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The lentil (Lens culinaris), also known as Lens esculenta, is an edible pulse. It is a bushy annual plant of the legume family, known for its lens-shaped seeds. It is about 40 cm (16 in) tall, and the seeds grow in pods, usually with two seeds in each.

Lentil
3 types of lentil.jpg
Lentils
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Tribe: Vicieae
Genus: Lens
Species: L. culinaris
Binomial name
Lens culinaris
Medikus

In South Asian cuisine, split lentils (often with their hulls removed) are known as lentils. Usually eaten with rice or rotis, the lentil is a dietary staple throughout regions of India, Sri Lanka, Pakistan, Bangladesh and Nepal. As a food crop, the majority of world production comes from Canada, India and Australia.

Contents

BackgroundEdit

HistoryEdit

The history of lentil started by the origin of Agriculture. Lenti is the oldest pulse crop and probably one of the earliest crops domesticated in the Old World. It was found alongside human habitation up to 13’000 years BC and it was mainly grown in India, Bangladesh, Pakistan, Egypt, Greece, Italy, countries in the Mediterranean region and North America.

The origin of lentil is due to the near East and Central Asia.[1]

NameEdit

There are many different names in different parts of the world for the crop lentil. Here are just a few examples: lentil (English), adas (Arabic), mercimek (Turkey), messer (Ethiopia), masser or massur (India) and heramame (Japanese) are the most common names.[1]

The first usage of the word lens to designate a specific genus was in the 16th century by the botanist Tournefort.[2]

SystematicsEdit

The genus Lens is part of the subfamily Faboideae which is contained in the flowering plant family Fabaceae or commonly known as legume or bean family. This family is part of the order Fabales in the kingdom of Plantae.[2]

 
Lentil plants in the field before flowering

Lens is a small genus which consists of the cultivated L. culinaris and six related wild taxa. Among the different taxa of wild lentils L. orientalis is considered to be the progenitor of the cultivated lentil and is now generally classified as L. culinaris subsp. orientalis. Therefore the genus Lens comprises seven taxa in six species:[1]

  • Lens culinaris (and L. culinaris subsp. orientalis)
  • Lens odemensis
  • Lens ervoides
  • Lens nigricans
  • Lens lamottei
  • Lens tomentosus

Botanical descriptionEdit

 
Illustration of the lentil plant, 1885

Lentil is hypogeal, which means the cotyledons of the germinating seed stays in the ground and inside the seed coat. Therefore, it is less vulnerable to frost, wind erosion or insect attack.[3]

The plant is a diploid annual bushy herb of erect, semi-erect or spreading and compact growth and normally varies from 30 to 50 cm (10 to 20 in) in height. It has many hairy branches and its stem is slender and angular. The rachis bears 10 to 15 leaflets in 5 to 8 pairs. The leaves are alternate, of oblong-linear and obtuse shape and from yellowish green to dark bluish green in colour. In general, the upper leaves are converted into tendrils, whereas the lower leaves are mucronate. If there are stipules, they are small. The flowers, one to four in number, are small, white, pink, purple, pale purple or pale blue in colour. They arise from the axils of the leaves, on a slender footstalk almost as long as the leaves. The pods are oblong, slightly inflated and about 1.5 cm long. Normally, each of them contains two seeds, about 0.5 cm in diameter, in the characteristic lens shape. The seeds can also be mottled and speckled. The several cultivated varieties of lentil differ in size, hairiness and colour of the leaves, flowers and seeds.

Lentil is self-pollinating. The flowering begins from the lowermost buds and gradually moves upward, so-called acropetal flowering. It takes about two weeks until all the flowers are open on the single branch. At the end of the second day and on the third day after the opening of the flowers, they close completely and the colour begins to fade. After three to four days the setting of the pods takes place.[1]

TypesEdit

 
Red and brown comparison
  • Brewer's: a large brown lentil which is often considered the "regular" lentil in the United States[4]
  • Beluga, black, bead-like shape, lens shaped, dicotilidon, almost spherical, named for resemblance to Beluga caviar[5]
  • Brown/Spanish pardina
  • French green
  • Puy lentils, Lens esculenta puyensis, (small dark speckled blue-green), Protected Designation of Origin name
  • Dark/Light Green
  • Indianhead
  • Yellow/tan lentils (red inside)
  • Red Chief (decorticated yellow lentils)
  • Eston Green (Small green)
  • Richlea (medium green)
  • Laird (large green)
  • Masoor (brown-skinned lentils which are orange inside)
  • Petite crimson/red (decorticated masoor lentils)
  • Macachiados (big Mexican yellow lentils)

ProductionEdit

 
Worldwide lentil production

Lentils are relatively tolerant to drought, and are grown throughout the world. FAOSTAT reported that the world production of lentils for calendar year 2013 was 4,975,621 metric tons, primarily coming from Canada, India and Australia.[6]

About a quarter of the worldwide production of lentils is from India, most of which is consumed in the domestic market. Canada is the largest export producer of lentils in the world, and Saskatchewan is the most important producing region in Canada (growing 99% of Canadian lentils).[7] Statistics Canada estimates that Canadian lentil production for the 2009/10 year was a record 1.5 million metric tons.[8] The most commonly grown type is the Laird lentil.[7]

The Palouse region of eastern Washington and the Idaho panhandle, with its commercial center at Pullman, Washington, constitute the most important lentil-producing region in the United States.[9] Montana and North Dakota are also significant lentil growers.[10] The National Agricultural Statistics Service reported United States 2007 production at 154.5 thousand metric tons.

Top Lentil Producing Countries, 2014
Country Metric Tons
  Canada 1,987,000
  India 1,100,000
  Australia 348,080
  Turkey 345,000
    Nepal 226,830
World 4,885,271
Source: UN Food & Agriculture Organization, Statistics Division[11]

CultivationEdit

Soil requirementsEdit

Lentil can grow on various soil types, from sand to clay loam. It grows best in deep sandy loam soils with moderate fertility. A soil pH around 7 would be the best. Lentil does not tolerate flooding or water- logged conditions.[2]

Lentils improve the physical properties of soils and increases the yield of succeeding cereal crops. Biological nitrogen fixation or other rotational effects could be the reason for higher yields after lentils.[12]

Climate requirementsEdit

The conditions under which lentils are grown differ across different growing regions. In the temperate climates lentils are planted in the winter and spring under low temperatures and vegetative growth occurs in later spring and the summer. Rainfall during this time is not limited. In the sub-tropics lentils are planted under relatively high temperatures at the end of the rainy season and vegetative growth occurs on the residual soil moisture in the winter season. Rainfall during this time is limited. In West Asia and North Africa some lentils are planted as a winter crop before snowfall. Plant growth occurs during the time of snow melting. Under such cultivation seed yields are often much higher.[12]

Seedbed requirements and sowingEdit

The lentil requires a firm, smooth seedbed and most of the previous crop residues incorporated. For the seed placement and for lather harvesting it’s important that the surface is not uneven or has large clods, stones or protruding crop residue. It’s important that the soil is made friable and weed free so that seeding could be done at a uniform depth.[2]

The plant densities for lentil are variable between genotypes, seed size, planting time and growing conditions and also from region to region. In south Asia a seed rate of 30–40 kg/ ha is recommended. In west Asia countries a higher seed rate is recommended and also leads to a higher yield. The seeds should be sown 3-4 cm deep. In agriculturally mechanized countries, lentil is planted using grain drills, but elsewhere it is still hand broadcast.[2]

Cultivation management, fertilizationEdit

A big problem in lentil cultivation are weeds. The short high of lentil and it’s slow growth makes the lentil poorly competitive with weeds. Weed competition can lead to very high yield reduction as compared to weed free plots. In addition to yield reduction, weeds often produce similar seeds like lentil, what leads to problems in separation. In inter cropping systems (what is a very common system for lentils) herbicides need to be carefully selected, so that they are safe for both crops.[12]

Lentil is a legume, so it can fix atmospheric nitrogen in the soil in association with specific rhizobia. So the Lentil can fix two-third of its nitrogen needs from the atmosphere.[12] Lentils grow under very low input conditions. Some nutrients are sometimes given through fertilizers, containing P, N, K and S[2].

DiseasesEdit

Below is a list of the most common lentil diseases.

Fungal diseasesEdit

Fungal diseases
Alternaria blight

Alternaria alternata
Alternaria sp.

Anthracnose

Colletotrichum lindemuthianum
Colletotrichum truncatum

Aphanomyces root rot

Aphanomyces euteiches

Ascochyta blight

Ascochyta fabae f.sp. lentis
= Ascochyta lentis
Didymella sp. [teleomorph]

Black root rot

Fusarium solani

Black streak root rot

Thielaviopsis basicola

Botrytis gray mold

Botrytis cinerea

Cercospora leaf spot

Cercospora cruenta
Cercospora lentis
Cercospora zonata

Collar rot

Sclerotium rolfsii
Athelia rolfsii [teleomorph]
= Corticium rolfsii

Cylindrosporium leaf spot and stem canker

Cylindrosporium sp.

Downy mildew

Peronospora lentis
Peronospora viciae

Dry root rot

Macrophomina phaseolina
= Rhizoctonia bataticola

Fusarium wilt

Fusarium oxysporum f.sp. lentis

Helminthosporium leaf spot

Helminthosporium sp.

Leaf rot

Choanephora sp.

Leaf yellowing

Cladosporium herbarum

Ozonium wilt

Ozonium texanum var. parasiticum

Phoma leaf spot

Phoma medicaginis

Powdery mildew

Erysiphe pisi
= Erysiphe polygoni
Leveillula taurica
= Leveillula leguminosarum f. lentis
Oidiopsis taurica [anamorph]

Pythium root and seedling rot

Pythium aphanidermatum
Pythium ultimum

Rust

Uromyces craccae
Uromyces viciae-fabae
= Uromyces fabae

Sclerotinia stem rot

Sclerotinia sclerotiorum

Stemphylium blight

Stemphylium botryosum
Pleospora tarda [teleomorph]
Stemphylium sarciniforme

Wet root rot

Rhizoctonia solani
Thanatephorus cucumeris [teleomorph]

Nematodes, parasiticEdit

Nematodes, parasitic
Cyst nematode Heterodera ciceri
Reniform nematode Rotylenchulus reniformis
Root knot nematode

Meloidogyne incognita
Meloidogyne javanica

Root lesion nematode Pratylenchus spp.
Stem nematode Ditylenchus dipsaci

Viral diseasesEdit

Viral diseases
Bean (pea) leaf roll virus Beet western yellows virus
Bean yellow mosaic Bean yellow mosaic virus
Broad bean mottle Broad bean mottle virus
Broad bean stain Broad bean stain virus
Cucumber mosaic Cucumber mosaic virus
Pea seedborne mosaic Pea seed-borne mosaic virus

ProductEdit

ProcessingEdit

A combination of gravity, screens and air flow is used to clean and sort lentils based on shape and density. After destoning, they may be sorted by a color sorter and then packaged.

A major part of the world’s red lentil production undergoes a secondary processing step. These lentils are dehulled, split and polished. In south Asia, this process is called dhal milling[2]. The moisture content of the lentils prior dehulling is crucial to guarantee a good dehulling efficiency[2]. The hull of lentils usually accounts for 6 to 7% of the total seed weight, which is lower than most legumes[13]. Lentil flour can be produced by milling the seeds, like cereals.

Culinary useEdit

 
Split red lentils (size 6 mm)

Lentils are consumed in many ways. They can be eaten soaked, germinated, cooked, fried and baked. The most common preparation method is cooking[2]. The seeds require a cooking time of 10 to 40 minutes, depending on the variety; shorter for small varieties with the husk removed, such as the common red lentil. Most varieties have a distinctive, earthy flavor. Lentils with husk remain whole with moderate cooking; lentils without husk tend to disintegrate into a thick purée, which leads to quite different dishes. The composition of lentils leads to a high emulsifying capacity which can be even increased by dough fermentation in bread making[14].

Lentil dishesEdit

Lentils are used worldwide to cook many different dishes. Lentil dishes are most widespread throughout South Asia, the Mediterranean regions and West Asia.

 
Dal tadka (lentil soup)

In the Indian subcontinent, lentil curry is part of the everyday diet, eaten with both rice and roti. Boiled lentils and lentil stock are used to thicken most vegetarian curries. They are also used as stuffing in dal parathas and puri for breakfast or snacks. Lentils are also used in many regional varieties of sweets. Lentil flour is used to prepare several different bread varieties, for example Papadum.

They are frequently combined with rice, which has a similar cooking time. A lentil and rice dish is referred to in Arab countries as mujaddara or mejadra. In Iran, rice and lentil is served with fried raisin; this dish is called Adas Polo. Rice and lentils are also cooked together in khichdi, a popular dish in the Indian subcontinent (India and Pakistan); a similar dish, kushari, made in Egypt, is considered one of two national dishes.

Lentils are used to prepare an inexpensive and nutritious soup all over Europe and North and South America, sometimes combined with some form of chicken or pork. In western courties, cooked lentils are often used in salads[2].

Lentils are commonly eaten in Ethiopia in a stew-like dish called kik, or kik wot, one of the dishes people eat with Ethiopia's national food, injera flat bread. Yellow lentils are used to make a non-spicy stew, which is one of the first solid foods Ethiopian women feed their babies.

Lentils were a chief part of the diet of ancient Iranians, who consumed lentils daily in the form of a stew poured over rice.

Nutritional ValueEdit

CompositionEdit

Lentils, raw (dry weight)
Nutritional value per 100 g (3.5 oz)
Energy 1,477 kJ (353 kcal)
63 g
Sugars 2 g
Dietary fiber 10.7 g
1 g
25 g
Vitamins
Thiamine (B1)
(76%)
0.87 mg
Riboflavin (B2)
(18%)
0.211 mg
Niacin (B3)
(17%)
2.605 mg
Pantothenic acid (B5)
(43%)
2.14 mg
Vitamin B6
(42%)
0.54 mg
Folate (B9)
(120%)
479 μg
Vitamin C
(5%)
4.5 mg
Minerals
Calcium
(6%)
56 mg
Iron
(50%)
6.5 mg
Magnesium
(13%)
47 mg
Phosphorus
(40%)
281 mg
Potassium
(14%)
677 mg
Sodium
(0%)
6 mg
Zinc
(35%)
3.3 mg
Other constituents
Water 8.3 g

Percentages are roughly approximated using US recommendations for adults.

According to the USDA National Nutrient Database, 100 g of raw lentils (variety unspecified) provide 353 calories; the same weight of cooked lentils provides 116 calories. Raw lentils are 8% water, 63% carbohydrates including 11% dietary fiber, 25% protein, and 1% fat (table). Lentils are a rich source (20% or more of the Daily Value, DV) of numerous essential nutrients, including folate (120% DV), thiamin (76% DV), pantothenic acid (43% DV), vitamin B6 (42% DV), phosphorus (40% DV), iron (50% DV), and zinc (35%), among others (table).[15][16] When lentils are cooked by boiling, protein content declines to 9% of total composition, and B vitamins and minerals decrease due to the overall water content increasing (protein itself is not lost).[17]

Lentils have the second-highest ratio of protein per calorie of any legume, after soybeans.

Digestive effectsEdit

The low levels of readily digestible starch (5%) and high levels of slowly digested starch make lentils of potential value to people with diabetes.[18][19] The remaining 65% of the starch is a resistant starch classified as RS1.[20] A minimum of 10% in starch from lentils escapes digestion and absorption in the small intestine (therefore called "resistant starch").[21] Additional resistant starch is synthesized from gelatinized starch, during cooling, after the lentils were cooked[22].

Lentils also have antinutrient factors, such as trypsin inhibitors and a relatively high phytate content. Trypsin is an enzyme involved in digestion, and phytates reduce the bioavailability of dietary minerals.[23] The phytates can be reduced by prolonged soaking and fermentation or sprouting[24].

BreedingEdit

Although lentil has been an important crop for centuries, lentil breeding and genetic research has a relatively short history compared to many other crops. Since the inception of The International Center for Agriculture Research in the Dry Areas (ICARDA) breeding programme in 1977 significant gains have been made. It supplies landraces and breeding lines for countries around the world, supplemented by other programmes in both developing (e.g. India) and developed (e.g. Australia and Canada) countries. In recent years, such collaborations among breeders and agronomists are becoming increasingly important.[1]

The focus lies on high yielding and stable cultivars for diverse environments to match the demand of a growing population.[25] In particular, progress in quantity and quality as well as in the resistance to disease and abiotic stresses are the major breeding aims.[1] Several varieties have been developed applying conventional breeding methodologies. Serious genetic improvement for yield has been made, however, the full potential of production and productivity could not yet be tapped due to several biotic and abiotic stresses.[25]

Wild Lens species are a significant source of genetic variation for improving the relatively narrow genetic base of this crop. The wild species possess many diverse traits including disease resistances and abiotic stress tolerances. The above mentioned L. nigricans and L. orientalis possess morphological similarities to the cultivated L. culinaris. But only L. culinaris and L. culinaris subsp. orientalis are crossable and produce fully fertile seed. Between the different related species hybradisation barriers exist. According to their inter-crossability Lens species can be divided into three gene pools:

  1. Primary gene pool: L. culinaris (and L. culinaris subsp. orientalis) and L. odemensis
  2. Secondary gene pool: L. ervoides and L. nigricans
  3. Tertiary gene pool: L. lamottei and L. tomentosus

Crosses generally fail between members of different gene pools. However, plant growth regulators and/or embryo rescue allows the growth of viable hybrids between groups. Even if crosses are successful, many undesired genes may be introduced as well in addition to the desired ones. This can be resolved by using a backcrossing programme. Thus, mutagenesis is crucial to create new and desirable varieties. According to Yadav et al. other biotechnology techniques which may impact on lentil breeding are micro-propagation using meristamatic explants, callus culture and regeneration, protoplast culture and doubled haploid production.[1]

See alsoEdit

ReferencesEdit

  1. ^ a b c d e f g Lentil : an ancient crop for modern times. Yadav, S. S. (Shyam S.), McNeil, David L. (David Leslie), Stevenson, Philip C. Berlin: Springer Verlag. 2007. ISBN 9781402063121. OCLC 213090571. 
  2. ^ a b c d e f g h i j The lentil : botany, production and uses. Erskine, William. Wallingford, UK: CABI. 2009. ISBN 9781845934873. OCLC 435462765. 
  3. ^ "Pulse Australia - Southern guide". pulseaus.com.au. Retrieved 2017-11-18. 
  4. ^ "What To Do With Lentils And Why Bother". The Chalkboard. 2014-03-17. Retrieved 2017-11-06. 
  5. ^ "Cook's Thesaurus: Lentils". Foodsubs.com. Retrieved 15 December 2015. 
  6. ^ "2013 World Production Statistics for Lentils". Food and Agricultural Organization of the United Nations, Statistics Division. 2015. Retrieved 24 March 2015. 
  7. ^ a b "Lentil (Lens culinaris)". Pulse Canada. Retrieved 24 January 2015. 
  8. ^ "Crops Market Information - Canadian Industry". Retrieved 19 September 2014. 
  9. ^ "Crop Profile for Lentils in Idaho". Department of Plant, Soil and Entomological Science, University of Idaho (web site). 2000. 
  10. ^ Leah A. Zeldes (16 February 2011). "Eat this! Lentils, a prehistoric foodstuff". Dining Chicago. Chicago's Restaurant & Entertainment Guide. Retrieved 4 August 2011. 
  11. ^ "Production of Lentils by Countries". UN Food & Agriculture Organization, Statistics Division. 2013. Retrieved 24 March 2015. 
  12. ^ a b c d Lentil : an ancient crop for modern times. Yadav, S. S. (Shyam S.), McNeil, David L. (David Leslie), Stevenson, Philip C. Berlin: Springer Verlag. 2007. ISBN 9781402063121. OCLC 213090571. 
  13. ^ HUGHES, Joe S.; Swanson, Barry G. (1986). "Microstructure of lentil seeds (Lens culinaris)". Food Structure. 5: 241–246 – via digitalcommons.usu.edu. 
  14. ^ Bora, Pushkar Singh. "Functional properties of native and succinylated lentil (Lens culinaris) globulins". Food Chemistry. 77 (2): 171–176. doi:10.1016/s0308-8146(01)00332-6. 
  15. ^ US Department of Agriculture, National Nutrient Database for Standard Reference Release 28 (2016). "Full Report (All Nutrients): 16069, Lentils, raw". Retrieved 15 December 2015. 
  16. ^ "Nutrition Facts for Raw Lentils, 100 g". Conde Nast, USDA National Nutrient Database, version SR-21. 2014. Retrieved 24 March 2015. 
  17. ^ "Lentils, mature seeds, cooked, boiled, without salt per 100 g". Conde Nast, USDA National Nutrient Database Release SR-21. 2016. Retrieved 6 October 2016. 
  18. ^ Ramdath D, Renwick S, Duncan AM (2016). "The Role of Pulses in the Dietary Management of Diabetes". Can J Diabetes (Review). 40 (4): 355–63. doi:10.1016/j.jcjd.2016.05.015. PMID 27497151. 
  19. ^ Mudryj AN, Yu N, Aukema HM (2014). "Nutritional and health benefits of pulses". Appl Physiol Nutr Metab (Review. Research Support, Non-U.S. Gov't). 39 (11): 1197–204. doi:10.1139/apnm-2013-0557. PMID 25061763. 
  20. ^ Kawaljit Singh Sandhu, Seung-Taik Lim Digestibility of legume starches as influenced by their physical and structural properties Elsevier, 16 March 2007
  21. ^ Tovar J (1996). "Bioavailability of carbohydrates in legumes: digestible and indigestible fractions". Arch Latinoam Nutr. 44 (4 Suppl 1): 36S–40S. PMID 9137637. 
  22. ^ Johnson, Casey R.; Thavarajah, Dil; Thavarajah, Pushparajah; Payne, Scott; Moore, Jayma; Ohm, Jae-Bom. "Processing, cooking, and cooling affect prebiotic concentrations in lentil (Lens culinaris Medikus)". Journal of Food Composition and Analysis. 38: 106–111. doi:10.1016/j.jfca.2014.10.008. 
  23. ^ Vidal-Valverde C, Frias F, Estrella I, Gorospe MJ, Ruiz R, Bacon J (1994). "Effect of processing on some antinutritional factors of lentils". J Agric Food Chem. 42 (10): 2291–2295. doi:10.1021/jf00046a039. 
  24. ^ Egli, I.; Davidsson, L.; Juillerat, M.a.; Barclay, D.; Hurrell, R.f. (2002-11-01). "The Influence of Soaking and Germination on the Phytase Activity and Phytic Acid Content of Grains and Seeds Potentially Useful for Complementary Feedin". Journal of Food Science. 67 (9): 3484–3488. doi:10.1111/j.1365-2621.2002.tb09609.x. ISSN 1750-3841. 
  25. ^ a b Kumar, Jitendra; Gupta, Sunanda; Gupta, Priyanka; Dubey, Sonali; Tomar, Ram Sewak Singh; Kumar, Shiv (2016). "Breeding strategies to improve lentil for diverse agro-ecological environments". Indian Journal of Genetics and Plant Breeding (The). 76 (4). doi:10.5958/0975-6906.2016.00071.7. ISSN 0019-5200. 

Further readingEdit

External linksEdit