How Do Kuro-tamago Get Their Black Color?

  • FOOD
  • Japan has over 100 active volcanoes around the country. It is the reason for the existence of several volcanic valleys. These valleys have become active tourist sites such as the one located in Hakone called Owakudani. Owakudani is known for its beautiful scenic view, volcanic activity, and most especially, kuro-tamago. These are black eggs considered to be a specialty in the area.

    The Black Eggs


    Owakudani is often known as “The Great Boiling Valley” due to some active sulfur vents and hot springs in the area. Because of this, it greatly affects the color of the kuro-tamago. It is said that these black eggs have been sold for over 60 years. However, these are just ordinary chicken eggs which turned black due to the sulfur activities in the valley. In order to get one, you have to purchase them in certain areas such as Tamago-jaya. This is where the eggs are being boiled in the hot spring next to it. It is open daily from 9 am to 4 pm.


    How do the Eggs turn Black?


    Owakudani’s hot springs contain rich amounts of sulfur and iron. Once the eggs are boiled in it, these two elements react with calcium which is a natural element found in egg shells. It results in a chemical compound known as iron sulfide which adheres to the egg shell’s bubbles and, in turn, gives its black color. The eggs are soaked in boiling water for an hour with a temperature of 80 degrees Celsius. Since this process doesn’t harden the eggs yet, another 15 minutes of steaming is done in a caldron. You can buy them in sets of 6 for 500 yen which comes with a free pack of salt.

    The catch in eating the black eggs come from a belief that it gives good luck to people. Each egg is believed to add seven years in a person’s life. However, eating more than 2 1/2 eggs can give you bad luck. Whether you believe in it or not, eating kuro-tamago will definitely give you the added energy needed for your travels.

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