Potassium bicarbonate for reducing acidity in must.

[rbqricchi]

I’ll be making another Concord wine from concentrate soon and I’ve been considering using K-bicarbonate to lower the T.A. of the must, but I am not sure of the procedure.

Typically northern grown grapes like Concord are a little high in acidity and low in sugar. The traditional method of dealing with this combination of problems is to add water to dilute the acidity, and add sugar to boost the gravity.

Since I’ll be starting with pure unadulterated Concord juice concentrate of 68 brix, I want to dilute the concentrate to somewhere around 1.090 or 1.095 so that all of the fermentables will come from the grape juice. I believe this will result in a fuller flavored wine (typical Concord grape juice comes in around 1.067 gravity).

One method I could use would be to ferment the wine and then cold condition it for a few weeks and rack off the tartrate precipitate, but I don’t have the refrigerator capacity to do this, and although it will be cold enough here next month to cold condition in my garage, the temperature fluctuates too much for that to be a good option.

I’ve read that K-bicarbonate could be used to treat the wine after it’s fermented but you risk losing some fruity aroma/flavor from the fizzing off that would result from the treatment.

The couple of papers I’ve read on the subject recommended treating the must instead, prior to fermentation, but both talked about letting the “wine” (they both switched from talking about must to talking about wine) sit for a few weeks in cold storage before racking off of the tartrate.
So, not much help to me.

I’m wondering if I can just treat the must with the K-bicarb and proceed with the fermentation and hopefully if there are tartrate crystals to be concerned about they will settle out with the yeast at the end of fermentation.

Any thoughts? Thanks!

 

[David Violante]

I just fermented my Concords and the pH was a bit lower than I would have liked (3.2) and the SG also. I brought the brix up by chaptalization.

I’m usually a bit hesitant to add things that bring up the pH because (I feel) it tends to add a little bit of a mineral-ish taste to the wine. This is merely my personal experience. Other ways to reduce acidity are cold crashing (which you were referencing above), blending afterwards with other similar types (DeChaunac works well for this), MLF for malic acid co-inoculation, yeast selection (Lallemand 71B), adding water (this however will thin it out), sur lie aging, sweetening afterwards…

This also sounds like an opportunity for experimenting to me. Do you have a way to ferment half with one of the methods above, and half with the potassium bicarbonate? You could see at the end how each one does. That would give you an idea of taste by each method without affecting the whole batch. If you had the means, you could try each method even if you ended up combining them at the end.

If you do decide on the potassium bicarbonate, go slow and test often. It will create a small and immediate reaction in the must so be prepared for a minor eruption depending on how much you add at a time. Yep. That's experience on my part LOL... also, you don't want to overshoot and then yo-yo back and forth by adding acid, then bicarb, then acid...

How much are you going to make?

 

[winemaker81]

My experience with chemically reducing TA / increasing pH is the same -- it negatively affected flavor.

Unless your pH is below 3.0, I'd leave it alone for now. Try cold stabilization and blending, and if it's still a bit acidic at bottling time, add a small amount of sugar, which will balance the acid.

 

[BigDaveK]

The pH of Concords can be all over the place. Maybe you won't need to do anything?

I've had to deal with super high acid a couple times and also don't want to add chemicals. I used potato water made with very old potatoes. The water will approach pH 6.0 and some amylaze enzyme added to the must for the starch is a good idea. It's my goto method until I find something better.

Beet water can also be used but I find that the flavor comes through.

BTW, I recently bottled my pure potato wine and after back sweetening the darn thing tastes like a grape wine! Blew me away!

 

[Rice_Guy]

If I was in Michigan I would ferment in the garage and let the acid naturally decrease. My last tool would be add bicarbonate. ,,, When you have the numbers you may find that 2023 has been a fantastic year for ripening grapes.

 

[wood1954]

I would add enough potassium bicarbonate to get the ph up to 3.2 and inoculate with mlb during the AF , that will help, cold crashing will also drop a lot of acid. If you calculate how much potassium to add cut the amount in half. If you add just enough you won’t taste it and potassium is good for your blood pressure.

 

[rbqricchi]

I have a 2.5 gal cube of the concentrate, so I should get around 9 gallons at 1.094. I might add a little more water and 2# sugar to get to 10 gallons so I’ll be sure to end up with 9+ gallons after primary, which would work out well since I have a 6 gallon and a 3 gallon carboy.

I thought about 71B but experimented with it and 3 other yeasts in a Welch’s grape juice wine to see what the flavor differences were, and the only one I didn’t like the flavor of was the 71B.
I plan on using EC-1118.

The package of K-bicarb says not to lower TA with it by more than .3% but doesn’t say why. I suppose because it might negatively effect the flavor or push the ph too high. Depending on what the TA of the must is, I was just thinking of nudging it downward .1 or .2% if needed. I’d like this to be a dry wine, or maybe very slightly sweetened, so that the final gravity is no more than 1.000.

Perhaps the alkalinity of my water will help (144 ppm total alkalinity). Everyone here seems against using the K-bicarb so I will shelve that idea and see how it goes. Thank you all for your advice.

 

[winemaker81]

I have a 2.5 gal cube of the concentrate, so I should get around 9 gallons at 1.094. I might add a little more water and 2# sugar to get to 10 gallons so I’ll be sure to end up with 9+ gallons after primary, which would work out well since I have a 6 gallon and a 3 gallon carboy.

The problem with thinning the concentrate more to get volume is you thin the final wine. Sugar adds ABV, but doesn't add body, flavor, or aroma. The result can be disappointing. Find something else to add to the mix, which can include raisins and Zante currants.

Fit the container to the materials, not the materials to the container.

 

[rbqricchi]

That's true, but it's only an 11% dilution. Without the sugar, 10 gallons should be 1.085, which I would think would be plenty of body and flavor. Concord grapes only yield 1.067, typically, so this would be much richer than a traditional concord wine from grapes.

Then again, I do have a spare 5 gal carboy I could pair with that 3 gallon one...Hmmmm................

 

[winemaker81]

That's true, but it's only an 11% dilution. Without the sugar, 10 gallons should be 1.085, which I would think would be plenty of body and flavor. Concord grapes only yield 1.067, typically, so this would be much richer than a traditional concord wine from grapes.

Then again, I do have a spare 5 gal carboy I could pair with that 3 gallon one...Hmmmm................

One thing with winemaking is that by the time you realize you made a mistake, it's too late. You're looking at a noticeable difference.

 

[wood1954]

This year my harvest came in at 3.23 or so, I added enough potassium to get to ph 3.41, I pressed the grapes today and the ph is 3.83. I coinoculated with VP41 MLB which is well underway. If I had known the ph would rise so much I wouldn’t have added any potassium. Like winemake81 says once you realize you made a mistake it’s too late. I haven’t added any so2 yet so when I do the ph should drop a little. So next year no potassium.