I got a question on facebook a week or so ago: how do you avoid that green edge on a hard boiled egg yolk?

That green ring is the result of a chemical interaction between the sulfur in the egg white and the iron in the egg yolk.  The reaction occurs when the egg is overheated.  It doesn’t look pretty but is harmless.  Some common suggestions to get nice yellow (or orange if your hens get green in their feed) yolks follow:

  • Put the eggs in ice water, or under running cold water, immediately when done.
  • Don’t overcook the eggs.  Most common method suggested is to put cold eggs in cold salted water.  Cover. Bring the water to a boil and then turn off the heat. Let sit for about 15 minutes.  Immediately run under cold water.  This method prevents overcooking and keeps the eggs from “popping” if there are hairline cracks.
  • Salting the water helps with peeling farm-fresh eggs.
  • I usually bring the salted water to a boil, shut the heat off, then add the eggs.  Let set for 10-12 minutes.  Rinse in cold water.  This seems quicker, but the eggs do sometimes pop.
  • Cook the eggs in a single layer in the pan.

If you are cooking eggs from a local farmer you trust, and especially if the hens are on pasture, don’t be afraid to undercook the eggs just a bit.  Heat kills the enzymes in food.  Cooking things till “thoroughly done” isn’t always advantageous–you are just killing it twice.  Eggs are one of those things.  The white should be thoroughly cooked  if you have allergies because the proteins in it are harder to digest.  The yolk is the part with all the good stuff–the fatty acids and enzymes as well as protein.   It’s a package deal, to my mind.  Nature gave us both parts to eat and so we should, as a rule.  But if you leave the yolk soft, even runny, you preserve the proteins and enzymes for your body to make the most of.  Plus, you won’t get that green ring around the yolk.