For preparing Sultana raisins, the grapes are picked and soaked in a solution and then spread on the ground for a few days to dry in the sun to prepare the desired raisins. The role of this solution in the production process is to accelerate the drying of grapes. Unlike other raisins, such as sun-dried raisins, Sultana raisins are usually coated in a solution containing oil or the same liquid before drying to speed up the process. For this reason, they are often lighter in color than other raisins. In preparing Iranian Sultana raisins, an acceptable alkaline solution is used, and the world standards must be observed in its production.