A few decades ago Amaranthus was rediscovered as a most promising plant genus that may provide high-quality protein, unsaturated oil, and various other valuable constituents. Since then research has focused on various Amaranthus spp. and has been rapidly expanding, and a large number of reports have been published. Several review articles focusing on different aspects, such as botanical, agrotechnological, compositional, biological, chemical, and technological properties, as well as applications and health effects, have also been published since then. This comprehensive review is focused on amaranth composition, antioxidant properties, applications, and processing. The composition includes macrocomponets (lipids, proteins, carbohydrates, and dietary fiber) and other important constituents, such as squalene, tocopherols, phenolic compounds, phytates, and vitamins. These aspects of amaranth studies have not been comprehensively reviewed for a long time.

Antioxidant properties of amaranth extracts isolated sequentially by acetone and methanol/water from defatted plant leaves, flowers, stems and seeds were assessed by ABTS(+•), DPPH(•), ORAC and total phenols content (TPC) assays. In addition, antioxidant properties of solid plant material were evaluated by the direct QUENCHER method using the same assays. Leaves and flowers of amaranth as well as their extracts possessed the highest antioxidant activities. Radical scavenging capacity in ABTS(+•) assay for leaves, flowers, stems and seeds evaluated by QUENCHER method were 144.24 ± 2.41, 112.33 ± 7.45, 19.05 ± 1.13 and 21.82 ± 1.06 μmol trolox equivalents in 1 g of dry weight, respectively. On-line HPLC-DPPH(•) assay was used to determine the activity of separated compounds and it was observed that rutin was the main radical scavenger in amaranth extracts. Preliminary screening of extract composition was performed by UPLC/ESI-QTOF-MS and rutin, nicotiflorin, isoquercitrin, 4-hydroxybenzoic and p-coumaric acids were identified by measuring their accurate mass and retention time.

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Coffee beans contain a large amount of antioxidants, which are subjected to various changes during roasting. In this study, antioxidant potential of raw and roasted to different degree (light, medium, dark) C. arabica and C. robusta coffee beans was evaluated by the four antioxidant assay methods, TPC, FRAP, TEAC, and DPPH˙.The obtained results revealed signifi cant differences between the coffee types, roasting degree, and antioxidant activity assessment methods. FRAP and TPC appeared to be the most appropriate methods for revealing the differences in antioxidant potential of different coffee types and the effects of roasting. The results obtained by these methods were in good correlation. ABTS and DPPH˙ methods are not enough sensitive for the determination of roasting degrees.In general, based on statistical data evaluation, antioxidant activity is more dependent on the coffee type than on the degree of roasting, however, the selection of analytical method may also be signifi cant.

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