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Sequencing Acid Removal

I have a recently fermented red wine with TA of 0.9 (0.2 of which is malic) and pH of 3.2. It has not started malics.

Assume that my goal is to end up with a wine with TA of 5.5 and pH under 3.8. I am working with three tools: potassium carbonate, cold stabilization and malolactic fermentation.

I've read in various places that malos will lower my TA by approximately 1/2 of the malic content - in this case, I would lose

0.1. So I now need to get to 0.65. I cannot do this with just potassium carbonate as it would drive the pH through the roof. In a trial, a 1.5 g/l addition brought acid down by about 0.15 but drove my pH up to about 3.6. Since I want to keep my pH under 3.65 for cold stabilization (to drive pH down and not up), I figure that's at the limit of what I can add.

So now I'm at TA of 3.75 and I cold stabilize. How do I estimate how much cold stabilization buys me? What if I overshoot? Should I cold stabilize first and then add potassium carbonate after because I more control over it? Can I do this in multiple steps? For instance, just add 1 g/l potassium carbonate, cold stabilize, check numbers, do it again?

Reply to
MB
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All of this is guesstimate, but it sounds like you are Ok. Cold stabilizing usually takes mine down 1 g/l. That would be 8 g/l, the potassium carbonate another 1.5 to 6.5 g/l and the ML another 1g/l.

I might do the ML now, then do the potassium carbonate test over (but cold stabilize the sample).

Joe

Reply to
Joe Sallustio

MB - Your math confuses. You start at 0.9%TA. ML fermentation lowers this to 0.8%TA. Your test with K carbonate lowers TA by 0.15% and raises pH to

3.6. You should now be at 0.65%TA. What's wrong with that? A couple of questions; What wine are you working with? How do you know the wine contains 0.2% malic acid? Have you done a freeze-thaw test to estimate how much acid can be lost with a good, hard cold conditioning?

Regardless, I would do ML first followed by cold conditioning. Test to see where you. Then if you need to use K carbonate (I would us K bicarb) you can proceed. Just a note ~ if you do add the carbonate be sure the wine has warmed back up to about 70F or the reaction will be very slow.

Bill Frazier Olathe, Kansas USA

MB wrote "I have a recently fermented red wine with TA of 0.9 (0.2 of which is malic) and pH of 3.2....my goal is to end up with a wine with TA of 5.5 and pH under 3.8. I am working with three tools: potassium carbonate, cold stabilization and malolactic fermentation.

Reply to
William Frazier

I've heard it's recommended to do the Potassium (bi)Carbonate before fermentation, has less of an effect on taste, so it was said.

Reply to
Charles H

It's cabernet. Malic acid % was done by a lab. 0.65 may be fine - but for the sake of this discussion let's assume that 0.55 is the goal.

I have not done a freeze-thaw test yet. My challenge is that right now I can cool to 40 degrees or down to 0, but not in-between. If I do need to cold stabilize then I will invest in something that will enable me to chill in the upper 20's. Can I do a freeze-thaw test at

0F? How do I do it?

Why do you recommend K bicarbonate over K carbonate? I've seen recommendations for both and don't understand why one is better. Do they both have the same impact on pH levels?

Mike

Reply to
MB

It takes twice as much KHCO3 (bicarbonate) as K2CO3 (carbonate) to react with the same amount of acid.

---The Mad Alchemist---

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Reply to
Darren George

The numbers I've seen have been 1g/l (bicarbonate) vs. 0.9g/l (carbonate) to lower acid by 0.1... not twice as much. Are you sure?

Also, I still don't know what differences there are between the two in terms of effectiveness, flavors, time or impact (e.g., effect on pH).

Mike

Reply to
MB

Well, I was thinking in moles, not mass, so let's do some actual calculations.

To neutralize 1 mole of acid (a random amount) would require one mole of bicarbonate or half a mole of carbonate. The molar mass of KHCO3 is 100 g/mol, so 100 grams. The molar mass of K2CO3 is 138 g/mol, so neutralizing the same amount will take 69 grams. So I would expect 1 g/L vs 0.7 g/L.

Of course, this assumes that the acids we're dealing with are reasonably strong so that we don't have to muck around with equilbria. Most organic acids that you'll find in wine (lactic, malic, tartaric, oxalic) are strong enough for this.

Cheers,

---The Mad Alchemist---

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Reply to
Darren George

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