I’m sometimes asked what’s going on in the wine cellar during winter. Well, there are a number of things always happening, but the most important thing to me is to chill the wine in the tanks. We don’t have large equipment to do so once temperature starts to rise in spring. So we utilize the chilly winter air outside – it’s quite natural and environmentally friendly way to cool the wine down.
Wine is an acidic drink. The major component of the acids is tartaric acid that comes from grapes. When wine gets cold, so-called the solubility of tartaric acid decreases. It’s sort of like you are putting sugar in your coffee. Hotter the coffee, easier to stir more sugar in. Right? If you dissolve a lot of sugar into your hot coffee, part of the sugar will precipitate as the coffee gets cold. A similar phenomenon happens in wine. When wine temperature goes down, tartaric acid combines with potassium that is also a natural ingredient of grapes. They form potassium bitartrate and precipitate at the bottom of the tank. As the acid level comes down, the wine becomes softer and milder. It is called cold stabilization of wine. Incidentally, potassium bitartrate is cream of tartar you use in baking. Did you know that?
So monitoring acid level in wine is an important task for winemakers. Here is the way my lab table looks like when I test the acid. The acid in wine samples is neutralized by a basic reagent to measure how acidy it is. It changes as the cold stabilization progresses.
Another thing I do once the fermentation completes is to test the alcohol level in wine. This is called Ebulliometer. It boils a small amount of wine and tells me its boiling point. Consequently, I figure out the percentage of alcohol in the sample by looking up a chart. Alcohol boils lower temperature than water and the boiling point of the sample depends on the alcohol content in wine and the ambient atmospheric pressure. This is a sophisticated sensitive apparatus that the old owner, Bob Straubing, Sr., left behind.
So, where does the “art” come into winemaking? I’ve always thought that’s a very good question as there is so much science behind winemaking starting from growing grapes. Lots of analyses, observations, calculations, etc. etc… Then one day I face the wine samples in the glasses in front of me. They have to go into the bottle one of these days. I sniff, taste and start mixing the samples in different portions – add some sugar time to time. At some point one of the glasses comes to me on its own – there it is! Winemaking is not the art but the wine itself is.
I pick the glass up and taste it again. Sure, I like it. Did I keep track of the blending portions? My notes are full of scribbles — well, looks like I did. And to me sometimes the hardest part is to replicate the contents of the glass exactly the same way in the tank. That’s called the challenge of winemaking.