I've been making fruit wines for a long time. Fiejoa, blackberry, kiwifruit, prune, elderberry, etc.
I commonly leave the wine in a 20+ litre container for a year or two before bottling. It seems that no matter how long it's left, the wine always tastes a bit rough when I open it up for bottling, but improved drastically over the next few weeks. Something happens as a result of the bottling process, that I'd like to understand better.
What is this process?