Olive oil is a superb example of a minimally processed food. Once purchased, olive oil can be used immediately or stored for quite a long time. The olive is actually a fruit, so the length of time that oils will last really depends on several factors. Some of these factors include the ripeness of the olive when it was originally picked from the tree and the type of pressing or crushing which was used to create the oil. Olives for olive oil are normally plucked from the tree while they are still green. This unripe olive contains the highest amount of vitamin E and polyphenol.
These two chemical properties in olive oil are called antioxidants. Antioxidants help to protect the oil and the person consuming the oil, from free-radicals carried by oxygen. An olive which is picked and processed prior to ripening will provide oil which lasts much longer because there is little chance of oxygen causing rancidity. Oxygen and light are the two greatest enemies of fresh olive oil. The longer an olive ripens, the more this fruit is exposed to both light and oxygen.
The technique used to extract the oil from the olive can also help to determine the shelf life of the product. Some pressing or crushing styles will cause the olive to be exposed to air or light for an extended period of time. Some of these techniques also employ the use of hot water or cold water to garner more oil from the olive paste. Any time that the oil is exposed to light or air, the shelf life of the oil shortens. A perfectly pressed and preserved olive oil can last about a year in an unopened container. Once the container has been opened, the life of the oil is shortened to about six months.
There are several options to choose when preserving olive oil for use. Storing the oil in a container which is not clear is an excellent method to retain freshness. Storing the oil in a cool and dark place is also an excellent way to minimize spoiling. Olive oil benefits from refrigeration, unlike many other oils. Placing the oil in the refrigerator does cause it to thicken and become cloudy, but once it is warmed, it will return to its original clear coloring.
Choosing an olive oil in a container that is small enough to ensure complete use in a short period of time is also a terrific way to keep fresh oil on-hand for cooking. Olive oil can be purchased in a large container and divided into smaller containers when it is brought home to store. This allows for multiple containers of fresh oil with the least expense possible.