About Olive Oil

"Extra Virgin" is the top grade of olive oil with the following characteristics:

• Must be made from fresh olives - extracted from the fruit solely by mechanical means.
• Fruit must be of high quality, processed soon after harvest, and with clean equipment.
• Temperature during processing can not exceed 86F (30C). oo
• No solvents can be used in the process.
• Must not be mixed with oils made from seeds, nuts, or pomace (milling leftovers).
• Must meet specific standards for over 20 laboratory tests.
• Free fatty acid level can not exceed 0.8% and peroxide value must be < 20 meq O2.
• Contains naturally occurring antioxidants and polyphenols.
• Must be able to pass a taste test by an International Olive Council (IOC) recognized panel indicating some fruitiness and zero defects.

Extra virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 0.8 grams per 100 grams, and the other characteristics of which correspond to those fixed for this category in this standard Virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 2 grams per 100 grams and the other characteristics of which correspond to those fixed for this category in this standard. Ordinary virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 3.3 grams per 100 grams and the other characteristics of which correspond to those fixed for this category in this standard.1/.

This is refined olive oil (which is odorless and tasteless) that has been flavored with a little extra virgin olive oil. As long as it is not rancid, and the flavoring oil was good, this is a fine product for cooking and any use that does not require a lot of fruity olive oil flavor. It is much less expensive than real extra virgin.

Light Olive Oil:

This is essentially the same thing as "pure" olive oil.  It is made from refined olive oil that is "light in flavor." The amount of fat and number of calories are the same as any other olive oil.

Maximum Acidity (or Free Acidity):

The free fatty acid level is an indication of the quality of the fruit going into the olive oil. It is a measure of quality. International Olive Council standards require less than 0.8% free acidity for "extra virgin" classification.
First Cold Press: This is a relic of the days when olive paste was actually pressed between mats to extract the oil (nowadays almost all extraction is done with a centrifuge). The second (hot) press was done to squeeze out more oil from the fermented waste pomace producing a very low quality oil which was then refined or burned in lamps.

Harvest Date: Look for recently made oil. Some producers indicate the date when the olives were harvested, others put a "use by" date, which is usually two years after the oil was made. The flavor of the oil with change with age becoming more mild in flavor.

Bottled (or produced) in Italy: Because of the way the laws are written and enforced, this is not always a reliable indicator that an oil was really made in Italy from Italian olives. Some producers put an indication of the source of the oil (usually Spain, Greece or Tunisia) on the back label. Check the lable on your bottle at home, toss your old oil and order a bottle of the REAL Italian stuff!

Information from http://ucce.ucdavis.edu/files/filelibrary/2161/43056.pdf