Ask Wine Wizard

Moldy Odor In My Wines


John Battistini — Via email asks,

The last couple of years I have been sanitizing corks the morning of bottling Frescati Italian Juice. The wine is filtered the day before bottling and corking and there is no sign of mold. Everything is sanitized with a S02 solution and everything seems to be mold-odor free. But then a couple of weeks later we opened a bottle in which the wine had a moldy odor. What am I doing wrong?

Would you be surprised to know that you may be doing absolutely nothing wrong? Even though you tried to sanitize your corks (assuming you are using natural corks and not artificial corks) by soaking in a sulfite solution before bottling, it’s almost impossible to completely eradicate all of the organisms that could cause TCA (trichloroanisole) in a cork. The main reason is because the mold spores might be inside the pores of the cork rather than on the surface where your sanitizing solution reached. There are also many other ways that TCA can crop up later in bottled wines. It should also be noted that there should be no need to sanitize corks from new, unopened bags since these are shipped with SO2. TCA, or the “corked” off-aroma, is caused by ambient molds interacting with a chlorine molecule of some kind, usually from domestic water supply. When these mold spores metabolize anything containing chlorine they can produce the noxious and easy-to-smell TCA molecules. These mold spores are frequently found in corks but they also can live in drains, on stacked
Response by Alison Crowe.