Below, we give you some tips on how to tell if an olive oil is in poor condition, apart from checking the best-by date printed on the label:
1) The olive oil has a strange or unusual color. Extra virgin olive oils can range in color from deep green to golden yellow. However, color alone is not a reliable indicator of the quality or condition of an olive oil.
For example, olive oil packaged in a transparent glass bottle or PET container that has been exposed to sunlight or strong light in a store for a long period of time can develop a reddish color, similar to that of whiskey or cognac.
Another example is olive oil that has been exposed to repeated frying cycles. This can eventually cause the oil to become very dark and may even cause some foam to develop.
2) A rancid smell and taste. Most olive oils in poor condition available to consumers will have become rancid. This means that the extra virgin olive oil has gradually oxidized, either while stored in stores or in the kitchen, and has eventually become rancid.
Rancidity is an unavoidable process in olive oil. It will happen sooner or later, but it can be significantly delayed by following good storage practices.
What does rancid olive oil taste like?
The smell of rancid olive oil can remind you of varnish, solvents, or a freshly painted room, often with a sweet and unpleasant aroma. Olive oil is very likely to have become rancid if it has been open for more than three years and has been stored in a bottle throughout that time.
Is it possible to remove rancidity from olive oil?
It is not possible to recover olive oil once it has become rancid. Rancidity is an irreversible process. A mistake that is sometimes made is to mix rancid olive oil with fresh extra virgin olive oil in an attempt to compensate for or mask the rancid flavor. This is not recommended, as the rancid oil already contains oxidation products that can accelerate the deterioration of the fresh olive oil with which it is mixed.
What is the best-by date on extra virgin olive oil?
The best-by date is set by the producer at the time of packaging. It is determined based on the condition of the olive oil, its analytical characteristics, and the expected storage conditions from the time it is packaged until it reaches the final consumer.
For example, if a producer has a very stable extra virgin olive oil, such as Picual, and packages it in an opaque glass bottle, its properties and extra virgin status can be expected to be preserved for longer than those of a less stable variety, such as Arbequina, packaged in a transparent PET container.
For this reason, it is common for producers to set a best-by date between one and two years after packaging.
It is important to emphasize that the best-by date is not calculated from the date the olive oil was produced, but from the date it was labeled and packaged. Therefore, you may find two extra virgin olive oils packaged on the same date with the same best-by date, even though one was produced two years earlier and the other only recently.
The best-by date should not be confused with an expiration date. The best-by date refers to the period during which the producer expects the olive oil to retain its quality and characteristics when stored correctly.