An extra-virgin olive has a maximum of 1 percent oleic acid because it comes solely from the first cold pressing of the olives. Virgin olive oil has a moderately higher acidity level (between 1 and 4 percent). This occurs when the olives are pressed harder or are pressed more than once. This extra processing extracts more oil, but at the expense of drawing out more of the unwanted acids from the olive pits and skins. Olive oils with acidity levels above 4 percent were refined with heat or chemicals and cannot use the term "virgin". They are simply labeled "olive oil".