It usually takes about eight minutes to boil an egg. In this case, there are two ways to boil eggs. One is to add water directly, then put the eggs into the water, light the water and cook them on the fire. After eight minutes, the eggs will be cooked. The other is to pour cold water into a container, light the water to boil, and then put the eggs in boiling water to cook for about eight to nine minutes. Eggs cooked directly with boiled water have the best nutritional value, and because no seasoning is added, protein, fat and lecithin are not destroyed, which can maximize human immunity. Moreover, the vitamin content is high, which can nourish nerves and whiten skin. Among them, calcium ions and potassium ions are also rich, which can supplement iron and blood and increase the strength of bones. Promote the growth of children's bones and reduce the probability of osteoporosis in the elderly. Preparation of boiled eggs is a prerequisite. The surface must be washed before boiling eggs. Clean up the dirt and accumulated food on the surface of the egg, dry it and put it in a container to cook the boiled egg. Under normal circumstances, if you cook with cold water, you usually cook for three minutes after the water is boiled, but when the eggs are cooked, the nutritional value is relatively high at this time.