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Can Cooking Oil Go Bad?

Cooking oil can be found in pretty much every kitchen, though many people likely don’t use cooking oil every day. So, how long should you keep that giant bottle of cooking oil in the pantry? Can cooking oil go bad? Read on to find out!

Can Cooking Oil Go Bad?

Like all types of oil, cooking oil can go bad. “Cooking oil” is a general term for various types of seed and vegetable oils used in cooking. These oils all have different shelf lives, depending on how refined the oil is, the composition of the oil, and the storage method. Oils like canola oil, sunflower seed oil, safflower oil, olive oil and blended vegetable oil lasts for about two years unopened. Their shelf life reduces to about a year once the bottle is opened. if the oil is stored properly.

More delicate oils like corn oil, sesame oil and many nut oils have a shelf life of only a year unopened. When opened, these oils will last for between four and nine months, if properly stored. Because these oils are more likely to spoil quickly, it’s important to test them before cooking, to avoid an unpleasant surprise!

Crisco Pure Vegetable Cooking Oil

Image used under Creative Commons from Mike Mozart

How to Tell When Cooking Oil Goes Bad

Cooking oils won’t grow mold, or start rotting, but they will still go bad. The most obvious sign that cooking oil has spoiled is rancidity. Rancid oil will have quite a strong unpleasant smell. You should always check your oil for rancidity before using. Consuming rancid oil can be damaging to your health in the long term, and is not recommended. In the short time, rancid oil can cause digestive discomfort, and bring an unpleasant taste to your food.

Refrigerated oils may become cloudy, and solidify a bit, but this does not mean they’ve gone bad. Simply leave the oil out at room temperature for a while and the oil will return to a liquid state. Certain oils like olive oil may seem to have sediment when stored at colder temperatures, but this is also a reaction to the refrigeration and does not indicate spoilage.

How to Store Cooking Oil

Unopened cooking oil should be stored in a tightly sealed container, and kept in a cool, dark place. Storing the oil away from light and heat will extend the shelf life as long as possible. Once the oil is opened, refrigerating the tightly sealed bottle can keep the oil from going rancid for as long as possible, though the shelf life will remain at a year.

Freezing cooking oil to extend its shelf life is not recommended. Freezing will not extend the shelf life, and will only serve to speed up the spoiling process once the oil thaws. Because freezing and thawing the oil can change its structure, it will become oxidized more rapidly and go rancid.

When purchasing a bottle of cooking oil, try to buy brands that store the oil in a dark glass, or opaque container. Blocking out light will keep the oil from spoiling as quickly. Of course, since many brands of cooking oil come in clear plastic containers, it’s important to properly store the bottle once you get home. You should also check the dates on the bottles, and try to buy an oil that has at least a year remaining of its shelf life. This will ensure that you get the most use out of the bottle of oil.