Thank you, Matteo. I am not a chemist, but I think what you are saying is that it was the result of some level of oxidation. That is what happens to apples, potatoes, etc. and the solution when cutting them up is to soak the cut fruits or vegetables in acidulated water to avoid the browning. The "browning" is the result of the reaction with oxygen and is not only cosmetic but does change the taste of the fruits and vegetables.
Which brings me to my second point and that is, what, if anything, can be done with wine that is already made, is dark and lacks acidity? That is where I am at present. The Sauvignon Blanc that I made is very clear but extremely dark in color and it is very flabby, lacking any tartness which I feel is characteristic of an SB. Any insight that you can provide on this would be greatly appreciated.
Thank you.