Why You See Rainbow Spots On Roast Beef And Deli Meat - Chowhound

Again, while iridescence can occur with all sorts of meats, it does seem to be oddly prevalent on those smooth-cut deli meats, like sliced roast beef. There are a few reasons for this: Number one is the ultra-smooth surface of deli meat, usually produced by a mechanical slicer. Because iridescence is caused by light hitting the meat fibers, and because deli meat is cut against the grain, exposing a lot more of…