The cooking oil is out of date and can't be eaten. Edible oil, especially residual oil, contains more plant residues, which may lead to rancidity of oil. Edible oil contains linoleic acid, which easily reacts with oxygen in the air. This phenomenon is called "oil oxidation". A series of reactions such as grease and hydrolysis can produce small molecular aldehydes, ketones, carboxylic acids and other oxides, peroxides and other decomposition products with special odor.

After rancidity, the oil is heated and smoked, which contains decomposition products such as epoxypropanal, which is easy to be poisoned after eating. Expired edible oil will be oxidized to produce lipid peroxide, which is not only bad for blood vessels, but also carcinogenic.

Extended data:

First, the treatment method of expired edible oil

1, used as hand oil or body oil.

If the skin on your hands or feet is dry, you can soak your hands or feet in cooking oil for a period of time, or you can wipe the dry skin with cooking oil. Some girls who love beauty can often soak their fingers in oil, so that their nails will grow well, that is, transparent and firm.

2, used to grow flowers

Expired edible oil can be used as fertilizer. Put a small cup in a flowerpot at a time, and the flowers can absorb the nutrients in the edible oil and grow healthily, such as Clivia. But be careful not to water too much at once, and don't water too much.

Second, identify edible oil

1, look at the color. The normal colors of edible oil are light yellow, light yellow, yellow and brownish yellow, and the color depth of oil is slightly different due to different varieties. Generally, high-quality edible oil is light in color, and inferior edible oil is dark in color (except sesame oil), and inferior edible oil is darker than qualified edible oil.

Step 2 look for sediment. High-quality edible oil has no precipitation and suspended matter, and its viscosity is small. Sediments, commonly known as oil feet, mainly impurities, sink into the oil bottom under certain conditions. Buy oil with high transparency, light color (except sesame oil) and no sediment.

3. It looks oily. Take a dry, clean, tiny glass tube, insert it into the oil, plug the upper opening and slowly pull it out. Look at the oil If it is milky white, it means there is water in it, and the whiter it means more water. Oil with high water content will be turbid and easy to deteriorate. When heated, there will be a lot of foam and water explosion, and the lampblack will be bitter.

People's Network-Can edible oil be eaten after its expiration? How can expired edible oil turn waste into treasure?