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Amaranth is an old cultivated crop originating on American continent. The Aztecs, Incas and Mayas considered amaranth as their staple food together with maize and beans. It used to be one of the most important crops in America before Spanish colonialists conquered it and further cultivation of the crop was banned. Amaranth was preserved on hard to reach places of mountainous Central and South America. Amaranth was first introduced as an ornamental plant in Europe in the 16th century. Different species of amaranth spread throughout the world during 17th, 18th and 19th century. In India, China and under the harsh conditions of Himalayas this plant became important grain and/or vegetable crop.
At present amaranth is grown in the USA, South America, India, China and Russia. The Czech Republic is the most important grower in Europe (approx. 250 hectares).
Amaranth is an annual plant with C4 type of photosynthesis. Depending on species amaranth leaves vary in shape, size and colour (green, red, purple). This plant can grow up to 3 m. Its stem, sometimes branched, is terminated by branched inflorescence (panicle). Inflorescence is usually indeterminant and reaches different lengths. Basic unit in inflorescence is called glomerulus containing female, male or both flowerets. Seed has lenticular shape (1-2 mm). Amaranth shows a high coefficient of propagation.
This plant is valued for the positive chemical composition of seed that does not contain gluten. Amaranth is very interesting crop from the point of its high production potential. It grows intensively, photosynthesises fast and effectively, does not suffer from major diseases and is tolerant to various extreme conditions.
Amaranth seeds have high content of proteins, essential amino acids and minerals. All compounds are usually in following ranges: 14-19 % of protein, 5-8 % of lipids, 62-69 % of starch, 2-3 % of total carbohydrates and 4-5 % of fibre. The seed composition is comparable with seed composition of oat. Amaranth bioavailability of protein reaches 78 %. Seed does not contain gluten causing celiac disease to sensitive individuals. In contrast to cereals amaranth has higher content of amino acids mainly lysine, methionine, treonin and cysteine. Starch is the major part of carbohydrates and starch granules are small (1-3 µm) easily degradetable by alpha-amylases. Amaranth starch is highly stabile during freezing and highly resistant to mechanical stress. Lipid content in amaranth seed ranges from 5 to 8 %. Most of it is placed in embryo as linoleic, oleic and palmitic acid. According to the seed composition amaranth oil is similar to the ones made from cotton or maize but has lower digestibility. Amaranth oil contains about 8 % of squalen, a sterol precursor, used in medicine and cosmetic industry. Content of minerals depends on species, and growing conditions. Amounts of calcium and magnesium are higher than amounts in other cereals. Seeds are a good source of vitamins mainly ascorbic acid and B-complex, and antioxidants alpha-tocopherol and beta- and gama tocotrienols.
Amaranth is used as an ingredient primarily in bread, pasta, baby's food, instant drinks, etc. For such purposes seeds have to undergo various processing technologies - boiling, swelling, flaking, extrusion, puffing, roasting, grinding, sprouting, etc. The most common product is flour, whole amaranth seeds in breads, müsli bars, breakfast food and porridges, pastas and biscuits and cookies. Leaves and stems are interesting vegetable suitable for soups, salads or other meals.
Amaranth is a valuable nutritious feedstuff with high production ability.
Amaranth starch, protein concentrates, natural dye, a good source of squalen and antioxidants. It is been intensively tested as one of the interesting energy crop.
The most optimal are humid and well-structured soils but the crop tolerates any soil conditions. Amaranth is thermophilous plant and especially for germination higher temperature of soil is necessary; otherwise older plants tolerate even short-term frost. This crop is resistant to drought thus it does not require as much moisture as other crops. The only exception is germination stage and first couple of weeks in growing season until strong root system is established. Dry and warm weather is welcome at harvest time to press losses of crop on minimum.
The best crop rotation is between small grains or potatoes. Amaranth has a good response on nitrogen fertilisers that provide for higher growth and yields. The crop requires a good soil preparation prior to sowing because amaranth seed is tiny.
Under the conditions of the Czech Republic fields can be sown with amaranth from the beginning of May until the first decade of June. Generally daily temperatures have to reach 15 °C and soil should be warmed up to 12 °C. The most suitable depth of sowing is 1,5 cm and final plant density ranges from 350 to 400 thousands plants per hectare.
Especially at the beginning of growing season plants develop slower and certain inter-row cultivation might be applied in order to maintain the crust-free soil and low occurrence of weed. During whole season wild species of amaranth and goosefoot should be regularly removed.
Amaranth matures irregularly and the best timing of harvest is at the stage when two thirds of seeds are mature. Generally all species are susceptible to partial shatter losses. At the harvest time plants of amaranth contain high percentage of water, which increases losses up to 50 %. The most convenient conditions for harvest are after first frost providing lower moist content in plants and during dry days. Combine-harvester has to be adjusted to the moist content of the crop and small size of the amaranth seed.
Seed has to be clean of foreign material and other impurities that could affect aroma, bring about mildew or lower its quality. The crop should be stored at 12 % moisture content after gradual drying.