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An illustration of a slab of ham.

The iridescent color on ham is not a sign of deteriorating quality or an indication of a safety problem with the meat.

Green eggs and ham are normal

From eNews, March 2005

Don't be alarmed by a bit of green color on the hard-boiled eggs or baked ham that you may be serving at Easter. The green ring around that egg yolk is harmless and safe to eat, says Suzanne Driessen, a University of Minnesota Extension Service educator specializing in food safety. So is the glistening, sometimes greenish, rainbow iridescent effect on cut ham, she adds.

The green ring around the yolk of a hard-boiled egg is caused by hydrogen in the egg white combining with sulfur in the yolk. This tends to happen when you boil the eggs too long, or it can also be caused by high iron levels in the cooking water, says Driessen.

Although the green ring is harmless, there's a good chance you can avoid it by "hard cooking," instead of hard boiling, the eggs. Driessen suggests these steps:

The greenish or yellowish cast on ham and other cured meats is caused by curing compounds undergoing pigment changes when exposed to light and air. (These are the same compounds that cause meat color to remain rosy red, even when fully cooked.) To prevent it, Driessen suggests wrapping the meat in airtight packages and storing it away from light. She also advises against leaving that Easter ham out for people to "graze" on.

"It can be convenient to leave leftovers out instead of putting them away, but it could make someone sick," Driessen says. The Staphylococcus aureus bacteria causes foodborne illness, and it's been found in high-protein foods, even salty ones like ham.

Symptoms of this foodborne illness show up within one to six hours after eating the contaminated food. To avoid getting sick, it's important to wash hands well and refrigerate leftovers within two hours of preparing them. "These bacteria are found on our hands, in our noses, and in infected cuts and can be transferred to food very easily," she says.

For more information on food safety, including cooking Easter hams safely, call the University of Minnesota AnswerLine at 800-544-1678 to speak with an Extension household expert.

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