Description Top Ten Dry Bean Producers (million metric ton), 2007 Brazil 3.2 India 3.0 Myanmar 1.7 China 1.2 United States 1.1 Mexico 0.9 Tanzania 0.5 Kenya 0.4 Argentina 0.4 Uganda 0.3 World Total 18.3 Source: FAO , FAOSTAT Top Ten Green Bean Producers (million metric ton), 2007 China 2.47 Indonesia 0.87 Turkey 0.52 India 0.42 Spain 0.22 Egypt 0.22 Italy 0.19 Morocco 0.18 United States 0.12 Belgium 0.11 World Total 6.61 Source: FAO , FAOSTAT Black beans and Kidney beans. The common bean is a highly variable species with a long history. Bush varieties form erect bushes 20–60 cm tall, while pole or running varieties form vines 2–3 m long. All varieties bear alternate, green or purple leaves , divided into three oval, smooth-edged leaflets, each 6–15 cm long and 3–11 cm wide. The white, pink, or purple flowers are about 1 cm long, and give way to pods 8–20 cm long, 1–1.5 cm wide, green, yellow, black or purple in color, each containing 4–6 beans. The beans are smooth, plump, kidney-shaped, up to 1.5 cm long, range widely in color, and are often mottled in two or more colors. Toxicity The toxic compound lectin phytohaemagglutinin is present in many varieties, but is especially concentrated in red kidney beans. Although in the case of dry beans the ten minutes at 100 degrees Celsius required to degrade the toxin is much shorter than the hours required to fully cook the beans themselves, outbreaks of poisoning have been associated with the use of slow cookers whose low cooking temperatures may be unable to degrade the toxin. The British public health authority, PHLS , has recommended soaking kidney beans in fresh water for 5 hours prior to cooking. [ 2 ] Sprouts of pulses high in haemaglutins (such as kidney beans) should not be eaten. [ 2 ] [ 3 ] Dry beans Similar to other beans, the common bean is high in starch , protein and dietary fiber and is an excellent source of iron , potassium , selenium , molybdenum , thiamine , vitamin B6 , and folic acid .Dry beans will keep indefinitely if stored in a cool, dry place, but as time passes, their nutritive value and flavor degrade and cooking times lengthen. Dried beans are almost always cooked by boiling , often after having been soaked for several hours. While the soaking is not strictly necessary, it shortens cooking time and results in more evenly textured beans. In addition, discarding one or more batches of soaking water leaches out hard-to-digest complex sugars that can cause flatulence , though those who eat beans regularly rarely have difficulties with flatulence as intestinal microbes adjust. There are several methods including overnight soaking, and the power soak method, which is to boil beans for three minutes, then set them aside for 2–4 hours, then drain and discard the water and proceed with cooking. Common beans take longer to cook than most pulses : cooking times vary from one to four hours but are substantially reduced with pressure cooking .In Mexico, Central America and South America, the traditional spice to use with beans is epazote , which is also said to aid digestion. In East Asia a type of seaweed, Kombu , is added to beans as they cook for the same purpose. Salt, sugar, and acidic foods like tomatoes may harden uncooked beans resulting in seasoned beans at the expense of slightly longer cooking times.Dry beans may also be bought pre-cooked and canned as refried beans , or whole with water , salt , and sometimes sugar . Green beans Cut green beans Main article: Green beans Green beans (snap beans) Nutritional value per 100 g (3.5 oz) Energy 129 kJ (31 kcal) Carbohydrates 7 g Sugars 1.4 g Dietary fiber 3.4 g Fat 0.1 g Protein 1.8 g Vitamin A equiv. 35 μg (4%) Vitamin C 16 mg (27%) Calcium 37 mg (4%) Percentages are relative to US recommendations for adults. Source: USDA Nutrient database There are three commonly known types of green beans: string or runner beans , stringless or French beans (depending on whether the pod has a tough, fibrous "string" running along its length), and snap beans , with a thin flat pod that requires less cooking time. Compared to the dry beans, they provide less starch and protein, and more vitamin A and vitamin C . The green beans are often steamed , boiled, stir-fried , or baked in casseroles . Shelling beans Common beans can be used for shell (or shelling) beans, which have the pods removed before they are cooked or dried. The term can be used to refer to other species of beans, such as lima beans , soybeans , peas , or fava beans , that have their shell removed before it is eaten. Nutritionally, shell beans are similar to dry beans, but in the kitchen are treated as a vegetable, often steamed, fried, or made into soups. Popping beans The nuña is an Andean subspecies, Phaseolus vulgaris subsp. nunas (formerly Phaseolus vulgaris (Nuñas Group) ), with round multicolored seeds that resemble pigeon eggs. When cooked on high heat, the bean explodes, exposing the inner part, in the manner of popcorn and other puffed grains .