Ask Wine Wizard

The Sulfite Blues


Roger Mattar — Corona, California asks,

I have a Merlot to which I added SO2 thirteen days ago and it smelled ok. but last night I pulled a sample and it had a bruised apple smell and tasted sweet. The fruit is from the Dry Creek AVA in California (great fruit) at pH 3.5, but I tested SO2 yesterday and it was at 20 ppm so I boosted it to 45 ppm. I think the bung on my 100-L (26.4-gal) barrel is what caused the problem. It has a “burper” and I should have installed a solid bung.

Is there a fix? should I rack it or not? What about a tannin addition? I talked to someone at one of the wine lab supply houses and they suggested an aging tannin. Your thoughts?

Your nose (bruised apple/sweet smell) and your chemical analysis (loss of Free SO2) are telling me that you have an oxygen ingress problem and aldehydes and perhaps an increase in VA (volatile acidity) are the result. Please do your future wines a favor and always switch from fermentation “burper” bungs to hard bungs upon racking and adding SO2 for the first time, right after the wine is done with malolactic fermentation and topped up. Aldehydes are aromatic (detectable by smell, but not necessarily always pleasant) compounds formed by the oxidation of alcohol and may be familiar to wine aficionados as one of the key elements of Sherry wine. Sherry is deliberately oxidized during the aging process to give it that bruised apple, nutty aroma that many people find so appealing in its profile. Unfortunately, it’s not so appealing in still red wines like your Merlot! You did the right thing by adding SO2. Often a slight aldehyde defect, if it hasn’t gone too far and the wine hasn’t been exposed to oxygen for too long, can be reversed by a
Response by Alison Crowe.