From a microbiological and bacteriological perspective, frying oil is not a product that can go bad. However, the quality of frying oil can certainly deteriorate due to several factors. For example, when frying oil is exposed to light and/or air, it oxidizes, causing the quality to decline.

In other words: as long as the oil or frying oil remains unopened, it is advisable to store it in a dark place where it does not come into contact with light.

Once the oil or frying oil is opened, it is exposed to air and light, and its quality will gradually decline—even if the oil is not used for frying.

Frying oil can remain in a fryer for a short time without being used, but this should not last too long.

Both professional fryers and home cooks are advised to replace frying oil regularly.