1, cooking oil will produce oxidation phenomenon, the generation of small molecules with a special smell of aldehydes, ketones and carboxylic acids, such as oxides, peroxides and other decomposition products, showing a "halo flavor". Expired cooking oil, contains more rancid harmful substances, can not be used again, consumption of expired cooking oil will be harmful to the human body.

2, cooking oil must pay attention to the shelf life, shelf life is generally 18 months, after the expiration date can not be consumed.

3, the use of expired produce rancid cooking oil will appear in the following varying degrees of acute poisoning:?

(1) After consuming rancid cooking oil, there will be nausea, vomiting, abdominal pain, diarrhea and other mild acute poisoning.

(2) Consumption of expired rancid cooking oil peroxide and other toxic substances will make the hemoglobin 2-valent iron into hemoglobin 3-valent iron, so that hemoglobin loss of oxygen-carrying function, resulting in hypoxia, and mucous membranes, cyanosis of the skin, and other moderate acute poisoning phenomena.

(3) After consuming cooking oil containing oxides of rancid substances, it will have a direct destructive effect on succinate oxidase, cytochrome oxidase and other important enzymes in the human body's enzyme system, interfering with the intracellular tricarboxylic acid cycle, oxidative phosphorylation, causing obstacles to the energy metabolism of the cells, and intracellular asphyxiation, which will lead to acute respiratory and circulatory failures, such as severe acute toxicity.

After eating expired and spoiled cooking oil, the above nausea, vomiting, skin bruising and other toxic phenomena, should be sent to the doctor in a timely manner, timely gastric lavage, diarrhea and other symptomatic treatment.