Ask Wine Wizard

Tartrate Crystals


Roy McGuill — Monson, Massachusetts asks,

If potassium bicarbonate was added to my must (or juice for my whites) and my acid now is where I want it, do I still have to move it outside to cold stabilize? I am only in my third year of winemaking and The first two years I added potassium bicarbonate (KHCO3) in February and moved my high-acid wine outside for a week or so in hopes to lower acidity. This year I was advised to try adding it at the start (September/October). I did and now my acid is where I want it.

I always think that trying to precipitate out some of the worst crystals that could form is a good idea, especially for any wine that may be sold commercially or entered into competitions. You probably won’t change your pH/titratable acididty (TA) balance that much. In my experience, doing a traditional cold stability where you chill the wine down and then filter off any precipitation won’t shift the acidity enough to notice it in the taste. It’s far better that you got it down to where you liked it style-wise in the first place. If you’d rather not go through the bother of chilling and fermenting (however, this would be my top advice to prevent these crystals from forming to the sides of your bottle or bottom of the cork, as pictured to the left) and want to prevent some if not all crystals from forming, you could try adding one of the newer carboxymethyl cellulose (CMC) products that many winemaking suppliers are selling. CMC is an FDA- approved cellulose gum commonly used in food as a thickener and emulsifier. If
Response by Alison Crowe.