Analysis on Phenols and Antioxidant Activities of Quinoa Resources in Qinghai

In order to clarify the difference of phenolic content and antioxidant activity in quinoa resources in Qinghai,the quinoa resources with high phenolic substances and antioxidant activity were screened out. The free phenols and phenols in 90 quinoa resources were analyzed by chemical method. The in vitro antioxidant activity of each component was evaluated by DPPH· and ABTS⁺· scavenging activity and Ferric ion reducing antioxidant power(FRAP). The results showed that there were significant differences in the content of different phenolic substances in quinoa,and the content of combined phenols had obvious difference,and the content of free phenols was relatively small. There were significant differences in the removal of DPPH·,ABTS⁺·,and FRAP between free phenols and combined phenols. Among them, combined phenols had strong ability to scavenge DPPH·, ABTS⁺· free radicals,which were 4732.56,3371.97 μmol Trolox Eq/100 g DW, respectively. The free phenols had a relatively strong FRAP of 1408.64 μmol Trolox Eq/100 g DW. The combined phenolic substances of white and yellow quinoa had significantly higher DPPH· and ABTS⁺· ability than red quinoa,reaching 4657.41,5056.66 μmol Trolox Eq/100 g DW,3532.37,3355.72 μmol Trolox Eq/100 g DW. The phenolic substance of red quinoa had the strongest FRAP (3264.42 μmol Trolox Eq/100 g DW). Cluster analysis showed that most of the quinoa resources in Qinghai had lower phenolic content,the scavenging capacity of DPPH· and ABTS⁺· were weak,but the FRAP was strong. 6 quinoa resources had the highest content of bound phenols and 5 quinoa resources had the strongest antioxidant activity. This result provided high quality resources and guiding significance for the selection of new functional buckwheat varieties.