Jumbo raisins is a dehydrated form of shahani grapes. Shahani grapes are big and oval in shape and dark purple in color and after drying the color turns to black.
The major difference between mavis and other types of raisin is the special black color and meaty flesh texture of this kind and also the unique sweetness. Both method of sun-dried and shadow-dried is practical for producing jumbo raisins but of course drying in shadow is better due to more saving of minerals and vitamins.