Why should not re-use cooking oil?

First, it must be confirmed immediately that repeated use of oil frying food at high temperatures will cause oxidation of oil which is not good for health and also cause cancer. Not to mention that the vitamin A and E in the oil are destroyed, reducing the nutritional value, but only talk about the effects of high temperatures (above 1800C) will cause chemical reactions, produce aldehydes, peroxides ... are substances that are very harmful to the body.

Repeated use of frying oil at high temperatures causes the oxidized oil to produce unhealthy substances.

The higher the oil temperature, the greater the number of times the used oil is used. Among those substances that cause air pollution, the inhaled person is also toxic, the substance is deposited into the oil, the person eating is very harmful. Light, dizziness, nausea, vomiting, abdominal pain, difficulty breathing, slow heartbeat, high blood pressure, tired limbs. Long-term eating can also cause cancer.

In order to prevent such danger, it is necessary first to control the temperature when cooking, generally not to exceed 150-1800C, which means do not let oil fume. Second, do not reuse used oil many times.