Many people like to buy a large barrel of oil, and we often think that the shelf life written on the packaging of edible oil is 18 months or longer. During this period, the quality of the oil is good.
But in fact, edible oil is not necessarily safe even if it is within the shelf life after it is opened!
So, how long can the cooking oil be stored after it is opened?
According to my country’s “General Standards for Food Labeling”: The shelf life of edible oil packaging of 18 months refers to the period during which it can be circulated as a commodity on the market under specified conditions
The 18 months refers to the shelf life of the edible oil before it is opened, and once the product is opened, the shelf life of the edible oil has nothing to do with the 18 months on the trademark.
There are many factors that affect the shelf life of edible oil. The three most important ones are the type of oil, the antioxidants added to the oil, and the storage environment.
Different types of oils have different natural antioxidant components and fatty acids. These substances have different effects on the oxidation stability of edible oils. Therefore, different types of edible oils have different unsealed shelf life after being opened.
The five common edible oils, the degree of difficulty of deterioration, from easy to difficult are: sunflower oil, soybean oil, corn oil, rapeseed oil, and peanut oil.
Antioxidants in oil
Studies have found that under normal living conditions, edible oil without antioxidants will generally reach the critical point of deterioration after 2 months of opening. In a few days, the unique “hala smell” of fat rancidity will appear.
In addition to the natural antioxidants contained in the edible oils mentioned above, synthetic antioxidants are generally added to edible oils.
Most of the edible oils on the market now have antioxidants added, and the commonly used ones are “tert-butyl hydroquinone” (TBHQ) and “dibutyl hydroxytoluene” (BHT).
Edible oil added with antioxidants can be stored longer after opening the lid, but there is no research conclusion for how long it takes.
Under normal circumstances, it is recommended that everyone eat it within 3 months.