What happens if i soak a slice of apple in milk for 1 week and left in the refrigerator and if i soak a slice in gatorade?

All we can predict in advance is that you will have made two slices of apple
inedible, and also ruined a cup of milk and a cup of Gatorade.

Concerning the changes that would take place in these three substances,
I personally don't know, and I doubt that it has ever been tried.  This would
make a super science experiment that you could do at home !