Why do most marinades contain some type of oil?
If I understand correctly, marinades are intended to either tenderize or enhance flavor, or both, right?
That's why marinades are usually acid based, or use alcohol, in addition to herbs, spices and other seasonings.
But why do most marinadess contain oil? What does oil, usu. EVOO, add to the equation?
I've heard that oil (or things like milk) add moisture. Is that really true? How does soaking in oil add moisture? Wouldn't brining be a better way of making a tough piece of meat more juicy?
I'm not slamming the idea of using oil in marinades -- as I sometimes do it myself almost reflexively without giving it a second thought -- but I want to know why.
Am I doing it out of foolish habit, or out of necessity?