Once you open a bottle of olive oil, its freshness begins to decline due to exposure to air, light, and heat. Generally, opened olive oil should be used within three to four months for optimal flavor and quality, as recommended by the North American Olive Oil Association. Some experts suggest that using it within 30 to 60 days is even better, especially for high-quality extra virgin olive oil, which is more perishable (source: We Olive).

The shelf life of olive oil can be influenced by several factors:

Type of Olive Oil: Extra virgin olive oil has a shorter shelf life compared to refined olive oils.
Quality of the Oil: Higher quality oils often have better preservation due to their polyphenol content.
Storage Conditions: Olive oil should be stored in a cool, dark place, away from heat sources and direct sunlight (source: Martha Stewart).

To extend the shelf life of your opened olive oil, proper storage is essential. Here are some tips:

Temperature: Store olive oil at a temperature between 60°F and 72°F. Avoid storing it near the stove or in a place where it will be exposed to heat (source: We Olive).
Light Protection: Use dark glass or tin containers to protect olive oil from light, which can cause it to deteriorate more quickly (source: Taste of Home).
Sealing: Always keep the cap tightly sealed to minimize exposure to air, which can lead to oxidation.

Even with proper storage, olive oil can go rancid. Here are some signs that your olive oil may have spoiled:

Rancid olive oil often has a smell reminiscent of crayons or putty, and the taste can be described as stale or greasy (source: Taste of Home). Fresh olive oil should have a vibrant, herbaceous flavor.

While color alone is not a reliable indicator of freshness, if you notice any unusual cloudiness or sediment that wasn’t present before, it might be time to discard the oil.

In summary, once opened, olive oil should ideally be used within three to four months, with a preference for using it within 30 to 60 days for the best flavor and health benefits. Proper storage in a cool, dark place with a tightly sealed cap can help extend its shelf life. Always check for off flavors or smells before using, as these can indicate that the oil has gone bad. By following these guidelines, you can enjoy the rich flavors and health benefits of olive oil at its best.