Last updated: 20th September 2002

AMARANTH

Family: Amaranthaceae

Genus: Amaranthus

Species: spp.

Amaranthus hybridus Amaranthus caudatus
Source: http://plants.usda.gov Source: http://www.wisc.edu/botany

Contents

General Background
Details of Quality Characteristics
Current Production and Yields
Constraints upon Production
Markets and Market Potential
Other Information
Research
Useful Websites
BioMat Net
Contacts
References

General Background

Amaranth is a herbaceous annual growing to 15-100cm tall. In optimum conditions it can reach 300cm tall. The leaves are long-stalked with prominent whitish veins. The taproot is often pinkish to red. The flowers vary greatly depending on species i.e. A. hybridus has inconspicuous green flowers borne in spike-like clusters in leaf axils and at stem ends, while A caudatus has a conspicuous inflorescence, which forms stout, branched, dense spikes which may be coloured pink or deep red. In temperate climates amaranth shows slow and poor seedling emergence due to low soil temperatures. When grown in Austria, planting takes place after mid-May to avoid frosts, at a rate of up to 2kg/ha. Amaranth requires no nitrogen because it lodges easily. Plants are generally combine harvested when half the grain has achieved ripeness - usually in early September. Amaranth spp. can produce over 100,000 seeds per plant although the seeds are tiny. Yield ranges from 1t/ha to 3t/ha (Crops, June 1998).

Amaranth was once nearly as important a food as maize and beans in Central and South America and is still grown in mountainous areas of India, Africa and China. Its flour is used in bread, cakes and other products like popcorn. Danish research shows it to have more minerals, protein and fat than other cereals. Present grain amaranth types are more suitable for south European climates, but efforts are being made to select for hardier lines since the crop is increasingly popular with farmers throughout the EU.

Details of Quality Characteristics

Amaranth grain contains between 4.8 and 8.1% oil (J Budin et al 1996), although A. spinosus and A. tenuifolius are reported to contain as much as 17.0 and 19.3% respectively.

Amaranth seed contains between 12 and 15% crude protein. The grain types including A caudatus and A hybridus, have a high lycine protein content running from 10 to 17% (Crops June 1998). The amino-acid composition compares favourably with other crops, since amaranth has a high lysine, threonine and tryptophan content. Lysine, with valine are normally the limiting amino acids in most cereal crops.

Squalene
Amaranth seed oil is rich in squalene (2.4 to 8.0%) compared to other vegetable oils.
Squalene and its hydrogenated form squalane are relatively high value lipids. Squalene is an expensive terpenoid compound, derived primarily from shark and whale liver oils. It has many applications in the pharmaceutical and cosmetic industries, for example
1. As an ingredient in cosmetics
2. For skin penetrants
3. Lubricants for computer disks.

Tocotrienols
Amaranth oil is reported to contain relatively high concentrations of tocotrienols. These are rare forms of vitamin E which have been shown to inhibit the key regulatory enzyme in cholesterol biosynthesis.

Approximate fatty acid composition of oil (% by wt)

Fatty acid % by weight
C16: 0 13.4
C18: 0 2.7
C18: 1 20.4
C18: 2 62.1
C18: 3 1.1
C18: 4 0.7
Squalene 6.96

Current Production and Yields

Fresh shoot yields of 20t/ha have been obtained with transplanted amaranth, harvested by up-rooting (Mistra et al 1985). In 1998 in Austria grain yields ranging from 1t/ha to 3t/ha were reported for A caudatus and A hybridus.

Constraints upon Production

Domesticated members of the genus Amaranthus have traditionally been cultivated in areas of the tropics and sub-tropics where warm temperatures favour seed germination and growth. As a new crop in temperate climates Amaranthus exhibits slow and poor seedling emergence because of the low soil temperature. Amaranth is probably not best suited to growing in more northerly parts of Europe due to a lack of frost resistance which reduces the growing season considerably.

Markets and Market Potential

Potentially important products of Amaranth are proteins, carbohydrates and oils. Possible applications for these are as health foods and for starch. Amaranth was an important and sometimes staple food during the pre-colombian period in Mexico and Central and South America, being almost as important as maize and beans. Amaranth leaves were used as a vegetable (being similar in taste to spinach), whilst the seed was ground into flour for baking and other products. Amaranth is still grown in Nepal and mountainous areas of Southern and Northern India.

Currently Amaranth is grown in Belgium, Finland, Italy, the Netherlands, Sweden and the UK although there is no real industrial demand for it.

Most studies have been carried out on A. caudatus, A. hybridus, A. cruentus and A. hypochdriacus. These varieties have also been investigated for suitability as a food source.

Amaranth flour can be used as an ingredient in bread, cakes or popcorn. It has a higher mineral content than wheat, maize or barley but contains some acids that can retard mineral uptake. Amino acid composition of Amaranth is favourable in comparison with other crops. It has a high lysine, threonine and tryptophan content, which are normally those amino acids found in limiting quantities in most cereals. However, the leucine content of Amaranth is relatively low. In rats, Amaranth has a digestibility comparable with that of barley ('New Crops for Temperate Regions, 1993).

Other Information

Cultivation
A well prepared soil is essential. Direct drilling between 2-8 kg/ha or transplanting into 25 x 25 cm spacing. An established population of 30 plants per m2 is desirable.
The seeds of warm season plants must be shallow sown in cooler soils in order to obtain reasonable emergence. The highest emergence percentages are obtained at a sowing depth of 13mm and at temperatures between 24ºC and 34ºC, although emergence may be satisfactory with soil temperatures between 18.5ºC and 24ºC.
Amaranth requires about 200mm of rainfall per year, although plants will tolerate some degree of soil drought. Amaranth will also tolerate some degree of salinity.
Nitrogen fertiliser at a rate of 125kg/ha is also recommended.

No herbicides have been proved safe for Amaranth, hence early weed control is essential. However, once established, the crop canopy is effective at shading out the weeds. Amaranth is susceptible to avian damage at maturity when the ripe seeds are desirable to foraging birds. The beet-cyst nematode also damages plant roots which may effect overall yield.

Research


Useful Websites

http://www.hort.purdue.edu/newcrop/afcm//amaranth.html - Alternative Field Crops Manual: Amaranth

BioMat Net

Amaranth

Crops for Biopolymers/Gums

Crops for Pharmaceuticals/Cosmetics

Crops for Paints/Coatings/Plastics

Contacts


References