Have you ever noticed whether the "white frost" on the surface of fruit is pesticide residue or a normal phenomenon?

Recently, some netizens left a message to consult that the plums they bought have a layer of "white frost" on the surface, and it is difficult to wash them off. Is this layer of frost really pesticide residue?

In fact, not only plums have white frost, but fruits including grapes, plums, sugar cane, blueberries and even wax gourd also have a similar layer of white frost. In fact, this layer of frost is the sugar alcohols secreted by fruits and vegetables themselves, also known as fruit powder, not pesticide residues!

The scientific name of this kind of "frost" is "fruit powder". It is a natural substance secreted by fruits and vegetables, which is completely harmless to the human body. These compounds are insoluble in water, but soluble in organic solvents such as chloroform, so no matter with blisters, washing or rubbing, this layer of frost can not be completely removed from the peel. But it doesn't matter if you can't wash off the frost. Because they are not harmful to our health, and even help to protect the liver and anti-virus, there is no need to avoid taboos. It is said that the white frost can be washed off with flour, but it does not really wash off the white frost, but only changes the structure of the white frost or closes the gap between the crystals of the white frost.

This layer of fruit powder has a protective effect on fruit, such as this layer of fruit powder on the surface of grapes can reduce water evaporation, so as to prevent rapid water loss and shrinkage after picking, which plays a positive role in adapting to dry environment. The insolubility of fruit powder in water can avoid the formation of a moist environment on the surface of grapes, thus reducing the infection of pathogenic bacteria. The white frost on the grape surface also contains yeast, so homemade wine can be fermented without adding yeast. What needs to be explained is that grapes are not easy to grow insects, and now most of them are bagged, and the chances of using high concentrations of pesticides are very small, so if it is determined to be the white frost of the grape itself, it is not necessary to wash it off.

To some extent, wearing white frost is a sign of fresh grapes, but it can not prevent some merchants from spraying low concentrations of germicidal pesticides. The specific method of distinction is: the normal "white frost" is naturally and evenly distributed, and does not cover the color of the grape skin itself, making the grapes look more beautiful. If it is the drug "white frost", the appearance is uneven, in which there will be traces of dark blue.

Therefore, if you see the "white frost" fruit in the future, you can rest assured to buy it, because it is the freshest fruit!