To remove the white powdery look on some table grapes (especially red ones), put two bowls on the counter. Make an ice bath in one bowl (half ice and half water) and, in the other heat-safe bowl, put water just off the boil (or very hot tap water). Dip the grape bunch into the hot water for two or three seconds, then put it in the ice bath for several seconds to completely cool it down. Remove from the water and drain on a towel. To store grapes that won’t be eaten that day, place them in a paper towel-lined bowl, cover with plastic wrap and store in the refrigerator.