Videojet Systems (Wood Dale, IL) has released InkSource® ink 16-2340, an invisible ink (below, left) that only appears under fluorescent light (above, right).
The ink will withstand both retort/steam cooking and dry heat exposure without bleeding fading or becoming visible. It will work on metal glass and plastic containers typically used for packaging food and beverages. The ink also works well on aerosol cans. For use with Videojet noncontact ink-jet printers.