That quote is from an interesting article on the history of St. Patrick's Day food. Thought some might find it interesting.

http://www.slashfood.com/2010/03/10/history-of-st-patricks-day-food/

And here is a 50 page report on the history of food coloring (I haven't read it yet.)
http://leda.law.harvard.edu/leda/data/758/Burrows06_redacted.pdf

Probably most people don't find these kinds of things interesting; guess I'm just weird! Enjoy!