Well, after having racked both carboys of wine several weeks ago, I thought it was about time I ran some labs on them.
So I took some samples to school and ran SO2‘s, pH and TA (titratable acidity) tests, as well as doing a chromatography test on them. This test tells me whether the wines have converted malic acid to latic acid. Malic is a harder/sharper acid; think sour apple. Lactic acid is much softer. As I suspected from tasting as well as watching pH and TA’s go up and down, it looks like the Petite Verdot/Cabernet Sauvignon blend have almost completely converted to latic acid. The Sangiovese/Cabernet Sauvignon still have a way to go.
After going through all the trouble of running an SO2 test on my wines, I realized that I had used the wrong strength of NaOH, so I’m still not sure how much free SO2 is present. So I decided I will run them again once they are through with malic/latic conversion. I won’t want to add any now anyway, since that would stop the conversion process.
About a month ago, I discovered that my wine had developed a terrible funk. The smell could be described as burnt match stick with a touch of smoke. This “funk” is often caused by H2S production or Hydrogen Sulfide. This can occur because grapes were sprayed with chemicals too close to harvest, or leaving the juice on the gross lees too long amongst other reasons. After doing a little research I decided I need to rack right away. And that did help, but the Sang/Cab. blend had quite a bit of “funk” so we racked again and that seemed to do the trick! Which is great, because that means I didn’t have to add Copper Sulfate or add more SO2. Few! I was worried that the wines were ruined beyond the point of no return!
Lab Numbers Update: As of 12-11-11, the pH and TA for the Petite Verdot, Cabernet Sauvignon blend are 3.44 and 6.75 and the Sangiovese/Cabernet Sauvignon blend are 3.25 and 7.2. It appears that secondary fermentation has taken place with the P. Verdot blend as the pH as gone up and TA down. But it’s hard to tell with Sangio blend because it looks the pH dropped and that doesn’t make sense. I will have to re-test pH, and TA in the next few week. Hopefully I will be able to test for SO2 content as well as run the wine through MLF (malolactic fermentation) chromatography.
That’s it for this update. Now to think of some names for the wines while they spend the winter in our new wine shed. Will have to post pictures of that soon!