No, they don't go moldy, just cut them fairly thin - no thicker than 2mm, and have an open window. I cut the apple into four pieces, cut the pips out and slice up each piece.

Make sure they're totally dry before you put them into a contaner. I use old honey glasses. Don't let them touch each other, or they will stick together. I suppose you could do it with sweet potatoes too.

Oh yeah, store bought dry fruits are so expensive!