Why does scrambled egg go grey if kept warm in a bowl on hotplate?

When scrambled eggs are kept warm on a hotplate, they may turn grey due to several factors:

1. Overcooking: Prolonged exposure to heat can cause the eggs to overcook, leading to changes in their texture and color. Overcooked eggs can become tough, rubbery, and may develop a grey or brownish discoloration.

2. Maillard Reaction: The Maillard reaction is a chemical reaction between amino acids and reducing sugars that occurs when food is heated. In the case of scrambled eggs, the proteins in the eggs (primarily albumin and globulin) interact with the glucose present in the eggs, leading to the formation of brown pigments. This browning reaction can contribute to the grey color of overcooked scrambled eggs.

3. Oxidation: The oxygen present in the air can react with the fats and proteins in the eggs, causing them to oxidize. Oxidation can also contribute to the development of off-flavors and a grey or brownish color in scrambled eggs.

4. Metal Ions: If the scrambled eggs are in contact with metal utensils or cookware, the metal ions can react with the egg proteins and cause them to denature and discolor. This can also contribute to the grey color of the eggs.

To prevent scrambled eggs from turning grey, it is important to avoid overcooking and reheating them. They should be cooked until they are just set and creamy, and then removed from the heat source. If you need to keep them warm for a short period, it is best to transfer them to a heat-proof container and place them in a warm oven or a low-temperature setting on the stovetop.