Many housewives, for the convenience of access while cooking, often place cooking oil within easy reach of the stove. Unbeknownst to them, this method of storage is unscientific and can easily lead to the spoilage of the cooking oil.
Because the temperature near the stove is typically high, high temperatures can accelerate the oxidation of oils, easily causing rancidity. Furthermore, the intense light from the stove flame can also accelerate the rancidity of the oil. This causes vitamins A, D, and E to undergo varying degrees of oxidation, reducing their nutritional value, while also producing harmful aldehydes and ketones to the human body. If rancid oils are consumed for a long period, it can easily cause chronic damage to organs such as the liver, kidneys, and skin, and may even lead to cancer.
Since an oil only shows some visible changes when it has become rancid to a certain extent—such as a darker color, increased sediment, cloudy liquid, and a unpleasant "stale" smell—it is very difficult for the average person to tell if the cooking oil has spoiled by its appearance. To avoid this potential hazard, experts recommend adopting proper methods for storing cooking oil: Low-temperature storage
The optimal storage temperature is 10°C—25°C. When not in use, oil should be kept away from the stove and also from places like heating pipes and high-temperature appliances. It is best for household use to buy oil as needed and not to use it for longer than one year. Protect from light
Cooking oil should be stored in a place away from light and that is well-ventilated, because the ultraviolet and infrared rays in sunlight can also promote oil oxidation and the formation of harmful substances. Select the right container
The container for storing oil must be clean, dry, and have a good seal. It is best to use dark-colored glass bottles rather than transparent ones. If possible, using an earthenware jar is even better. Although plastic buckets are lightweight and convenient, they are not suitable for storing oil, because plasticizers in the plastic can accelerate oil rancidity. Metal containers such as iron, copper, and aluminum are also not suitable for holding oil, as they all have the effect of accelerating oil rancidity. Add protective agents
Here's a little tip: adding hot salt to the cooking oil at a ratio of 40:1 can help absorb moisture and keep the oil clear in color and fragrant in aroma. You can also add 1-2 vitamin E capsules to the cooking oil to enhance its antioxidant capacity.