Readers of this blog will remember that I am a big fan of ketchup, so when Burger King had free French fries and green(!) ketchup on that weekend, I had to go try it.
Of course I needed to order onion rings to have a complete test. The ketchup was a dark green and looked more opaque than a red ketchup. There was definitely a pigment to get the color required.
As expected all of that pigment could color more than just ketchup. My tongue was also colored green.
Perhaps the ethics committee should have intervened before this self-experimentation, but the subject survived with a final conclusion that green ketchup tastes like regular ketchup.