Help with mycoderma infection!

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Sep 25, 2022
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2023 Cabernet Sauvignon, Santa Cruz mountains, 12.5% ABV

Primary went great
Secondary went great

Sealed up the VCT and took off for vacation over Xmas. Returned to find VCT gasket failure. Probably 7 days exposed around the edge of the lid in a 220L Speidel in my cellar at about 60F. A few weeks later noticed mycoderma film on top. Very very thin whitish film floating over the top in small segments due to oxidation.

Followed rough Pambianchi protocol. Scooped out film, filtered everything with a 3 micron filter. Bumped up the So2. Bought a new gasket, tightly sealed.

Everything seemed to be going fine. But I checked just now and the film has returned, albeit a little less than before.

Do I have to sterile filter and bottle? I was hoping to bulk age for much longer. But it seems like this will just not go away. BTW the wine tastes and smells just fine so far. How long can I let this go? My So2 levels are OK around 25PPM. SHould I bump them up higher?

What you did with filtration was good. Spoilage is a number/ population game. In your situation I would have added meta for a kill step 100mg range, ,, not to simply produce the ideal level of free SO2.
One technique is to estimate what your total meta might be and then add it in one shot. As a country wine maker I will also reduce the pH to get close to 3.2 since low pH is a preservative. If I am targeting long shelf life I might even drop pH to 2.8.

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