sin production standpoint, Thompson grapes are ideal because they ripen fairly early in the season and do not stick to each other during shipping.Two minor varieties of grape that find some use as raisins include the Sonakka and the Rudstalk. The Fiesta is a white seedless grape with a good flavor. A major problem with these grapes is that their stems are more difficult to remove. The Sonakka raisin variety is long in size.