It has been around for thousands of years and is enjoyed the world over for its fruity taste and healthful benefits.
Extra-virgin oil is the highest quality; neither chemicals nor heat has been used in the extraction (hence the term "cold-pressed" on labels), which occurs shortly after the harvest. Virgin has a higher acidity than extra-virgin and is less flavorful. Other olive oils are usually a blend of virgin and extra-virgin. Light means very mild in flavor, not lower in calories.
Color and Taste
Color and taste are affected by three factors: the region where the olives were grown, when they were harvested, and which extraction process was used. The color, golden to green, indicates the type of olives and how ripe they were; it is not a sign of quality. Try different oils; you'll find (even within the extra-virgin category) a range of flavors: mild (good for vegetables), citrusy and herbal (for salads and chicken), or peppery and pungent (for roasting meats).
How to Buy
Heat or light (as well as time) can cause olive oil to turn rancid. Choose cans or tins that are not displayed in bright sunlight or right under fluorescent lights. A dark bottle is better than a clear one; you can also decant oil into a dark bottle, or wrap foil around a clear one.
How to Store
Keep containers well capped or corked in a cool, dark spot. Refrigerating may affect the oil's flavor; freezing it will not. Once thawed, it should be used within a week or so.
Studies have shown that olive oil has powerful antioxidants, helps control high blood pressure, and may protect against heart disease and some types of cancer. And although high temperature destroys some nutrients in any oil, using olive oil for frying is a healthful alternative to frying in more saturated fats.