LEGUMES Legume Family Fabaceae All types of beans

LEGUMES

Legume Family - Fabaceae All types of beans and peas l Soybean, peanut, alfalfa, clover l Also includes various trees such as black locust, redbud l One of the largest dicot families 13, 000 species l Ranks right behind grasses in human impact l

Family characteristics Five-petalled irregular flower with bilateral symmetry l Fruit is a legume (dry dehiscent fruit two lines of dehiscence) with one row of seeds l Seeds contain two large cotyledons l

Legume flower l l Irregular flower with bilateral symmetry Often butterflyshaped

Legume seeds l l Important food staple worldwide Rich in both oil and protein » Higher in protein than any other food plants » Close to animal meat in protein quality » Often called "poor man's meat"

Legumes and nitrogen-fixing bacteria l High protein correlated with root nodules which contain nitrogen-fixing bacteria » convert atmospheric nitrogen to useful form l Because of this legumes enrich the soil » Farmers often rotate legumes with crops that deplete soil nitrogen (soybean & corn) » "Green manure" crops plowed sometimes » Reduces need for fertilizers - legumes can be cultivated worldwide - even in poor soils

Nitrogen cycle l Nitrogen » essential elements for all living organisms » major component of amino acids, proteins, nucleic acids l Nitrogen gas (N 2) about 79% of the air » most living organisms cannot use this form of nitrogen

Nitrogen-fixing bacteria l Certain bacteria and cyanobacteria have ability to reduce nitrogen (N 2) gas to ammonium NH 4+ » cells can convert NH 4+ to compounds » called nitrogen-fixation » organisms are called nitrogen-fixing

Nitrogen-fixing organisms Some bacteria and some cyanobacteria l Some live freely in the soil l Most are found in symbiotic associations in the root nodules of legumes l Azolla is known to have a symbiotic association with a nitrogen-fixing cyanobacterium l

Non-legume plants Must rely on the nitrogen compounds present in the soil l During decomposition microorganisms break down proteins and other nitrogencontaining molecules into ammonium NH 4+ l

Nitrogen compounds in soil Some plants take up ammonium directly l Bacteria in the soil quickly convert ammonium to nitrite (NO 2) and then nitrate - (NO 3) l Nitrate is the form of nitrogen usually absorbed by plants l Fertilizer contain a mixture of both ammonium and nitrate l

Nitrogen Cycle Non-legume plants bacteria NO 3 bacteria NO 2 NH 4 bacteria

Other sources of nitrogen Burning fossil fuels, volcanic activity, and lightning combine nitrogen and oxygen into NO 2 and NO 3 l These are washed into the soil by rain and contribute to the nitrogen cycle l Denitrifying bacteria actually break down ammonium and nitrates returning nitrogen gas to the atmosphere l

Legume food crops l Cultivated for thousands of years in both the Old World and New World » seeds easily harvested » seeds low water content and easily stored for long periods of time l These features plus their high protein content and ease in growing make them ideal crops

Beans and peas -- Pulses Some of the oldest and most common food crops l Good source of protein average about 25% for beans and 21% for peas l Traditionally cultivated for dry seeds l Some varieties today have edible pods l Beans warm season annuals l Peas grown during the cooler seasons l

Common Edible Beans & Peas l l l l Black-eyed peas Butter beans Chick peas Fava (broad) beans Green peas Kidney bean Lentils l l l l Lima beans Mung beans Navy bean Pinto beans Snow peas Split peas Wax bean

Peanuts Also called goobers and groundnuts l Native to South America l Time of domestication is unknown l » gold and silver peanut-shaped jewelry dicovered in Peru in the tomb of a Moche warrior priest » peanut played a prominent role in the ancient Moche civilization » Carbon dating of tomb - 290 A. D.

Sixteenth century Spanish explorers discovered peanuts in South America and took to Europe l Trading introduced peanuts to Africa where it became widely cultivated l The slave trade brought the peanut to North America l Today a staple crop in the south grown in Georgia, North Carolina, Texas, Alabama, Oklahoma and Virginia l

Peanut - Arachis hypogea l l l Unusual plant After pollination the flower stalk grows downward pushing the developing fruit into the soil Fruit matures underground typically with two seeds (peanuts)

Nutrition Highly nutritious with 45 -50% oil and 2530% protein l Over one billion pounds per year consumed in the US l Mainly as a snack food, in candy, and in peanut butter l Half the U. S. crop is used to make peanut butter l

Peanut butter First developed by a St. Louis physician in the 1890's as a nutritious and easily digested food for invalids who had difficulty chewing l Consume enough peanut butter each year to “fill the Grand Canyon” l

Peanut oil Found in margarine, shortening, salad dressing, and cooking oil l Soaps, cosmetics, and shaving cream l Industrial products such as plastics and paints l Pressed cake that remains after the extraction of oil is used as a high protein livestock feed l

Versatility of the peanut l George Washington Carver (1864 -1943) » Developed over 300 food and industrial uses for the peanut » Encouraged its cultivation in the South » Revitalized Southern agriculture exhausted by years of cotton cultivation » Also introduced other soil-enriching legumes like soybean

Soybean - Glycine max l l l Relatively new to the West but used in the Orient for centuries It was considered one of the sacred crops of the ancient Chinese Domesticated in northern China at least 3000 years ago

History in North America Introduced in late 18 th or early 19 th century l Little interest until the 1920's l Today U. S. - world's leading producer l Often called the "Cinderella crop" l Reasons: versatility of the soybean and its suitability for growing in the corn belt region l

Nutritional value of soybeans One of the richest foods with 13 -25% oil and 30 -50% protein l Higher protein content than beef l Although originally used solely as animal feed, the soy protein is used more and more in the human diet l

Food use of soybean Since ancient times in Asia, soybeans have been consumed in hundreds of different ways l Not edible raw l Cooked they can be eaten whole l Often made into a paste, curd, or "milk" l

Soy Products l Soy sauce » Traditionally made by fermenting soybeans in brine but today some synthetic l Soy milk » Beans soaked in water and pureed » Mixture is heated and the liquid poured off as soy milk » Non-dairy substitute for milk and baby formula (for lactose intolerant) individuals

Tofu Made from the curds of soy milk l Extremely versatile and used in main dishes in Japanese and Chinese meals l Made into cheeses, sour cream, and other imitation dairy products l Ice cream-like desert - Tofutti l

Soy flour After the extraction of oil, the meal that remains can be made into flour l Can be mixed with wheat flour in a variety of bread, pasta, baked goods, and breakfast foods l Replacing just a small fraction of the wheat flour with soy flour significantly improves the protein content l

Other soybean foods l l Miso - (from Japan) prepared from soybeans, salt, and rice; fermented by fungi for a several months and then ground into a paste and used as a spread, in soups, etc Tempeh- (from Indonesia) fermented soybean cakes made by inoculating parboiled soybeans with a fungus and allowing it to grow for a few days. The fungal mycelium binds the soybeans together into a cake which can be sliced and cooked in various ways

More Soy Products l Textured vegetable protein » Produced by spinning the soy protein into long slender fibers » Picks up flavors from other substances » Made into imitation meats and used as meat extenders l Lecithin - common food additive » Lipid extracted from soybeans » Stabilizes and extends the shelf life » Added to packaged foods - cake mixes, instant beverages, whipped toppings, and salad dressings

Soybean oil l Food uses » Cooking oil, salad oil, margarine, shortening, and prepared salad dressings » Americans consume almost 6 gallons per year l Industrial uses » Paints, inks, soaps, cosmetics, biodiesel fuel » Soybean-based "plastic" car body built by Henry Ford in 1940 – Ford's commitment to the soybean was so great that at one point he stated his goal was to "grow cars rather than mine them"

Other legumes of interest Forage plants - alfalfa and clover l Super tree - Leucaena leucocephala l » tropical tree that is one of the fastest growing species of woody plants for fire wood, wood pulp, and enriching the soil l Beans of the future: » Winged bean - all parts of plant are edible pod, seeds, leaves, flowers, root » Tepary bean - adapted to arid tropical areas

Summary l l l Legumes are second only to the cereals in their importance in human nutrition and are an excellent source of high quality protein Nitrogen fixation is important for generating nitrogen compounds that can be used by plants Soybean has been transformed into a variety of food products and is increasing its role in the human diet