The shells are bluish white and in Asia many people prefer them to hen eggs because they are larger, more highly flavoured and the albumen is stronger, making for lighter cakes. However, ducks are not the most particular of creatures when it comes to where they lay their eggs. It is important to be very sure of freshness when using duck eggs, because they can carry dangerous bacteria when stale. The bacteria is destroyed by 10 minutes boiling, or by baking in a cake for not less than an hour.

Duck eggs are much used in making the steamed sponge cakes popular in Asia. They are also used for salted eggs and century eggs. Yolks of salted duck eggs are used in the fillings of moon cakes made for the moon festival, and look like a large golden harvest moon in the centre of the sweet filling of lotus nut paste which is much paler in colour.Salted eggs are sold at Chinese stores and should be kept in the refrigerator, where they will hold for months. Once opened the yolks will keep for one or two days, covered and refrigerated. They are boiled for 10 minutes before eating as a condiment.