Many corn allergy sufferers have reported trouble with eggs. Not just eggs in general, but certain eggs. Eggs from one farm are fine, eggs from another cause a corn reaction. It sounds insane. Many sufferers are hesitant to bring it up, because obviously it must be in our heads.
Eggs are a shelled food. As long as no shell cracks into the bowl (or pan) they should be safe. You can't really tamper with the ingredients, right?
Xanthophylls is a naturally occuring compound which imparts the sunny yellow color in egg yolk. Apparently, the quantity of xanthophylls changes with feed sources and the variation in availability can seriously impact the color of the poultry product. Never to fear, scientists everywhere have been busily working on a solution for years. And the solution is to isolate xanthophylls and add the isolated compound back to poultry feed.
Unfortunately, until relatively recently, this was an expensive and painstaking process. Luckily, while exploring the wonders of the magical maize plant, someone somewhere noticed that xanthophylls are isolated when they attempt to purify corn zein; xanthophylls is a wasted by product. Lightbulbs went on; dollar signs abounded...and the next thing you know, there is a patent on this process. Xanthophylls is now an affordable product. Its readily available for any farmer who wants to improve the aesthetic value of his products.
And...it isn't going to end up on any ingredient lists because, of course, it isn't an ingredient of your farm fresh eggs. It is simply a tool used to get them to look nicer, without tampering with the end product.
Xanthophyll is also known as Lutein. It is a naturally occuring substance in many plants, especially marigold petals, and a vital part of human plasma. However, as a supplement it can be derived from corn. It can be used in cosmetics, pharmaceuticals and animal feed.