What is an electro-dialysis machine?
After unexpected delays, as our bottle supplier ran out of bottles, we’re finally getting ready to cold stabilize our wines prior to bottling in July. This year, we decided to ask a contractor from France to bring an electro-dialysis unit. We wanted to see how it works and familiarise ourselves with it before we actually purchase one, hopefully in early 2018, so we can treat the 2017 wines prior to bottling.
We want to avoid the formation of crystals of tartrates because crystals form a nucleation point from which carbon dioxide bubbles will appear. This would be problematic both during disgorging, as the wines would gush and generate a substantial loss, but also when a customer opens a bottle, with the same phenomenon.
The wines contain a lot of tartaric acid, as well as calcium and potassium ions. Potassium bitartate salts exist in the wine and they can precipitate when the wine gets cold. Calcium tartrates exist as well to a certain extent, but the concentration of Potassium in wines is much higher. When these compounds are in a supersaturated state, the wine is considered unstable, as crystals will form at low temperatures.
The electro-dialysis unit consists of different membranes and electric currents that attract ions through these membranes: this is why we talk about subtractive method, as we remove ions from the wine matrix. Interestingly, not all the tartaric acid and calcium and potassium ions are removed, but just enough to not be in a supersaturated state anymore. With laboratory testing we can determine the percentage of each compound that needs to be removed in order to get to a stable state.
We are thrilled to finally try this technology: to process all our 2016 wines it will take less than 10 hours. Using other methods would last from a couple of days to several weeks.