Amaranthus is a species with immense potential; however, information on its nutritional properties is limited, though widely cultivated in some countries. The objective of this work is to characterise the grains of three species of Amaranthus sp. aiming at their food potential, comparing two species considered as weed with a commercially grown species. The selected materials were cultivated and submitted to the same culture method and the experiment was performed as a randomized block design with three replicates. Harvested grains were transformed into flour and centesimal composition was determined, as well as macro and micronutrients, starch content and non-nitrogenous. The results were submitted to analysis of variance and compared in Tukey's test. It can be inferred that in the majority of the analyses for centesimal composition, the species A. hybridus and A. viridis presented higher levels than the A. retroflexus (commercial cultivar). A. hybridus has the highest amount of N, Mg, B, Mn and Fe, A. retroflexus of P, K, S, Cu and Zn whereas A. viridis of Ca and Cu. The content of starch in the grains of the species ranged from 32.86 to 36.21%. Regarding the anti-nutritional constituents, the nitrate content present in these three species does not pose a health risk if consumed moderately. Invasive species A. hybridus and A. viridis present great potential for grain production, whose nutritional properties of flour in most of the analyses performed in this study were superior to the commercial species.
Key words: Amaranthus hybridus, Amaranthus retroflexus, Amaranthus viridis, organic agriculture, unconventional vegetables.