All you need is to Wash your grapes and then sprinkle a 1/4 of a packet of crystal light on them then put them in the freezer. they aren’t sour. They are more sweet. You could try different flavors. Lime, strawberry, etc. Maybe dry the grapes and then squeeze a lemon or lime all over them before coating them in powder. If you want to avoid gelatin like me you can use crystal light powders or any other kind that are similar like starbursts etc. You can Freeze the grapes for about 30mins to an hour which gives the grape skin more of a “snap” when you bite down 😋 Basically whatever flavor powder you use and grape! Almost like a cotton candy grape I think. 🧐