When buying grapes and blueberries, you often notice a white, misty powder on the skin. Many people's first thought is, 'Is this pesticide residue that wasn't washed off?

' and they immediately scrub them with water at home. In fact, this white substance is usually not pesticide, but 'fruit powder' or a waxy layer that the fruit naturally forms. It not only serves as an indicator of freshness but also protects the fruit. If you buy them and don't eat them right away, washing off the powder too early might actually make the fruit spoil faster.What is the white substance on grapes?

It's actually natural 'fruit powder'The Food and Agriculture Education Information Integration Platform of the Ministry of Agriculture points out that the white powder evenly distributed on the surface of fresh grapes is 'fruit powder' naturally produced by the grapes. It is a fine waxy layer covering the fruit's surface and is also an indicator of grape quality. For example, in the case of Kyoho grapes, complete and rich fruit powder is even listed as a feature to look for when selecting high-quality grapes.Therefore, seeing a white mist-like layer on the surface of grapes does not indicate pesticide residue, nor should you avoid buying them just because you see the white powder.This natural waxy layer is like a 'protective film' that the fruit has, helping to reduce moisture loss and protect the fruit's surface. Blueberries are the same. The University of Minnesota's agricultural extension materials point out that when harvesting blueberries, you should try to minimize contact to preserve the white waxy fruit powder on the surface, as this layer helps protect the fruit and reduce the chance of fungal infection.How to tell the difference between grape white bloom and pesticide?

Look at the 'distribution pattern'However, not all white marks on fruits can be directly identified as natural fruit powder.The Ministry of Agriculture points out that the natural fruit powder of grapes is usually 'evenly' distributed on the surface of the berries, looking like a thin, misty white powder, and can be easily wiped off with a light touch. If you see irregular spots, patches, circular marks, or light yellow traces that are unevenly distributed, especially concentrated at the bottom of the berries, and are not easily removed by touch, they may not be natural fruit powder.In short, you can make an initial judgment from the appearance:Natural fruit powder is usually thin and evenly covers the entire fruit, and can be easily wiped off with a light touch; irregular patches, circular marks, or localized accumulations are different from the appearance of natural fruit powder.However, whether or not there is white bloom on the surface, you should still wash the fruit before eating. You should not skip the washing step just because you have confirmed that it is natural fruit powder.Don't wash grapes and blueberries right after buying them!

Washing them actually makes them spoil fasterMany people have the habit of washing all the fruit at once after buying it and then putting it in the refrigerator for convenience when eating. However, for fruits like grapes and blueberries, this method might actually shorten their storage time.The Ministry of Agriculture recommends that if you buy grapes and don't plan to eat them right away, you should not wash them first. Instead, when you are ready to eat, cut off the portion you need and rinse it with clean water. If the grapes have already been washed, you should thoroughly drain the water and then store them in a sealed container or bag in the refrigerator.Blueberries are the same. Pennsylvania State University points out that fresh blueberries are best washed just before eating. The University of Minnesota also recommends that, unless the surface of the fruit is obviously dirty, it is best to wash it just before eating to help maintain quality and extend storage time.In other words, 'washing off the white bloom' is not the only problem; the water remaining on the surface of the fruit after washing also increases the difficulty of storage. Therefore, to make grapes and blueberries last longer, the key is to 'not touch water' when you first bring them home.How to wash grapes and blueberries?

Clean water is enoughWhen you are actually ready to eat, you don't need to worry about pesticides and soak the fruit in salt water, baking soda water, or cleaning solution and scrub them repeatedly.The University of Minnesota recommends that fresh vegetables and fruits should be rinsed with cool running water; soft berries like blueberries can be placed in a strainer and gently rinsed with cold water, avoiding long soaking. The unit also points out that current research has not shown that using vegetable and fruit cleaning agents at home has a significant food safety advantage over using running water. You should not use soap, cleaning solution, or bleach to wash vegetables and fruits.Grapes can be cut from the stem in the portion you plan to eat and then washed with clean water, avoiding pulling the grapes off the stem directly, which can damage the skin and increase the chance of spoilage.How to store blueberries to make them last longer?

After buying blueberries, you can first pick out any that are already moldy, soft, or broken to prevent one bad berry from affecting the others, and then refrigerate them in an unwashed state.The University of Oregon's agricultural extension materials recommend that fresh blueberries can be stored in a shallow container with air circulation holes in the refrigerator and rinsed with cold water before eating; under appropriate refrigeration conditions, it is recommended to consume them within about 10 days to maintain better quality.Therefore, the next time you see a white powder on the surface of grapes or blueberries, don't immediately assume it's pesticide. The white bloom that is evenly distributed on the skin is usually natural fruit powder formed by the fruit itself and is a line of defense to protect the fruit. To really make the fruit last longer, it's better to not wash it right after bringing it home and only wash the portion you need to eat, rather than washing off all the white bloom and then refrigerating it.