This discoloration is more likely to occur when eggs are cooked for too long or exposed to excessive heat. Although the eggs may look less appetizing, they are generally safe to eat if they have been handled and stored properly.
Fortunately, preventing the green ring is relatively simple. Cook eggs gently for approximately 9 to 12 minutes, depending on their size and how firm you want the yolks. Avoid prolonged boiling, as excessive heat encourages the chemical reaction.
Another helpful trick is to cool the eggs immediately after cooking. Transfer them into a bowl of ice water or very cold water. This stops the cooking process, prevents residual heat from affecting the yolks, and makes peeling easier.
It is also important to recognize genuine signs of spoilage. If a cooked egg has an unpleasant smell, slimy texture, or other suspicious changes, it is best to discard it rather than risk eating it.
