When you think of biting into a sweet, juicy grape, probably the last thing on your mind is the sulfur dioxide used on them after harvesting. Sulfur dioxide is a foul-smelling, colorless gas that's emitted when sulfur-containing fuel, including diesel and fuel oil, are burned. In its chemical form it's used as a preservative for instant potatoes, wine, dried fruits and applesauce—and also as a fungicide on grapes. This could be one of the reasons grapes frequently make the Environmental Working Group's Dirty Dozen list of produce that's most likely to be contaminated with pesticides and other chemicals.
The takeaway: better wash those grapes! It's a simple job.
Place the grapes into a colander and rinse them under cool water. Use your hands to rotate the grapes to ensure all of them are thoroughly rinsed.
Shake the colander gently to remove any excess water and dump the grapes onto a piece of paper towel.
Wipe off the grapes with a second piece of paper towel to remove any excess water or remaining dirt and fungicide.