Prepare Plump, Juicy Homemade Raisins by Baking Whole Grapes in the Oven
These oven-cooked raisins are not like the shriveled (but still delicious) kind you buy at the store. No, they are more flavorful, juicy and plump, and you have control over how juicy and plump you want them to be. You could even say that they are … raisins in the bar.
The oven is ideal for creating really great-tasting raisins that retain their grape flavor because, according to Serious Eats, even at the lowest setting, the oven is hotter than a fruit dehydrator. This way you can control how much you dry them. You can use any grape variety, place it on a rimmed baking sheet, and place it in the oven at the lowest possible temperature (about 225 degrees Fahrenheit, but up to 300 degrees if you want to dry them faster).
If you bake them at a temperature of 225 degrees, then in three to four and a half hours you can get a wonderful product. The result is juicy grape-flavored lumps that can be added to oatmeal , salads, cookies, rice pudding , muffins, or any other recipe you wish.