Biol 1300 Unit 5: Legumes or Pulses - Past Paper

**Biol 1300 Unit 5** **LEGUMES OR PULSES** Legumes, or pulses, belong to the **Fabaceae (Legume or Pea)** family, which consists of eudicots and includes both herbaceous plants (e.g., peas, beans, lupines) and woody trees (e.g., acacia, tamarind, and many tropical rainforest trees) found worldwide...

**Biol 1300 Unit 5** **LEGUMES OR PULSES** Legumes, or pulses, belong to the **Fabaceae (Legume or Pea)** family, which consists of eudicots and includes both herbaceous plants (e.g., peas, beans, lupines) and woody trees (e.g., acacia, tamarind, and many tropical rainforest trees) found worldwide. The fruit, known as a **legume**, is a single-chambered pod with seeds attached along one edge (e.g., pea pod). Both the male and female are found on the same flower, resulting in an asymmetrical shape. Dried legume seeds are high in protein, up to 25-30%, comparable to red meat, and can be eaten fresh or dried. They are a crucial protein source, especially where meat is scarce or expensive, and are essential for vegetarians and those opposed to eating meat, as they contain all essential amino acids. Legumes are also vital high-protein forage for domestic animals, with species like clover, sweet-clover, and alfalfa being important forage plants. Legumes produce root nodules containing nitrogen-fixing bacteria (genus *Rhizobium*), which convert atmospheric nitrogen (N~2~) into nitrate (NO~3~) usable by plants (curiously, very few other plant families have evolved root nodules). This mutualistic relationship benefits both the legumes and the bacteria, as the plants provide sugars to the bacteria through starch from photosynthesis and receive essential nitrogen in return (an essential nutrient for plant growth). Nitrogen is incorporated into the plant tissues, especially seeds, as protein. (nitrogen is an important component of all proteins). Additionally, some nitrate leaks into the soil from decomposing legume parts, making legumes valuable for naturally improving nutrient-impoverished (nitrogen-limited) soils. **SOME ECONOMICALLY IMPORTANT LEGUMES** **COMMON or KIDNEY BEAN** (Phaseolus vulgaris): The common bean is native to Central and South America. Several cultivars have been developed; whole pods may be eaten fresh (green or string beans), or the seeds harvested and dried (kidney beans). Dried kidney beans contain about 20% protein. The closely related scarlet runner bean (P. coccineus), native to Central America, is less commonly grown. **PEA** (Pisum sativum): The pea is an ancient legume crop, having been cultivated for at least 7,000 years. It is thought to be native to the Mediterranean, Middle East (Southwest Asia), and northeastern Africa. Many pea cultivars have been developed by plant breeders. The seeds may be dried (about 25% protein) or eaten fresh, and in some varieties (\"sugar peas\") the immature pods are eaten fresh. Peas were an important source of protein in Medieval Europe, and a mainstay of the European diet prior to introduction in the 1500s of new crop plants from the Americas and Asia. **SOYBEAN** (Glycine max): The soybean, likely derived from wild soya (*Glycine soya*), is native to China, Japan and Korea (East Asia) and was first cultivated over 3,000 years ago in northeast China. The seeds are very high in protein (35-40% dry weight) and contain all essential amino acids. Economically, soybeans are the world's most important legume crop, with over 100 million tons produced annually, mainly in the United States, China, and Brazil. Soybeans require warm temperatures and a long growing season. They are used for various purposes, including fresh and dried beans, bean sprouts, edible oil products (e.g., cooking oils, margarine, mayonnaise), industrial oils (e.g., soaps, paints, plastics), Asian cooking products (e.g., miso, tofu, soy sauce, soy flour), processed protein products (e.g., vegetarian dairy and meat analogues), food additives, and livestock and pet food. **PEANUT or GROUNDNUT** (Arachis hypogaea): The peanut, native to Central and South America, was first domesticated over 3,500 years ago. Though often classified as a "nut," it is a legume with 1-3 seeds per pod. There are two main types: the prostrate Virginia type and the upright Spanish type. Over 30 million tons are harvested annually, with India, China, Nigeria, and the United States being the largest producers. A unique feature is that the flower stalk elongates after pollination, pushing the maturing fruit into the soil, so peanuts are best grown in loose, sandy soils. Most peanuts are processed into edible and industrial oils or used for animal feed. They are typically roasted if eaten as a snack and are also processed into various pastes and sauces, such as peanut butter and satay. They are also added directly into stews and stir-fries. **TROPICAL PULSES (VARIOUS SPECIES)**: Tropical pulses are an important seed protein source in much of India, Africa, Asia and South America. Examples include: -**the lima bean** (Phaseolus lunatus), big green beans native to Central and South America -**broad bean** (Vicia faba), like lima beans, originated in the old world and has been grown for centuries. -**chickpea** (Cicer arietinum), one of the oldest cultivated legumes, used for hummus, and key in Mediterranean and Middle Eastern cuisine -**black gram or urd** (Vigna mungo), black beans with a white line -**mung bean or green gram** (V. radiata), like black gram but green instead with a white line -**black-eyed bean** (V. unguiculata), white with black stripes -**asparagus or yard-long bean** (V. unguiculata var. sesquipedalis), viny, can climb up to 12 ft -**pigeon pea** (Cajanus cajan), hardy and can grow in any soil, tolerant to poor conditions -**lentil** (Lens culinaris). Lentils, an ancient crop from the Southwest Asia, are widely grown on the Indian subcontinent to produce dahl, a lentil puree. Numerous cultivars of this drought-tolerant species have been developed. **CAROB** (Ceratonia siliqua): Carob is a subtropical tree native to the Arabian Peninsula (Southwest Asia). Its large pods, known as St. John's Bread, contain seeds rich in protein and sugar. Carob pods are often sold fresh for the edible \"sweetmeat\" around the seeds (another tropical leguminous tree, the tamarind (Tamarindus indica), is used in the same way). These pods can also be processed into a paste used as chocolate substitute. The gum from the seeds is used as a stabilizer and thickener in various food products like ice cream, salad dressing, processed meat and other food products. Thus, both the pod and seeds are edible. Other leguminous plants, such as gum Arabic (Acacia senegal) and guar gum bean (Cyanopsis tetragonoloba), also produce similar stabilizing agents. **TAMARIND** (Tamarindus indica): is a large tree native to India. Like carob, it has large pods. The sweet meat around the seeds is used. It is particularly important in tropical cuisines in India, Philippines, Middle East and so on. **FENUGREEK** (Trigonella foenum-graecum): Fenugreek is native to the Mediterranean and Southwest Asia. The seed has been used medicinally and as a food source since ancient times, and fenugreek remains an important crop in India, the Middle East, and Africa. Fenugreek seed is also an important spice in curry dishes. In India the fresh leaves are used as vegetable, and the dried leaves as an aromatic spice. **LIQUORICE** (Glycyrrhiza glabra): Liquorice, which is native to the Mediterranean region and central Asia, was known to the ancient Greeks and Romans. It has been cultivated for centuries as a flavouring and sweetener. Liquorice flavouring, extracted from the rhizome (underground stem) using boiling water, is used in candies, dark beers (stout), and some liqueurs. Most of the \"licorice\" candy produced today is synthetically flavoured, but in recent years natural liquorice has made a comeback. True liquorice candy is made by mixing the concentrated juice with gum arabic, sugar and other flavouring agents. **FORAGE CROPS** (VARIOUS SPECIES): Several legume species are used as forage and fodder plants; they are an important natural source of high-quality protein for domesticated animals. Legumes are also widely utilized as fallow crops, grown in rotation with non-leguminous crops such as cereals to naturally increase soil nitrogen content. Species used as fallow, forage and fodder crops in temperate regions include red clover (Trifolium repens), sweet-clover (Melilotus officinalis) and alfalfa or lucerne (Medicago sativa).