No. Cooking oil can't be eaten after the expiration date. Cooking oil for a long time, especially the residual crude oil, containing more plant residues, can appear the phenomenon of rancidity of fats and oils. Cooking oil contains a linoleic acid component, easy to chemical reaction with the oxygen in the air, this phenomenon is called "grease oxidation".

Oil and grease, hydrolysis and a series of reactions, can generate a special smell of small molecules of aldehydes, ketones and carboxylic acids, such as oxides, peroxides, and other decomposition products, halo flavor is the result of oxidation and rancidity of fats and oils.

After the rancidity of fats and oils, when heated, the smoke is big and choking, which contains decomposition products such as epoxy propionaldehyde, easy to be poisoned after eating. Expired cooking oil will be oxidized, producing lipid peroxide, not only bad for blood vessels, but also carcinogenic.

Transparency declines after adulteration, the oil from the bottle quickly poured into the cup, observe the oil flower, pure peanut oil, the moorings flower foam, around a lot of small foam and not easy to fall, when mixed with cottonseed oil or cotton oil, the oil flower foam is slightly greenish-yellow or brownish-black.

Smell its odor can be smelled cottonseed oil flavor. The oil mixed with rice soup, noodle soup and other starchy substances in its blue-purple or blue-black color. Or put into a transparent cup for two days and then observe, will inevitably appear cloudy suspension.

After adulteration, the color becomes darker, such as adulterated cottonseed oil is black-red, adulterated rapeseed oil is dark yellow. In addition, the small milled sesame oil itself, no oil flower, pouring oil appeared when the oil flower is very easy to disappear, if the oil flower foam disappears very slowly, indicating that the adulteration. You can also use chopsticks dipped in a drop, drop to the calm water, pure small milled sesame oil appears colorless transparent thin large oil flowers, adulteration will appear thicker small oil flowers.

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