In response to the appearance of”fading chives” in individual farmers’ markets, gently wipe the chives leaves with a paper towel, and the paper towel will appear light blue. This phenomenon has attracted the attention of major media and consumers.
Why do chives need to be”dyed”? Is it still edible after dyeing? What are the effects of eating”fading chives” on the body? How to remove pesticide residues? Let’s take a look at the expert’s interpretation.
Light blue is not a stain, but a protective fungicide
After testing by the inspection department, the source of the light blue shallot is due to the spray of Bordeaux mixture. So what is Bordeaux mixture? Bordeaux mixture is a kind of inorganic copper protective bactericide, which is made of copper sulfate, lime and water in a certain proportion. It is widely used to prevent and control fungal and bacterial diseases of fruit trees, vegetables, cotton, hemp and other crops. After the Bordeaux mixture is sprayed on the surface of plants, it can form a protective film, which can effectively prevent the invasion of pathogenic bacteria. Under the action of plant secretions, carbon dioxide in the air, and organic acids secreted by germ spores, basic copper sulfate is transformed into Soluble copper sulfate releases soluble copper ions and interacts with the enzymes on the cell membrane of bacteria or fungi, causing the cell membrane proteins to condense and denature. Part of the copper ions can also penetrate into the cells of the bacteria to affect the enzyme activity and cause the bacteria to die and produce a bactericidal effect. . As a result, Bordeaux mixture has the characteristics of a broad bactericidal spectrum and resistance to germs, and is widely used.
Does Bordeaux mixture affect human health?
The bactericidal effect of Bordeaux mixture is copper ions, so will the intake of chives containing copper residues affect human health? Copper is a heavy metal, but not toxic heavy metals such as arsenic and lead. It is a trace mineral element that the human body needs to take in. It participates in various physiological metabolic reactions of the human body and plays a very important role. Copper is also widely distributed in various foods, such as cereals, beans, nuts, liver, kidney, shellfish, etc. A certain amount of copper is also consumed in the daily diet.
Is too much copper harmful to the body? The answer is yes. If the intake exceeds the safe dose, it will have an impact on human health. So what is the safe dose? How much discoloring chives can I consume to exceed the safe dose of copper? According to the recommendation of”WS/T 578.3-2017 Chinese Residents’ Dietary Nutrient Reference Intake Part 3:Trace Elements”, the recommended daily intake of copper is 2 mg/d, and the tolerable maximum intake is 8 mg/d , As long as the intake is below the tolerable amount, it is safe for the human body. According to related reports, the copper residues detected in the color-fading shallots ranged from 1.23mg/kg to 3.68mg/kg, that is, the daily intake of 2 kg of color-fading shallots is close to the tolerable maximum copper intake of 8 mg. This is quite different from the actual consumption and daily consumption, so the risk of fading chives to the human body is extremely low.
If you buy the”fading chives”, don’t be too panic and worry, you can rinse the chives under running water two or three times to remove the Bordeaux mixture residue.
How to eliminate pesticide residues in fruits and vegetables
In daily life, if you want to remove or reduce the pesticide residues on fruits and vegetables as much as possible, you can use the following four methods:
1. Remove the peel and leaves:Peeling can reduce pesticide residues in the edible parts. Cabbage, cabbage, cabbage and other leafy vegetables can be peeled off several layers of leaves.
2. Washing and soaking:Rinse vegetables and fruits with running water before eating, and then soak them for 15-30 minutes, and then rinse them with running water after they are taken out, which can effectively reduce pesticide residues. Adding a little baking soda or fruit and vegetable cleaning agent is better.
3. Heating and blanching:Heating can degrade many pesticides to varying degrees, and blanching cold vegetables can greatly reduce pesticide residues.
4. Place a”safety interval”:the plant itself has a certain ability to metabolize pesticides. Therefore, storage-stable fruits and vegetables, such as potatoes, cucumbers, and Chinese cabbage, can be eaten for a few days after they are bought home.
Manuscript Source:School of Food Science, Nanchang University