Risk Elements, Antioxidant Activity and Polyphenols in Pseudocereal Grains

Abstract

Pseudocereals, with their irreplaceable nutritional composition and amounts of bioactive substances with a positive effect on human health, are becoming a trend in human nutrition. In this work, we compared the safety of individual types of pseudocereals, namely buckwheat (Fagopyrum esculentum var. Zita), quinoa (Chenopodium quinoa var. Carmen), amaranth (Amaranthus cruentus var. Pribina), and sorghum (Sorghum bicolor var. Ruzrok) in terms of the content of hazardous metals. We assessed the ability of individual species of pseudocereals to accumulate hazardous metals from the soil in the consumable parts of the plant. The ability of heavy metals to accumulate was calculated using a bioaccumulation factor. We also evaluated the influence of the content of selected hazardous metals on the antioxidant capacity of grains of individual types of pseudocereals. We determined the total polyphenol content and the total antioxidant content using the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical spectrophotometrically. We determined the content of hazardous metals by the AAS method (Atomic Absorption Spectrometry). In the soil from all plots with cultivated species of pseudocereals, we recorded an increased content of Cd, Pb, Co in comparison with the limit value set by Law no. 220/2004. The content of risk elements was not exceeded in the consumption parts of plants and the content of Cd and Pb was below the detection limit. From a safety point of view, it is possible to prefer the Chenopodium quinoa, which had the lowest content of heavy metals in the grains. Buckwheat follow, and at about the same level are amaranth and sorghum. The safest or the most resistant plant species with the lowest ability to accumulate hazardous metals from soil to grains, from the group of crops we monitor, is the Chenopodium quinoa.