The plant
The genus Amaranthus is cosmopolitan in tropical regions. The name amaranth was originally applied to the closely related genus Celosia. The plant can grow from 1 to 2.5 metres tall with a succulent, hollow stem. Parts of the plant vary from green to reddish. Catkin-like cymes of densely packed flowers grow in the summer or fall. Since ancient times, three species of amaranth have been grown entirely for grains: A. cruentus (red amaranth), A. caudatus (love-lies-bleeding), and A. hypochondriacus (Prince-of-Wales feather).
Seed oil and squalene
Plant oils are generally squalene-poor, but amaranth oil has the highest weight concentration of squalene, at 1-7%. Squalene is a triterpene with the formula C₃₀H₅₀ and is a colourless oil. In four genotypes of A. cruentus and A. hypochondriacus grown in southwest France, the crude oil content of the seeds ranged from 4.3 to 6.4%, and the squalene yield varied between 5.3% and 7.7%. Amaranthus seed extracts were shown to have potential skin-whitening properties, owing to the presence of myoinositol and squalene. Oil from seeds of A. cruentus was found to give pre- and post-UVA protection in skin fibroblasts.
Volatile compounds
The main volatile compounds of raw A. caudatus seeds were 2,4-dimethyl-1-heptene, 4-methylheptane, a branched C₁₁H₂₄ alkane and a dodecene C₁₂H₂₄ isomer. These compounds made up about 70% of the total volatile compounds of the raw seeds. Hexanal and acetic acid were the most abundant compounds detected in amaranth samples. More than a hundred volatile compounds of different classes were identified in crude and heat-treated amaranth samples. Heat treatment by popping changed the composition of volatile organic compounds dramatically. Most of the volatiles identified in popped A. caudatus seeds were aldehydes formed by Strecker degradation, including 2-methylpropanal, 3-methylbutanal, 2-methylbutanal and phenylacetaldehyde. Alkylpyrazines such as methylpyrazine, vinylpyrazine, 2,5-dimethylpyrazine and 3-ethyl-2,5-dimethylpyrazine were also found in the popped seeds. The optimum popping temperature for A. caudatus seeds was 180 °C.
Food uses
Grain and leafy amaranths are gluten-free and contain protein, unsaturated fatty acids, vitamins, minerals and low-glycaemic-index carbohydrates. The grain can be ground into a flour, popped like popcorn or flaked like oatmeal. Amaranth species are cultivated and consumed as a leaf vegetable in many parts of the world. In Mexico, the grain is used to make a candy called alegría at festival times. Alegría, once called tzoalli, is made from popped amaranth seed mixed with brown sugar, maguey syrup or honey. In Tlaxcala, a fresh beverage similar to horchata is prepared with amaranth, cinnamon and sugar.
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Related: Alder · Alpha Humulene · Amberever · Amburana Bark · Antillone · Apple Tree · Araucaria
