Metal detectors are required by the FDA to screen out bits of metal that may get into food during processing. This reminds me of one we had while I was working in QC at a soda factory.....someone sued saying they found a mouse in a can of soda, and they knew the mouse got into the can at our plant because there were little bits of welding flash on the mouse. Only one problem with that claim, aluminum cans aren't welded, they have a rolled seal in them.