I recently replied to someone on the Avoiding Corn forum who was trying to determine the cause of her child’s allergic reactions. The list of foods she was feeding her son was impeccable, however the Sun Maid raisins threw a red flag.
In our home every food allergy investigation starts with a look in our trusty Blumenkrantz Passover digest. He mentions (2012 Edition, Page 237) that Methyl Esters of Fatty Acids(1)(2) that contain animal fat or by-products can be used in the drying process of grapes to make raisins. Even though these raisins would most likely not be kosher, there is a chance that the drying agent contained a corn derivative quite capable of causing an allergic reaction.
My wife reminded me that the Sun Maid kosher certification (Triangle-K) doesn’t meet our standards, which suggests that there are concerns about the supervision, ingredients or processes used. This led me to dig even deeper into what might not be kosher when drying fruit. As usual, there was a lot more to it than I knew. Here is a good article from the Star-K that explains the processing of dried fruit, the numerous kashrut concerns and should help to clarify many of the very real dangers of dried fruit for those with food allergies: http://www.star-k.org/kashrus/kk-palate-driedfruit.htm.