Kuromame beans are one of the important osechi ryori items. Just like many other beans’ cooking method in Japan, they are stewed with sugar. However, unlike adzuki beans, kuromame beans are handled more carefully. Properly cooked kuromame beans are big, plump, shiny, black, soft, unbroken without wrinkles.
Americans may not be familiar with kuromame beans, but they are actually special soy beans with black skin. They can be found at Asian grocery stores, as Chinese, Koreans, as well as Japanese eat them. Kuromame beans were believed to deflect evil in Japan.
I heard that some Japanese in the U.S. use black turtle beans instead of kuromame beans. If I can use black turtle beans, which are sold almost any grocery stores in the United States, it’s convenient and more economical.
So I conducted an experiment to cook those two kinds of beans using exactly the same recipe, and the same equipment. I bought a 1lb bag of kuromame beans at a Chinese grocery stores. As I was concerned with a lot of agricultural problems in China, I bought the one with a USDA organic mark on it. A 1lb bag of black turtle beans are from my neighborhood grocery store.
I soaked both of them overnight, and cooked in the way as I would cook kuromame beans in Japan. I used the same amount of water, the same amount of sugar using the same pot. I checked the tenderness of the beans time to time, and stopped cooking when I determined the beans are soft enough.
See the picture on the right. Black turtle beans are on the right hand side, and kuromame beans are on the left hand side. Even though I can observe slight differences, they look almost the same. I tasted both, and I also asked my husband to try them both.
The biggest difference is the texture of the beans. Kuromame beans are soy, so that they have firm and crisp texture of soy beans. If you’ve ever eaten edamame, boiled young green soy beans in a pod, you know the texture of soy. Cooked kuromame beans are softer than boiled edamame. On the other hand, black turtle beans are meaty like kidney beans.
Black turtle beans became soft enough in 2.5 hours after start cooking, while kuromame beans took about 4 hours to reach the similar degree of tenderness. But, I have to note that the cooking time of beans also depends on how old the beans are. This year’s beans take less time to cook than the last year’s beans. The kuromame beans I bought at a Chinese store might have been the last year’s. There is no way of knowing it.
Both beans released white foamy impurities when the beans are initially boiled up, but kuromame beans had more impurities than black turtle beans. I removed them carefully as they look ugly and taste unpleasant, if left in the cooking water.
Black turtle beans are easier to cook. There are several precautions to take when cooking kuromame beans, but they don’t seem to apply to black turtle beans. If you prefer quicker easier cooking beans with meaty texture, black turtle beans are good choice. My husband preferred black turtle beans over kuromame beans, as they can be eaten like adzuki beans for dessert.
I definitely like kuromame beans over black turtle beans. If flavor of black turtle beans is one dimensional, kuromame beans have multi dimensional flavor. I can swear that I even taste slight honey or molasses, even though they are not added. Kuromame beans deserve to be tasted one by one picked by chopsticks to enjoy the distinctive flavor and texture.
You can choose whichever you like. Black turtle beans are much easier to get after all. But through the experiment, I understand why Japanese reserved kuromame beans to be eaten on the new years day, the most important holiday for Japanese.