You can tell lunch meat is past its prime by appearance, color, texture and smell. If it has become slimy or ropey, has odd things growing on it (like mold or pink slime), has changed color, turned...
According to Jane Ann Boles and Ronald Pegg (who wrote a guide called "Meat Color"): Iridescence in Processed Meat Products Iridescence is a common problem in sliced roast beef and ham products. The...