Fresh grapes often have a white bloom that cannot be washed off even with water, and it is difficult to clean the dust and dirt between the grapes. In this case, you can use flour for help.
First, put the grapes in clean water, making sure the water covers the grapes. Then add 1-2 spoonfuls of flour and stir well. Let it sit for two minutes. Hold the main stem of the grapes and gently swish them in the water to allow the flour to fully contact the dust and dirt between the grapes. After 3 minutes, rinse the grapes twice under running water. Flour has an adsorbent effect, which can easily remove the dirt between the grapes without leaving any detergent residue.