A few orchids i have recieved have had both red and white wine corks used in the media. The one the catt was on was red wine too. When i queried about acidity, the response was
"Soak for a week in 2 parts lime (the ground CaCO3, not the fruit) and 3parts untreated water (if you dont have untreated water, stand it for about 4 days to let the chlorine and fluoride diffuse out as gas). Drain every two days and replace."
It works a treat! And use it for white and red corks, because even though red wine is more acidic, that is caused by the tannins, and white wine as only slightly les acidic.