Nutritional composition, total phenolic compounds and antioxidant activity of quinoa (Chenopodium quinoa Willd.) of different colours

Abstract

Quinoa (Chenopodium quinoa Willd.) has been nutritionally highlighted when compared to other grains. In recent years the research on this pseudocereal has increased. In this work, six quinoa samples were studied: three from Peru, one from Brazil and two commercial samples. The samples were physically and physicochemically characterized, including macro- and micronutrient analysis, phenolic compounds content and antioxidant activity. Black, red and white samples showed as main difference the size, weight, ashes and dietary fibre content. Black samples were the smallest and lightest and had the lowest starch content but presented the highest levels of ashes and dietary fibre. The protein content (16.9 %) in the white Brazilian variety was higher than the others. Red and black samples had the highest levels of most minerals analysed. The antioxidant capacity measured by the DPPH method was higher for black and red samples in comparison with the white ones. However, the white Brazilian variety showed a significantly higher antioxidant capacity measured by the ABTS assay. With regard to the phenolic content, a difference was found between the samples which ranged from 55.5 to 95.5 g GAE 100 g−1. The colour of the grain was found as not related to a higher content of phenolic compounds. Because their compositions are generally similar to light-coloured grains, and in some parameters such as dietary fibre and content of some micronutrients are superior, the grains of dark-coloured quinoa varieties (RPP, BCP) would have to be explored to develop foods that take advantage of this colour diversity.

Farklı kabuk renklerine sahip kinoa tohumlarının toplam fenolik ve saponin içerikleri ile antioksidan aktiviteleri üzerine yıkama işleminin etkisi

“…Black quinoa was found to contain significantly less protein (12.72%) than its white (13.78%) and red (13.82%) counterparts (p<0.05). This disagrees with the reports published by USDA (2019) and Diaz-Valencia et al (2018) who stated that black and white quinoa samples have the highest concentration of protein. The lipid concentration of red (8.98%) and black quinoa (8.34%) was found to be significantly (p<0.05) higher than that of white quinoa seeds (5.90%).…”

“…The ash values were higher than that was determined by Ogungbenle (2003) and lower than that reported by Repo-Carrasco-Valencia and Serna (2011) and Villa et al (2014). Pellegrini (2018) and Diaz-Valencia et al (2018) found that white quinoa contained less ash than its red and black counterparts. The variations in these findings could be attributed to not only color but also regional, climatic, and genetic differences (FAO, 2011).…”

“…Tang et al (2015a) determined that black quinoa seeds had the highest phenolic content followed by its red and white counterparts, respectively. Moreover, black and red quinoa seeds were found to have higher phenolic contents than white ones in different studies confirming that the darker the color of quinoa seed, the higher the phenolic content it has (Tang et al, 2015a;Han et al, 2019b, Pellegrini et al, 2018, Diaz-Valencia et al, 2018. Similarly, Abderrahim et al (2015) reported a negative correlation (r=-0.619, p=0.024) between phenolic content and brightness value of colored quinoa seeds suggesting that black and red quinoa seeds to have higher phenolic contents.…”

“…They are mostly white, also black and red, but available in a wide range of intermediate colors, which has been found to affect the bioactivity of quinoa seeds (Tang et al, 2015a). The effects of seed color on the phenolic content and antioxidant activity of quinoa were investigated in different studies (Brend et al, 2012;Escribano et al, 2017;Diaz-Valencia et al, 2018;Han et al, 2019b). Brend et al (2012) found that red quinoa possessed higher antioxidant activity with higher concentrations of phenolics and flavonoids, confirming the reports of Tang et al (2015a) which shows that the darker the color of quinoa, the higher phenolic concentration, and antioxidant activity.…”

Chia, Quinoa, and Their Coproducts as Potential Antioxidants for the Meat Industry

“…Polyphenols are natural organic chemicals with large multiples of phenol structural units. The TPC reported in quinoa grains ranged between 0.2 and 10.6 mg GAE/g quinoa with significant differences depending (in addition to the other variation factors previously discussed) on their color: darker quinoa seeds (such as red and black quinoas) showed higher TPC than white varieties [ 4 , 18 , 48 , 49 , 67 ]. Not only the TPC was suggested to differ according to the color of quinoa grains, but also the phenolic profiles and their antioxidant activity.…”