Ask Wine Wizard

Wine Press Mold Growth


Philip Feiner — San Carlos, California asks,

Last year I brought out our press and found the slats covered in a white mold, so we took it upon ourselves to use 180 °F (82 °C) water to clean the press slats, and figured that would do it. After the 2016 harvest, and press, we sanitized it with SO2 sanitizer solution. The press again has mold on it. Help!

Ah, yes, the joys of wood. We use wood in the winery for barrels and barrel-alternatives of course but, especially for the small-scale winemaker, wooden presses are still often part of our crush equipment. It’s interesting, but not strange, that this mold pops up periodically. I would scrutinize your ambient humidity and temperature; it’s very possible this mold bloom was caused by a change in the weather or a change in your cellar environment. Once, while working out of a winery in Santa Cruz, California, we noticed that we tended to grow mold on the outside of our wooden upright tanks when we experienced a period of particularly wet, damp, and muggy weather. When the sun came out and it warmed up for good, we cleaned and dried the tanks well (installing a couple of big fans blowing outside air into the tank room) and the white mold didn’t come back until the following fall. At another winery on California’s Central Coast, I used to have a small wooden press and we occasionally experienced the same problem you describe above:
Response by Alison Crowe.