How to judge whether peanut oil has gone bad

Peanut oil is a common edible oil. It has a relatively high nutritional value and tastes very fragrant. When eating peanut oil, you should also understand some aspects of peanut oil deterioration. This is because if peanut oil deteriorates, aflatoxin will exceed the standard. We know that aflatoxin is a very strong carcinogen. If you eat deteriorated peanut oil, it will cause great harm to your body. Let's take a look at this aspect.

What does peanut oil look like when it goes bad?

If cooking oil is left for a long time, especially residual crude oil, which contains more plant residues, the oil may become rancid. Cooking oil contains a component called linoleic acid, which easily reacts chemically with oxygen in the air. This phenomenon is called "oil oxidation". A series of reactions such as oil and hydrolysis can generate small molecule aldehydes, ketones, carboxylic acids and other oxides, peroxides and other decomposition products with special odors. The rancid smell is the result of oil oxidation and rancidity. When oil becomes rancid, it produces a lot of smoke and is choking when heated. It contains decomposition products such as glycidaldehyde, which can easily cause poisoning if consumed.

How to prevent peanut oil from going rancid

1. Choose a storage container for peanut oil. When there is a lot of oil, you can choose a ceramic cylinder and try to reduce the diameter of the container; when there is little oil, you can choose an opaque dark glass bottle. After the oil is filled, the bottle mouth should be sealed to isolate the oil from the air and prevent the edible oil from oxidation and deterioration. Do not use metal or plastic bottles (barrels) to hold cooking oil because metal molecules and plasticizers in plastics can accelerate the rancidity and deterioration of cooking oil, leading to excessive aflatoxin levels.

2. The storage container should be placed in a cool, dark, dry and low temperature place. Because the ultraviolet and infrared rays in sunlight can promote the oxidation of oils and accelerate the formation of harmful substances. Oil storage containers should minimize contact with air and sunlight.

3. Avoid high temperatures when storing peanut oil. The best storage temperature is 10℃-15℃, and generally should not exceed 25℃. It is not suitable for storage in summer. You should try to buy fresh peanut oil and eat fresh oil frequently. Be careful not to mix water into cooking oil, otherwise it will easily emulsify the oil, become turbid and deteriorate. You can also add hot oil to the oil at a ratio of 40:1 to absorb the water.

4. Prevent peanut oil from oxidation and deterioration. If there is too much cooking oil to be consumed at once, you can add a small amount of antioxidants such as pepper, fennel, cinnamon, cloves, vitamin C, etc. to the oil to delay or prevent the oxidation and deterioration of the cooking oil. Except for colored small-mouth glass bottles, the storage period of other containers should be half a year, and the longest should not exceed one year.