Douchi (), also known as tochi, fermented black soybeans, Chinese fermented black beans (), or salted black beans, is a type of fermented and salted black soybean most popular in the cuisine of China, where they are most widely used for making black bean sauce dishes.
Douchi is made by natural fermentation and salting of black soybeans. Douchi can be classified as Aspergillus-type douchi, Mucor-type douchi, bacterial-type douchi, or Rhizopus-type douchi. There are two main stages to the douchi-making process: first the cooked black soybeans undergo natural mold growth and fermentation, then they are salted to continue fermentation. A maturation stage may follow, in which the douchi is aged in brine or with other ingredients to develop flavor. Black soybeans are most commonly used. The process turns the beans soft, and mostly semi-dry (if the beans are allowed to dry). Regular soybeans (white soybeans) are also used, but this does not produce "salted black beans"; instead, these beans become brown. The smell is sharp, pungent, and spicy; the taste is salty, somewhat bitter and sweet. The product made with white soybeans is called mianchi.
Douchi, "Chinese salted black beans", and "black soybeans" are not the same as the black turtle bean, a variety of common bean that is commonly used in the cuisines of Central America, South America, and the Caribbean.
History
Fermented black soybeans are the oldest-known food made from soybeans. In 165 BCE, they were placed, clearly marked, in Han Tomb No. 1 at Mawangdui Tomb Site in South Central China. The tomb was sealed about 165 BCE and was first opened in 1972. black bean garlic sauce (蒜蓉豆豉酱), or tochidjan (豆豉醬), prepared from douchi, garlic, and soy sauce, is popular in Chinese cuisine.
See also
- List of fermented foods
- List of fermented soy products
- Yellow soybean paste