To effectively boil eggs in an egg cooker, the recommended cooking time is typically around 6 to 7 minutes for a soft-boiled egg and 10 to 12 minutes for a hard-boiled egg. This duration ensures that the eggs are cooked to perfection without overcooking, which can lead to rubbery textures.

The reason for these specific times lies in the science of heat transfer and the internal temperature required to achieve the desired egg consistency. In an egg cooker, water is heated to a boiling point, and the eggs are submerged in this water. The heat gradually cooks the egg whites and yolks from the outside in. For a soft-boiled egg, the internal temperature needs to reach around 160°F (71°C) to 165°F (74°C), which is typically achieved in 6 to 7 minutes. In contrast, a hard-boiled egg requires an internal temperature of around 212°F (100°C), which takes longer to reach due to the higher temperature needed to fully cook the egg whites and yolks. Research from the United States Department of Agriculture (USDA) suggests that cooking eggs to an internal temperature of 160°F (71°C) is sufficient to kill harmful bacteria like Salmonella. However, for a hard-boiled egg, the longer cooking time ensures that the egg is fully cooked and safe to consume.