Simplifying Deacidification: A Sommelier's Guide

Chemical Deacidification? What's that?

We know wine has acid. Sometimes, it has too much and can taste like biting into a lemon. Not great. To fix this, we can use "chemical deacidification". It's a fancy way of saying we add stuff to the wine to neutralize some of that sourness.

Ok, what can we add to the wine?

Under the Australian New Zealand Food Standards rules, we can use calcium carbonate, potassium carbonate, or potassium bicarbonate.

So, what happens when we add these things?

They react with the acid when we add one of these to the wine. The end result? Less acid, more water, and some carbon dioxide gas (don't worry, the gas bubbles out).

Now, if we use potassium carbonate or potassium bicarbonate, they cause something else. They cause a kind of salt called potassium bitartrate, to form and settle at the bottom. This further reduces the acidity of the wine. Calcium carbonate does something similar, but the salt that forms (calcium tartrate) doesn't help to reduce the acidity.

Which one should I use?

You could use any, but there's a catch with calcium carbonate. The salt it forms (calcium tartrate) doesn't settle down quickly. It can take months, sometimes even after the wine is bottled. So, the potassium ones are usually a safer bet; among them, potassium bicarbonate is gentler on the wine.

How much will this lower the acid levels?

Giving a perfect number is hard as it depends on the wine. Still, as a rough guide: If you want to reduce the acidity by 1.0 g/L, you'll need around 0.6 g/L of potassium carbonate, 0.9 g/L of potassium bicarbonate, or 0.67 g/L of calcium carbonate.

How do I go about deacidifying?

First, test this out in a small sample of the wine. You don't want to dive in and mess up the whole batch. Once you've found the right amount to add, slowly add it to the wine below 4°C, mix well, and let it settle for a few hours.

In short, deacidification is like tweaking a recipe.

You're trying to balance flavors to make the wine taste its best. But always remember, less is more.

Don't overdo it!