Q: I bottled some bulk wine in clean used bottles. There's now a white film where the wine meets the air under the cork. Any ideas on what this is, and more importantly, is the wine safe to drink? -Michael, Buffalo, N.Y.
A:Chris Gerling, Cornell extension associate for enology, answers:
"No harmful pathogens can survive in wine due to the alcohol and low pH, but this doesn't mean harmful substances can't be added externally. If I were the one who had been in possession of the bottles and I knew what materials had been used to clean them and what had been in them previously, I wouldn't be too concerned. There are lots of possibilities for the white film, and without an analysis it would be tough to tell for sure where it came from. If I were to speculate, I would assume that the wine is probably the more likely suspect than the glass. If this were the case, then there would probably be no real danger from the wine other than any bad flavors that might be associated with the origin of the film. On the other hand, if these bottles showed up on my doorstep "used but clean," I would definitely be pretty cautious."