The ideal cooking time for egg custard using a steam egg cooker is typically around 10 to 15 minutes. This duration ensures that the custard is set and has a smooth, creamy texture without being overcooked or dry. The precise time can vary slightly depending on the specific model of the steam egg cooker and the desired consistency of the custard.

The reason for this cooking time lies in the delicate balance of heat and moisture required to cook the egg custard. Steam cookers provide a gentle and even heat distribution, which is crucial for cooking eggs without curdling or separating. The eggs are gradually heated as they are steamed, allowing the proteins to coagulate and the liquid to evaporate slowly, resulting in a rich and creamy texture. If the cooking time is too short, the custard may be runny and undercooked. Conversely, if the cooking time is too long, the custard can become dry and rubbery.

According to a study published in the Journal of Food Science, the ideal temperature for steaming egg custard is between 160°F (71°C) and 180°F (82°C). This temperature range ensures that the eggs are cooked through without becoming tough. The study also found that the cooking time within this temperature range can vary from 10 to 15 minutes, depending on the specific conditions of the steam cooker and the size of the egg custard. Therefore, a cooking time of 10 to 15 minutes is generally recommended for the best results.