racked the batch into a 5gallon carboy and will rack it off the gross lees this weekend. After discussing it with my buddy, we figured some residual sweetness won't kill us as it is turning out to be a mighty tasty beverage.