Sodas contain flavorings and colorings that may contain grain based alcohol which is not kosher for Passover. Kosher for Passover sodas must contain kosher for Passover ingredients. Everyday sodas also need kosher certification for everyday use since a number of innocuous sounding ingredients may be non-kosher. Oils are used in some sodas and these need certification. Dried fruits and raisins need to have kosher certification year-round and special certification on Passover.
Producers put oils or waxes on the raisins to prevent clumping.
Glycerol is also added to raisins to keep them moist, these need to have proper kosher for Passover certification. Dried fruit and raisins may also be dried in ovens used for processing chometz.