I ordered an egg and cheese bagel from a restaurant. The egg patty was unusually thick, uniformly bright yellow on the outside, and grey on the inside (although the computer photo shows a greenish tint).

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What could have caused this? Does it tell us anything about the cooking practices of the restaurant? For example, could the patties have been premade in batches from liquid egg yolk, put in the refrigerator, and then microwaved on demand which caused too much heat on the inside, like overcooked hard-boiled eggs? Is something like this safe to eat?

2 Answers 2


Yes, too high temp will/can turn egg yolk blue-is/greenish/grayish.

But doing it in microwave will probably not. Mostly beacuse it's harder to heat anything inside than outside in a microwave.

From experience I can tell that in places made to feed a lot of people in short amount of time any breakfast items are premade and then just keep warm. So the patty would be cooked in temperature allowing inside to be done an then kept in an oven or over the lamp. Making inside of the patty to still boil (as energy exchange is slowed) allowing sulfur o bond with water in patty. The longer the heat is provided the longer this process take place.

A) the patties are safe too eat but they might be rich in sulfur
B) you might bought the food some time (few hours) after it was made and it wasn't made fresh

Overall nothing bad but personally that is something I would expect from a food stall rather than restaurant.

  • Thanks for your answer. To clarify what I meant by restaurant, it came from a brick and mortar establishment with its own kitchen and tables for dining-in, but no waiting service. The item in the photograph cost $5.25 and it's their most popular item. People who visit the shop can see the kitchen, so it's possible they're cutting corners for online orders in the age of COVID by serving old premade food. Oct 22, 2020 at 10:04

It doesn't take long for cooked eggs to develop a greenish hue. And while it isn't dangerous or have any noticeable taste, it does look unappetizing. Most breakfast buffets add a little lemon juice and cream to their scrambled eggs to prevent this from happening. While you can't taste the lemon it does magically prevent them from changing color.

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