Rice has been the main staple in the Japanese diet and a cornerstone of Japanese culture since its introduction from China in Yayoi period (5th century BC.) For centuries, meat eating was all but prohibited due to Buddhist strictures, yet during this same time the population of Japan grew more quickly than Europe. The key to the success of this Spartan diet is the soybean. Rice, while a nutritional powerhouse among grains, is missing the essential amino acid lysine, abundant in soy.
Soybeans were first cultivated in Japan in the first century AD, and although they are the basis of some of Japan’s essential traditional foods—soy sauce, miso, tofu, natto—they have never really been a major crop in Japan. In feudal times, farmers grew them on the narrow, raised ridges separating rice paddies for their own consumption as a critical nutritional supplement. While the rice paddies belonged to the feudal lords, the narrow ridges between them “belonged” to the farmers. In Japanese, these ridges are called aze; an alternate name for soybeans is “aze mame” or “ridge beans.” This practice continues even today in rural areas, and the observant visitor can find patches of soybeans and edamame scattered among the ripening rice.
The word “edamame” first appears in Japanese records during the Heian period (between 794 and 1185 AD), where according to some accounts it was used as a special food for festivals and celebrations. During the Edo period, edamame fully became a food for common people, and edamame vendors would carry loads of them on their backs, selling them to customers in the street. Customers purchased the fresh boiled edamame and walked around eating them as a portable snack—a kind of samurai fast food.
The word edamame means literally “branch bean.” This refers to the fact that one of the earliest ways to eat edamame was to boil them on the branch as is. Even today, edamame is unique among beans in that it is often sold still on the branches in Japanese supermarkets. It is believed that this is the freshest way to sell edamame—and in the future, we would like to try this, too, at the farmers’ markets.