|Maca hypocotyl and root|
Lepidium meyenii, known as maca or Peruvian ginseng, is an edible herbaceous biennial plant of the Brassicaceae family that is native to South America in the high Andes mountains of Peru. It was found exclusively at the Meseta de Bombón plateau close to Lake Junin in the late 1980s. It is grown for its fleshy hypocotyl that is fused with a taproot, which is typically dried, but may also be freshly cooked as a root vegetable. If it is dried, it may be further processed into a flour for baking or as a dietary supplement. It also has uses in traditional medicine. As a cash crop, it is primarily exported as a powder that may be raw, or processed further by the supplement industry: gelatinized or made into an extract.
Antonio Vázquez de Espinosa gave a description of the plant following his visit to Peru circa 1598 and Bernabé Cobo gave a description of this plant in the early 17th century. Gerhard Walpers named the species Lepidium meyenii in 1843. In the 1990s, Gloria Chacon made a further distinction of a different species. She considered the widely cultivated natural maca of today to be a newer domesticated species, L. peruvianum.
Most botanists now doubt this distinction, however, and continue to call the cultivated maca L. meyenii. The Latin name recognized by the USDA similarly continues to be Lepidium meyenii. Debate is still ongoing about the correct nomenclature and whether the distinction between meyenii and peruvianum is botanically correct.
The growth habit, size, and proportions of maca are roughly similar to those of radishes and turnips, to which it is related, but it also resembles a parsnip. The green, fragrant tops are short and lie along the ground. The thin, frilly leaves sprout in a rosette at the soil surface, not growing more than 12–20 cm (4.7–7.9 in) in height. The leaves show a dimorphism according to reproductive stage. They are more prominent in the vegetative phase, and are continuously renewed from the center as the outer leaves die. The off-white, self-fertile flowers are borne on a central raceme, and are followed by 4–5 mm (0.16–0.20 in) siliculate fruits, each containing two small 2.0–2.5 mm (0.079–0.098 in) reddish-gray ovoid seeds. Seeds are the maca’s only means of reproduction. Maca reproduces mainly through self-pollination and is an autogamous species. The genome consists of 64 chromosomes. From experiments with different day lengths, maca is a short-day plant. Some sources consider the maca to be an annual plant, as in favorable years it can complete a lifecycle within a year.
Maca is the only member of the Lepidium genus with a fleshy hypocotyl, which is fused with the taproot to form a rough inverted pear-shaped body. Maca does vary greatly in the size and shape of the root, which may be triangular, flattened circular, spherical, or rectangular, the latter of which forms the largest roots. Traditionally, native growers have acknowledged four varieties of maca, based on their root color: cream-yellow, half purple, purple, and black; varying levels of anthocyanin is primarily responsible for the color differences. Maca hypocotyls may be gold or cream, red, purple, blue, black, or green. Each is considered a "genetically unique variety", as seeds of the parent plants grow to have roots of the same color. Specific phenotypes (in maca, 'phenotype' pertains mainly to root color) have been propagated exclusively to increase commercial interest. Cream-colored roots are the most widely grown and are favored in Peru for their enhanced sweetness and size. Black maca is both sweet and slightly bitter in taste.
The natural environment of the maca is at 11-12ºS latitude and at an elevation of 3,800–4,400 m (12,500–14,400 ft) above sea level. At this elevation, temperatures of the growing season vary from −2 to 13 °C (28 to 55 °F) in monthly mean minimum or maximum, respectively. Temperatures can decline, however, as low as −10 °C (14 °F) and frosts are common. Of the cultivated plants, maca is one of the most frost tolerant. Strong winds and sunlight also are characteristics of the native habitat of the maca. Maca today is still mainly cultivated in Peru, in the high Andes of Bolivia, and to a small extent also in Brazil. Maca can be cultivated beyond its natural elevation range, over 4,400 m (14,400 ft) above sea level.
Maca (Peruvian ginseng) seedlings usually emerge about one month after sowing with the onset of the rainy season in October. In the vegetative phase, until May to June, the lower part of the hypocotyl, as well as the upper part of the tap root, grows in size. After 260 to 280 days, it is formed to the harvestable hypocotyl. If the root is left in the soil, it is dormant for two to three months in the time of the cold, dry season until August. Then it will form a generative shoot on which the seeds ripen five months later. One plant is capable of forming up to 1000 tiny seeds, 1600 of which weigh about one gram. Thus, only relatively few plants are needed for propagation. The plants for cultivation are selected for preferred size and color, then placed 50–100 mm deep in pits with alternate layers of grass and soil to protect them from drying out. They are fertilized heavily, as maca is a soil exhaustive crop. The cultivation cycle is strictly linked to seasonality.
Traditionally, land preparation was done by hand. Nowadays, tractor plowing also is used. As maca grows on sites where no other crops can be cultivated, it is often found after long fallows of sheep grazing pastures. Maca croplands thus traditionally are only fertilized with sheep and alpaca manure; however, fertilizer application could prevent soils from depleting in nutrients.
Weeding or pesticide application usually is not necessary as the climate is not suitable for most weeds or pests. Nearly all maca cultivation in Peru is carried out organically, as maca itself is seldom attacked. Maca is sometimes interplanted with potatoes, as it is known to maca farmers that the plant naturally repels most root crop pests.
The yield for a cultivated hectare may reach an estimated 15 tons in fresh hypocotyls resulting in around 5 tons of dried material. According to the Ministry of Agriculture of Peru, however, average maca yields for 2005 were only 7 t/ha, with a great variation between different sites. Although maca has been cultivated outside the Andes, it is not yet clear whether it develops the same active constituents or potency outside of its natural habitat. Hypocotyls grown from Peruvian seeds form with difficulty at low elevations, in greenhouses, or in warm climates.
Maca contains glucotropaeolin, m-methoxyglucotropaeolin, benzyl glucosinolates, polyphenols, (1R,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, and p-methoxybenzyl isothiocyanate. Alkamides are present in maca.
There are no pharmacokinetic data for maca. The presence of 1R,3S-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) in the extracts of maca indicate a potential safety issue as a monoamine oxidase inhibitor and possibility as a mutagen. Due to these potential mutagenic properties of MTCA, the Agency for Sanitary Security in France warned consumers about the possible health risks of powdered maca root, a declaration disputed on the assumption that MTCA would be deactivated by boiling to process maca roots. MTCA-like compounds are associated with craving behaviour.
Due to its purported effects on fertility, maca grew in agricultural, commercial and research interest over the decades of the 1990s to 2014. Market studies showed low acceptance of the particular maca taste by consumers when first exposed to it, creating a barrier for popularity of this food as a culinary vegetable. The economic interest existed more in the perceived, but unproven, health effects of the root's constituents supplied as an extract in a dietary supplement.
By 2014, agricultural and market interest for maca grew in China, but with challenges from Peruvian institutions who accused Chinese companies of illegally exporting maca and of biopiracy, as several Chinese patents had been filed to improve the propagation and genetic diversity of maca.
Uses and preparation
Maca is mainly grown for consumption of its root. The majority of harvested maca is dried. In this form, the hypocotyls can be stored for several years. In Peru, maca is prepared and consumed in various ways, although traditionally it is always cooked. The freshly harvested hypocotyl may be roasted in a pit (called huatia), and is considered a delicacy. Fresh roots usually are available only in the vicinity of the growers. The root can also be mashed and boiled to produce a sweet, thick liquid, then dried and mixed with milk to form a porridge, mazamorra. The cooked roots are also used with other vegetables in empanadas, jams, or soups. The root may be ground to produce a flour for bread, cakes, or pancakes. If fermented, a weak beer called chicha de maca may be produced. In 2010, a U.S.-based brewery called Andean Brewing Company, became the first company to produce and commercialize beer made from maca under the brand KUKA Beer. From the black morphotype, a liquor is produced. Also, the leaves are edible or may serve as animal fodder. They can be prepared raw in salads or cooked much like Lepidium sativum and L. campestre, to which it is closely related genetically.
The prominent product for export is maca flour, which is a baking flour ground from the hard, dried roots. It is called harina de maca. Maca flour (powder) is a relatively inexpensive bulk commodity, much like wheat flour or potato flour. The supplement industry uses both the dry roots and maca flour for different types of processing and concentrated extracts. Another common form is maca processed by gelatinization. This extrusion process separates and removes the tough fiber from the roots using gentle heat and pressure, as raw maca is difficult to digest due to its thick fibers and goitrogen content.
There is archaeological evidence for varying degrees of cultivation of maca in the Lake Junin region from around 1700 BC to 1200 AD. Maca has been harvested and used by humans in the puna grasslands of the Andean Mountains for centuries. Contrary to frequent claims that maca's cultivation was common in what is today Peru, until the late 1980s, maca has been cultivated only in a limited area around Lake Junin, in central Peru. Historically, maca often was traded for lowland tropical food staples, such as corn, rice, manioc (tapioca roots), quinoa, and papaya. It also was used as a form of payment of Spanish imperial taxes.
Maca has been marketed for its supposed traditional medicinal effects, although there is insufficient evidence that it has any effect on human health or disease. A 2016 systematic review found limited evidence from a small number of studies to improve semen quality in healthy and infertile men. A 2011 review found no good evidence for the effectiveness of maca as a treatment for menopausal symptoms, with no evidence of its safety.
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