The shelf life of olive oil
Olive oil 101
Contrary to wine, the taste of olive oil does not improve with age. The supreme moment is the day of milling the fresh harvest. After that day the taste goes slowly downhill, because of oxidation. So, it’s important to know how old your olive oil really is when buying a bottle in your local supermarket. So far only China requires producers to mention the year of harvest on olive oil labels, but is seems logical that also E.U. and U.S.A. will follow suit in the coming years. After all, the more information the consumer can get, the better. Best before dates are mentioned on labels, of course, but these are calculated with a time factor departing from the moment of bottling, not harvest.
The good news is that the best grade olive oil, fresh Extra Virgin, keeps well until at least 2 years, which is more than any other vegetable oil due to its high content of anti-oxidants. This span of time can be prolonged by as much as a year if you keep tightly sealed containers in a cool and dark place.
It is best to keep olive oil in (tinted) glass, earthenware, porcelain or non-reactive metals such as stainless steel containers. Also green or brown PET containers are good receptacles.
If the temperature of your olive oil happens to drop below +14ºC (57º F), it will start to “freeze”. Olive oil consists of some 27 different strains of oleic fatty acid, each with its own fractional freezing temperature. So between +9ºC (48º F) and +14ºC (57º F) you will see all sorts of cloudy patterns developing in your olive oil. At below +7ºC (45º F) your whole bottle will be solid and cloudy. Don’t worry, just put it at room temperature again and it will clear up completely in a day or two, without losing any quality. If you can’t wait, just warm your bottle a short while by putting it in an inch or two of hot water.
But air, heat, light and time will have eventually a negative effect on the shelf life of any olive oil.
Be your own judge and trust your sensory organs. A rancid taste or smell tells you when it cannot be consumed any longer.