Most raisins are dried in open fields, before being processed and many insects are attracted to them. While drying, the fruit shrivels up and becomes sticky, insects stick to the raisins and are concealed inside the folds and even inside the fruit (Illustrations 398-400). In addition, during prolonged storage, storage insects get stuck to them (Illustrations 401, 402). Even raisins sold as “oven-dried” are often infested. Therefore, it is hard to clean or check raisins and get them absolutely clean, so it is preferable to avoid them. For many purposes, craisins (see “Craisins”) can be substituted nicely.
If you nevertheless want to use raisins, use only kosher l’mehadrin raisins that were sample-checked before marketing by the kashrus hashgochah as explained below (see footnote). These raisins should be checked before use as follows:
A. Separate any raisins that are stuck together. Soak the raisins in hot water for fifteen minutes. Swish them around and wait for the water to stop moving. Inspect the water for light-colored worms or brown bugs floating on the surface. If infestation is found, the raisins should not be used (Illustration 403).
To facilitate identifying insects floating in the water, you can pour the upper layer of water onto a white plate and examine carefully.
B. Rinse the raisins under running water while rubbing with your fingers.
Raisins without bugs can be made at home in a household oven: Dry grapes, after cleaning them, at a temperature of 230-250 F (110-120 C) for about three hours (it’s best to keep the oven door slightly open). When the raisins are ready, they should be kept in the refrigerator or freezer. (For instructions for cleaning grapes, see “Grapes”.)
Instructions for kashrus supervisors: For a thorough, professional check of a sample of raisins, soak them in hot water for two hours, rub them inside the water, strain the water through a cloth, and examine the cloth on a lightbox.