This is an outdated term. Years ago the olive oil was actually “pressed” from the paste, and the first pressing was said to be the best. Cold-pressed referred to the temperatures during the extraction process. Today the paste can be heated (which happens only through movement and through water jackets in the malaxor chamber) though it can never go over 28 C (82 F). If it is heated too high it can destroy some of the taste quality characteristics. Thus, as a consumer, what is to be looked for is a certification for extra virgin olive oil (EVOO). An olive oil can be cold pressed and still not meet the required attributes to be EVOO.
When tasting olive oil, there are several attributes of which you should be aware, and terms that you can use to describe the details of the taste experience. Some attributes are positive while others are negative. The International Olive Council (IOC) has defined the following positive and negative attributes.
Positive Attributes in Olive Oil
Three senses are primarily used to identify olive oils: olfactory, which refers to one’s sense of smell; gustatory, one’s sense of taste; tactile, perceptible to the sense of touch.
Negative Attributes in Olive Oil
All negative attributes in olive oil come from either defective fruit, or poor processing techniques.
Olive oil coming out of the press is sometimes a brilliant emerald green. Chlorophyll and carotenoid pigments create the color. Olive oil undergoes many changes after production. Oxidation from the air in the bottle, auto-oxidation and exposure to heat and light drive these changes. Olive oil usually lightens in color as pigments are used up by oxidation. As the oil in the bottle ages it will lighten in color and the flavor can continue to mellow. In 12 to 20 months the olive oil will eventually become rancid. Heat and light speed this up but unless frozen, these changes inevitably occur even in well-stored olive oil. Varieties are another factor. Some of them have a natural occurring higher dose of chlorophyll.
If properly stored out of the sun and heat, olive oil should last 12 or 18 months. Unfiltered olive oil and oil made from certain varietals with fewer polyphenols may only last 6 months. Olive oils made with the needed care for having a good polyphenol count will last until the next harvest/production. California olive oil producers usually store their oil in large tanks and bottle at the last minute to ship to retail locations. This keeps the oil fresher.
Shelf life is variable, depending on the olive variety, ripeness when pressed, care in processing, filtering, etc. It also depends on storage after it has left the producer, something they have no control of, so it is hard to “guarantee” a certain lifespan. Look on the label for a date. Remember that most olives are picked in the late fall or winter and are sold the next year, so 2006 oil will be the freshest until early 2008 when 2007 oil will come on the market. “¨”¨Lifespan can be as little as 3 months for an unfiltered, late-harvest olive bottled in clear glass and displayed on a supermarket shelf above hot deli foods, which is then stored by the consumer in bright light on a hot stovetop with the cap unscrewed. Olive oil should be consumed within 18 months of production and within 8 to 10 weeks after opened. The fresher the olive oil, more polyphenols and nutrients will be present. It’s best to buy small quantities of oil packaged in dark bottles or to buy by the gallon and bottled the olive oil in clean bottles of 500ml or less. Store in a cool dark place. Any vegetable oil will go rancid with time. The olive oil is still edible but will taste bad.
When olive oil is properly made it has Omega 3, 6 and 9 in the same proportion as found in mother’s breast milk.