Total phenolic and flavonoids content and antioxidant activity of cold pressed amaranth microgreens juice

Abstract

Microgreens are recognized as new crops and potential foods of the future, because they are a rich source of highly valuable bioactive compounds with health-beneficial effects. Besides fresh consumption, microgreens can be successfully used for the production of some novel food products. Most often cultivated and analysed microgreens species are from Amaranthaceae families, primarily beet, chard and amaranth. Previous characterization of amaranth microgreens has showed a high content of different biocompounds such as vitamins, phenolic compounds and betalains. However, functional products from amaranth microgreens have only become attractive in recent years and have not been widely investigated until now. So, the aim of this study was production of cold pressed juice of amaranth microgreens and determination of its total phenolic (TPC) and flavonoid (TFC) content, as well as evaluation of antioxidant activity. Amaranth (Amaranthus tricolor L.) microgreens juice was obtained by pressing in a super slow cold juicer and further analyzed by well-known spectrophotometric methods such as Folin-Ciocalteu’s assay for TPC and colorimetric assay with aluminum chloride for TFC. Antioxidant activity was evaluated using the following assays: ABTS + radical scavenging activity (ABTS +), DPPH radical scavenging activity (DPPH ) and Ferric reducing antioxidant power assay (FRAP), which are based on different mechanisms of activity. Results were expressed in mg equivalents (gallic acid, quercetin and trolox) per 100mL of the juice. Determined TPC and TFC were 50.86 ± 0.26 mg GAE/100 mL and 45.94 ± 0.63 mg QE/100 mL, respectively. Results for the antioxidant activity were 101.61 ± 2.55 mg TE/100 mL for ABTS +, 14.98 ± 0.06 mg TE/100 mL for DPPH and 99.93 ± 1.32 mg TE/100 mL for FRAP. As can be seen, the antioxidant activity of the amaranth juice high depends on the nature of amaranth biocompounds and their affinity according to ABTS + and DPPH radicals, i.e., the tendency to reduce the [Fe3+-(TPTZ)2]3+ complex. Finally, the cold pressed amaranth microgreens juice showed the high content of phenolic compounds and good antioxidant activity using some in vitro screening assays, so it can be potentially defined as a novel functional product, however further research is necessary.