What you should know about the oil before buying?
Extra-virgin" and "virgin" olive oils are processed by crushing olives into a mash, which is pressed to extract the oil (this is called the first press) without the use of heat (called cold pressing).
Extra-virgin oils are of higher quality, as the olives used to make them are processed within 24 hours of picking—the longer olives go between picking and processing, the higher their free fatty acid content (extra-virgin olive oil can have up to 0.8 percent, virgin oils 2 percent). Extra-virgin oils also have more polyphenols than virgin oils.
Oils can be "filtered"—or not. Unfiltered oils have tiny particles of olive flesh in them, which reduces shelf life, and may appear cloudy if those particles haven’t settled at the bottom of the bottle.
"Pure" olive oil or simply olive oil are below extra-virgin and virgin standards and are heavily processed to remove off flavors and aromas. Though the oil still is a source of monounsaturated fat, its been stripped of healthful polyphenols.
"Light," "lite" and "extra-light" are purely marketing terms used on highly refined oils that refer to mild flavor and/or color, not reduced calorie content.
"Product of Italy" means the oil was processed in Italy, not necessarily that the olives were grown there. You can find oils that use solely Italian olives—or olives from Greece or California. Often made from olives from single estates or particular growing regions, these high-quality artisan oils have more distinct flavors—and are more expensive. When seeking out these oils, look for seals and designations as helpful indications of quality. Denominazione d’Origine Protetta (DOP) in Italy, Appellation d’Origine Contrôlée (AOC) in France and Denomination of Origin (DOP) throughout the European Union (EU) identify products produced, processed and prepared in regions known for expertise in that particular product. The California Olive Oil Council (COOC) and International Olive Council (IOC) certify and give their mark to quality extra-virgin olives oils, from California and the EU respectively, based on taste and quality.
Light exposure causes the oil to become rancid and lose its healthful properties—buy extra-virgin olive oil in dark glass bottles and metal cans and store it in a cool, dark place.
Bottling and/or expiration dates provide guidance on how long the oil will keep.
If you don’t use extra-virgin olive oil regularly, buy small bottles—polyphenols and flavor can diminish as the oil is exposed to air.
The color of the oil doesn’t indicate its quality—rather the variety and ripeness of olives used to make it.
What You Need to Know about Smoke Point
You might have heard that you can’t cook with extra-virgin olive oil because it breaks down when heated, creating harmful substances and destroying its beneficial properties. But all oils break down when they are heated to their smoke point or reheated repeatedly. However, an oil’s smoke point is really a temperature range (olive oil’s is between 365-420°F), not an absolute number because many factors affect the chemical properties of oil. You can safely and healthfully cook with any oil by not heating it until it’s smoking—to get your oil hot enough to cook with, just heat it until it shimmers.