Can soaking fruits and vegetables in vinegar remove pesticide residues?

Recently, a method of washing fruit with vinegar has been circulating online, making people's eyes "light up." The method claims: "Kaohsiung Senior Industrial Vocational School's chemical engineering department found that dropping three drops of ordinary white vinegar into water and soaking cauliflower for two minutes can remove pesticides. This method also applies to fruits such as strawberries." Is this method really effective?

For acidic pesticides, the effect is not good

A reporter from this newspaper found that this message is not only widely shared on WeChat and Weibo, but was also frantically forwarded in Taiwan, China through instant messaging tools.

According to local media reports in Taiwan, China, many people sought verification of its authenticity from Kaohsiung Senior Industrial Vocational School through various channels. The school's response was: "Washing vegetables with vinegar cannot remove all pesticides. Only pesticides with amino and alkaline group structures can be dissolved out and removed by vinegar." This shows that vinegar can dissolve out some pesticides, but not all of them. Therefore, vinegar is by no means a universal cleaner for fruits and vegetables.

In principle, the method of washing fruit with vinegar uses the principle of acid-base neutralization. Some pesticides are acidic, and some are alkaline. Among them, alkaline pesticides can react to a certain extent with acid, thereby achieving the effect of washing off pesticides. But for acidic pesticides, the effect of vinegar is not good.

Organophosphorus pesticides and organochlorine pesticides are commonly used in China. Most of the former are water-soluble and can be washed off directly with clean water; the latter are fat-soluble and not easily soluble in water, and even soaking with white vinegar makes them very difficult to remove. "For common pesticide residues, soaking with baking soda may be more effective," said Zhu Yi, associate professor at the College of Food Science and Nutritional Engineering, China Agricultural University.

Secondary chemical residues remain incompletely resolved

In addition to vinegar and baking soda, methods of washing with salt water, rice washing water, and the like are also circulating online. Experts say these methods each have advantages and disadvantages, and a "one trick" cannot "work everywhere"; the washing method should be chosen specifically according to the type of fruit or vegetable.

In fact, there is another perspective for judging the effect of removing pesticide residues. Pesticide residues on fruits and vegetables are usually divided into two types: one is adhesive, where the pesticide residue only attaches to the surface of the fruit or vegetable; the other is systemic, where the pesticide residue penetrates into the interior of the fruit or vegetable. By rinsing with water or detergent for several dozen seconds, accompanied by rubbing, most adhesive residues can be removed. The latter can only be partially removed by peeling, heating, and other methods.

It should also be noted that the method of using special fruit and vegetable cleaning agents has a secondary chemical residue problem that has not yet been completely solved. On September 22 this year, China's "National Food Safety Standard Detergents" will begin implementation. This stricter new standard divides detergents into Class A, for direct use in washing food, and Class B, for washing tableware and tools, equipment, containers, etc. that come into contact with food. Therefore, consumers should be more careful when choosing cleaning agents in the future. (Song Hui)