Is eating onions and garlic with black spots poisonous? Should I eat them or throw them away?

Even though you see onions and garlic are still dry and not spoiled, according to experts, if you see black spots, you absolutely should not eat them.

Professor Jesada explains why you should not eat onions and garlic with black spots, saying that this is an agent that causes liver cancer, the leading type of cancer in Thai people. Recently, a Facebook post by user Time Rtnpk shared about eating onions and garlic with black spots, with the following content:

"Most cancers originate in the kitchen, no need to go far. Garlic and onions with black spots should not be used to prepare food. Even if it is just a little moldy or the moldy part is removed, because these molds will create carcinogens that spread throughout the garlic, which are very difficult to remove. The heat during cooking cannot completely destroy them. Eating them will accumulate in the liver, causing liver cancer, the leading type of cancer in Thai people."

Recently, Dr. Jesada Denduangboripant, lecturer at the Faculty of Biology, Chulalongkorn University, explained this issue on Facebook Jessada Denduangboripant as follows:

"It is right not to eat onions and garlic with black spots."

Black spots on foods such as onions, garlic, cereals or even bread are at risk of being molds that produce toxins and carcinogens such as aflatoxin. Therefore, we should avoid eating these foods and store food in a dry place, away from mold.

However, it is not necessary to throw it away completely as in the original article. If it is unavoidable, you can cut off the moldy part and cook it at high temperature. This way, it can still be eaten and the risk of aflatoxin is minimized.

According to information from the Institute of Nutrition, Mahidol University (written by Isaya Withubanjerd), there is an explanation about where the black spots on garlic come from, and whether or not you should eat it. The summary is as follows:

Sometimes, we may encounter garlic with black spots. Professor Dr. Ekachai Ketwal, a food and nutrition expert at the Institute of Nutrition, Mahidol University, shared information about garlic with black spots, that black spots on garlic can come from two causes: one is bruising due to improper storage or garlic left for too long, leading to bruising; the other is due to mold such as Aspergillus flavus or Penicillium, a type of mold commonly found on agricultural products.

When you look at the outside, you can see black mold on the garlic cloves and it spreads easily. If left for a long time, the garlic can be completely damaged. The mold can produce aflatoxin, an extremely dangerous carcinogen, and if the food is contaminated with aflatoxin, the temperature must reach 270°C to destroy the aflatoxin.

Research shows that garlic contains allicin and diallyl sulfide, which have the ability to inhibit the growth of fungi. While garlic can be contaminated with fungi, the fungi do not thrive and do not produce aflatoxin. So if you come across garlic with black spots, it means that the fungus has grown more than normal and should be avoided.

Therefore, eating raw garlic with black spots may be unsafe due to the risk of fungal infection. Raw garlic with black spots should not be eaten. However, if this is unavoidable, it is best to cut off the black spots and cook the garlic before eating.

Consumers should choose fresh, firm garlic that is not soft, not wilted and not moldy