Elsevier

Food Chemistry

Volume 234, 1 November 2017, Pages 285-294
Food Chemistry

Characterization of betalains, saponins and antioxidant power in differently colored quinoa (Chenopodium quinoa) varieties

https://doi.org/10.1016/j.foodchem.2017.04.187Get rights and content
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Highlights

  • Quinoa (Chenopodium quinoa) grains of different colors are a source of betalains.

  • Betaxanthins were detected for the first time in red and yellow grains.

  • Betaxanthins present in the yellow varieties make the grains glow with green light.

  • High antiradical and antioxidant activities were demonstrated for colored grains.

Abstract

Quinoa was the traditional grain crop used by the prehispanic civilizations in America. Grains are white, black, yellow, and red-violet and plants are cultivated in vast areas of Peru, Bolivia and Ecuador. The recent description of the betacyanin pigment betanin in red-violet varieties is here further analyzed detecting the presence of amaranthin not previously identified in quinoa grains. Yellow-orange grains are characterized for the first time and up to four different betaxanthins are found to be responsible for this coloration. The native fluorescence of the identified betaxanthins makes the surface of the yellow quinoa grains glow with green fluorescent light. The presence of betalains is correlated with high antioxidant and free radical scavenging activities measured under the FRAP, ABTS and ORAC assays in grain extracts of 29 Peruvian varieties. TEAC equivalence is as high as 44.1 and 47.4 mmol Trolox/kg for the yellow and red-violet varieties analyzed respectively.

Keywords

Antiradical
Betalains
Bioactive
Fluorescence
Quinoa
Secondary metabolism

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