High acid reduction?

[M38A1]

I'm stuck again.

Couple nights ago I thawed out 48lbs of Muscadine grapes I harvested early July. Got them pressed and came up with four gallons of juice, pulpy thick mess and all. Using Jack Kellers ratio, I calculated to added six gallons of water which was done leaving me 10 gallons of starting must. That has been split into two 5gal primaries where it sits at this moment. Five Campden tabs were added to each at that time (yesterday/Friday) I'm think I'm good to that point.

Testing tartaric acid, I keep coming up with 1.1% as measured by both titration and a calibrated pH meter (the magic 8.2pH number was achieved when I put 11cc's of reagent in my test cup) The juice of these grapes WILL irritate/burn the skin if it gets on you. I'm confident that 1.1% number is correct. It's acidic grape juice.

Looking at what I have available to me, all I have is potassium bicarbonate. Package says to "add 1-1/3tsp per gallon prior to fining lowers acid 0.1%. Cold stabilize before racking off the tartrate precipitate. NOT recommended to reduce acid more than 0.3% or to use on wines higher than 3.5".

Wow. I'm not sure what all that means other than to get this down into the .7% range I need to add 26 tsp to get it right? And then it's not even recommended for more than .3% change and I need to go .4%. AND I need a place in the fridge to let this sit for a few days? My fridge isn't that big.

I'm trying to not dilute it anymore with water and I don't have room in the fridge to crash it.

What would you do to get this acid under control?

 

[stickman]

What is the current pH of the juice in the primary? I wouldn't drop the acid all the way to .7 unless you determine it's really necessary, there may be a significant tartrate precipitation during fermentation due to reduced solubility in alcohol solution. The tartrates dropping out during fermentation will lower the TA. Pull a sample of juice, maybe 1 liter, and determine how much potassium bicarbonate is required to get to a pH of 3.5, then use this to scale up the addition for the carboys, at a pH of 3.5, any tartrates that fall out during fermentation will cause the TA to drop and the pH will also drop, keeping you in a good range. If your pH is already high, over 3.5, then forget everything I just said.

 

[M38A1]

The primary is sitting with a pH of 2.8 at the moment. No yeast has been pitched.

 

[Stressbaby]

Potassium bicarbonate raises the pH more than calcium carbonate. That's why the label says not to use if pH > 3.5. I'd say you are probably safe at 2.8.

 

[M38A1]

Potassium bicarbonate raises the pH more than calcium carbonate. That's why the label says not to use if pH > 3.5. I'd say you are probably safe at 2.8.

So you are saying to get the SG correct now and pitch the yeast as 2.8 is safe? Or are you saying it's ok to use the Potassium bicarbonate to get the pH to 3.5 if done in very very small increments and not over-shoot that mark? I thought we all tried to get pH in the 3.5 range due to the yeast having difficulty in that acidic environment.

And then if I do use the Potassium Bicarbonate, is it required to cold crash the contents at some point? If so, when? (my fridge isn't big enough for this.... ugh.) It will be 45*F tonight and 36*F tomorrow night so maybe set it outside if needed?

 

[Stressbaby]

I'm saying 2.8 is low enough you are unlikely to overshoot the pH using potassium bicarbonate. Yeast may struggle at 2.8.

 

[user 36973]

It is always best practice to grab a 1L sample of juice from your must and test the addition while measuring the pH. I would not raise the pH over 3.5, but starting at 2.8 gives you a LOT of head room to do your de-acidifying. Potassium bicarb should take about 0.9g/L to reduce acid by 1g/L.

The larger question for you is that your intended style of wine (sweet or dry) will determine the targeted TA. If you want it dry, I'd shoot for about 7g/L for the TA or less but a sweet wine can take upwards of 8.5g/L. The cold stabilization process will drop about 0.5g/L.

And yes, you will need to cold stabilize to drop the tartrate crystals. If your fridge isn't big enough, perhaps you can decant the wine into freezer safe plastic containers (milk jug?) and freeze. This will very quickly drop your crystals. I've done this with smaller batches and it works like a charm.

 

[user 36973]

Yeast may struggle at 2.8

Totally agree. Your yeast will only slowly ferment at this pH and be rather unhappy.

 

[M38A1]

Thanks for the replies....
When I get home from work today I'll start the acid reduction. My goal is a dry wine this time around.

As far as the cold stabilization, that will prove to be my stumbling block.... 10 gallons is a lot of wine for my little freezer/fridge. I might be able to see if my beer friend(s) have space in their coolers, but if that's not available I'm not sure what I'll do.

 

[M38A1]

OK, so I got the first five gallon primary to a pH of 3.4 by the addition of 10tsp of K-Bicarbonate. I had leftover 3L water bottles so I shuttled the must (juice pulp, spring water, k-bicarbonate) to eight of them and they are in my fridge at the moment.

How long should they stay there before I pull them out? I'm guessing when they come out I'll warm the up to room temperature, dump into a clean/sanitized primary and get my SG where I want it and then pitch yeast? Never done this before. Oh, and when would the pectic enzyme go in? Couple hours before yeast pitch?

Sorry to be a pain with this yet never done a cold crash/acid reducer like this before so it's all new to me.

Thanks-

 

[Stressbaby]

I've never cold stabilized PRIOR to pitching the yeast. The closest I've come is a "cold soak" which I generally do for 3 days. But the idea there is extraction, not stabilization. I think you'd be fine pitching now and cold stabilizing after fermentation. Hopefully others will chime in.

 

[M38A1]

I've never cold stabilized PRIOR to pitching the yeast. The closest I've come is a "cold soak" which I generally do for 3 days. But the idea there is extraction, not stabilization. I think you'd be fine pitching now and cold stabilizing after fermentation. Hopefully others will chime in.

What you say sort of makes sense.... I know I've had excess after a racking and I'll re-size my carboys usually with some left over that's just too small of a quantity to mess with and it goes in the fridge where it settles out quite nicely. So I think I might just do that now or wait a few hours to see if anyone else chimes in.

How long can the non-yeasted must sit on pectic enzyme before you pitch yeast?

Thx.

 

[robert81650]

I have been making Southern muscadine wine for 4 years now, never had that low of a TA before.... I think you are gonna have a weak flavored wine due to that much addition of water. I make my muscadine out of 100% pure juice, no added water other than when I use simple syrup mixuture to back sweeten. Just my thoughts...dry muscadine wine has no taste at all other than being very harsh and a strong acid taste. Back sweetening brings the flavor forward... Not bragging but I won a gold and silver medal in Winemaker Magazine Amateur contest for 2018.

 

[Newine]

At that T/A I would just go with a 71 B yeast, my experience is a 15 to 30 percent reduction in acids. Successful fermentation as low as 2.8 pH. After alcohol fermentation (or if you wish, coinnoculate) with malolactic bacteria so it's goes through MLF, converting malic (harsh) acid to lactic (mellow) acid and CO2, further reducing total acid, then I would cold stabilize to precipitate out tartaric acid and then rack. You can make huge moves in T/A that way. I plan to try Lavlin C next year which is purported to reduce acid more than their 71 B. My 2 cents. I had a wine go down by 67 percent in T/A this year with this acid reduction program.

 

[Newine]

I have been making Southern muscadine wine for 4 years now, never had that low of a TA before.... I think you are gonna have a weak flavored wine due to that much addition of water. I make my muscadine out of 100% pure juice, no added water other than when I use simple syrup mixuture to back sweeten. Just my thoughts...dry muscadine wine has no taste at all other than being very harsh and a strong acid taste. Back sweetening brings the flavor forward... Not bragging but I won a gold and silver medal in Winemaker Magazine Amateur contest for 2018.

Congrats on medals!

 

[robert81650]

Thanks......

 

[Newine]

I've never cold stabilized PRIOR to pitching the yeast. The closest I've come is a "cold soak" which I generally do for 3 days. But the idea there is extraction, not stabilization. I think you'd be fine pitching now and cold stabilizing after fermentation. Hopefully others will chime in.

Agre, putch yeast, cold stabilize later. You'll reduce tartaric acid at cold stabilization, probably a bunch of other solids and protiens and come up with a clearer wine with less acids.

 

[robert81650]

Cold stabilization is the best way to drop out tartaric acid crystals.

 

[M38A1]

Awesome, thanks guys.... Both are rocking and rolling along and the house smells wonderful with all this fermentation going on.

Newline - that's all bit over my head at the moment, but I'll try and digest it in small chunks for later use. Thx.

 

[M38A1]

Update and need some direction again.....

My 6gal batch #1 has been at SG .992 for three consecutive days now so I"m ready to do the cold thing. Just 'how' do you do that as I've never done it before? I was simply going to put my racking cane in the primary and pump it out into 1 gallon bottles and then put them in my fridge for a couple days to let them separate. Then I was going to do the racking cane thing but only removing the clearer stuff on what I presume will be a lot of sediment on the bottom back to a glass carboy. Is that how's it's done? And once that's done, do I add minimal K-Meta based on volume and just let it sit in a carboy for my aging period?

I just love learning new stuff here. You all have been fantastic!