I can't find the other posts that talk about which racks are safe. We built a homemade smoker out of an old freezer, using the freezer racks as shelving, but now we're not sure if these shelves are safe to use for jerky? when we peel off the jerky, a little shiny stuff from the shelf is left on the jerky and has a metallic taste -- this does not seem good! A couple of the shelves are from an old oven - are these okay? how do you tell if they have been coated with something unsafe? I've also tried something like a "frogmat" but after a few uses, they are becoming brittle and cracking as I'm peeling off the dried jerky pieces.