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

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 47.4mmol Trolox/kg for the yellow and red-violet varieties analyzed respectively.

Yellow‐coated quinoa (Chenopodium quinoa Willd) – physicochemical, nutritional, and antioxidant properties

“…In the case of the other cultivars, parameters *a and *b ranged from 4.78 to 6.44 and from 17.58 to 21.45, respectively. A similar brightness of yellow quinoa seeds was recorded by Escribano et al ., but at the same time these authors noted more intensive red and yellow colors (*a: 6.41–12.94, *b: 26.81–32.10). The brightness of the seeds in our study is significantly negatively correlated (R = −0.34, P < 0.05) with the content of phenolics (e.g.…”

Suitability of unmalted quinoa for beer production

“…This indicates that quinoa contains greater amounts of coloring compounds than barley, even though pale and dehusked quinoa seeds were used. Most pigment compounds are located in the outer layers of cereal and pseudocereal grains / seeds …”

Microencapsulated betacyanin from colored organic quinoa (Chenopodium quinoa Willd.): optimization, physicochemical characterization and accelerated storage stability

“…A pseudo‐cereal quinoa ( Chenopodium quinoa Willd.) has been recognized as an extremely nutritious grain all over the world and has recently been found to be a novel and good betalain source . Betalains are not widely used in the food industry owing to their poor stability during processing and storage .…”