Peanut oil sour is spoiled, can not be eaten, containing more oil and fat food for a long time, such as oil, pastries, fish and meat products, walnuts, peanuts, melon seeds, etc., will produce a bitter and hemp, pungent and unpleasant taste, commonly known as "halo flavor". This is because fats and oils are prone to rancidity, resulting in harrying flavor.

The lipid peroxide produced during the oxidation of fats and oils will not only cause the appearance, texture and nutrition of the food to deteriorate, but will even produce mutagenic substances, such as hydroperoxides, which can react with almost all the molecules or cells in the body to destroy DNA and cell structure.

Expanded Information

Studies have found that under normal living conditions, cooking oils with no added antioxidants generally reach a critical point of deterioration 2 months after opening. After a few days, the characteristic "harry odor" of rancid fats and oils will appear.

Adding antioxidants to cooking oil can be stored for a longer period of time after opening the lid, but how long, there is no research conclusion. In general, it should be eaten within three months.

People's Daily News - How long can cooking oil be stored open

People's Daily News - Spoiled food often has 5 odors, don't eat it!