Olive oil is an essential ingredient for many recipes -- but when blended can turn terribly bitter. There is a scientific explanation for this, however.

Approximately 90% of harvested olives are used for oil production, yielding a variety of oils from blended to single-origin ... compared to other methods. After water curing, the olives can ...

A green olive will change color to black after a few months on the branch ... which makes them easier to blend into the background of a more complicated recipe. Chopped black olives are also ...