How long can cooking oil be stored after opening? How dangerous is it to consume expired oil?
Many people like to buy cooking oil in large containers, and we often assume that if the expiration date printed on the package is 18 months or more, the oil will remain good throughout that entire period. However, even within the stated shelf life, once cooking oil has been opened, it is not necessarily safe!
According to our country’s General Standard for Food Labeling, the 18-month shelf life indicated on cooking oil packaging refers to the period during which the product can circulate on the market as a commodity under specific conditions.
How long can cooking oil be used after opening?
Nowadays, all major supermarkets sell refined cooking oil that is individually packaged. The shelf life of this type of oil is usually around 18 months. If the seal is not broken and the oil does not come into contact with air, its shelf life can be even longer.
However, cooking oil is purchased for cooking, so it inevitably has to be opened. In this case, the shelf life will be affected by many factors.
If a large drum of oil is opened and poured into a household oil container, then tightly sealed and stored in a cool, well-ventilated place, it can last for about one and a half years. In normal household conditions, however, a 5-liter bottle of cooking oil is usually consumed within about 3–6 months, so expiration is generally not an issue.
How dangerous is expired cooking oil?
1. Changes in oil quality
When the oil container is not tightly sealed, cooking oil will change in flavor due to exposure to moisture and air. Once the flavor changes, not only will it develop an unpleasant odor, but food cooked with it will also taste bad. At that point, it can only be discarded, which results in serious waste.
Under normal circumstances, a container of ordinary cooking oil costs around 100 yuan, which is a significant expense for many families. Therefore, it is important to pay attention to proper storage methods to avoid oil expiring due to careless handling.
If, out of fear of wasting it, expired oil is still frequently used for cooking, it will inevitably cause harm to your health.
2. Loss of nutrients
Cooking oil is rich in nutrients and beneficial to health when used properly. However, once it expires, these nutrients break down, and the oil is no longer suitable for cooking.
Oil that has lost its nutrients is comparable to the waste oil collected in a kitchen exhaust hood—essentially tasteless and useless. Under normal conditions, if cooking oil is directly exposed to air, its nutrients are lost very quickly. Basically, within about a week, a container of oil can lose most of its nutritional value. Continued consumption may easily lead to physical weakness, obesity, and even cardiovascular diseases.
3. Deterioration and poisoning
Expired cooking oil deteriorates rapidly and allows large numbers of bacteria to grow. If it is still used for cooking under these conditions, it can cause serious harm to your family’s health.
In severe cases, it may even lead to chronic poisoning. Nausea, vomiting, diarrhea, and abdominal pain are all common symptoms of cooking oil poisoning.
4. Accelerated aging
Long-term consumption of expired oil not only causes problems in the gastrointestinal tract but also accelerates skin aging. Harmful substances in expired oil can accumulate in the body, and if they are not eliminated through normal metabolic pathways, they will interfere with metabolism. This can seriously damage skin tissue, with the most obvious manifestation being accelerated skin aging.
From the above explanation, it is clear how harmful expired cooking oil can be to health. Cooking oil is an essential item in every household kitchen, which means everyone should learn more about proper storage methods to avoid consuming expired oil. When oil goes rancid or exceeds its shelf life, discarding it in time helps protect the body from unnecessary harm.
