The following result is obtained by our Internet Research Algorithm: Proteins inside eggs are coiled into tight balls, heat causes them to uncoil and firm the egg up. This is called denaturation. At 140 degrees F, the egg white turns milky and begins to get jelly-like. When the yolk reaches 170 degrees F, it becomes pale yellow and crumbly. Continue cooking to the egg above this temperature will cause hydrogen sulphide to develop, which produces a rotten egg smell, an overcooked egg will form a harmful greenish ring around the yolk. Iron from the yolk reacts with sulfur from the egg white to produce ferrous sulfide.