Deacidification with Potassium Carbonate and Cold Stabilization

[BI81]

Hi All, long time lurker, first time poster. I've searched a bit through previous threads for an answer, but seem to have only confused myself more.

I'm currently making a Zinfandel from grapes and have a low pH of 3.31, but my TA is in a good spot at 6.65. The wine is acidic to the taste so I need to adjust it down, but want to make sure I'm taking the right approach.

I purchased some potassium carbonate and was planning to use this to drop the pH, until I read further into the required cold stabilization. From what I'm reading wines with a pH below 3.6 will drop pH after cold stabilization. The cold stabilization is required after the potassium carbonate addition, so in essence the potassium carbonate would raise my pH as desired then the required cold stabilization will drop it back down?

I'm also struggling to find out the correct dosage of potassium carbonate as it correlates to pH, everything I've been able to find so far states 3.8g/gal will drop TA by 0.1, but I can't seem to find the dosage associated with pH. I've also read that you should not attempt to adjust by more than 0.3 or will negatively impact the flavor of the wine.

Any help will be greatly appreciated, thanks in advance!

 

[pillswoj]

How old is the wine, and has it been fully degassed? Dissolved CO2 in the wine will throw off the pH reading and taste of a young wine always seems acidic to me.

 

[NorCal]

The best thing to do is bench trials, as every wine is different. I would definitely keep it in the fridge for a week or two as well, to make sure anything that is going to fall out, has fallen out. I made that mistake last season and have 11 cases of wine with solids in the bottom of the bottle. Not a lot, but enough that I don’t like to give it away.

 

[BI81]

The grapes were picked in mid September of last year. Yes it has been degassed.

 

[BI81]

NorCal, would you suggest putting it in the fridge for a few weeks before adding the potassium Carbonate to see what will drop out, or after the dosage. I’ll definitely run a bench trial and add in small amounts/test prior to dosing everything.

 

[BI81]

I went ahead with a bench trial and I'm glad I did, 1.9 g/gal rose the pH to 3.6 and the taste was significantly less acidic/harsh. I dosed one of the 6 gal carboys and it's now in the fridge undergoing cold stabilization for a few weeks. I'll check back in then with an update. Thanks for the warning NorCal!!

 

[NorCal]

NorCal, would you suggest putting it in the fridge for a few weeks before adding the potassium Carbonate to see what will drop out, or after the dosage. I’ll definitely run a bench trial and add in small amounts/test prior to dosing everything.

Yes...after the dosage. The base and salts will combine with the acid and some solids could precipitate out. Mine was substantial. At this point, I would toss the meter and base the dosage on taste alone. Here is a link to my thread, earlier in the year, when I was going through a similar trial.

Also if you put the "@" sign before someone's name @BI81, they will get notified that they were mentioned in a thread and likely to look at it later.

 

[BI81]

Yes...after the dosage. The base and salts will combine with the acid and some solids could precipitate out. Mine was substantial. At this point, I would toss the meter and base the dosage on taste alone. Here is a link to my thread, earlier in the year, when I was going through a similar trial.

Also if you put the "@" sign before someone's name @BI81, they will get notified that they were mentioned in a thread and likely to look at it later.

Thanks @NorCal, that was a very informative post, I appreciate the link