Oil expired is not recommended to eat again. Oil after the expiration of fat oxidation to produce harmful substances, the appearance of hara odor, taste changes, may cause gastrointestinal discomfort, damage to the health of the body. 1, odor, taste changes: expired oil whether or not high-temperature heating, the unsaturated fatty acids contained in the easy to oxidize, decomposition, resulting in a special odor of oxides, peroxides and other decomposition products, this irritating smell and bitter taste, may lead to human Discomfort, nausea, vomiting and other performance; 2, cause gastrointestinal discomfort: expired oil sour, spoiled not only nutrients will be destroyed, but also produce harmful substances, after consumption will cause gastrointestinal discomfort, abdominal pain, diarrhea and other symptoms, and in serious cases, even cause food poisoning; 3, damage the body’s health: the oxidation products of sour fats and oils on the body’s enzyme metabolism has a damaging effect, thus causing the body metabolic disorders It may reduce the immune function. If long-term consumption will cause imbalance in the normal physiological and biochemical functions of the cells, so that the normal structure of tissues and organs are destroyed, resulting in liver and kidney disease, endangering human health. Therefore, daily oil should be stored in a cool place away from light, and should be consumed within the expiration date.