Grapes should be washed under cold running water right before consuming or using in a recipe. After washing, either drain the grapes in a colander or gently pat them dry. If you are not going to consume the whole bunch at one time, use scissors to separate small clusters of grapes from the stem instead of removing individual grapes. This will help keep the remaining grapes fresher by preventing the stem from drying out.
While some recipes call for peeled grapes, evaluate the recipe to see whether including the skin would actually greatly change the taste and texture, since the grape skin contains many of the fruit's vital nutrients. If retention of the skin isn't objectionable for recipe reasons, we recommend that you always include the skin on account of its nutrient richness. If you decide to use peeled grapes, it's easier to use the American varieties since their skin more readily pulls away from the pulp.
Grapes retain their maximum amount of nutrients and their maximum taste when they are enjoyed fresh and not prepared in a cooked recipe. Cooking temperatures used in baking of 350°F/175°C can damage some of the unique and delicate phytonutrients found in this amazing fruit.