(noun) Olive oil is made from olives, which grow in the Mediterranean, California, South America, and many other parts of the world. Olive oil is an essential ingredient in Mediterranean cooking, and it is also extremely good for you, since it is high in monounsaturated fat and antioxidants. Olive oil raises HDL levels (the “good” cholesterol) and controls LDL (“bad” cholesterol).
Extra virgin olive oil is obtained from the first pressing of olives. This is the most flavorful, healthy, and expensive olive oil. The next grade is called virgin olive oil, and the third simply olive oil or pure olive oil.
Cold-pressing is the best method of extracting the oil from the olives. Other methods create heat, which leads to a lesser quality olive oil.
The best olive oils are therefore the extra virgin, cold-pressed varieties, though these two labels do not necessarily guarantee a good olive oil. In the end, it all comes down to what tastes best to you.
Filtering and Refining
The question of filtered/refined vs unfiltered/unrefined olive oil has mainly to do with what you plan to do with the oil and how you want it to look. Filtered/refined olive oil is suitable for sautéing, while unfiltered/unrefined cannot be heated to a high temperature – it should be used for salad dressing and drizzling. In addition, unfiltered olive oil is usually cloudy, which may make it unattractive to some.
Olive oil is good for about a year from the day it is pressed, and should be stored in a fairly cool, dry place (though not the refrigerator, as it will solidify and you’ll have to let it warm up each time you want to use it).
I keep at least three different types of olive oil around. They are all organic and extra virgin, but I have a refined, cheapish bottle that I use for cooking, a mid-priced bottle for vinaigrette, and an expensive bottle that I drizzle on bread, vegetables, and salads.