Black, or turtle, beans are small roughly ovoid legumes with glossy black shells. The scientific name for black beans is Phaselous vulgaris, an epithet shared with many other popular bean varieties such as pinto beans, white beans, and kidney beans. These legumes are associated with Latin American cuisine in particular, although they can complement foods from many places. They are available in most grocery stores in dried and canned forms.
The history of black beans is ancient. They were first domesticated over 7,000 years ago in the region of South America now known as Peru. Since the beans grew readily in warm weather and preserved well, they quickly became an integral part of the South American diet. Other varieties of beans also entered cultivation during this period, with different people selecting for different bean traits. The ubiquitous food entered Europe when early explorers brought beans back with them in the 1500s.
Like other legumes, beans pack a serious nutritional punch. They are very high in fiber, folate, protein, antioxidants, and vitamin B, along with numerous other vitamins and minerals. When combined with whole grains such as brown rice, black beans make a complete protein, which is one of the reasons they are commonly included in a vegetarian diet. Since the beans are cheap to produce, they are an important part of a balanced diet for people of low income around the world.
The flavor of black beans is hearty and rich, and sometimes compared to mushrooms. The beans have to be cooked for an extended period of time before they are digestible, and they soften during the cooking stage. The black shells of the beans are retained through cooking, since they carry a lot of the flavor and nutritional value of the beans.
A warm climate with no risk of frost is required to grow black beans. The beans grow on vines, so it also helps to have trellises for the beans to climb as they grow. Typically, the beans are allowed to dry on the vine, and the vines are plowed back into the field for mulch at the end of the season. Beans are nitrogen fixers, so they enrich the soil that they are grown in. When stored in a cool dry place, dried black beans will keep for up to one year, or the beans can be cooked and canned for storage.
The black beans of Latin American should not be confused with douchi, or fermented black beans, a popular Asian food. Douchi is made with soybeans, a related but entirely different legume. The soybeans are heavily salted and allowed to ferment, creating an aromatic and intense concentrate. Many Asian markets carry douchi for inclusion in sauces and stir fries. The product is intended to be used in moderation, since it is formidably salty.