Evolution. Fats. Melting. And why Peking duck has crispy skin.
Peking duck is one of the most famous dishes in Chinese cuisine and is considered a “must try” for visitors to Beijing. A very distinctive feature is the crispy skin that melts in our mouths. How do chefs and cooks create such an amazingly crispy skin?
Peking duck takes advantage of one peculiar characteristic of ducks: most of the fats are found beneath the skin and not in the muscles. All we need to do is cook the duck in a way where the fats act as a barrier between the meat and the skin, so that the latter stays crispy.
Ducks have lots of fats under their skin because they used to be migratory waterfowl. Migratory waterfowl evolved to have readily accessible energy for long migratory flights, as flying takes a lot more energy than simply waddling around.
Storing fats is a good way to ensure such a supply because they have double the energy of proteins or carbohydrates. Fat provides 9 calories per gram while carbohydrates and proteins have 4 calories per gram, so fats are a compact source of energy.
When cooking Peking duck, air is blown into the duck. This blows up the skin like a balloon and separates the skin — with its fats — from the meat (I know some of you are going to make some jokes about the blowing… don’t!). Take a look at the video above to see what happens when air is blown into a duck (in this case, a machine is used).
When the duck is cooked, steam and hot air keep the skin separated from the meat, allowing the skin to dry and become crisp. The fats also mostly melt away, leaving behind only a thin layer.
When the cooking stops, the skin stays crispy because the meat and skin continue to be separated by this thin layer of fats, and by the steam and hot air from the continued evaporation. The chef quickly slices the crispy skin off the duck, and serves them together with garnishes such as thin pancakes, spring onion/scallion slices, cucumber sticks, and hoisin sauce.
How much more energy is needed for flying? Ducks use 12x more energy in flight than when they are resting. For comparison, according to a Harvard study, we burn about 6x more calories when we run for 30 minutes at 6 miles per hour (about 10 km per hour) than when we are sitting at a desk for the same length of time.
Now that you know much of the fats in Peking duck skin has been removed by the cooking process, might you feel less guilty consuming it? What do you like best about Peking duck?
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photos: in order –istockphoto/Radist; depositphotos/DiversityStudio; Ivankmit; kittimages; mohamedmaaz86; paulbrighton