If stored properly, a bottle of quality extra virgin olive oil can last up to two to three years. However, once olive oil is exposed to heat, light and air the oil will start to deteriorate.
There are ways to maximise the freshness and life of your olive oil. When purchasing oil, look to buy oil packaged in dark glass bottles or dark containers. This will help to guard it from the harmful effects of light. Also keep the oil in a dark cool place with the lid firmly closed. Try not to store it near cook tops, BBQs, in kitchen windows or on shelves above ovens. Too much heat, light and air will shorten the shelf life of the oil and turn it faulty and rancid very quickly (within months).
Olive oil can also be stored in the refrigerator. This cool dark environment is probably the best for olive oil but be warned; the oil will thicken and become very cloudy. This will make it very difficult to pour straight from the fridge so just leave it at room temperature for a couple of minutes and it will quickly return to a runny clear liquid.
Oil can also be stored in the freezer but take care if it is packaged in a glass bottle. Once again you will need to keep it at room temperature to make it runny enough to pour from the bottle.
How long does olive oil last?
Unlike wine or vinegar, olive oil does not improve with age. Extra virgin olive oils are best used in the year they are harvested as this is when they are the freshest and most aromatic.
Premium extra virgin olive oil like redisland and njoi can last up to 2-3 years unopened. This long shelf life is due to the oil's high natural antioxidant and polyphenol properties that protect it from oxygen and light damage. It is these same antioxidants that provide health benefits to humans including lowering blood pressure, helping to reduce bad cholesterol and protecting against certain malignant tumours. For more information on the health benefits of olive oil click here (link to health benefits page).
However, once the oil is opened and it is exposed to air the oil will slowly begin to deteriorate. The antioxidants will protect the oil from oxidation and deterioration until they are no longer able to work. At this stage, there is nothing to protect the oil and it will deteriorate rapidly. An open bottle, once open and stored in the correct conditions should keep its freshness for 3-5 months. Stored incorrectly, it will become rancid and inedible within months.
Another way to maximize quality extra virgin olive oil's freshness is to buy it in smaller bottles more often. This means that you won't have half empty bottles or cans on your shelf oxidizing and declining in edibility.
All good oils should clearly state a best before or use by date on their packaging. Some producers also have a harvest year on their packaging which indicates the year the oil was made.