Usually the shelf life of "edible oil" is 18 months. Others, such as "Salad Oil" (6 months), "Premium Cooking Oil" (12 months), "Blending Oil" (12 months), etc. have different shelf lives. Please refer to the shelf life instructions on the packaging for details. shall prevail. It is true that these oils are no longer fresh a month after opening the bottle, but they are still edible. Deterioration does not happen in an instant, but occurs all the time. Due to the chemical reaction taking place between the edible oil and the external environment such as air, the oil also deteriorates little by little. The instability of edible oil is due to the existence of "unsaturated bonds", which are easily oxidized by air and cause rancidity. When using "edible oil" in your daily life, you must pay attention to its storage. There are four dangers with edible oil: