ArticleThe Sulfite Blues, Curing A Stuck Fermentation and Freezing GrapesWritten by Alison CroweQ 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? Roger Mattar Corona, California A 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 fromAlready a member? Log InYou'll Also Like Article MEMBERS ONLY Late Malolactic, Wine Kit Ingredients, and Color Questions Your Zinfandel probably had a good reason (in the wine’s opinion, anyway) why it didn’t go through ML fermentation. Article MEMBERS ONLY “Fruit Floaties”, Sweetening Wine, Free SO2 levels Because sulfur dioxide is so easily-oxidizable, hydrogen peroxide naturally ‘finds’ the easily-oxidized SO2 and the two hopefully cancel each other out.